Physicists find black holes in globular star clusters, upsetting 40 years of theory

Nov 04, 2013 by John Davis
The black hole above was discovered in the M62 star cluster, which is 23,000 light years away from Earth. These star clusters contain some of the oldest stars in the galaxy.

(Phys.org)—A Texas Tech University astrophysicist was part of a team of researchers that discovered the first examples of black holes in globular star clusters in our own galaxy, upsetting 40 years of theories against their possible existence.

Tom Maccarone, an associate professor of physics, said the team detected the existence of the black holes by using an array of radio telescopes to pick up a certain type of radio frequency released by these black holes as they eat a star next to them.

The results were published in The Astrophysical Journal and featured in the National Radio Astronomy Observatory's ENews news bulletin.

Globular are large groupings of stars thought to contain some of the oldest stars in the universe. In the same distance from our sun to the nearest neighbor, Proxima Centauri, its nearest neighbor, these globular star clusters could have a million to tens of millions of stars, Maccarone said.

"The stars can collide with one another in that environment," Maccarone said. "The old theory believed that the interaction of stars was thought to kick out any black holes that formed. They would interact with each other and slingshot black holes out of the cluster until they were all gone."

He compared it to water vapor coming off a hot cup of coffee. As some water molecules get hot enough to turn to steam, they are let go from their environment to float off into the atmosphere even though the coffee may be below the boiling temperature of water.

The old theory stated that the would kick the black holes out in the same fashion – occasionally, some black holes would have enough energy to escape the cluster, and gradually, they all would leave.

While the theory may still be displaced, Maccarone said it might still be somewhat true. Black holes might still get kicked out of globular star clusters, but at a much slower rate than initially believed.

Radio image (left) and x-ray image (right). The yellow circle shows the black hole found in the M62 star cluster in our Galaxy. The red circle denotes a neutron star close by.

Black Hole Spotted

In 2007, Maccarone made the first discovery of a black hole in a globular star cluster in the neighboring NGC4472 galaxy. But rather than finding it by using radio waves, Maccarone found it by seeing an X-ray emission from the gas falling into the black hole and heating up to a few million degrees.

"Six years ago I had made the first discoveries in other galaxies," he said. "It's surprisingly easier to find them in other galaxies than in our own, even though they're a thousand times as far away as these in our own galaxy are."

This year, he and his team discovered two examples of globular star clusters in our own galaxy which host black holes by finding radio emission by using the Very Large Array of in New Mexico.

"As the black hole eats a star, these jets of material are coming out," he said. "Most of the material falls into the black hole, but some is thrown outwards in a jet. To see that jet of material, we look for a radio emission. We found a few radio emissions coming from this that we couldn't explain any other way."

Maccarone said seeing black holes in globular clusters may provide a way for them to get close enough to one another to merge into bigger .

"These mergers may produce the 'ripples in spacetime' we call gravitational waves," he said. "Trying to detect gravitational waves is one of the biggest problems in physics right now, because it would be the strongest test of whether Einstein's theory of relativity is correct."

Other researchers included Laura Chomiuk and Jay Strader at Michigan State University; James Miller-Jones at Perth Curtin University in Perth, Australia; Craig Heinke at University of Alberta in Edmonton, Alberta, Canada; Eva Noyola at the University of Texas at Austin; Anil Seth at University of Utah; and Scott Ransom at the National Radio Astronomy Observatory in Charlottesville, Virginia.

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More information: iopscience.iop.org/0004-637X/777/1/69/article

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User comments : 83

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foolspoo
1.6 / 5 (16) Nov 04, 2013
another character on the first page of our book of understanding... so much to learn. so little is understood. an open mind is the only way forward.
Tuxford
1 / 5 (23) Nov 04, 2013
No surprise here. See my comment of Feb 15 in the following. I predicted as such. Only, they are not entirely black, and not entirely holes.

http://phys.org/n...ter.html

And my comments about the clusters' origin in these.

http://phys.org/n...lky.html

http://phys.org/n...ole.html

Still the merger mania continues in the faint hopes of the fanciful minds of modern astronomers.
katesisco
1 / 5 (16) Nov 04, 2013
As for the bright young stars close to the MW center, a burp from the bh would produce the extremely hot pressurized gas that is needed and there would be no call for these fantastical collisions of two bh or galaxies.
antialias_physorg
3.8 / 5 (4) Nov 04, 2013
Assuming that black holes do get kicked out as per the old theory: With that many stars in close proximity (even colliding sometimes) shouldn't there also be a production rate of black holes in such a cluster?
If so then you should never have a total lack of them but get an equilibrium (or near equilibrium) number after some time.
Lurker2358
1.1 / 5 (17) Nov 04, 2013
Conservation of Angular Momentum defeats the old Theory.

If a close encounter gives a black hole enough momentum to be kicked out, then "something" of stellar size got thrown deeper into the core of the cluster, where it can likely collide with something else and make a new black hole.

I agree with A_P.

Even if the BH are being kicked out, there would almost always be replacements until equilibrium happens.
RealScience
4.2 / 5 (5) Nov 04, 2013
With that many stars in close proximity (even colliding sometimes) shouldn't there also be a production rate of black holes in such a cluster?
If so then you should never have a total lack of them but get an equilibrium (or near equilibrium) number after some time.


Essentially all stars in the cluster form at the same time. Black holes only form from heavy star (>~~10 solar masses) and these have short lifetimes (<~50,000,000 years). So black holes form for a while but then stop forming when their heavy progenitor stars have all died. Thus today's clusters should have formed black holes only for ~0.5% of their lifetime.

As you point out, stellar mergers can create bigger stars that can create black holes. But this slows down as the stars get smaller and it takes more of them. However kicking out of black holes also slows down as the cluster's heaviest stars die, so an occasional black hole should survive.
Tuxford
1.4 / 5 (17) Nov 04, 2013
Worth noting that multiple grey holes have already been discovered in a cluster.

http://phys.org/n...tml#nRlv

RealScience
4 / 5 (6) Nov 04, 2013
-continued-
Also black holes will sometimes merge, and heavier black holes are harder to eject. On the other hand the merger may also kick the combined black hole out, so the merged black hole also has to be 'lucky' to stay in the cluster.

