Supermassive black holes may be lurking everywhere in the universe

Supermassive black holes may be lurking everywhere in the universe
A sky survey image of the massive galaxy NGC 1600, and a Hubble Space Telescope closeup of the bright center of the galaxy where the 17-billion-solar-mass black hole -- or binary black hole -- resides. Credit: ESA/Hubble image courtesy of STScI.

A near-record supermassive black hole discovered in a sparse area of the local universe indicates that these monster objects - this one equal to 17 billion suns - may be more common than once thought, according to University of California, Berkeley, astronomers.

Until now, the biggest supermassive black holes - those with masses around 10 billion times that of our sun - have been found at the cores of very large in regions loaded with other large galaxies. The current record holder, discovered in the Coma Cluster by the UC Berkeley team in 2011, tips the scale at 21 billion and is listed in the Guinness Book of World Records.

The newly discovered black hole is in a galaxy, NGC 1600, in the opposite part of the sky from the Coma Cluster in a relative desert, said the leader of the discovery team, Chung-Pei Ma, a UC Berkeley professor of astronomy and head of the MASSIVE Survey, a study of the most and black holes in the local universe with the goal of understanding how they form and grow supermassive.

While finding a gigantic black hole in a massive galaxy in a crowded area of the universe is to be expected - like running across a skyscraper in Manhattan - it seemed less likely they could be found in the universe's small towns.

"Rich groups of galaxies like the Coma Cluster are very, very rare, but there are quite a few galaxies the size of NGC 1600 that reside in average-size galaxy groups," Ma said. "So the question now is, 'Is this the tip of an iceberg?' Maybe there are a lot more monster black holes out there that don't live in a skyscraper in Manhattan, but in a tall building somewhere in the Midwestern plains."

While the black hole discovered in 2011 in the galaxy NGC 4889 in the Coma Cluster was estimated to have an upper limit of 21 billion solar masses, its range of possible masses was large: between 3 billion and 21 billion suns. The 17-billion-solar-mass estimate for the central black hole in NGC 1600 is much more precise, with a range (standard deviation) of 15.5 to 18.5 billion solar masses.

Interestingly, the stars around the center of NGC 1600 are moving as if the black hole were a binary. Binary black holes are expected to be common in large galaxies, since galaxies are thought to grow by merging with other galaxies, each of which would presumably bring a central black hole with it. These black holes would likely sink to the core of the new and larger galaxy and, after an orbital dance, merge with the emission of gravitational waves. The proposed Evolved Laser Interferometer Space Antenna, or eLISA, is designed to detect gravitational waves produced by the merger of massive black holes, while other groups are looking for evidence of gravitational waves from massive black hole mergers in nanosecond glitches in the precisely timed flashes of millisecond pulsars.

Behemoth black hole found in an unlikely place
The elliptical galaxy NGC 1600, 200 million light-years away -- shown in the center of the image and highlighted in the box --, hosts in its center one of the biggest supermassive black holes known . Until the discovery of this example, astronomers assumed that such huge black holes could only be found in the centers of massive galaxies at the center of galaxy clusters. NGC 1600, however, is a rather isolated galaxy.The image is a composition of a ground based view and observations made with the NASA/ESA Hubble Space Telescope. Credit: NASA, ESA, Digital Sky Survey 2

Ma and her colleagues will report the discovery of the black hole, which is located about 200 million light-years from Earth in the direction of the constellation Eridanus, in the April 6 issue of the journal Nature.

In search of quasar remnants

Black holes form when matter becomes so dense that not even light can escape its gravitational pull. In the early universe, when gas was abundant, a handful of voracious black holes grew to become extremely massive by swallowing it up, emitting immense amounts of energy. Looking back in time at the distant universe, these supermassive black holes appear as very bright quasars. As astronomers look closer to Earth, however, they see galaxies with little gas - it's already turned into stars - and no quasars. The most massive of these local galaxies may, however, house old quasars at their cores. Ma says that the monster black holes her team discovered in 2011 in NGC 4889 and NGC 3842, each weighing about 10 billion solar masses, may be quiescent quasars.

Because NGC 1600 is an old galaxy with little new star formation, Ma suspects that it, too, may harbor an ancient quasar that once blazed brightly but is now asleep. It would be the first discovered in a sparsely populated region of the local universe, she said.

"The brightest quasars, probably hosting the most massive black holes, don't necessarily have to live in the densest regions of the universe," she said. "NGC 1600 is the first very that lives outside a rich environment in the local universe, and could be the first example of a descendent of a very luminous quasar that also didn't live in a privileged site."

The MASSIVE Survey was funded in 2014 by the National Science Foundation to weigh the stars, dark matter and central black holes of the 100 most massive, nearby galaxies: those larger than 300 billion solar masses and within 350 million light-years of Earth, a region that contains millions of galaxies. Among its goals is to find the descendants of luminous quasars that may be sleeping unsuspected in large nearby galaxies.

The found in NGC 1600 is one of the first successes of the project, proving the value of a systematic search of the night sky rather than looking only in dense areas like those occupied by large clusters of galaxies, such as the Coma and Virgo clusters. The new findings combine image data from the Hubble Space Telescope and spectra taken by the Gemini Telescope in Hawaii and the McDonald Observatory in Texas.

Based on the Gemini spectra of the center of NGC 1600, most stars inside the sphere of influence of the black hole - a region about 3,000 light-years in radius - are traveling on circular orbits around the black hole, with very few moving radially inward or outward. It is as if the stars on radial orbits towards the black hole have been slung away, Ma said.

This would be the case only if the closest stars were scattering off a black hole pair and slingshotted away, just as NASA slingshots space probes around other planets to move them more quickly through the solar system.

The black hole's sphere of influence - the region within which the gravity due to the black hole wins out over that due to visible stars - is much larger than the event horizon, the point of no return, which would be about eight times the size of Pluto's orbit for the NGC1600 black hole.

"Somehow the stars have been scared away from the center of very massive galaxies, and either were afraid to come in, or came in and got kicked out," Ma said. The stellar orbits around the center of NGC 1600 indicate the latter, which "may be support for a binary black hole formed by a merger."

Binary black holes and core scouring

Because stars flung out by a binary black hole sap energy from the orbiting pair, the two move closer together and eventually merge. If NGC 1600 does contain a binary black hole with a combined mass of 17 billion suns, orbiting a fraction of a light-year apart, the ongoing pulsar timing arrays have a chance of picking up the emitted gravitational waves, Ma said.

NGC 1600 suggests that a key characteristic of a galaxy with at its core is that the central, star-depleted region is the same size as the sphere of influence of the central black hole pair, Ma said. Images taken by the Hubble Space Telescope revealed that the center of NGC 1600 is unusually faint, indicating a lack of stars close to the black hole. A lack of stars close to the galactic center distinguishes massive galaxies from standard elliptical galaxies, which are much brighter in their cores.

"One dynamical footprint of a binary black hole is core scouring," Ma said.

This signature will help Ma and her colleagues refine the MASSIVE Survey and more quickly find the supermassive in Earth's vicinity.


Explore further

Hubble image: The sleeping giant

More information: A 17-billion-solar-mass black hole in a group galaxy with a diffuse core, Nature, nature.com/articles/doi:10.1038/nature17197
Journal information: Nature

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Apr 06, 2016
Question to the physicists in here, could " shy " super-massive blackholes fill in the gap that dark matter is filling?

I.e., to take up as much mass as DM, by which factor should we have underestimated the amount of SMBH (let's say average size) lurking in the Universe?

Apr 06, 2016
@Bulbuzor According to the Dense Aether model that mainstream physics continues to ignore, we can expect to find... Just kidding! Good question, let's hope 'The Clevers' get here to answer before 'The Crazies' do

Apr 06, 2016
This comment has been removed by a moderator.

Apr 06, 2016
i think scientists have ruled that out bulb. there would have to be extreme black holes everywhere in the cosmos and they would not all stay "shy" as u say. there are definitely lots of rogue SM black holes but they don't have the necessary mass to rule out dark matter by any stretch of the imagination sadly. also these blackholes would be moving through space pretty fast i assume since they were launched from their orbit with another black hole. So they wont form the structure DM does with gravity.

Apr 06, 2016
Black holes are lurking only in mind of modern shamans. Nowhere else.

There is no way to exist something in the physical structure of vacuum of space, that violate the physical laws of the Creator tha support the originaly established prderr in the universe in interest of life.
This mantras are reflection of the humanistic cult to lawlessness due to the pride and vanity. Simpel and predictable as usual.

Apr 06, 2016
Singularities are still candidates for the missing mass. This category of explanations isn't favored by most physicists, who would prefer to break the Standard Model by adding exotic particles, but the correct answer to the missing mass riddle hasn't been nailed down - not even a little bit.

You might hope, but in vain, that if singularities are responsible for the missing mass, we should have detected that fact by now. Truth is a black hole is *very* hard to detect without a substantial inflow of matter to light it up. In the vast deeps between galaxy clusters and even within them, quiet black holes would be visible to us only through their long-range gravitational effects. We' see the gravitational effects, right enough. But to this point we can't rule out any of the candidate explanations for it.

This study is interesting, because it shows we're still underestimating singularity mass in the universe. But it doesn't tell us what the right estimate should be.

Apr 06, 2016
If anybody points out the fact that simulations of solar systems fly apart when gravity travels at c, the response will of course invoke Einstein's field as a defense. What nobody seems to notice is that the black hole mixes Newtonian mathematics into this field.

It's all very sloppy.

Apr 06, 2016
Why are the logic challenged always the first to witter on about methodological sloppiness? Doesn't get much sloppier than their arm chair pipe dreams.

physman5 /5 (4) 2 hours ago
@Bulbuzor According to the Dense Aether model that mainstream physics continues to ignore, we can expect to find... Just kidding! Good question, let's hope 'The Clevers' get here to answer before 'The Crazies' do


Literally posted seconds before compost and that complete gimboid of an ape, viko_bs.

Apr 06, 2016

compost 1 / 5 (2) 2 hours ago
The crackpots are two steps ahead by their very definition


When you were in boy scouts (sorry girl guides wouldn't have ya) I'll bet you were the kind that hastily paged through the manual looking at the requirements on various merit badges and concluded you could do most of it- and promptly started announcing what you had "earned". We're talking about accomplishment, not being a step ahead in your own delusional thinking. Personal citations? No, you've never accomplished anything. The only thing you'll ever be two steps ahead of anyone at is getting back to your favorite place to jerk off.

Apr 06, 2016
HannesAlfven, you seem to be citing this source:

http://physics.st...computer

This programmer who kicked off that thread is having difficulty incorporating GR into his simulation, using a physics engine designed for games.

No physicists are collaborating in his simulation. He is not publishing findings in a peer-reviewed physics journal. He's just a guy trying stuff out on his PC.

I am self-censoring very negative comments directed at your person for willful misunderstanding of how science proceeds.

Apr 06, 2016
Question to the physicists in here, could " shy " super-massive blackholes fill in the gap that dark matter is filling?

I.e., to take up as much mass as DM, by which factor should we have underestimated the amount of SMBH (let's say average size) lurking in the Universe?


From what I have read on the DM I think that the only way that could be is if the "shy" black holes are arranged just the right everywhere in the whole universe. The DM is organized just so and that is the way they even think the DM, because where he is makes the stuffs they look at do what it does.

Maybe IMP-Skippy or davejones-Skippy or Techno-Skippy or xyz-Skippy or one of the science trained Skippys will come along and explain that in better words than I can. (If Bennie-Skippy or Really-Skippy or Hannes-On-Ignore-Skippy come along and try to explain him, you would be better off ignoring them on this.)

Apr 06, 2016
GR is only mathematical (not physical) theory that does not consider the physical structure of the vacuum of space that filed the geometric 3d space of the universe and actively interact with matter particles. The one inportant propertiy of this structure is the electromagnetic waves which are in facts periodical oscilations of this stracture. The are part of it and as any other type of waves can not be consider separate from teh phisical environment in which propagate.