From this I would expect the black hole population in old clusters to be bimodal - some clusters will retain an ancient mid-sized black hole of perhaps a few hundred or even a few thousand stellar masses, and others will have younger merger-induced minimal-mass black holes, with not many having between a few tens and a few hundreds of stellar masses.
barakn
5 / 5 (3) Nov 04, 2013
The high density of stars in a globular cluster should allow them to very efficiently capture foreign black holes via dynamical friction.
cantdrive85
1 / 5 (21) Nov 04, 2013
Tom Maccarone, an associate professor of physics, said the team detected the existence of the black holes by using an array of radio telescopes to pick up a certain type of radio frequency released by these black holes as they eat a star next to them.
The results were published in The Astrophysical Journal and featured in the National Radio Astronomy Observatory's ENews news bulletin.


So, is the APJ part of Marvel or DC Comics? That's one fanciful piece of fiction right there!
aroc91
5 / 5 (5) Nov 05, 2013


So, is the APJ part of Marvel or DC Comics? That's one fanciful piece of fiction right there!


What a compelling mathematical argument. You should get that published.

RJOGuillory
1.2 / 5 (17) Nov 05, 2013
...love to read about physics and the study of how the Universe works....definitely not a religious person...(in a standard human style)...as I have no idea of the "context" of our universe or existence....as much as I love to read about the genius of learning more and more of how our world works....when does the work of explaining our existence...and putting our existence into some "context" happen?

I mean, what lays beyond the things you can study with radio-telescopes, etc....why do we exist? If there is a God.....who is their God? Can physics get to the point where they can "explain" that? I know religion has been trying for thousands of years.....but I think for the most part, other than "civilizing" mankind to some degree...religion = control...not explanation of the context of our existence....then again...there is always the blind obedience to an "all-powerful God...that has always existed"...ha!

Regards,

RJ O'Guillory
Author-
Webster Groves - The Life of an Insane Family
Fleetfoot
4 / 5 (4) Nov 05, 2013
If there is a God.....who is their God? Can physics get to the point where they can "explain" that?


Nope. If powerful beings are bound by the physics of the universe, we now call them "aliens", not gods. If gods are then by definition non-physical, science can never prove them to exist. The Russell's Teapot argument means you can never disprove them.
Fleetfoot
5 / 5 (3) Nov 05, 2013
As you point out, stellar mergers can create bigger stars that can create black holes. But this slows down as the stars get smaller and it takes more of them. However kicking out of black holes also slows down as the cluster's heaviest stars die, so an occasional black hole should survive.


"Evaporation" of general stars has the effect of hardening the cluster, so as it cools (dynamically speaking) mergers should become more commonplace. The higher fraction of blue straggglers in globulars seems to confirm this, and if they can produce BH then they may keep the equilibrium level a bit higher.
GSwift7
3.7 / 5 (7) Nov 05, 2013
Several comments above, in regard to rates of collision and mergers.

Since the observation above detected a radio source of infalling matter, the black hole in question has actually been caught in the act of absorbing another star. I would say that counts as proof enough for me that mergers continue in these systems.

There's only two things I know of that can generate the radio signal they see here. One of them is a black hole, and the other is cantdrive's mystical plasma electricity perpetual motion machine galactic radio antena.

So I must agree with anti_alias' comment above in regard to the likelihood that any given globular cluster will contain some quantity of black holes. I can't think of any logical reason that the cluster would selectively toss out objects larger than 10 solar masses, but not objects smaller than that. As far as orbital mechanics go, a black hole is mass with inertia, just like any other object.
RJOGuillory
1 / 5 (14) Nov 05, 2013
Dippy....

....is this the best you can manage with regard to my reasonable and appropriate comment?

...."Damn Skippy, this is an article about black holes in globular star clusters. I realize that you are claiming to be insane, but when you are also a moron, maybe the best thing you can do is SIT DOWN and SHUT UP. Golly gee where are all you idiot democrats coming from?"...

Now...if "black holes" do not have some relationship to the existence of our cosmos...then why would people be studying them...commenting on them....and looking to understand them...? If that doesn't have anything to do with understanding our existence...or you cannot see that....I hope no one is wasting their money on someone with such a limited imagination. I can't imagine finding out that I'd spent my funds on someone with such a limited, one-sided outlook who felt the need to attack someone for a neutral, conversational comment...?
You must be a very sad, angry person.

Regards,

RJ O'Guillory
RealScience
5 / 5 (2) Nov 05, 2013
"Evaporation" of general stars has the effect of hardening the cluster, so as it cools (dynamically speaking) mergers should become more commonplace. The higher fraction of blue straggglers in globulars seems to confirm this, and if they can produce BH then they may keep the equilibrium level a bit higher.


Yes, individual mergers become more frequent. But since the remaining stars are much smaller it takes the same star merging again and again to become massive to become a black hole. In an >11 billion year old cluster the largest un-merged stars will only be the mass of the sun.

There will be corpses that are more massive, but since larger stars shed much of their mass at the ends of their lives, even these are not as massive as one might think so even with 5-billion-year-old corpses it will take several mergers.
RealScience
5 / 5 (3) Nov 05, 2013
I can't think of any logical reason that the cluster would selectively toss out objects larger than 10 solar masses, but not objects smaller than that


When lighter stars get tossed out the massive ones tossing them settle toward the center of the cluster. Light objects outnumber massive ones by such a large ratio that losing many for each massive star makes little difference to 'the swarm'.

But as the massive object settle to the VERY dense center of the cluster, they frequently interact among themselves, leading to a high rate of heavy objects getting kicked out.

As the cluster ages, all the heaviest objects become black holes. Asymmetric merges among these are also theorized to produce a gravity-wave kick that can also kick the merged hole out.

How efficient these processes are at kicking out massive objects is still very much in debate, but the biggest hole should survive, and mid-sized one should settle faster than small ones and hence be kicked out faster.
-cont-
RealScience
3.7 / 5 (3) Nov 05, 2013
And as well as getting kicked out faster, the mid-sized black holes would also fall prey faster to to the larger central hole.

Therefore I would expect one big (by cluster standards) black hole to occupy the middle, and a depleted range of mid-sized black holes (depleted relative to the number formed in the cluster's life), around it, and then a decent number of smaller black holes that are still migrating inward.