Apr 06, 2016
Each wave atenuate with the increasing the distance between the source and the observer thanks to scattering and resistance of the physical environment in which it propagate. This explains intuitively the the reason dor the observer red shift of light that coming from distant objects in the universe. The other reason for this rec shif is the rotation of the large cosmic stuctures in which part of the emitting light matter go away from the observer, and the other part part of it moves in the direction of the observer which cause both red and sblue shifts in the spectrum of light due to the Doppler effect in static environmen. Which has nothing to do with the imaginary expansion of the universe ideologists of metaphysics preach.

Apr 06, 2016
Chile wrote, "The only thing you'll ever be two steps ahead of anyone at is getting back to your favorite place to jerk off."

I think he was ridiculing cranks. A joke.

Compose wrote, "The matter curves space-time and this curvature has an energy. The space-time curvature should therefore exhibit its own gravity..."

This might be a serious question.

Consider a heavily curved spacetime. Suddenly remove the mass which curves it. What happens?

The curved spacetime instantly snaps back to being flat, and very likely emits gravitational waves while doing it.

Gravitational waves transmit energy.

It's a difficult experiment to perform, of course. But there is, at the least, an argument to be made that curving spacetime stores energy.

But it's a big, big leap from there to concluding that DM is explained by spacetime curvature. Stored energy in curvature would be found where large masses already exist. DM mappings tell us something different is going on.


Apr 06, 2016
For example, we've seen two galaxies that collided and passed through each other, and we've mapped DM which appears to be separated from *both* galaxies, in apparently empty extragalactic space. In the absence of visible mass from the two parent galaxies, that DM is now occupying relatively flat space, less curved, than when it was directly associated with those two galaxies. Yet the DM gravitational effects remain quite large, on a par with what we observe when DM is found in more conventional locations (associated with galaxies). If curvature explained DM gravitational effects, we'd expect those gravitational effects to be considerably diminished outside of the spacetime curvature of galaxies.

Apr 06, 2016
Ira wrote, "...the only way that could be is if the "shy" black holes are arranged just the right everywhere in the whole universe."

I don't regard myself as anyone's 'Skippy,' Ira, but I don't mind conversations.

Your objection applies to *every* theory of Dark Matter. Whether you imagine exotic particles or singularities or puss-emitting carbuncles, the mass has to be where its gravitation manifests, and not where it doesn't.

Apr 06, 2016
I don't regard myself as anyone's 'Skippy,' Ira,
Well good for you. I am Ira-Skippy's Skippy me. Glad to make your acquaintance.

Maybe you don't realize about the Skippy thing, it don't mean anything more than "dude" or "man" or "guy" or "fellow" or if you are one of those Australia Skippys "mate" or "bloke" or like that.

Your objection applies to *every* theory of Dark Matter. Whether you imagine exotic particles or singularities or puss-emitting carbuncles, the mass has to be where its gravitation manifests, and not where it doesn't.


Yeah, that's what I was trying to say, you say him better than I can.

The DM whatever he is has to be arranged just so. And it can't act on other things except for gravity. That is why I think the "shy" black holes might not be the DM. It would give himself away long ago by doing what the DM does, and have to also clump up just so. If black holes can do that maybe that is right, I don't know.

Apr 06, 2016
There is no doubt that adding in a delay of c to orbital simulations destroys orbital stability. This has been known FOR MANY DECADES NOW, and there is no debate about it. Tom van Flandern of Yale was the first to raise the issue. He helped the Navy develop GPS. More people would understand this if there wasn't a blockade in place on papers which exhibit some critique of Relativity.

Apr 06, 2016
Ira, I've read your comments for years. I know you don't mean an insult. Usually, heh.

You wrote, " If black holes can do that maybe that is right, I don't know."

Nobody knows. DM is a mystery. No, it's a great honking snot-drooling get-it-off-my-face! mystery. Every physicist, including the armchair variety (that's me), desperately wants an answer.

No question, the *real* physicists don't prefer an explanation involving singularities. They want to break the Standard Model and find new physics.

But singularities are not ruled out, and they most particularly are not ruled out by the 'just-so' argument.

It should not escape your attention that there has been a steady stream of studies announcing that we're finding singularity mass where we didn't expect to find it. We're playing catch-up: the universe has more singularity mass than we've estimated, and we still don't have it right.

But that isn't an answer. We don't have an answer yet, darn it.

Apr 06, 2016
HannesAlfven, I would enjoy a link to van Flandern's comments, or study, or whatever is driving your view on this, if you can provide one.

All I could find is an unserious gamer programmer's attempts to add GR to his game physics engine.

Apr 06, 2016
But singularities are not ruled out, and they most particularly are not ruled out by the 'just-so' argument.
That was my language failing me again. I was trying to say something like: If we took one of those DM maps they have been making, and put the black holes throughout it, just the way needed to produce the maps then, Would black holes arranged that in the universe be something we would have noticed doing something more than what we see now making the maps?

I don't know, it's why over my pay grade.

It should not escape your attention that there has been a steady stream of studies announcing that we're finding singularity mass where we didn't expect to find it. We're playing catch-up: the universe has more singularity mass than we've estimated, and we still don't have it right.
That's why I like the physorg, all the new stuffs they are discovering is exciting.

We don't have an answer yet, darn it.
The longer it takes, the more we will enjoy the answer.

Apr 06, 2016
Until the discovery of this example, astronomers assumed that such huge black holes could only be found in the centers of massive galaxies at the center of galaxy clusters. NGC 1600, however, is a rather isolated galaxy.


OK merger maniacs, give us another patch! This one is just another example of growing naturally from within like a plant, where the nutrients are the underlying etheric undetectables permeating everywhere.

most stars inside the sphere of influence of the black hole - a region about 3,000 light-years in radius - are traveling on circular orbits around the black hole, with very few moving radially inward or outward.


Since the extreme periodic activity of the core has pushed the stars outward, and the winds ejected therefrom prevent other stars from forming therein.

Binary? Fission of the central core, a natural consequence of a core grown too big.

Apr 06, 2016
Urgelt, what HA is either ignorant of or willfully ignoring is that while waves in space-time curvature travel at c, the effects of gravity are not 'time-retarded' solutions. Ie, for v << c, the 'force' of gravity points to where the other body 'is right now' not where it was some time ago (The Earth is attracted to where the sun is right now, not where it was 8 minutes ago).

This is because the maths are, surprise, more challenging than simply adding in a delay on gravity. The solution involves the fact that momentum is a part of the stress-energy tensor, and that the terms act so that the momentum of a body tells you where it will be later on.

The standard reference is Carlip's paper: http://arxiv.org/...87v2.pdf

Apr 06, 2016
Hah Just noticed the very first line of Carlip's paper is:
In a recent paper in Physics Letters A [1], Van Flandern has argued that observations
show that gravity propagates at a speed much greater than c


So he's obviously directly addressing HA's supposed 'concerns' about GR.

That's the problem with crackpottery. They hear "something's wrong in science" and then ignore "oh no, wait, this is what's going on" that happens later.

Apr 06, 2016
There is no doubt that adding in a delay of c to orbital simulations destroys orbital stability. This has been known FOR MANY DECADES NOW, and there is no debate about it. Tom van Flandern of Yale was the first to raise the issue. He helped the Navy develop GPS. More people would understand this if there wasn't a blockade in place on papers which exhibit some critique of Relativity.
Sounds like a Newtonian simulation. If it was compliant with general relativity, the spacetime around a star in all directions is already curved, just waiting for the planets to get to where they're going next. Any sudden change to the distribution of mass of the star would propagate outwards at a speed of c as a change in "g", (gravitational acceleration) of the star's gravitational field.

Apr 06, 2016
Ira, you wrote: "If we took one of those DM maps they have been making, and put the black holes throughout it, just the way needed to produce the maps then, Would black holes arranged that in the universe be something we would have noticed doing something more than what we see now making the maps?

Maybe. And maybe not.

Problem: our DM maps are, at the scale of a star or black hole, really loose and vague. The stuff is very far away and DM's presence is inferred by observations of visible bodies. The statistical error is large, like hundreds of millions of light years large, in many cases. Singularities with no infalling matter are not only unable to be pinned down to match the map, they're completely undetectable - save from their gravitic effects. Which might be due to a different explanation.

Apr 06, 2016
If you posit that we *should* be able to detect them, if singularities are behind the missing mass, then you're positing they aren't dark.

Astronomers are pretty sure that whatever it is, it's dark.

That fact alone isn't enough to rule out singularities of various kinds, since they *can* be dark to our instruments. Even very large singularities can be dark.

I'm not arguing for singularities as DM, only pointing out that science hasn't ruled them out. It's a category of explanations that's still in the hunt.

Apr 06, 2016
Worth mentioning that most of the DM is in halos outside the visible disks of galaxies, according to observations which show the rotation curve continuing up well outside those same visible disks. Given that, DM could easily be a halo of black holes that aren't radiating much because there isn't much for them to feed on.

It's still a viable hypothesis, as you correctly point out, @Urgelt.

The problem with it is, and it's a big one, where the heck did they all come from, and how come they're in a halo rather than fairly evenly spread through the disk, perhaps with a density gradient tending upward toward the center of the galaxy? It's a real conundrum, and one reason astrophysicists don't favor the explanation. Too many moving parts and not enough data.

Apr 06, 2016
I'm not arguing for singularities as DM, only pointing out that science hasn't ruled them out. It's a category of explanations that's still in the hunt.


I suppose all that sounds right to me. I guess where I got off wrong is thinking the DM stuffs was sort of like spread out and diffused in the places it is and that if 75% of the missing matter is black holes, we would see a lot more of them as they pass through clouds of gases and such like. I realize that the black holes are dark, but not when passing through clouds of stuff to interact with. According the DM maps they have inferred, there is gas and clouds mixed all through it. That is what we could see pretty easy (especially as long as they have been looking at galaxies and clusters and clouds.)

I am just not knowing enough about these things to be sure one way or another way. That's why I like it when the science smart Skippys chime in (not the smart crankpots) on articles like this..

Apr 06, 2016
shavera, when I got to the phrase "the quadrupole nature of gravitational radiation," my armchair physicist eyes glazed over.

Science doesn't even know if gravitons are a thing, and this guy says they're 'quadrupole.'

I'm not the guy to contradict or endorse that viewpoint, my armchair isn't big enough. Or maybe it's my head that isn't.

But thank you for the link. I do enjoy reading the various arguments that physicists with actual physics day jobs are advancing.

The only thing I'm certain of is that you can't plonk part of GR (gravitation propagating at c, but not all of the GR equations) into a game physics engine and expect anything useful to come of it. Those engines don't even simulate Newton correctly. They have no *need* to simulate Newton correctly; all they need to do is to entertain. Which they do very well.

A full-blown, completely accurate GR simulation of the sun and planets wouldn't even run on a desktop PC.

Apr 06, 2016
Da Schneib, wrote, "The problem with it is, and it's a big one, where the heck did they all come from, and how come they're in a halo rather than fairly evenly spread through the disk, perhaps with a density gradient tending upward toward the center of the galaxy?"

Very true. Since we have no theory for their formation or characteristics, it's hard to like the singularity explanation.

But you know, we aren't much farther ahead on exotic particle explanations, either. Really, the entire DM thing has physicists flailing about and conjecturing like mad.

Which is fun! But we'd all enjoy getting to an answer.

Apr 06, 2016
It's still a viable hypothesis, as you correctly point out, @Urgelt
Observations of events as with the Bullet Cluster don't seem to show any interaction with visible baryonic matter. Wouldn't you expect swarms of black holes to light up like fireworks? Wouldn't they still be glowing as they digested discs of filamentary galactic entrails?

Apr 06, 2016
The stuff is very far away


........it is? How do you know this, that it's "very far away"? Everything I read about it is that it constitutes 80-95% of the mass of the Universe. You are aware aren't you that the Milky Way is part of the Universe & is one of those types of galaxies that was the focus of Zwicky's thesis when he posited his hypothetical envelopes of DM enveloping ONLY SPIRAL GALAXIES. Spiral galaxies comprise only 1/3 the mass of the Universe

Zwicky's thesis specifically excludes ELLIPTICALS, but do you know why? Elliptical galaxies comprise 2/3 the mass of the Universe.

and DM's presence is inferred by observations of visible bodies


What "observations" & which "visible bodies"?