The population of smaller black holes would be replenished by mergers of stars, white dwarfs, and neutron stars, and the merged entities would settle inward. While an equilibrium would thus be established, that equilibrium would decrease over time as the population of pre-merger building blocks became depleted of larger cores (by mergers and migrations) and larger stars (through supernovas losing mass at the end of their lives), requiring more complex merge histories to aggregate enough mass to form a black hole.
GSwift7
3.4 / 5 (5) Nov 06, 2013
to RealScience:

Yes, that makes sense, except when it doesn't happen that way. The interaction between stars in a cluster should be similar to planets in a solar system. Some get pushed inwards, some get kicked out. Our system has little guys in the center, largest planets half way out, and the medium planets fartest out. However, we frequently observe systems with the largest planets in the smallest orbits, and we think we see them very far out as well. I know it's not exactly the same, but the transfer of angular momentum is comparable. I guess my point is that random chance seems to be very poweful, perhaps dominating over any systematic process, in these types of interactions. I'm not surprised to see numerous exceptions to the general rules in clusters. The group as whole should show general patterns like what you describe, but careful observation should also reveal anomalies with some regularity.
RealScience
3 / 5 (4) Nov 06, 2013
@GSwift - Yes, it has some resemblance to planet formation and planet migration. However there are significant differences as well:
In a planetary system the central sun exceeds the entire mass of the planets by a huge margin.
Also while the initial planetesimals may number in the millions, the finished planets do not, so chance has a bigger role to play with smaller numbers of objects.
And planetary systems also tend to be quite planar, whereas globular clusters have spherical symmetry.

But I agree that the 'only one hole survives' theory probably greatly underestimates the variability of clusters, and even the graded distribution of hole sizes migrating inward is too simplistic to cover more than the prototypical case.

You said it very well with:
The group as whole should show general patterns like what you describe, but careful observation should also reveal anomalies with some regularity.


RJOGuillory
1 / 5 (13) Nov 06, 2013
Dippy....again...for such a "smart person"....is this the best you can do?

..."You mean your comment about seeing beyond radio telescopes and finding god? I suppose that is reasonable to a dude who wrote a book about his genetic insanity. But appropriate? Do you really think a god has something to do with black holes? Or radio telescopes? You should leave your god stuff in that black hole of a brain you have and just SHUT the hell UP. Damned democrats, always with your wordy foolishness. Sit down Skippy and let the smart people teach you something"

If you slowed your anger and brain down a bit...you might want to try reading my comment again, and understand that it was not in support of any God, nor was it any kind of challenge to the physics field....it was a fairly simple question ....can either of those two entities..religion or physics.... explain our existence?

Why does that anger you so much?

For such a "smart person"...you must lead a miserable life?

RJ....
RJOGuillory
1 / 5 (13) Nov 06, 2013
Dippy...

You've got to stop embarrassing yourself...especially among your "genius compatriots" on this site...(many of whom I admire and are polite to me )

The way you respond to serious questions is really fascinating for someone who is supposed to be a "scientist" searching... "for answers"...?

Regarding my question about our "existence" and your claim that...."it is a stupid question"?

Why then would all of you be studying the subject of physics, stars, black-holes and space..?

Do you intend to open a McDonald's Franchise in space and you needed some engineering work done?

No, Dippy...you are studying the cosmos to determine some of the how-what-where-when- why of our existence, in what context it exists...and what exists beyond our understanding of the physical world around us.

I did not get to college, but I lived all over the world teaching Communications and Business management for US DoD for 24 years.

Your parental ego-state is showing...sad man that you are.

RJ
GSwift7
3.8 / 5 (4) Nov 06, 2013
I hate to intrude on such a productive discussion, but I personally don't mind entertaining metaphysics and philosophy discussions from time to time (no pun intended).

I see no harm in talking about the nature of the unknowable things beyond the bounds of our Universe, both in time and space. Even Einstien voiced stong opinions on the limitations of physical science, and some of the most profound thinkers of antiquity made vast contributions to our modern civilization through purely philosophical reasoning.

Belief in a god in the biblical sense is better left for a thread outside of cosmology, but in some ways cosmology makes questions regarding origins inevitable. For example, what lies 'outside' the Universe, or 'before' the big bang, or why do we think we are real?

I don't really want to get into any of that here, but I don't see any problem with the tone or context of RJOGuillory's original statement. What lies beyond the Universe is part of the context that everthing else is in
RJOGuillory
1 / 5 (12) Nov 06, 2013
...well...to those of you decent enough to consider my questions respectfully... and have responded with the semblance of intelligent, reasonable responses...

...my regards...

RJ...

..to those incapable of such adult interactions...my sympathies...it will be a long, bitter life for such souls....
Fleetfoot
5 / 5 (1) Nov 06, 2013
"Evaporation" of general stars has the effect of hardening the cluster, so as it cools (dynamically speaking) mergers should become more commonplace. The higher fraction of blue straggglers in globulars seems to confirm this, and if they can produce BH then they may keep the equilibrium level a bit higher.


Yes, individual mergers become more frequent. But since the remaining stars are much smaller ..


As stars are lost, the whole cluster shrinks and mergers will occur randomly between stars of all sizes. There may be a bias towards more massive mergers but it will be slight.

it takes the same star merging again and again to become massive to become a black hole. In an >11 billion year old cluster the largest un-merged stars will only be the mass of the sun.


True but merged stars are just as likely to merge again as other stars so you get exponential growth.
Fleetfoot
5 / 5 (2) Nov 06, 2013
When lighter stars get tossed out the massive ones tossing them settle toward the center of the cluster. Light objects outnumber massive ones by such a large ratio that losing many for each massive star makes little difference to 'the swarm'.

But as the massive object settle to the VERY dense center of the cluster, they frequently interact among themselves, leading to a high rate of heavy objects getting kicked out.


Virialisation results in approximate equipartition of kinetic energy hence more massive stars tend to move more slowly and it is the tail of the velocity distribution of lower mass stars that tends to evaporate. The more massive stars have lower mean speed so sink to the core and are less likely to be ejected.

Since it is always the highest speed stars that randomly exceed escape velocity, each lost star reduces the mean kinetic energy and since the relaxation time is quite short for a cluster, that reduces the mean potential energy compressing the cluster.
Fleetfoot
5 / 5 (2) Nov 06, 2013
Yes, that makes sense, except when it doesn't happen that way. The interaction between stars in a cluster should be similar to planets in a solar system. Some get pushed inwards, some get kicked out.