Spiral galaxies are visible bodies, where's the evidence for DM surrounding our galaxy? Is there some odd gravitational anomaly we should be looking for? Or is our galaxy just not "far away" enough for DM to make it's presence a cosmological factor?


Apr 06, 2016
Ira wrote, "we would see a lot more of them as they pass through clouds of gases and such like."

Possibly not. Gas clouds might not reliably yield an inflow of matter to the accretion discs of singularities to generate radiation we can observe with our instruments. Those clouds are pretty diffuse. We can detect greedy monsters easily enough when they're dining on a companion star or a galactic core's worth of nearby mass, but out in a diffuse cloud? Dunno about that. They'd have to be pretty close to be noticeable.

The only reason we're kinda sorta sure there's no singularity in the Oort Cloud is we can't see evidence of it from gravitational effects on observable bodies. Absence of radiation reaching our instruments doesn't carry much weight, even that close.

The primary reason to dislike the singularity explanation is, as Da Schneib said, we can't explain how they would get there. But that only means we can't think of an explanation, not that one doesn't exist.

Apr 06, 2016
Worth mentioning that most of the DM is in halos outside the visible disks of galaxies, according to observations which show the rotation curve continuing up well outside those same visible disks. Given that, DM could easily be a halo of black holes that aren't radiating much because there isn't much for them to feed on.

It's still a viable hypothesis, as you correctly point out, @Urgelt.

Careful, The Da - By saying "disk", Benni will chime in saying you believe DM halo's are only around spiral galaxies...:-)
And then he'll call you a Zwicky groupie, too...:-)

Apr 06, 2016
Benni, you seem to be (angrily) dismissing DM observations entirely.

Why? Instrument error? Errors in assumptions regarding calculation of gravitic influences?

I'm convinced that DM observations represent a genuine phenomenon in nature. We don't know why DM appears to clump, but it does seem to clump.

Refusing to accept DM observations in other galaxies on the grounds that we don't see anything local is like disbelieving in sand because you live in a box on a parking lot.

Apr 06, 2016
It's still a viable hypothesis, as you correctly point out, @Urgelt
Observations of events as with the https://en.wikipe..._Cluster don't seem to show any interaction with visible baryonic matter. Wouldn't you expect swarms of black holes to light up like fireworks? Wouldn't they still be glowing as they digested discs of filamentary galactic entrails?


I have no idea if that is right or not. But thanks, you said what I was trying to say, better.

Apr 06, 2016
Whydening Gyre wrote, "Careful, The Da - By saying "disk", Benni will chime in saying you believe DM halo's are only around spiral galaxies...:-) And then he'll call you a Zwicky groupie, too...:-)"

Need to work on your timing, WG. :P

Apr 06, 2016
It's still a viable hypothesis, as you correctly point out, @Urgelt
Observations of events as with the https://en.wikipe..._Cluster don't seem to show any interaction with visible baryonic matter. Wouldn't you expect swarms of black holes to light up like fireworks? Wouldn't they still be glowing as they digested discs of filamentary galactic entrails?
Good point, Proto.

Apr 06, 2016
Benni will chime in saying you believe DM halo's are only around spiral galaxies
.......not me, I didn't write the dissertation, Zwicky did. If you'd just go read his paper on the subject, trust me, you won't find my name in it.

Apr 06, 2016
Refusing to accept DM observations in other galaxies on the grounds that we don't see anything local is like disbelieving in sand because you live in a box on a parking lot.


.......and you still won't even tell us what "observations" you're talking about. OBSERVATIONS are not a substitute for MEASUREMENTS. But so far you won't even discuss the "observations" much less get into issues of MEASUREMENTS, which I imagine you don't want to do because MEASUReMENTS of DM are impractical because DM is just so "far away".

Apr 06, 2016
@Da Schneib,Urgelt,Whydening Gyre, Proto. Da Schneib hinted on a point that has intrigued me about DM (which I'm not against). Whatever DM may be it seems to produce gravitational effects (yeah I know, stated the obvious) and assuming DM has been around for a long time why hasn't it collapsed to form, say, DM 'planets' or other bodies? I don't include BH's because from what I've read DM doesn't produce BH effects. Another related question is, does, say, DM halo appear to attract other galactic bodies. If not, is there a theory as to why not? If a DM halo does attract galactic bodies is it possible it might strip some galactic material away? Thanks in advance.

Apr 06, 2016
Whydening Gyre wrote, "Careful, The Da - By saying "disk", Benni will chime in saying you believe DM halo's are only around spiral galaxies...:-) And then he'll call you a Zwicky groupie, too...:-)"

Need to work on your timing, WG. :P

Was typing it when he "chimed in".... Dang old fingers...

Apr 06, 2016
@Da Schneib,Urgelt,Whydening Gyre, Proto. Da Schneib hinted on a point that has intrigued me about DM (which I'm not against). Whatever DM may be it seems to produce gravitational effects (yeah I know, stated the obvious) and assuming DM has been around for a long time why hasn't it collapsed to form, say, DM 'planets' or other bodies? I don't include BH's because from what I've read DM doesn't produce BH effects. Another related question is, does, say, DM halo appear to attract other galactic bodies. If not, is there a theory as to why not? If a DM halo does attract galactic bodies is it possible it might strip some galactic material away? Thanks in advance.

Thought I read an article a few weeks ago about satellite galaxies and the connection to DM. Don't remember exact when or where, tho...
Been on the road doing shows, so not keeping as good a track as usually do... sorry.
Edit - found it - http://phys.org/n...rth.html

Apr 06, 2016
Benni wrote, ".......and you still won't even tell us what "observations" you're talking about. OBSERVATIONS are not a substitute for MEASUREMENTS. But so far you won't even discuss the "observations" much less get into issues of MEASUREMENTS, which I imagine you don't want to do because MEASUReMENTS of DM are impractical because DM is just so 'far away'"

Benni, you're gibbering. There are no measurements without observations. What we observe are motions of visible bodies - galaxies and galaxy clusters. We can't explain why they move as they do by adding up visible mass. There is more gravity at work than we can explain, hence 'DM,' which is a stand-in term for an observable phenomenon we can't explain.

DM itself is *not* observable, only the motions of galaxies and galaxy clusters.

Apr 06, 2016
WG, we often see articles which add mass from singularities that we didn't know were there, as with today's article, or dwarf galaxies contributing more than we thought, or adjustments to particle densities in intergalactic space, or what have you. The estimated unknown DM gets refined, too, as mass shows up elsewhere.

Unfortunately, it's like digging a mountain with a spoon. DM still appears to greatly dominate over visible matter. The mystery remains mysterious.

Apr 06, 2016
Mimath asked interesting questions. My take:

"assuming DM has been around for a long time why hasn't it collapsed to form, say, DM 'planets' or other bodies?"

This question only makes sense if you postulate unknown exotic particles for DM. The short answer is, exotic particles can't interact with electromagnetism. It's tough to make planets out of stuff that doesn't do that.

"I don't include BH's because from what I've read DM doesn't produce BH effects."

There won't be any BH effects, apart from gravity, if there is insufficient infalling matter to generate enough radiation for us to detect it. Singularities are *not* ruled out, though they aren't favored at present by physicists.

"If a DM halo does attract galactic bodies is it possible it might strip some galactic material away?"

DM, whatever it is, exerts a gravitational tug. On galactic scales and higher it contributes to movement of visible bodies. In collisions, it influences where visible matter ends up.


Apr 07, 2016
They're everywhere yet nowhere at the same time. Unlike everywhere else there's no dark matter yet it's all dark matter. Infinite entities in a finite Universe. A paradox beyond reality, maths that strains credulity. Pseudoscientific metaphysical mumbo jumbo cloaked as science with a devout following not even surpassed by the likes of th Branch Davidians. The generations that follow will scoff at the ridiculousness of the current state of the space sciences. Dark epicycles rule astronomy.

Apr 07, 2016
Thanks Urgelt,Whydening Gyre. went to the link...interesting but I'm not sure if I'm reading it correctly viz;
'...Around large galaxies, such as the Milky Way, these dark matter sub-halos are large enough to host enough gas and dust to form small galaxies on their own...'
Should I read this as DM attracting gas and dust (where a sub-halo of DM aslo forms) or, that theoretical models suggest DM actually produces ordinary matter by some mechanism.
I suspect the former because if the latter then non halo DM might, I say might, exhibit the same type of conversion unless ordinary galactic triggers some process. Wow, fascinating stuff this, thanks again.

Apr 07, 2016
DM, whatever it is, exerts a gravitational tug. On galactic scales and higher it contributes to movement of visible bodies. In collisions, it influences where visible matter ends up.

- Urgelt
So are you saying that DM has gravitational properties similar to a BH but not as strong, and/or normal matter? And why isn't it visible? Please explain.

Apr 07, 2016
There is no doubt that adding in a delay of c to orbital simulations destroys orbital stability. This has been known FOR MANY DECADES NOW, and there is no debate about it. [sni]


Correct. Most of the terms terms cancel out, but not completely. Like any effect of relativity, it is marginal for slow (compared to c, like the sun-earth orbit) relative movement, but quite apparent for fast moving, heavy objects (e.g. 2 pulsars in close orbit).

Without it, there would be no gravitational waves, their energy has to come from somewhere

More people would understand this if there wasn't a blockade in place on papers which exhibit some critique of Relativity.


How? There are a lot of papers (mostly very heavy on math), which describe that. As you say it is known since a long time and very dry stuff, so there is no hype around it

Apr 07, 2016
@Da Schneib,Urgelt,Whydening Gyre, Proto. Da Schneib hinted on a point that has intrigued me about DM (which I'm not against). Whatever DM may be it seems to produce gravitational effects (yeah I know, stated the obvious) and assuming DM has been around for a long time why hasn't it collapsed to form, say, DM 'planets' or other bodies?


Baryonic matter cools down and contracts by (mostly) emitting EM waves. It seems DM can't do that (unknown reason for what I can tell, but it would not be dark otherwise). It seems there is no mechanism for it to cool down and contract, so it just stays stable for a long time

Apr 07, 2016
I think that Dark Matter is a spooky substance that may have existed long before the "Big Bang" happened. And if there never was a Big Bang, the Dark Matter still existed and has no "exotic" properties of its own...including a gravitational effect on anything. It's just there, whatever it is, and wherever "there" is.
Just my opinion.

Apr 07, 2016
Question to the physicists in here, could " shy " super-massive blackholes fill in the gap that dark matter is filling?


Well, I'll take a shot at representing the "crackpots".

Just exactly how many singularities do *you* think inhabit the universe?

Apr 07, 2016
is our galaxy just not "far away" enough for DM to make it's presence a cosmological factor?


It's been the experience of many other philosophers of science, that when a concept such as "dark matter" arises in a physical model, it represents the motive for a paradigm shift. I think Thomas Kuhn most recently observed that (to great applause from the rest of us in the peanut gallery).

Seriously. Dark Matter? Stuff we think has to be there because our model doesn't work if it isn't, but that we can't detect? Sir William would have a field day.

There's something fundamentally wrong with the Standard Model. The person who figures that one out will be the next Einstein.

Apr 07, 2016
That fact alone isn't enough to rule out singularities of various kinds, since they *can* be dark to our instruments. Even very large singularities can be dark.


So let's toy with the idea that scale is corrupting thinking on the subject? Astronomers tend to think in large terms. Particle physicists not so much, but they certainly aren't immune to assumptions of scale.

What about zero-point energy and the Casimir effect? Quantum field theory suggests all motion in space must, essentially, be present at all points in all space. Rather than look for huge chunks of "dark matter", might it not be reasonable to investigate its presence everywhere? When virtual particles appear and disappear in a Casimir cavity, where are they going/coming to/from?

Apr 07, 2016
@RCG Thanks

Apr 07, 2016
If anybody points out the fact that simulations of solar systems fly apart when gravity travels at c, the response will of course invoke Einstein's field as a defense.

The problem has been already addressed. Interested people can look after "retarded gravitation" or "speed of gravity". If gravity field moves with c, the Solar System is essentially stable as long as the Sun doesn't get accelerated. All instabilities affecting the planets manifest on scales of billions of years or far larger. These are due to planetary resonances that may appear and also to gravitational waves that dissipate energy - this is an extremely weak effect. One can argue that the Sun and planets are accelerated (since they both rotate around the Solar System's center of gravity), thus there is a retardation in the gravitational force, which no longer points towards the Sun, and thus destabilises the Solar System. But this is an extremely weak effect. So the Solar System is stable for billions of years.

Apr 07, 2016
An interesting work on retarded gravitation was carried by J.C. Hafele: http://arxiv.org/.../all/0/1

Apr 07, 2016
There is no doubt that adding in a delay of c to orbital simulations destroys orbital stability. This has been known FOR MANY DECADES NOW, and there is no debate about it. Tom van Flandern of Yale was the first to raise the issue. He helped the Navy develop GPS. More people would understand this if there wasn't a blockade in place on papers which exhibit some critique of Relativity.

The issue is discussed even on Wikipedia. So no blockade there. Just a different version than the one you are espousing.

Apr 07, 2016
What nobody seems to notice is that the black hole mixes Newtonian mathematics into this field.

It's all very sloppy.


What we need is experiment that falsifies the theory of Einstein's field then. Van Flandern's [corrected, I'm pretty sure it's Van Flandern?] argument is at least good enough to justify some thought but it does seem to me he's been dismissed and I don't think he deserves that.

Apr 07, 2016
The problem has been already addressed.


Well then, I suppose that just sews up the entire subject?

No. The problem hasn't already been addressed and it's a bit conceited of you to assert it has been.

Please address each of Van Flandern's criticisms of Einstein's field theory. I'm not just pulling your pud; I've been working on that problem for 20 years. Tom isn't my hero, but I do respect his thinking and I won't tolerate anything short of a real, scientific, rejection of his observations.

I would personally appreciate it if you would address all of the criticisms you've made in detail and with some attempt at references?

Apr 07, 2016
Benni, you're gibbering. There are no measurements without observations. What we observe are motions of visible bodies - galaxies and galaxy clusters. We can't explain why they move as they do by adding up visible mass. There is more gravity at work than we can explain


Urg......How do you know any of this? How do you know there is more gravity at work than we can explain if the Universe really exists as you imagine, that 80-95% of it's mass is MISSING?

Zwicky is the one who OBSERVED that radial arms of Spiral Galaxies move at a rate of 100-300 km/s, as opposed to the outer orbital stars of Ellipticals at 2 km/s. Have you ever wondered why the difference?

Explain in terms of "far away" how LOCAL PHYSICS for gravity is somehow different from NONLOCAL PHYSICS for gravity. By LOCAL PHYSICS what I mean is we launch satellites all over our solar system based on the math of Newtonian calculations for gravity.

Come on here guy, you want to be the next resident expert


Apr 07, 2016
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Apr 07, 2016
What we need is experiment that falsifies the theory of Einstein's field then.

There are many that could have. Pound-Rebka could have not shown red/blue shifting of light in gravitational wells, for one small instance. All of the experiments supporting GR are experiments that could have potentially falsified it. Yet the data was in agreement with prediction.

Please address each of Van Flandern's criticisms of Einstein's field theory


Please read this thread where the actual 'real, scientific rejection of his observations' is presented. (Look for where I posted Carlip's paper, which is the work that rejects his observations).

Apr 07, 2016
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Apr 07, 2016
Urgelt:
Science doesn't even know if gravitons are a thing, and this guy says they're 'quadrupole.'


So generally in particle physics, we know (some of) the properties of the kind of particle we're looking for before we actually find it. In this case, the rules of GR inform the kind of properties some theoretical graviton may actually have.

But moreover, Carlip's paper does not rely on the existence of gravitons. It's pretty much a direct translation of the maths from classical field theory in electromagnetics to GR. (Orbiting charges emit em radiation and fall closer together; GR's base maths are similar, but not precisely the same, as EM; They're similar enough to use certain mathematical techniques to come up with solutions).

Interestingly enough, the signal to support Carlip's result would be gravitational waves from orbiting bodies, which we have just recently observed.

Apr 07, 2016
The problem has been already addressed.


Well then, I suppose that just sews up the entire subject?

No. The problem hasn't already been addressed and it's a bit conceited of you to assert it has been.

It's not my field and I don't have time to search for articles. But once I was interested on the problem, so I did some research. Since I found results about it, the problem has been addressed. The above was my conclusion. If you want to search for more, use Google.

Apr 07, 2016
shavera wrote, "Carlip's paper does not rely on the existence of gravitons. It's pretty much a direct translation of the maths from classical field theory in electromagnetics to GR..."

Laymen (like me) often do not appreciate just how interconnected GR is to classical field theory, Maxwell, et al. When Einstein deduced the GR equations, he wasn't working in a vacuum.

That doesn't mean every classical field theory argument, extended to GR, is true. It's an interesting and persuasive argument, but the proof is in the pudding, not the recipe book. Experimental physics hasn't caught up.

"...the signal to support Carlip's result would be gravitational waves from orbiting bodies, which we have just recently observed."

I cry foul, shavera. GR itself predicted gravitational waves a full century ago.

What does Carlip predict that is unique to Carlip's conjecture?

Gravitons may exist, they may be quadrupole, Carlip may be right, but evidence, shivera, is the thing.

Apr 07, 2016
mimath wrote, "Should I read this as DM attracting gas and dust (where a sub-halo of DM aslo forms) or, that theoretical models suggest DM actually produces ordinary matter by some mechanism."

No. Conservation of matter and energy is still in play, and nobody in physics seems to think that DM *produces* visible matter by some mechanism.

The proposition is crankish, but as you offered it as a suggestion rather than trumpeting its certain truth, you've managed to evade the crank label. :-)

Apr 07, 2016
socks wrote, "So are you saying that DM has gravitational properties similar to a BH but not as strong, and/or normal matter? And why isn't it visible? Please explain."

No. I'm saying DM interacts gravitationally with visible matter. This interaction implies mass - we do not have any theories or experimental evidence that gravitation can be produced without mass, so. There is mass, and it can be estimated by observing the movements of visible matter.

Gravitation alone does not inform us as to the nature of the mass, which is why DM is mysterious.

Apr 07, 2016
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Apr 07, 2016
GR would have predicted gravitational waves, true, but it's specifically that of orbiting bodies that would support the maths Carlip lays out. (Since it's radiation due to orbits, and he provides the GR solution to orbits, and that solution includes terms cancelling the effect of motion to v^4)

That doesn't mean every classical field theory argument, extended to GR, is true.


As a physicist this sentence has precisely no meaning. Classical field theory is just a type of maths. Certain physical phenomena are usefully described by fields in that mathematical framework. GR is no more or less one of those physical phenomena being described by a field. (The tensor field representing stress-energy equals a tensor field describing curvature, more or less).

Apr 07, 2016
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Apr 07, 2016
The gravitational waves ipso-facto violate the general relativity,.... But in general relativity the space-time curvature has no mass or inertia at all.


Doesn't it carry energy, which is an equivalent of mass?

Being massless, there is no limit for its propagation with speed of light,


The limit is on information, not mass, right?

The mainstream physics models are full of such logical inconsistencies


Yes, but I can't see one in this case?Can you explain?

Apr 07, 2016
For example the existence of gravitational lensing implies, that the portion of vacuum slows down the light in such a way,


Why would it slow down? The whole idea of RT is that c is constant, but the clocks are out of sync and observers are not able to agree on length. This is causing the lens effect, not a changed speed of light

...the light gets refracted around massive bodies. But whole the relativity considers, that the light is propagating with fixed speed.

Apparently, both interpretations aren't possible at the same moment/reference frame. In another words, the mainstream physicists and their models are confused as hell and the above discussion just illustrates it.


Given that your first assumption does not match my understanding of RT, I fail to be confused

Apr 07, 2016
No. I'm saying DM interacts gravitationally with visible matter. This interaction implies mass - we do not have any theories or experimental evidence that gravitation can be produced without mass, so. There is mass, and it can be estimated by observing the movements of visible matter.


You keep prattling on about all this "unexplained gravity" that exists everywhere in the "far away" Universe creating all these mysterious OBSERVATIONS in the movement of Visible Matter. Knock it off with beating around the bush with whatever it is you're talking about & tell us what all these mysterious movements of VM is all about?

Then explain to us why we don't OBSERVE these mysterious movements of VM within our solar system as evidence for the existence of DM within the radial arms of a Spiral galaxy where it's presence should be easily & unmistakably MEASURED. Maybe you think our Solar System & Galaxy has a special location exempted from all the laws of physics elsewhere?


Apr 07, 2016
Doesn't it carry energy, which is an equivalent of mass?

Gravitational waves do carry away energy, but energy is not 'an equivalent' of mass. The relationship between energy and mass is: E^2 = (pc)^2 + (mc^2)^2 . Mass is the thing two observers in relative motion will agree on when they measure energy, momentum, and mass of some other thing.

in general, compose doesn't demonstrate a sufficient understanding of physics to talk about its deficiencies or contradictions. The subject matter described by 'physics' to them bears little to no resemblance to the actual science, save for some abused jargon words.

Apr 07, 2016
where it's presence should be easily & unmistakably MEASURED.

whoa there. That's some sweeping assertion you make. You're the one asserting we should easily be able to detect it. I don't think scientists make the same claim.

I think you fail to grasp just how *huge* space is. Just how empty most of it is of visible matter. On length scales of our solar system there simply may not be enough dark matter to visibly perturb orbits. ( I don't think it's expected to be that dense ). But galaxies are filled with so much empty space that dark matter can be in that it's perfectly reasonable to suggest that you need much larger length scales to see the relatively tiny effect it produces.

Apr 07, 2016
@shavera, thx for the details

Apr 07, 2016
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Apr 07, 2016
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Apr 07, 2016
I think you fail to grasp just how *huge* space is. Just how empty most of it is of visible matter. On length scales of our solar system there simply may not be enough dark matter to visibly perturb orbits. ( I don't think it's expected to be that dense ). But galaxies are filled with so much empty space that dark matter can be in that it's perfectly reasonable to suggest that you need much larger length scales to see the relatively tiny effect it produces.


There are actually good summary papers about this from the last 2 years or so. In summary we seem to be close to be able to measure them, but mass density is too tiny with existing probes (unless someone comes up with a cool new idea how to measure it). What we see on stellar level seems to match very well with the DM predictions

I couldn't add the link, spam filter somehow didn't like it :( Any helpful hints why welcome

Apr 07, 2016
@shavera, thx for the details


Yeah, lack of them..........just more prattling about "far away" stuff. Interesting how you DM Enthusiasts don't want to have a discussion about Zwicky's dissertations on the subject.

But galaxies are filled with so much empty space that dark matter can be in that it's perfectly reasonable to suggest that you need much larger length scales to see the relatively tiny effect it produces


........and so is our Solar System just as empty as all the other "far away" solar systems everywhere else in the Universe. What would you like to bet that if you were an alien looking at our galaxy from "far away", that you'd see our galaxy behaving just as we observe their galaxy behaving? If you don't believe that the laws of Conservation of Energy apply equally throughout the Universe, then you must of necessity believe our galaxy & solar system are SPECIAL, but you sure don't want to go there do you?


Apr 07, 2016
Benni the reason no one can address your concerns is because words mean entirely different things to you than they do to scientists, apparently. You are more than welcome to spend a decade in school like the rest of us to learn what these words mean in the context of physics.

Dark matter is expected to be just as present in the solar system as elsewhere in similar galaxies. Dark matter is not sufficiently dense to be detected (yet?) in gravitational perturbations on the orbits within our solar system. Our solar system is really really tiny, in the scope of things. On larger scales beyond our solar system, dark matter has sufficiently integrated mass (large volume of low density) to produce more pronounced effects on orbits.

I honestly haven't the foggiest clue what your ramblings about 'far away' physics are because we observe the same physics both here and in distant systems.

Apr 07, 2016
Similar (actual closely related) paradox: the photons and light is considered massless, nevertheless the stars are routinely believed to lose their mass/matter by radiation in the same way, like the black holes are supposed to lose their mass by radiation of gravitational waves.
Please, explain....