That's OK for small numbers of bodies but in a cluster of say 10^5 stars, there is no such well-ordered structure.

the medium planets fartest out.


Is that a new kind of recoil mechanism? ;-)

I guess my point is that random chance seems to be very poweful, perhaps dominating over any systematic process, in these types of interactions.


Exactly. In a cluster, the virial theorem rules, paths are random and the distribution is governed by statistics. The relaxation time is typically 100 million years, ~1% of the age of an average globular cluster.

https://en.wikipe...c_energy
GSwift7
2.7 / 5 (7) Nov 06, 2013
ah, good link fleet. I didn't have time to cross-reference till just now.

That makes sense. Open clusters don't have the density to stay together, but globulars have enough collecive gravity to slow evaporation out of the cluster.

Evapaporation of low mass objects and condensation of high mass objects would naturally lead to some black holes in the later stages of cluster lifespans then. I can't see how the title of this article makes any sense at all really. Black holes in older clusters would seem to be expected to me, and the observations above appear to prove that is correct.
RealScience
5 / 5 (4) Nov 06, 2013
@Fleetfoot - great link - thanks!

First the very light stars are essentially all kicked out because at the average kinetic energy of the cluster they are moving faster than escape velocity, and this happens on the 100 M year time scale. Many of these stars don't even reduce the average energy in the cluster as they leave.
Then stars whose average velocity is not sufficient to escape slowly evaporate because of the normal distribution of energies around the average energy. While this preferentially evaporates light stars, the preference is not as strong as mass alone would dictate because stars closer to the center experience more frequent interactions, boosting their ejection frequency proportionately.
And dense cores are theorized to have a additional ejection mechanisms in that mergers of spinning neutron stars or black holes can kick the resulting object out by emitting gravitational waves asymmetrically.
TimESimmons
1 / 5 (12) Nov 07, 2013
The cause of globular clusters:-
http://www.presto...ndex.htm
RJOGuillory
1.3 / 5 (13) Nov 07, 2013
For the poor little Zephir Fan......an educational quote....
---------------------------------------------
Once people discover

That "Life is not a problem to be solved,

But rather,

Is a Mystery to be lived"

Then it's clear that the truth has not been hidden from us ­

But rather

It is we who have been hiding from the truth.
----------------

Regards,

RJ O'Guillory
Author-
Webster Groves - The Life of an Insane Family
RJOGuillory
1.3 / 5 (13) Nov 07, 2013
Little Zephir Fan.....

Your response displays an inability to relate to anything other than yourself, math & physics ...and...perhaps your little penis...(in that order)...but it certainly shows you have a disturbed soul that calls out for help, from someone...a therapist...a mental ward somewhere....your Mommy (again)?....But have you noticed how your little diatribes against my question are not being supported by your colleagues?

That might be due to the fact that you are a disturbed douche who can only relate to one or two topics...cannot handle effective human interactions... and would probably be happier with a new computer and it's mechanical abilities....I'll even bet you have difficulty getting a woman...or getting a woman to engage you sexually...as you will always want to be trying to overcome your inadequacies....

Perhaps the world is better with you behind a computer screen, who knows what demented thoughts lurk in the mind of such as creature as yourself?

Regards,

RJ
NOM
5 / 5 (2) Nov 07, 2013
I only have one colleague here and he has been conspicuously absent for the last few days. I sure hope he hasn't gotten himself banned again.

Won't take him long to seeek back, or recognise the idiot. He posted and was banned as:

Zephyr
Alizee
Slotin
rawa1
Callippo
ValeriaT
Alexa
natello
ragtime
Terriva
ZephyrAWT

and now Franklins
NOM
5 / 5 (1) Nov 07, 2013
10 bucks says his new alias is Pastello
beleg
1 / 5 (8) Nov 07, 2013
@G7
Do globular star clusters need the dark matter assumption as well - are the outer region star velocities analogous to the outer regions of spiraled-armed galaxies?
Sionnach
2.1 / 5 (14) Nov 07, 2013
beleg,

Globular clusters are found within the dark matter halo of the host galaxy. Typically outside of the plane of the disk in a spiral galaxy. Since they don't possess a self centered concentration of dark matter, dark matter need not be heavily weighted in the individual stars motions.

The way you worded your question leads me to think you have some reason to doubt the existence of dark matter. The choice of the word "assumption". The phenomena in which dark matter is manifest is very robust and well tested science, it's very much more than an assumption. There just aren't any other workable mechanisms that don't fail in one or several other ways. Doubting dark matter is like doubting gravity, just because we can't touch it (yet or so far) doesn't mean it's not there.
RealScience
5 / 5 (3) Nov 07, 2013
@beleg - great question, answer still unknown.
But recent work has put an upper bound of twice the stellar mass on for NGC 2419, which is far less than the ~10x presumed for galaxies.
See http://inspirehep...12?ln=en
Minotaur
1 / 5 (11) Nov 07, 2013
I'm gonna go out on a limb,and say that,super massive, stars collapse,and when they do,they create,super-massive black holes. This is how universes are created.

However,what scientists are looking at,is on a much smaller scale.
beleg
1 / 5 (4) Nov 08, 2013
@Sion
I agree and replace the word 'assumption' with the word 'effect'.
RealScience
5 / 5 (1) Nov 08, 2013
@Sionnach - I agree that Dark matter is the most likely explanation, but saying that doubting it is like doubting gravity is an exaggeration.

A person can feel the earth's gravity, and can directly observe the same gravity pulling the moon into orbit. A person can even measure the gravitational pull of a test mass with home-made equipment, and laboratories can determine the gravitational pull of matter to >99.9% accuracy. The existence of gravity is thus shown beyond a reasonable doubt.

SOMETHING causes extra pull in galaxies and galaxy clusters, and dark matter fills the bill while also matching cosmic microwave background patterns, providing a decent cross-check and thus good evidence for dark matter. But the observational evidence is far from the accuracy of the orbits of our planets, and for experimental evidence even the best laboratories on earth are arguing over whether we have detect hints of it.

Dark matter isn't even 5-sigma yet, while gravity is way beyond that...
Sionnach
1.4 / 5 (11) Nov 08, 2013
""""""@Sionnach - I agree that Dark matter is the most likely explanation, but saying that doubting it is like doubting gravity is an exaggeration.""""""""

I'll grant that possibly my analogy might not be precisely accurate.

But you must accept that if gravity is as well tested and confirmed as you say, then there is no other reasonable explanation for the observations than dark matter. For the observations to be the result of anything other than dark matter, then gravity must be much less well measured than you state.

""""But the observational evidence is far from the accuracy of the orbits of our planets, and for experimental evidence even the best laboratories on earth are arguing over whether we have detect hints of it."""""

Dark matter is real if our measurements and models of gravity are correct. If dark matter is not real, then we require new science to define gravity. To dismiss dark matter one would have to also dismiss our current modeling of gravitation.
GSwift7
2 / 5 (4) Nov 08, 2013
I agree that Dark matter is the most likely explanation, but saying that doubting it is like doubting gravity is an exaggeration


I'll second that, and I might carefully go a step farther, depending on the audience. I personally wouldn't have chosen the name 'dark matter', but that's what stuck, so oh well. I guess it's really only a temporary name, until we actually figure out what's going on, and then we can give it a name that fits the circumstances. Same goes for the name 'dark energy', which is an even more unfortunate choice for a temporary name.
RealScience
5 / 5 (1) Nov 08, 2013
"Dark matter is real if our measurements and models of gravity are correct. If dark matter is not real, then we require new science to define gravity. To dismiss dark matter one would have to also dismiss our current modeling of gravitation."

I agree that if dark matter doesn't exist one of the alternate explanations is that our model of gravity is imperfect at low gravitational accelerations. However doubting details of our understanding of gravity in extrema we have not directly experimented with is far from doubting the existence of gravity itself (after all, we have reasonable doubt that our model of gravity near a singularity is incomplete, but that doesn't make me less certain that my coffee cup won't fall if I drop it).

I almost agree with "to dismiss dark matter one would have to also dismiss [the fine details of] our current modeling of gravitation", but even that leaves out possible unknowns so 'must accept' is a bit too strong.
Sionnach
1.4 / 5 (11) Nov 08, 2013
GSwift,

I agree with use of dark energy, were it up to me I would have chosen lambda and left it at that. But Zwicky was spot on with the term dark matter. I can't think of anything that would be as accurate and succinct, Dark, it does not radiate. Matter, it manifests by it's gravitational effects. What better term for something that defies direct observation but obviously has mass?

"Dark energy" on the other hand requires to many distracting explanations to put it into the proper context of "energy". Let's call it lambda until we can model the mechanisms more confidently.
Sionnach
1.7 / 5 (12) Nov 08, 2013
""""I almost agree with "to dismiss dark matter one would have to also dismiss [the fine details of] our current modeling of gravitation", but even that leaves out possible unknowns so 'must accept' is a bit too strong.""""""

I'll concede that. The only thing I see as having any chance of upsetting our current understanding of gravity and relativity is TeVeS and that only a slight chance. That has more problems than answers, so far. It's an exciting time in cosmology and we'll probably live to see many things confirmed that previous generations would have said it never be testable. We may even see some big ideas overturned but that will be rarer.
cantdrive85
1 / 5 (15) Nov 08, 2013
"Dark matter is real if our measurements and models of gravity are correct. If dark matter is not real, then we require new science to define gravity. To dismiss dark matter one would have to also dismiss our current modeling of gravitation."

Gravitation does fine in explaining why a hammer drops and "some" aspects of orbital properties, sadly though there is no mechanism which explains how the phenomena actually works. No new physics is required, only an understanding that EM offers the longest range force laws and nearly all of which makes up the universe is in plasma form which is driven by EM.
Fleetfoot
5 / 5 (5) Nov 08, 2013
"Dark matter is real if our measurements and models of gravity are correct. If dark matter is not real, then we require new science to define gravity. To dismiss dark matter one would have to also dismiss our current modeling of gravitation."

Gravitation does fine in explaining why a hammer drops and "some" aspects of orbital properties, sadly though there is no mechanism which explains how the phenomena actually works. No new physics is required, only an understanding that EM offers the longest range force laws and nearly all of which makes up the universe is in plasma form which is driven by EM.


New physics is required, long range EM forces are dipole hence inverse cube while gravity is inverse square (barring small relativistic effects) so EM isn't even vaguely close.
Fleetfoot
5 / 5 (3) Nov 08, 2013
"Dark energy" on the other hand requires to many distracting explanations to put it into the proper context of "energy". Let's call it lambda until we can model the mechanisms more confidently.


That's definitely the best approach. If anything, "dark pressure" would have been better if it is a physical effect, but it could also be nothing more than a constant in the geometry, we don't even know on which side of the equation it should go!
cantdrive85
1 / 5 (13) Nov 08, 2013

New physics is required, long range EM forces are dipole hence inverse cube while gravity is inverse square (barring small relativistic effects) so EM isn't even vaguely close.

EM manifests itself in more than one manner, parallel Birkeland currents for example which "slowly decay as 1√ r for large r" as Don Scott puts it.
http://electric-c...elds.pdf
BTW, an electric field decays as gravity does, this is unlikely a coincidence. Such a notion at least offers a legitimate mechanism for gravity rather than "bending space-time" into a "gravity well" or any other such nonsense.

RJOGuillory
1 / 5 (12) Nov 08, 2013
Little Zephir-Boy

...Hmmm?....a quote from one of your physics folks on this site....

..."Dark energy" on the other hand requires to many distracting explanations to put it into the proper context of "energy". Let's call it lambda until we can model the mechanisms more confidently."

...so, as dumb as I must be...by reading the comments and information published here....it seems that you folks use "theories"..."modelling" and math to explain the "context" of certain physical realities...

Wow! That sounds like my original question...? But it is good to know that there are less - arrogant people in the world of physics who understand that we really do not understand the smallest fraction of our existence...and that their determined, unbridled curiosity is the way forward....well, for most but yourself.

Anyone ever make fun of you for being an anger-laden Sheldon?

Regards,

RJ O'Guillory
Author-
Webster Groves - the Life of an Insane Family
GSwift7
5 / 5 (4) Nov 08, 2013
So, in terms of doubting the theory of dark matter, I would say that would be a contradiction of terms. The concept of dark matter is actually a question rather than an answer. The answer might be neutrinos or some such thing, but to say that you disagree with the theory of dark matter is really saying that you don't believe there's anything to look for. In that case, you're either doubting our observations, or you're doubting a lot of fundamental physics.
RJOGuillory
1 / 5 (12) Nov 08, 2013
Little Zephir-Boy....