Thank you, this is a simple one :)
Photon have 0 rest mass, so the energy they carry is
E^2 = (pc)^2 + (mc^2)^2 = e^2 = pc^2 + 0
(https://en.wikipe...perties)

Stars lose their mass, as fusing H to He reduces the rest mass, producing a photon and a neutrino with the same energy

This has nothing to do how black holes losing their mass though, however

Apr 07, 2016
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Apr 07, 2016
There are actually good summary papers about this from the last 2 years or so. In summary we seem to be close to be able to measure them, but mass density is too tiny with existing probes (unless someone comes up with a cool new idea how to measure it). What we see on stellar level seems to match very well with the DM predictions


Ok then, how about a 100 year old calculation in GR where Einstein calculated photon deflection at the peripheral disc of the Sun within 0.02% of error.

If what we see on "stellar level" seems to "match very well with the DM predictions", how is it the Sun's mass/gravity calculations by Einstein escape these new 2 year studies?

To make clear what I'm getting at, If Einstein missed calculating 80-95% of the Sun's mass/gravity his calculations for Photon Deflection should never have worked, but they did, 20 years before Zwicky came up with his DM hypothesis.

Have you ever studied the Photon Deflection section of GR?

Apr 07, 2016
Interesting how you DM Enthusiasts don't want to have a discussion about Zwicky's dissertations on the subject.


Unfortunately I'm not a DM enthusiast, anyway

https://en.wikipe...volution explains that elliptic galaxies are assumed to have formed after collisions

How barionic and elliptic galaxies can be separated by collisions of galaxies is explained here https://en.wikipe..._Cluster

As a result elliptic galaxies should not follow the same rules for DM as spiral ones

Apr 07, 2016
and assuming DM has been around for a long time why hasn't it collapsed to form, say, DM 'planets' or other bodies?
An excellent modern mystery. What if DM was composed of particles that behaved* like neutrinos? There are variety of constraints on the masses of the tau/muon/electron neutrinos which show they can't account for all the DM. But there's still much to learn about them and their oscillations.

*specifically, DM clumps but doesn't collapse. What could do that other than massive, weakly interacting particles that are hot when they're created? Hot meaning relativistic velocity, so the dimensions of the clump vary with the "temperature" of the particles.

There are lots of good guesses already mentioned by others in this thread. Viable candidates span a mass range that covers 75 orders of magnitude, see a Brief Survey of Dark Matter Candidates from MIT.

Apr 07, 2016
If Einstein missed calculating 80-95% of the Sun's mass/gravity


This is what I'm talking about when you're missing the point/using words in ways other than how physicists mean them. When we say 95% of the mass of the universe is dark matter, that doesn't mean that everything should have 20 times its measured mass. It means that on average, there's more mass out there than you might otherwise guess.

As an example consider a ball flying through the air. The ball doesn't have extra mass because of the air. But a very large volume containing both the ball and the air will mass significantly more than the ball alone. The sun doesn't have extra mass because of dark matter... but over a very large volume of space, there's a lot more mass in that volume than just the sum of masses of sun and moon and planets.

Apr 07, 2016
The physicists are doing exactly the same thing, like the crackpots here: they just downvote and ignore uncomfortable questions and proposals and continue in twaddling about their nonsensical off-topic substitutive problems as if nothing would ever happen. .


So far I think most of yours were answered or at least replied to and you were not down voted in most cases? But whenever one of your question is answered, you seem to add more questions, and it takes time to give a qualified answer

Apr 07, 2016
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Apr 07, 2016
As a result elliptic galaxies should not follow the same rules for DM as spiral one


OK, so what then is the stroke of magic by which Elliptic galaxies suddenly morph into following the laws of Newtonian Gravity calculations after Spiral mergers?

Somehow all the DM becomes a neutralized non-factor when the orbital velocities of stars within Ellipticals now comport with the laws of Newtonian Gravity. Why? How does DM suddenly know it needs to blink out of existence (or go neutral) so that that rotation rates of peripheral stars within Ellipticals must be reduced to 1/100 that of Spirals?

If there are all these DM Envelopes surrounding Spirals as Zwicky says there is at a 5:1 ratio, how is it that Einstein Field Equations based on Newtonian gravity can so accurately predict the orbital rates of velocities of Elliptical galaxy stars? Somehow there should be 5 times more mass than Einstein Field Equations predict after two Spirals merge.

Apr 07, 2016
If Einstein missed calculating 80-95% of the Sun's mass/gravity


Assuming dark matter is not concentrated in solar systems (there is no hint that this is the case) but more or less evenly distributed around the sun, and assuming there is one star per ly (much too high), the volume of the DM is ~7e+47 m^3
The volume of the sun is 1.41e+27 m^3
That is 20 orders of magnitude! So even if 90% of galaxy's mass is DM only 2e-18 % of sun's mass will be DM,which is way less than the 0.02%

Apr 07, 2016
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Apr 07, 2016
The questions about paradox of mass of photons, gravitational waves or speed of light during lensing were all downvoted and left unanswered in unison


There are answers to all of these above, including calculations. Not sure, what else you expect :(

There is no proof, that the main stream physics is correct, and never will be. The only reason why science exists is it's use as a tool. If a formula is not useful to derive something from it, it's not worth it

Apr 07, 2016
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Apr 07, 2016
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Apr 07, 2016
As a result elliptic galaxies should not follow the same rules for DM as spiral one


OK, so what then is the stroke of magic by which Elliptic galaxies suddenly morph into following the laws of Newtonian Gravity calculations after Spiral mergers?


Read the wiki article, it explains it. According to it DM matter and barionic matter seem to separate after the collision, depending on the details of the collision. This is one of the main argument against e.g. MOND

Apr 07, 2016
There are answers to all of these above, including calculations
So that once again: how is it possible, that the stars and black holes can radiate the matter in waves, if these waves should have zero mass? How is it possible, the light refracts around massive objects, if it has constant speed in vacuum? As you can see, very easy and trivial questions we have here...:-) No calculations are necessary for their answering. Once you can answer these questions clearly, it has a meaning to discuss more complex and particular problems, but not vice-versa.


Would be easier if you point out, what's wrong with the answers given above

Apr 07, 2016
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Apr 07, 2016
socks wrote, "So are you saying that DM has gravitational properties similar to a BH but not as strong, and/or..."

No. I'm saying DM interacts gravitationally with visible matter. This interaction implies mass - we do not have any theories or experimental evidence that gravitation can be produced without mass, so. There is mass, and it can be estimated by observing the movements of visible matter.

Gravitation alone does not inform us as to the nature of the mass, which is why DM is mysterious.
- Urgelt
DM has Mass? So are you saying that MATTER itself has to be present (with its own gravity) so that DM (with its own alleged gravity) can exert DM's gravitation ON or UPON that matter? IF that was the case, wouldn't that gravitational "attraction" from both Matter AND DM "locked" both into each other? Wouldn't that mean that ALL or most Matter contains DM, similar to a glue? It doesn't seem logical wrt DM. Are you SURE that DM has Mass, and therefore, exerts gravity?

Apr 07, 2016
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Apr 07, 2016
you don't check the answers


How do you know that?

the were already answered by someone else at Wikipedia. But they weren't.


Last try, sorry. What is wrong with the explanation given in the wiki article? Please point out, where the error is.
Calculations are not good, wiki articles are not good enough, papers are not good either, so, what is?

Apr 07, 2016
that the stars and black holes can radiate the matter in waves, if these waves should have zero mass?

Because waves don't require mass. They're not radiating "matter" either. Energy. Energy and mass are related, but not equivalent.
How is it possible, the light refracts around massive objects, if it has constant speed in vacuum?

Because the way you measure distances and times around a massive body change compared to observers very distant to that body. Again, feel free to work out the maths yourself. Hartle's Gravity is a really easy introduction to the subject.
No calculations are necessary for their answering.

Yes they are. If you won't take the physicists' word for it, then obviously you need to do the calculations on your own and see for yourself. You can either trust that I'm right when I say that light doesn't change speed when it bends around a massive body, or you can do the maths for yourself.

Apr 07, 2016
cite at least one of the alleged answers


Here you go: http://www.amazon...05386629

Have fun. Honestly. This was one of my all time favorite text books. When I calculated planetary orbits from relativity it was one of the single coolest class/homework problems I did. I guarantee, hands down, not the slightest doubt, that if you actually know GR and how the equations work and how to use it to predict physical experiments and data.... you wouldn't doubt how well it describes reality.

Contrarily, everyone who doubts GR it just screams how little they actually know about it. There's no way you can understand the theory and not see how well it fits experimental data and describes reality.

Sure there are certain specific things it can't do, but again, if you don't understand what it can do, then how can you hope to understand what it can't.

Apr 07, 2016
socks wrote, "DM has Mass? So are you saying that MATTER itself has to be present (with its own gravity) so that DM (with its own alleged gravity) can exert DM's gravitation ON or UPON that matter? IF that was the case, wouldn't that gravitational "attraction" from both Matter AND DM "locked" both into each other? Wouldn't that mean that ALL or most Matter contains DM, similar to a glue? It doesn't seem logical wrt DM. Are you SURE that DM has Mass, and therefore, exerts gravity?"

Unless gravity can exist in the absence of mass (physicists don't think so), then yes, DM has mass. But the devil is in the details. If a particle, it can't interact with electromagnetism, so it's not going to stick to visible matter but ghost on by in encounters. If DM is singularities, it *eats* visible matter that gets too close - but out in galactic halos singularities are on a starvation diet. They're quiet and dark to our instruments.

Or it's something else. No-one knows.

Apr 07, 2016
@Urgelt
As I said in an earlier post, IMO Dark Matter existed long before the Big Bang, whether or not the BB actually happened. But if it is as you say, DM itself has an inherent property of gravitation and has Mass, then it should be a constituent of all Matter due to the attractive forces of both to each other. But it's been said that normal, visible Matter is only ~5% of the Universe and DM ~27%. That leaves ~22% of DM that is not locked in with normal, visible Matter. Perhaps that 22% has been swallowed up by BHs and is no longer available? OR it is possible that DM doesn't have Mass nor does it have gravitational properties, and it is only a "medium" for Matter/Energy to float in, similar to a clear, inert liquid - without the liquid.
I think that DM exists, but doesn't interact with anything. It has always existed, just as Time has always existed and flows continuously without stopping, pausing or reversing.

Apr 07, 2016
"As I said in an earlier post, IMO Dark Matter existed long before the Big Bang".

How do you know this? Direct observation or shamanic trance? Do you believe in unicorns?

Apr 07, 2016
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Apr 07, 2016
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Apr 07, 2016
socks wrote, "But it's been said that normal, visible Matter is only ~5% of the Universe and DM ~27%. That leaves ~22% of DM that is not locked in with normal, visible Matter."

There is no connection between your musings and science, socks. No connection whatsoever.

Ditch the 'locked in' rhetoric, it isn't helping you to understand the nature of the mystery of DM.

DM interacts gravitationally with visible matter. That's the starting point. If you can't get to that starting point, it's probably better if you don't spin conjectures about DM.

Apr 07, 2016
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Apr 07, 2016
Next attempts for answer (not just the dull "RTFM" advices or "it was already answered" claims) are heartily welcomed here.


Not sure, how I can help you. There is a theory called RT, which says, that energy is indistinguishable from matter when it comes to gravity. It also explains, how both are calculated from each other (see above).

All measurements done so far, e.g. measuring quark mass, compared to proton mass, measuring weight of atoms, taking binding energy into account (and measures emitted photons and neutrino energy), or accellerating particles to high velocity and measures the weight are in line with this theory.
It does not explain, why, as Newton does not explain why there is gravity (actually Newton is much worse, he does not even try to explain the how)

Long story short, if H fuses to He they lose mass (which we can measure) and emit photons and neutrinos, which perfectly fit to the mass loss. This "mass" is emitted by the sun.

Apr 07, 2016
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Apr 07, 2016
Note to shavera: you've contributed substantially to making this conversation interesting and fun (despite the cranks trying to drag the discussion into la-la land). Many thanks and a tip of the hat.

Apr 07, 2016
compose has exhausted my patience. Someone else can talk to him. Or not.

Apr 07, 2016
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Apr 07, 2016
compose:
Suppose you have two photons travelling back-to-back with equal momentum. Each photon is massless, and has momentum. But the *system* of two photons is stationary. Each photon's momentum cancels the other; they have a center of momentum reference. In fact, for most pairs of photons we can find some reference frame in which there is a resting center of momentum.

We know, from measurements, that E^2 = m^2 + p^2 (using c=1 units for brevity) is a true relationship. Each photon has an energy but no mass, therefore E=p. But the system of two photons has no momentum... but still has energy. Therefore E=m. The SYSTEM of two massless particles has a mass itself.

In general, thermal motion of massless particles cancel out their net momenta to some rest frame. The energy of all those massless particles together has no momentum. Therefore, that energy must be mass, and can be nothing but mass.

Apr 07, 2016
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Apr 07, 2016
...just another example of pluralistic ignorance:


Meaning of course... facts everyone agrees on except you because you can't be bothered to actually learn what other people are saying.

Apr 07, 2016
why are photons massless? Because they don't couple to the Higgs field. Because the electromagnetic force propagates at c. Because that's the mass that a gauge boson has in an unbroken symmetry. Because it's the massless particle resulting from the combination of the primordial electroweak fields. Because we observe it to not have mass. Because the amount of deflection light takes around a body differs from what you might expect under mass-mass Newtonian gravitation by a factor of 2, IIRC. A whole host of data and experiment and theory and everything support that fact.

Apr 07, 2016
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Apr 07, 2016
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Apr 07, 2016
You haven't pointed out one logical paradox in what anyone is saying. You have repeatedly pointed out paradoxes in the thing you think is physics, but is not, because you don't know the physics for real. So instead of learning from people who actually know, you insist that your knowledge is correct (it isn't) and is full of paradoxes (which it is). You're simply starting from false pretenses. You're saying suppose P and Q, then doesn't P contradict Q? When P and Q are false to begin with.

Apr 07, 2016
supposed superluminal result: Again, you don't understand the words in the abstract to know what the scientist means when they write them. What they're calculating here is a long string of maths of regular EM that has a lot of cancellation terms that create a result that *looks like* a superluminal one, but is not. Essentially, the momentum of one charged particle can be used to predict where it will be in the future, and the other charged particle orbits around that future location, not the time-retarded one. Because the momentum of a particle creates a magnetic field in addition to the electric field by its charge. And for complicated maths reasons, those create effects that cancel out.

Stars lose mass because gas and ions leave their surfaces, predominantly. I've already explained above how multiple photons have a mass, so whatever mass loss exists from radiation I've explained to you already.

Apr 07, 2016
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Apr 07, 2016
What's the first thing we learn about Gravity? Objects fall at the same rate regardless of their mass. So it's absolutely trivial to plot the trajectory of a massless object that undergoes the same uniform acceleration as a massive one. Because you don't actually need the mass of the object to plot how it moves. The result from this approach is precisely the same as taking the limit of a particle's motion as its mass approaches zero. But the result is off by a factor of 2 compared to perfectly massless particles like photons.

The problem is that you think that the default state of a particle is to have mass. It's not. Mass is a property that has to come from something. Charge comes from the EM field, for instance. All particles are massless by default, unless we observe them to have mass. Therefore, not having observed mass of a photon, the scientific answer, until shown otherwise, is that a photon is massless.

Apr 07, 2016
"As I said in an earlier post, IMO Dark Matter existed long before the Big Bang".

How do you know this? Direct observation or shamanic trance? Do you believe in unicorns?
- Viko
The BB had no direct observation either, and yet it is proposed as fact. Even IF the BB started from a pinpoint as expressed by astrophysicists, there would have had to be room/place for all the Matter/Energy within that pinpoint to explode INTO. I am only suggesting that the room/place in which all Matter/Energy emerged was already populated with DM and that DM was/is inert and doesn't produce any energy of its own.
That my suggestion doesn't agree with mainstream science doesn't alter its possibility. I agree with the invisibility of DM, but I disagree with it having Mass/Energy. In order for DM to produce gravitation, it would need to have Mass of its own, in which case it would be an attractant to celestial bodies of Matter.

Apr 07, 2016
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Apr 07, 2016
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Apr 07, 2016
OK, single photon is massless and the three photons already have mass? Does it mean, that the mass of photon is not additive?

YES. MASS IS NOT ADDITIVE. Only when objects share a common frame of reference can you add the mass of those objects together. Whenever objects are moving with respect to one another, you cannot add their masses directly, you MUST use E^2 = p^2 + m^2. If you believe otherwise, you are wrong and inconsistent with a mountain of observational evidence.

Apr 07, 2016
Which experiment observed the mass of photon, actually?

None. No experiment has measured a mass of a photon. Many experiments have determined that the mass of a photon, if it existed, couldn't be above a certain value. But not one has found evidence that it has any mass whatsoever. So in the absence of evidence of mass, it is described as massless.

By example, we used to think neutrinos were massless. No experiment could find one. Then we found an experiment that did measure a property that could only occur if the neutrino has an actual mass. Since then we've been able to measure the difference in masses between kinds of neutrinos, but we still have work to do before we measure the mass of one itself.

Apr 07, 2016
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Apr 07, 2016
if the photons are moving in the same direction with the same momentum, then they are at rest (though in this case it's an abuse of the term for technical reasons) with respect to each other. therefore, the mass of these two photons, travelling in exactly the same direction with exactly the same momentum is 0+0 = 0; but for all the other photons the star emits, where they're not the same direction same momentum, we can find a mass that corresponds with those photons.

Let me reiterate and simplify. Most photons' momenta cancel out in a way that means that the collection of photons has some mass. Only in the case where photons have equal momentum (travelling in the same direction) does the system have no mass at all.

Feel free to search 'experiments limiting the mass of a photon' to look at the various experiments performed. This was not the field I worked in, so I don't have experience to talk about it.

Apr 07, 2016
obama_socks:
The BB had no direct observation either, and yet it is proposed as fact. Even IF the BB started from a pinpoint as expressed by astrophysicists, there would have had to be room/place for all the Matter/Energy within that pinpoint to explode INTO.


So... this is another case where misunderstanding the physics makes you think it's contradictory. The BB did not start from a pinpoint, in terms of what astrophysicists describe. Our part of the universe, what we can see, was at one point as small as a pinpoint. But there's more universe beyond what we're able to see. That additional space would have surrounded our pinpoint universe back then too.

While there's some disagreement about this, the data generally suggest that the universe is now and always has been infinite in size. What the big bang is is NOT an explosion, with stuff radiating away from a center. It's more like a loaf of bread rising, with new space being added between the material "stuff" within it.

Apr 07, 2016
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Apr 07, 2016
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Apr 07, 2016
So we did do that. There are other kinds of 'photons.' They're called W and Z bosons. Photons and W and Z bosons are all in the same family of particles. And for a very similar reason to neutrinos, we see that W and Z bosons should be the family members with mass (mass well predicted by theory, no less), and that the photon should be without mass. This is called Electroweak symmetry breaking.

About your example: It turns out that GR isn't *quite* as simple as mass=energy, mass curves space. There's a thing you can describe mass and energy and momentum and more with called a 'stress energy tensor.' Think of it as a description of all the stuff at any one point in space. That stress-energy tensor does describe something like gravity when you put in a spherical/point mass. But it describes something else when you put in a bunch of energy radiating out from a common point, even though that energy does have a mass associated with it. (ie, GR is a little more complex than your scenario)

Apr 07, 2016
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Apr 07, 2016
Conservation of momentum tells you what though? If you're firing your laser in one direction, the laser recoils in the equal and opposite direction. The system of laser apparatus (with recoil) and laser photons remains at rest, and the mass remains constant over the whole system. Essentially the same thing as a rocket engine.

Apr 07, 2016
obama_socks:
The BB had no direct observation either, and yet it is proposed as fact. Even IF the BB started from a pinpoint(...)had to be room/place for all the Matter/Energy within that pinpoint to explode INTO.


So... this is another case where misunderstanding the physics makes you think it's contradictory. The BB did not start from a pinpoint, in terms of what astrophysicists describe. Our part of the universe, what we can see, was at one point as small as a pinpoint. But there's more universe beyond what we're able to see. That additional space would have surrounded our pinpoint universe back then too.

While there's some disagreement about this, the data generally suggest that the universe is now and always has been infinite in size. What the big bang is is NOT an explosion, with stuff radiating away from a center. It's more like a loaf of bread rising, with new space being added between the material "stuff" within...

Thanks for clarifying the BB.

Apr 07, 2016
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Apr 07, 2016
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Apr 07, 2016
Because waves don't require mass. They're not radiating "matter" either. Energy. Energy and mass are related, but not equivalent.


WOW, you don't even know E=mc² is better known from Special Relativity as the Mass/Energy Equivalence Principle? No wonder you're unable to cogently explain ANYTHING about Energy, you deny the Equivalence Principle even exists.

So now you are way smarter than Einstein. You are espousing the same mistake that Hawking had to backtrack on, that there is such a thing as "Information Loss".


Apr 07, 2016
Why it should recoil, if the light is massless? At any case, it doesn't explain, why the lone photon shotted by laser should be massless and two or more photons shotted by the same laser already not.
There is actually interesting prediction of dense aether model, that the recoil of light beam should depend on wavelength of light used and for microwaves of longer waves it should become negative. The same would apply to radiation pressure exerted by this light: the beam of radiowaves should suck the obstacles instead of pushing them away.


Compose......when mass is transformed to energy "recoil" does not occur because there is no ACCELERATION as would be defined by KE= 1/2mv². Particles continuously changing velocity at speeds less than that of light-speed will always exhibit "recoil" but photons never exhibit recoil which has nothing to do with the Energy/Mass Equivalence Principle of Special Relativity that Shavera has so massively screwed up on.


Apr 07, 2016
I got the serious question on this stuffs. If photons "never exhibit recoil" like Bennie-Skippy just said, why they bounce off mirrors? And why they can make pressure to run a Crooke's radiometer? If they "never exhibit recoil" like Bennie-Skippy says wouldn't they just pass through the mirror and radiometer vanes?

I am not the scientist so maybe I thinking that out wrong.

Apr 07, 2016
NGC 1600 is 200 million light-years away, shouldn't we be observing gravitational waves produced by the stars in orbit around it's black hole?

Apr 07, 2016
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Apr 07, 2016
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Apr 07, 2016
why they bounce off mirrors? And why they can make pressure to run a Crooke's radiometer? If they "never exhibit recoil"


.....because light is not the source of the pressure that causes the vanes to rotate in the partial vacuum of the glass enclosure. The vanes will not budge even the slightest bit if the enclosure is in a state of a near perfect vacuum.

The energy imparted to the vanes is a result of expanding outer orbital electron shells of atoms caused by photons as they impart energy to the gas inside the glass case. As the outer orbital electron shell structures of the gases inside the the glass enclosure expands, the expansion imparts kinetic energy to the vanes causing them to rotate. No light pressure against the vanes involved here.

Apr 07, 2016
@shavera:
In general, thermal motion of massless particles cancel out their net momenta to some rest frame. The energy of all those massless particles together has no momentum. Therefore, that energy must be mass, and can be nothing but mass.
Wow!

That was a really cool explanation, if I could give you a 10 I would! That was a "eureka" moment for me, and I'm old and don't have many of those any more!

Apr 07, 2016
@RandomCommentGenerator

Welcome in! I'm enjoying this conversation very much and you're contributing to it significantly.

Apr 07, 2016
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Apr 07, 2016
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Apr 07, 2016
Essentially, the momentum of one charged particle can be used to predict where it will be in the future, and the other charged particle orbits around that future location, not the time-retarded one. Because the momentum of a particle creates a magnetic field in addition to the electric field by its charge. And for complicated maths reasons, those create effects that cancel out.
I know a good way to think about this that most people will get.