Ha!......

You didn't answer my... "Angry Sheldon"....question...he!-he!-he! That tells me all I need to know about you...and your intuitions....ha!

Regards,

RJ O'Guillory
Author -
Webster Groves - The Life of an Insane Family
RealScience
4 / 5 (4) Nov 08, 2013
@Gswift - dark matter appears at this time to be the best theory (especially with the cross-check from the CMB), but it is not the only possibility. Other possibilities include subtle differences in gravity (MOND or its relativistic extension TeVeS), other forces we don't yet know of, or even our observations being wrong (although that seems highly unlikely), or even something not yet thought of.

None of those other possibilities seems particularly likely (for example, it seems unlikely that gravity would stop diluting proportionately with the surface area of a sphere = 1/r2?). So if I had to bet right now I'd bet on dark matter.

But physics doesn't count things as discovered until it has 5-sigma odds against being wrong, and I certainly wouldn't bet 100,000 to 1 on dark matter (in fact I'll wager $1 against dark matter if you'll send $100,000 my way if dark matter turns out to explain less than half of force apparently needed to keep stars in their galactic orbits...).
Sionnach
2.1 / 5 (14) Nov 08, 2013
""""""But physics doesn't count things as discovered until it has 5-sigma odds against being wrong, and I certainly wouldn't bet 100,000 to 1 on dark matter (in fact I'll wager $1 against dark matter if you'll send $100,000 my way if dark matter turns out to explain less than half of force apparently needed to keep stars in their galactic orbits...)."""""""

The 5-sigma standard is only applied to accelerator experiments in particle physics. It is roughly 1 chance in 1 750 000 that a given result is a random fluctuation. It's not applied to astrophysical objects (or most other areas in physics) because it is such a high bar that few experimental or observational results could ever be considered valid. Outside of particle physics and quantum mechanics the methods of classical statistical mechanics must be used to assess validity, particularly when relativity or large scales are involved.
RealScience
5 / 5 (1) Nov 08, 2013
@Sionnach - Since direct detection of dark matter is likely to be particle physics, it was convenient to borrow the 5-sigma principle as a divide between the solidity of the evidence for the existence dark matter and the solidity of the evidence for the existence of gravity itself. But you are correct that 'physics' was too broad, and I should have said 'particle physics'.

5 sigma is indeed more stringent than 100K-to-1; I'm offering ~17x better odds than 5-sigma confidence in the hope that I actually get a taker on the bet. Even though it would very likely cost me a buck, I would consider it a much better wager than a lottery ticket...
Sionnach
1.7 / 5 (12) Nov 08, 2013
"""""""""Even though it would very likely cost me a buck, I would consider it a much better wager than a lottery ticket..."""""""""""

I'll bet two dollars on a lotto ticket. But I think you are right about the odds, it would be a better wager, so I'll pass on the other. Maybe one the people here who propose some of the more head scratching and eyebrow raising theories would accept it though.
Fleetfoot
5 / 5 (4) Nov 09, 2013
New physics is required, long range EM forces are dipole hence inverse cube while gravity is inverse square (barring small relativistic effects) so EM isn't even vaguely close.

EM manifests itself in more than one manner, parallel Birkeland currents for example which "slowly decay as 1�š r for large r" as Don Scott puts it.


Linear and other structures will produce different rates of reduction for gravity too, but the Sun is a slightly oblate sphere as are most planets, so as I said you are going to need "new physics" to explain simple planetary orbits with EM.

BTW, an electric field decays as gravity does, this is unlikely a coincidence. Such a notion at least offers a legitimate mechanism for gravity rather than "bending space-time" into a "gravity well" or any other such nonsense.


Sure, you could replace the "gravitational potential well" with an "electrostatic potential well", but if the Sun is positive and Earth is negative, what polarity is Venus?
Fleetfoot
5 / 5 (3) Nov 09, 2013
GSwift7:
... to say that you disagree with the theory of dark matter is really saying that you don't believe there's anything to look for. In that case, you're either doubting our observations, or you're doubting a lot of fundamental physics.


RealScience:
... dark matter appears at this time to be the best theory ...


Both are good posts but I think we should be careful about the use of "theory". Dark matter is not a theory in the scientific sense, it is a hypothesis or speculation about the nature of a number of observed phenomena. If dark matter is actually a form of matter then it calls into question the present "Standard Model" of particle physics. That model in turn is built on theories, principally QM and techniques such as Feynman diagrams.

Sorry if I'm being a bit pedantic here, I realise you were using the word in the lay sense of course, but I so often see laymen saying "but it's only a theory" thinking any theory in science is nothing more than a vague idea.
RealScience
5 / 5 (4) Nov 09, 2013
@Fleetfoot - I believe that my comments have been consistent with the use of 'theory' in science. In my opinion:

That something beyond normal gravity on currently observable mass is required to keep stars in their galactic orbits is well enough established to call it a DISCOVERY.

When the only observations that needed explaining were galactic rotation rates, unseen matter was a hypothesis. But with galactic cluster binding, gravitational lensing and the cosmic microwave background all supporting the dark matter hypothesis, dark matter (unseen matter of some sort) explains enough and has enough evidence to call it a THEORY.

However as to WHAT dark matter is (if indeed it is), even the leading proposals are still at the HYPOTHESIS state.

Some proposals on this board are at the WILD GUESS stage of not yet checked for self consistency or consistency with observations.

And some annoyingly repetitious proposals on this board are WRONG (already shown to conflict with observations).
Q-Star
3.4 / 5 (5) Nov 09, 2013
10 bucks says his new alias is Pastello


Hey now, what's this ya are saying? Did Zeph get banned again? Did I miss a good flame-out and meltdown? If so someone please post a link to the place it took place. Pastello that is so predictable.
cantdrive85
1 / 5 (12) Nov 09, 2013
Linear and other structures will produce different rates of reduction for gravity too, but the Sun is a slightly oblate sphere as are most planets, so as I said you are going to need "new physics" to explain simple planetary orbits with EM.