The net net is, magnetism and electricity are a single force; electricity is the representation of that force *without the speed of light delay* and magnetism is *the factor introduced by speed of light delay in the action of the electric force*. If we use a field representation of electromagnetism with the speed-of-light delay included in its action, there is no "magnetism," as a separate entity. It is our perception that there is no delay in its action that causes us to define two forces in the first place.

[contd]

Apr 07, 2016
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Apr 07, 2016
[contd]
Think about it this way:

Suppose two electrons are moving by your position as an observer. Suppose they are moving quite slowly. Their electrostatic fields will act upon each other, pushing them apart. This action will take place at a certain rate; the electrons will be accelerated away from one another.

Now suppose that they are moving at relativistic velocities. The electrons will experience time dilation (from the point of view of an observer). This will cause them to accelerate more slowly.

If you ignore relativity, then you will conclude that there is some extra force opposing the electric force; this force acts at right angles to their motion, and oppositely to the electric force. We call this force, "magnetism." Magnetism acts orthogonally to the motion of an electric charge, oppositely to the direction of the electric force.

Magnetism thus only acts on moving charges; without motion, there's no relativistic effect.

Apr 07, 2016
@Ira:
I am not the scientist so maybe I thinking that out wrong.
No, you got it exactly right.

Apr 07, 2016
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Apr 07, 2016
NGC 1600 is 200 million light-years away, shouldn't we be observing gravitational waves produced by the stars in orbit around it's black hole?
There are multiple reasons why such waves would be very weak from here and probably not detectable as a result.

1. The net momentum of such stars would be approximately symmetric in two dimensions (specifically the net plane of their combined orbits) constrained by the plane of the accretion disk around the black hole, and also in the case of a spiral galaxy by the plane of the galaxy itself, their origin. The net gravity waves produced would not be from the sum of the masses of the stars, but from their net momentum; and since most of those momenta would cancel out, the second mass in the equation would be far smaller than when two black holes coalesce, despite the total mass of the stars being comparable to a second black hole.

[contd]

Apr 07, 2016
[contd]
2. There is a "background" of gravity radiation in the universe produced by various events, including but not limited to black hole coalescences, neutron star orbital decays and coalescences, and the constant but individually very very small-- though additively huge-- gravity radiation from all orbiting bodies doing the same kind of radiating that we know happens in the black hole and neutron star cases (both of which are now observed facts, and the first of which has been detected by gravity wave observation at LIGO).

3. NGC1600 is very, very far away, and the gravity wave produced by a single star coalescing with the black hole would be very, very small, compared with the coalescence of two black holes coalescing.

[contd]

Apr 07, 2016
[contd]
4. Stars are not structurally nor gravitationally strong enough to withstand the tidal effects close to a supermassive black hole, so they are ripped apart into the accretion disk and their coalescence with the black hole is thus spread out over too much time to make anything but extremely weak gravity waves in the first place.

I will also point out that the "ringdown" signature of a black hole coalescence could not be present even if such waves could be observed.

Great question, @Nikstlitselpmur! I gave you a 5.

Apr 07, 2016
.....because light is not the source of the pressure that causes the vanes to rotate in the partial vacuum of the glass enclosure. The vanes will not budge even the slightest bit if the enclosure is in a state of a near perfect vacuum.
Bennie-Skippy, you don't want to make a habit of letting peoples see ME having to set you right. You got that exactly backwards. The only way the Crookes radiometer works IS IN A STATE OF NEAR VACUUM.

The energy imparted to the vanes is a result of expanding outer orbital electron shells of atoms caused by photons as they impart energy to the gas inside the glass case. As the outer orbital electron shell structures of the gases inside the the glass enclosure expands, the expansion imparts kinetic energy to the vanes causing them to rotate. No light pressure against the vanes involved here.
Bennie-Skippy, you bump your head Cher? That is way more stupid than most of the stuffs you say here.

Apr 07, 2016
@Ira, sorry but a Crookes radiometer does actually not work in a very hard vacuum; Benni is right about that, at least. The effect is caused by absorption of the light by the dark sides of the vanes, heating them, causing them to heat the gas in contact with them (and a little bit by heat radiation transfer to the gas), and causing a net transfer of gas from the light to the dark sides because of the pressure reduction due to the heating (see the ideal gas law), and pushing the black vanes and pulling the light vanes. So Benni is wrong about that, with all the "expanding outer orbital electron shell structures of atoms caused by photons as they impart energy to the gas" pseudoscience.

The radiometer you want to use to prove your point is not a Crookes radiometer, but a Nichols radiometer, which *does* measure radiation pressure. https://en.wikipe...diometer

I give you a 5 anyway, me, cher. And I fix your example, me. :D

Apr 07, 2016
There are multiple reasons why such waves would be very weak from here and probably not detectable as a result.


Thanks for taking the time to respond, could I pick your brain one more time?

Gravity is infinite in its reach,however its effects decrease over distance measured by the inverse square law. For example the Sun (one solar mass) propagates enough gravitational pull to hold the Oort cloud (one light year distant) in orbit around it. Wouldn't an object of 17 billion solar mass's at 2 hundred million light years away excerpt a gravitational pull on the Milky Way of some significance?

Apr 07, 2016
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Apr 07, 2016
There are multiple reasons why such waves would be very weak from here and probably not detectable as a result.


Thanks for taking the time to respond, could I pick your brain one more time?
Sure!

Wouldn't an object of 17 billion solar mass's at 2 hundred million light years away excerpt a gravitational pull on the Milky Way of some significance?
Remember that gravity decreases as the inverse of the *square* of distance; thus, 200 million light years introduces a factor of 40,000,000,000,000,000, or forty quadrillion, into the equation. This reduces the factor of 17 billion and means that the ratio of the attraction of the black hole 200 million light years away to the attraction of the Sun is exactly 1:2,352,941.1764705882352941176470588, or that the attraction of the black hole for the Milky Way is about two million times weaker than the attraction of the Sun for the Oort cloud.

Apr 07, 2016
@Ira, sorry but a Crookes radiometer does actually not work in a very hard vacuum; Benni is right about that, at least.
Non need to apologize. Unlike a lot peoples here I don't mind getting some help sometimes. And unlike a lot of peoples here, I get things mixed up sometimes. So thanks.

The radiometer you want to use to prove your point is not a Crookes radiometer, but a Nichols radiometer, which *does* measure radiation pressure. https://en.wikipe...diometer
Cool, now I know better. Thanks again.

I give you a 5 anyway, me, cher. And I fix your example, me. :D
Thanks for that again too.

Apr 07, 2016
Benni:
WOW, you don't even know E=mc²

Please do read all my comments. Above I mention, several times E^2=p^2 + m^2 (or in not c=1 units, E^2 = (pc)^2 + (mc^2)^2). E=mc^2 is only a specific VERSION of this equation when momentum is zero. Please do try to keep up or to learn actual physics before complaining about what's wrong in physics.

compose:
Not like you actually listen to my many answers to your dishonest questions, but the laser recoils because light has momentum. Momentum does not require mass, even though you may be most familiar with the physics 101 definition of momentum, but again there's more physics beyond the introductory lessons.

Apr 07, 2016
Niks:
Gravity actually *isn't* infinite in range. Newton's gravity is only an approximation of reality. And it's an approximation that only works within certain ranges near a massive body. Too close to the body and new GR effects appear (Mercury's orbit, for instance), too far from the body and the expansion of space distorts the result of GR too much to resemble Newton's gravity.
I've worked the maths here: https://www.reddi...ng_like/

Apr 07, 2016
Hey @shavera, if I understand the implications of the Higgs correctly, it gives mass to the massive particles. And if I understand quantum mechanics correctly, momentum-- not mass-- is an intrinsic property of particles, not involved with any interaction that provides it. One concludes that *all* particles have momentum, but only *some* particles-- those which have a Higgs charge-- have mass. The mass for massive particles is determined by their energy, and again, also if I understand quantum mechanics correctly, energy is another intrinsic property of particles.

Is this correct?

Apr 07, 2016
no, not all particles have momentum. This is trivially true when we say that a particle is at rest.

All particles have energy, because energy is the conservation quantity related to time-translation invariance. (ie when a physical description of a system stays the same over time, energy must be conserved. A particle existing over time must, therefore, have energy.)

Moreover, in relativity, when you want to find the separation between two 'events' in space-time, you use a formula (note there's a sign convention issue I'm glossing over) like this:
d^2 = (ct)^2 - x^2 - y^2 - z^2 . Generally speaking the stuff on the right is called a four-vector (t,x,y,z) and the value on the left is a "Lorentz-invariant quantity" (some number that all observers will agree on, regardless of relative motion). (*cont.)

Apr 07, 2016
Play around with some derivatives a bit and you get: (mc^2)^2 = E^2 - cPx^2 - cPy^2 - cPz^2. If you're familiar with modern physics all sorts of bells and whistles should be going off. Distance and Momentum have the same kind of relationship as Energy and time. There's a space-time 4-vec t,x,y,z and an energy-momentum 4-vec E,Px,Py,Pz. Stuff like Heisenberg's uncertainty principle relating Ps and Xs, E and t. Wave equations and so on.

There are deeper mathematical reasons with this, largely related to Noether's theorem. For every symmetry (the way a physical description of something can be modified but not actually change, like shifting a pendulum system 1m to the left) there must be a conserved quantity (left-right linear momentum). Every conserved quantity is a generator of that symmetry (in group theory meaning of the word generator)

Apr 07, 2016
no, not all particles have momentum. This is trivially true when we say that a particle is at rest.
Hmmm, I don't think that momentum = 0 means the particle has no momentum, but I do think that mass = 0 means the particle has no mass, because momentum is intrinsic but mass is not. But I'm willing to be convinced. I was more interested in whether my statement that momentum is intrinsic but mass is not was correct. Perhaps I phrased it badly.

I recognize d^2 = (ct)^2 - x^2 - y^2 - z^2 as a variant of the Minkowski spacetime interval equation, and know the sign convention, but others might not so it's good you mentioned it.

If you're familiar with modern physics all sorts of bells and whistles should be going off. Distance and Momentum have the same kind of relationship as Energy and time.
Yes, lots of bells and whistles, because both those pairs are Heisenberg complementary. That's pretty awesome; another thanks for you on this thread!

[contd]

Apr 07, 2016
[contd]
There are deeper mathematical reasons with this, largely related to Noether's theorem.
So Noether's theorem is also partly derived from GRT? Now that is fascinating; I suppose I should have known it, but you've made the basis much clearer with the overview you've provided of the underlying mathematical reasoning. You're totally on a roll!

Thinking about it, I note that momentum is Heisenberg complementary but mass is not; I strongly suspect this is what I was poking around the edges of.

Apr 07, 2016
Shavera,
Your recent comment about momentum, mass, distance and symmetry, etc, just took my eyebrows to the top of my head with all the whistles and alarms going off! Schwing!
While not deeplyt versed in the math (I'm an artist, -I don't have the attention span for it), I can see the "symmetry" and similarities you refer to.
Thanks for the understandable/relate-able descriptions!

Apr 08, 2016
So Benni is wrong about that, with all the "expanding outer orbital electron shell structures of atoms caused by photons as they impart energy to the gas" pseudoscience.


You're wrong Schneib, this is called the Thermal Expansion of gases & is what initiates movement of the vanes:

The energy imparted to the vanes is a result of expanding outer orbital electron shells of atoms caused by photons as they impart energy to the gas inside the glass case. As the outer orbital electron shell structures of the gases inside the the glass enclosure expands, the expansion imparts kinetic energy to the vanes causing them to rotate.


You also initiate movement of the vanes by quickly cooling the bulb, which effect causes outer orbital electrons to move into lower orbits of the electron shell structure. It is this expansion/contraction that initiates movement of the vanes. This windy explanation you launched into is simply a followup effect subsequent to thermal expansion.


Apr 08, 2016
E=mc^2 is only a specific VERSION of this equation when momentum is zero.


Keep trying to walk back that massive screwup Shav. If you didn't have Wiki quotes as a basis to chat from when you post to this site, you would be totally nonfunctional in discussing anything about nuclear physics, you made that crystal clear when you couldn't identify E=mc² as the Mass/Energy Equivalence Principle of Special Relativity.

Now it has really become entertaining watching as you try to walk back that screwup with a windy explanation that what you said is not what you meant even you were crystal making this totally ludicrous statement:

Because waves don't require mass. They're not radiating "matter" either. Energy. Energy and mass are related, but not equivalent


.......and now you want to convince this Nuclear/Electrical Engineer that your massive screwup was intended to be specialized application about something you were never talking about in the first place.

Apr 08, 2016
Benni: If you're a nuclear engineer and you don't understand 4-momentum, please let me know which power plants you work at so that I can be sure I don't live near any of them. That's like... basic relativity. E=mc^2 is known as the rest-mass energy equation for a very good reason. Because it's the energy of a mass at rest. When P=0.

DS: Momentum isn't an intrinsic property. Trivially, as one changes their relative motion to a particle, its momentum appears to change, all the way to moving along-side it, so that it seems at rest. Mass is an intrinsic property of a particle. For massless particles, there's no physical meaning to reference frames moving at c, so massless particles are always moving at c in all physical reference frames, and thus their energy is always their momentum... but again, depending on relative motion, it red or blue shifts momentum or energy respectively, so those aren't 'intrinsic' to the photon either.

Apr 08, 2016
Shav......your "walkback" isn't coming off very well. You should first get well grounded in nuclear physics from sitting in a classroom & actually learn to do the math in the the forms of Differential Equations like I have.

I can design a nuclear reactor system as well as design electronic circuits. I spent six years in Engineering School. What is your greatest "Claim to Fame"? Doing Stumpy & Schneib name calling imitations?

You can't even correctly identify the Mass/Energy Equivalence Principle from Einstein's Special Relativity, so for what good reason do you imagine I should be impressed with all the conjectured drivel with which you & Schneib engage one another with as you break your arms patting one another on the backs talking about "gluons".

Apr 08, 2016
OOoooohhh you know differential equations. They teach that all the way back in like... 2nd year of undergrad. That's sooooo much experience in physics I cannot possibly match your intelligence. You're sooooo well informed about relativity that you can only repeat the basic platitude any pop-culture reference to science includes without the slightest understanding that it's only part of a larger equation. Mass is a kind of energy, but not all energy is mass. Energy has precisely two forms, mass and motion. Mass is the energy intrinsic to something in all rest frames, regardless of relative motion. Momentum is the energy associated with motion, extrinsic and dependent upon relative motion. Energy and Momentum form a four-vector whose magnitude is the mass of the particle or system being described.

But sure keep repeating your big boy words like "differential equations" and "mass/energy equivalence principle." Hope it makes you feel like you're relevant.

Apr 08, 2016
Thanks, @shavera, I'm busy so I'll have to think about that. I'm sure I'll have more questions! :D

Apr 08, 2016
@Benni
Compose......when mass is transformed to energy "recoil" does not occur because there is no ACCELERATION as would be defined by KE= 1/2mv². Particles continuously changing velocity at speeds less than that of light-speed will always exhibit "recoil" but photons never exhibit recoil which has nothing to do with the Energy/Mass Equivalence Principle of Special Relativity that Shavera has so massively screwed up on.

Why do you post here when you don't even know that KE= 1/2mv² is a nonrealtivistic approximation that does not apply to photons?
Worse yet, he doesn't know the difference between kinetic energy and acceleration.

Apr 08, 2016
OK, @shavera, I get your point about momentum not being intrinsic. And I'm not going to ask the obvious question about whether position is intrinsic (it being the Heisenberg complement of momentum) because that's a result of SRT: there is no special position in the universe from which other positions can be referenced. All inertial frames are equivalent.

Since I learned "old math" SRT, it seems to me mass isn't intrinsic either; it also is dependent upon the state of motion of the observer. An observer sharing an inertial frame at rest with respect to the particle measures the particle's rest mass, whereas to an observer in a frame that's not at rest WRT the particle its mass is greater. I know they don't teach it that way these days, but it seems to me as valid to say that the particle gains mass as to say it gains energy.

So my question is, what remains as the intrinsic properties of the particle?

Apr 08, 2016
I'll start the answer:
Electric charge
Strong charge
Weak charge
Spin
Handedness
What else?

Apr 08, 2016
@shavera, don't misunderstand my post as I'm asking a question and I think the point is I may not quite understand your position on momentum not be intrinsic. Should one differentiate between momentum and angular momentum of a particle since, as I understand it the latter is intrinsic (spin). I'm not trying to be clever here (I can't 'cos I'm a layman Ha!) just a point of clarification that's all.
Take my hat off to you, Da Schneib, Whydening Gyre, Phys1 (Nikstlitselpmur, new here?) etc. These posts make great reading, maybe someone ought to put them together to make a book. Keep it up very informative.

Apr 09, 2016
Hi @Mimath, I got that one.

Yes, one must absolutely distinguish between spin and linear momentum; and one also must distinguish between classical angular momentum and spin angular momentum because they are not the same.

All particles are divided into two moieties by spin. There are the spin-1/2 and 3/2 and 5/2 etc. particles, called fermions, and the spin-0 and 1 and 2 etc. particles, called bosons. They behave in very different and often opposite ways. And the most important of the ways they behave oppositely is called the Pauli Exclusion Principle. Only fermions obey exclusion; bosons don't.

Pauli exclusion means that two identical fermions cannot be in the same place at the same time. Thus, as a group of fermions accretes, they take up space, and we see groups of fermions as matter.

Bosons obey an opposite rule: they not only are capable of being in the same place at the same time, they are *more likely* to be than not. This is called "coherence."

[contd]

Apr 09, 2016
[contd]
Because of coherence, and because bosons don't bounce off one another the way fermions do, we see groups of bosons as energy.

The reasons for exclusion and coherence are based in the wave function, and in how the probabilities the wave functions of two particles add up. The wave functions of bosons and fermions are essentially different; spin-1/2 means that a particle rotated through a full turn, 360°, is *distinguishable* from the unrotated version of itself. Spin-1, on the other hand, rotated the same way, is *indistinguishable*.

Now, in classical physics, a full turn is an identity operation; that is, if you turn any situation 360°, it is indistinguishable from before. This is a property of spacetime. If you think about it you will see that this is so.

[contd]

Apr 09, 2016
[contc]
A full turn is an identity operation for bosons, but not for fermions; and the distinguishability of a fermion from it's full turn alternative means that the wave equation for these full turn alternatives is opposite for fermions, but the same for bosons. And whenever you determine the wave function for a particle, you have to add up all the alternatives to get the final value, and square it to get the probability. Because the alternatives for the fermions are opposite, they cancel; this means their added up alternatives equal zero, and the square of zero is zero, so the probability of two identical fermions being at the same place at the same time is zero. On the other hand, the alternatives for bosons are equal; thus, their sum is non-zero, and the square of a non-zero number can never be zero, so the probability of two identical bosons being at the same place at the same time is non-zero, and greater than the probability for one boson alone.

[contd]

Apr 09, 2016
[contd]
This is the reason for the essential difference between mass and energy as we observe it. This cancellation and zero probability for fermion alternatives is Pauli exclusion.

In what exact manner are the alternatives opposite or the same, you might ask? The answer is phase. The phase of a boson subjected to the rotational identity (360° rotation) is the same as it was before; but the phase of a fermion is opposite, and this is the meaning of "spin-1" and "spin-1/2."

None of this should be confused with the existence of opposite spins; in fact, two fermions of opposite spin *are* allowed to exist in the same place at the same time, and this is the reason that the electrons in an atom in electron shells are always of even number, 2, 8, 18, 38, and so forth; they are built up from pairs of electrons with opposite spins. The first shell is only two such electrons, and they are always of opposite spin since the probability for them to have the same spin is zero.

[contd]

Apr 09, 2016
[contd]
Obviously, linear momentum and classical angular momentum do not behave in these ways; otherwise classical angular momentum could cancel after the identity operation just as half-integer spins do, and it doesn't. The identity rotation leaves both linear momentum and classical angular momentum unchanged, both in vector (i.e. direction) and in phase.

And that's why spin angular momentum is *essentially different* from both linear momentum and classical angular momentum.

Incidentally, it's worth mentioning that coherence is the reason that laser beams stay so close together, and also the reason for the rather odd behavior of Bose-Einstein Condensates, or BECs, which are groups of fermions that all have integer spins when added together and therefore behave like bosons.

And that's another excellent question from you!

Apr 09, 2016
@Da Schneib, many thanks. Yes, I understand. My (small) library is helpful in such but of course there is no substitute for experience, and here I mean, people who know. There are many questions I would like to ask of a book and/or sometimes books are written without full explanation and/or examples. Being a lab technician for most of my working life I am more comfortable with a bit of theory then examining the practice then adding a bit more theory and repeating. Obviously I have never been able to do that with QM (or GR etc) and that's why I come here. Sometimes I might differ (this is mostly about Time and related topics) but in the main I learn much. I am thankful for sites like this one because one can also get up to date info. I have another question that is mathematical and I think would be a reasonable 'next step' to your posts but I want to research it a bit more so perhaps will ask in the future. I really do appreciate you taking (and others) for you time.

Apr 10, 2016
My (small) library is helpful in such but of course there is no substitute for experience, and here I mean, people who know. There are many questions I would like to ask
@Mimath224
hey, i may be able to help a little: remember when i linked the MIT OCW site?
http://ocw.mit.ed...=science

it has lots of courses... but when you start a course, it often will tell you to start a profile at openstudy.com

http://openstudy....0Physics

there are QM (& many more) courses at the OCW site (MIT)
on the open study site there are math, physics and OCW specific links

the site (open study) has a lot of people who may be able to help

it may well help you with the problems you come across on PO, when you want to question the math or physics but need some help working through a problem

there are often professors helping others with work there, so it may be a good place to consider

Apr 10, 2016
@Captain Stumpy Thank you, unfortunately my own 'field of expertise' takes up much of my time so a proper structured study course is not possible. I do watch many of the MIT videos and others too (mostly on the math side) when I'm free. I will sign on the forum though. Thanks for your time to tell me anyway. Hope you have a good day.

Apr 10, 2016
Does MIT have a course on manners and professional conduct?

Real professionals do not scream "LIAR!" at others, like Sgt. Grumpy.

Apr 10, 2016
Thank you, unfortunately my own 'field of expertise' takes up much of my time so a proper structured study course is not possible
@Mimath224
You're welcome, and i understand
I will sign on the forum though. Thanks for your time to tell me anyway. Hope you have a good day
yeah, open study has a lot of helpful people on it... Enjoy that. if you link it through the video and/or class on the MIT math program, it will take you directly to the MIT OCW forum, just FYI

enjoy your day as well.
PEACE

Apr 11, 2016
I am curious: every black hole must contain second event horizon at their center (because gravity forces are compensating each other at center of gravity). Is it filled with mass or it hollow?

Apr 11, 2016
And, if it is "hollow" is it because it empties into some other space-time?

Apr 11, 2016
This comment has been removed by a moderator.

Apr 11, 2016
It would support Hollow Earth theory, according to which there is no gravity field inside it...;-)


Earth cannot be hollow, because it is not a black hole, so there is no event horizon in Earth core.

And, if it is "hollow" is it because it empties into some other space-time?


No. Gravitational force of black hole peaks at it surface and then it decreases in strength up into space and down to center. So, at some point below surface, gravity force will be no longer strong enough, so we have second event horizon, so particles should not be able to fall trough this event horizon. I.e. black hole cannot fill it center. Or can?

Apr 11, 2016
so particles should not be able to fall trough this event horizon. I.e. black hole cannot fill it center. Or can?
We don't yet know what happens inside a black hole but there are many, many interesting ideas, from an end of spacetime itself at the horizon to firewalls to singularities. The good news is we now have a way to infer what actually happens inside them by studying the "ringdown" phase of BH-BH mergers. We will soon be able to tell which of the many ideas are not correct, and which one(s) might be.

Apr 12, 2016
every black hole must contain second event horizon at their center (because gravity forces are compensating each other at center of gravity
It would support Hollow Earth theory, according to which there is no gravity field inside it...;-)
- compose
That is absurd. I HOPE that you are only joking.

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