Actually, the Sun is almost perfectly round, contrary to what your theory predicts.
http://phys.org/n...sts.html
And no "new physics" is required, classical electrodynamics suffices.
http://www.common...11n4.pdf
In reality does the Earth really "orbit" the Sun?
http://www.djsadh...-vortex/
RJOGuillory
1 / 5 (11) Nov 09, 2013
Hey Little-Zephir-Boy....

Sorry son.....but my book has already sold thousands of copies,....and is being considered for production by several major studios....as well as having many essays and opinion pieces printed by various on-line sites....it seems my claim to being an Author is a bit closer to your claim of being "smart"...as you have obviously displayed your inability to think rationally, calmly and effectively...you must be an idiot savant or something....?

Regards,

RJ O'Guillory
Author-
Webster Groves - The Life of an Insane Family
Fleetfoot
not rated yet Nov 09, 2013
10 bucks says his new alias is Pastello


Hey now, what's this ya are saying? Did Zeph get banned again? Did I miss a good flame-out and meltdown? If so someone please post a link to the place it took place. Pastello that is so predictable.


I haven't seen his "Teech2" account lately either but he is also back as "Walters1".
Q-Star
4.2 / 5 (5) Nov 09, 2013
10 bucks says his new alias is Pastello


Hey now, what's this ya are saying? Did Zeph get banned again? Did I miss a good flame-out and meltdown? If so someone please post a link to the place it took place. Pastello that is so predictable.


I haven't seen his "Teech2" account lately either but he is also back as "Walters1".


He's like that familial black-sheep,,,,, ya are constantly annoyed by him, but wonder what's wrong when he's not around. He's never been successfully suppressed yet (here) so I expect he'll make himself known.
Fleetfoot
not rated yet Nov 09, 2013
That something beyond normal gravity on currently observable mass is required to keep stars in their galactic orbits is well enough established to call it a DISCOVERY.


I agree, or an observation.

.. the dark matter hypothesis, dark matter (unseen matter of some sort) explains enough and has enough evidence to call it a THEORY.


You are building a model of the mass distribution based on a hypothesis (as you said) of dark matter added to the visible, and then using the theory called General Relativity to predict the rotation curves.

I believe that my comments have been consistent with the use of 'theory' in science.


I don't think so, it is not just about confidence but the nature of the beast. We talk of Newton's Laws but Einstein's theory of gravity. We distinguish the gas laws from the kinetic theory of gasses. Black body radiation is described by the Stefan–Boltzmann Law, Planck derived it from his early quantum theory. Models are built on laws and theories.
Fleetfoot
5 / 5 (1) Nov 09, 2013
Linear and other structures will produce different rates of reduction for gravity too, but the Sun is a slightly oblate sphere as are most planets, so as I said you are going to need "new physics" to explain simple planetary orbits with EM.

Actually, the Sun is almost perfectly round, contrary to what your theory predicts.


Which only makes your problem greater, Scott's paper which you quoted previously was talking of linear structures "hundreds of megaparsecs long".

In reality does the Earth really "orbit" the Sun?


Well that video shows the planets orbiting the Sun so what are you saying?
RealScience
5 / 5 (2) Nov 09, 2013
@Fleetfoot - I used 'theory' in responding to GSwift's "So, in terms of doubting the theory of dark matter..." to focus on the uncertainty of dark matter rather than on semantics, so I find it funny that I'm now arguing the strength of the evidence for dark matter to justify the term 'theory'.

But I enjoy a good argument. You say that "models are built on laws and theories", so I'll point out that dark matter is a solid enough candidate that many models of galaxy cluster and galaxy formation are built upon it.

Another attribute of a theory over a hypothesis is that a theory unites diverse observations and hypotheses, and for diversity DM is supported by CMB features, gravitation lensing strength, cluster evolution, cluster rotation and galactic rotation.

However I do agree that the case for elevating it to a theory is marginal, and I argue against the elevation for anything more specific than the most general 'there is some sort of extra mass there' case.
Q-Star
2.7 / 5 (12) Nov 09, 2013
@Zephyr,,,

10 bucks says his new alias is Pastello


Hey now, what's this ya are saying? Did Zeph get banned again? Did I miss a good flame-out and meltdown? If so someone please post a link to the place it took place. Pastello that is so predictable.


So it's Pastello and Walters1 now. Okay. Anyhoo, it's good to see ya hanging in there. Tenacious, ya are if nothing else.

P.S. Thanks for the down vote, I knew I could depend on ya for that.
Fleetfoot
not rated yet Nov 09, 2013
But I enjoy a good argument. You say that "models are built on laws and theories", so I'll point out that dark matter is a solid enough candidate that many models of galaxy cluster and galaxy formation are built upon it.


I didn't want it to develop into an argument, rather a mutual reconsideration of terms.

However I do agree that the case for elevating it to a theory is marginal, and I argue against the elevation for anything more specific than the most general 'there is some sort of extra mass there' case.


IMHO "theory" isn't a level to which lesser hypotheses may aspire, it is a fundamentally different species. We can hypothesise that galactic rotation is influenced by some unseen matter. How do we test that? Applying the theory called general relativity predicts that the extra mass should cause lensing. DM is not a theory itself but something specific to which theories can be applied. GR on the other hand is a theory which can be applied to any form of mass.
Fleetfoot
not rated yet Nov 09, 2013
This is a reasonable presentation of what I am saying:

https://en.wikipe...i/Theory

"In modern science, the term 'theory' refers to scientific theories, a well-confirmed type of explanation of nature, made in a way consistent with scientific method, and fulfilling the criteria required by modern science. ... Scientific theories are also distinguished from hypotheses, which are individual empirically testable conjectures, and scientific laws, which are descriptive accounts of how nature will behave under certain conditions."

and in particular

https://en.wikipe...i/Theory#In_physics

"In physics the term theory is generally used for a mathematical framework—derived from a small set of basic postulates ... which is capable of producing experimental predictions for a given category of physical systems."
Minotaur
1.3 / 5 (13) Nov 09, 2013
To the American right in here...A theory in science is a tested explanation of natural phenomena.A scientific theory has withstood countless tests.
RealScience
5 / 5 (1) Nov 09, 2013
IMHO "theory" isn't a level to which lesser hypotheses may aspire, it is a fundamentally different species.


So if we experimentally find DarkMatterons WIMPs in labs here on earth, and then find signatures of their annihilation in space in sufficient numbers and appropriate distributions to explain cluster and galaxy evolution, velocity curves and gravitational lensing, and understand how, when and where they were created and can from that make testable predictions on velocity curves for new galaxies and the fine details of the CMB pattern, you'll still call it a hypothesis?

And when Einstein first conceived of relativity, before any tests had been done to confirm its predictions, before he'd even finished fleshing it out, you'd call it a theory?
Minotaur
1 / 5 (12) Nov 09, 2013
@Fleetfoot...Also,a hypothesis is a tentative explanation of natural phenomena.Or,an educated guess.

A scientific axiom...Is simply the beginning of a hypothesis.
Minotaur
1 / 5 (12) Nov 09, 2013
Scientific Theories:

Gravity
Evolution
Big-Bang
Molecular gas theory (which states that gases are made up of tiny particles)
General Relativity
etc.

Benni
1 / 5 (13) Nov 09, 2013
As stars are lost, the whole cluster shrinks and mergers will occur randomly between stars of all sizes. There may be a bias towards more massive mergers but it will be slight.


@ Fleet
Eh there crickey mate, you're having a conversion from the science fiction realm of "cosmological entropy" to the same kind that works on Earth, Moon, & Mars. In Thermodynamics we refer to it as the 2nd Law,
cantdrive85
1 / 5 (12) Nov 09, 2013
Linear and other structures will produce different rates of reduction for gravity too, but the Sun is a slightly oblate sphere as are most planets, so as I said you are going to need "new physics" to explain simple planetary orbits with EM.


Which only makes your problem greater, Scott's paper which you quoted previously was talking of linear structures "hundreds of megaparsecs long".

The only problem is your understanding, once again.
The paper I referred to was a paper about the birkeland current, not the star or plasmoid along the BC. He covers the star in his book 'The Electric Sky', the physics of a plasmoid will be different than the BC's that power them.

vlaaing peerd
not rated yet Nov 11, 2013
religion is not a very popular subject here. Too many religionists here trying to either debunk reality with a book or running away with reality as undebatable facts of their beliefs.

....can either of those two entities..religion or physics.... explain our existence?


So let us get down to that most basic question of yours, I will answer it, hopefully to show you why to avoid the religious question on a science site.

Physics want to explain reality, but it may never completely will.
Religions already have explanations of reality and require you to believe in it. Not doing so or testing this explanation is usually heresy.

science did hi-jack the term "theory", as in most languages a theory is a not-yet-proven description of an observation, yet in science a "theory" also means this description had been greatly verified.

I address your common sense in not to mistake (even unproven) theory for belief and a friendly suggestion to leave religion to the religious.
antialias_physorg
not rated yet Nov 11, 2013
science did hi-jack the term "theory", as in most languages a theory is a not-yet-proven description of an observation, yet in science a "theory" also means this description had been greatly verified.

It just means something that has been greatly tested (and found to withstand those tests). There is no way to verify anything in physics with aboslute certainty (and hence even if physics one day could provide a complete explanation of everything we'd not know it for certain that we have found it)

....can either of those two entities..religion or physics.... explain our existence?

Neither can do so fully. However one has a track record of getting answers that work. The other...not so much. (additionally: 'Explain our existence' is a very nebulous statement. I think there's a number of things wrong with the question itself. Right down to the unspoken assumption of causality under ALL circumstances)
Fleetfoot
5 / 5 (1) Nov 12, 2013
As stars are lost, the whole cluster shrinks and mergers will occur randomly between stars of all sizes. There may be a bias towards more massive mergers but it will be slight.


@ Fleet
Eh there crickey mate, you're having a conversion from the science fiction realm of "cosmological entropy" to the same kind that works on Earth, Moon, & Mars. In Thermodynamics we refer to it as the 2nd Law,


Crickey mate, are you having a conversion to realise that the entropy used in cosmology is the same as is used in the rest of thermodynamics?

Proper motions in cosmology are small in comparison to the Hubble flow over large scales so any large co-moving volume is effectively a closed system, there is negligible nett flow across the boundary and the mean conditions in adjacent regions can be made arbitrarily close to being in equilibrium over an adequately large region.
Fleetfoot
5 / 5 (1) Nov 12, 2013
Linear and other structures will produce different rates of reduction for gravity too, but the Sun is a slightly oblate sphere as are most planets, so as I said you are going to need "new physics" to explain simple planetary orbits with EM.


Which only makes your problem greater, Scott's paper which you quoted previously was talking of linear structures "hundreds of megaparsecs long".

The only problem is your understanding, once again.
The paper I referred to was a paper about the birkeland current, not the star or plasmoid ...


The problem was yours, that was your response to my question about the nature of Sag A* which is and object smaller than the Solar System!
RJOGuillory
1 / 5 (1) Nov 12, 2013
antialias_physorg:

....can either of those two entities..religion or physics.... explain our existence?

"Neither can do so fully. However one has a track record of getting answers that work. The other...not so much. (additionally: 'Explain our existence' is a very nebulous statement. I think there's a number of things wrong with the question itself. Right down to the unspoken assumption of causality under ALL circumstances)"

OK...let us presume I asked a poor question....if so, then why do you folks in physics, astrophysics, etc....why use "Hypotheses" and "modelling" to determine or create a "theory" about the origin, behavior and science surrounding black-holes, dwarf-stars and other phenomenon that is not yet fully understood? If not to understand their role in our existence, what are you trying to discover...other than the way they behave?

BTW - For myself...Religion does nothing to "explain" anything, they simply want you to believe, accept & follow...

Regards,

RJ
Q-Star
5 / 5 (6) Nov 12, 2013
OK...let us presume I asked a poor question....if so, then why do you folks in physics, astrophysics, etc....why use "Hypotheses" and "modelling" to determine or create a "theory" about the origin, behavior and science surrounding black-holes, dwarf-stars and other phenomenon that is not yet fully understood? If not to understand their role in our existence, what are you trying to discover...other than the way they behave?


Hi RJ, I see ya struggling and ya do seem earnest. I think where the break down in communication is the word "why". For scientists the word is used in a more restricted context than in normal conversation. Why is philosophical-religious question. Science is only concerned with HOW. The mechanisms that nature operates with, not the why or purpose. Pure science is not about purpose. There is no proper question of "purpose" for the physical sciences. It's a meaningless term in physical science.

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