A video map of motions in the nearby universe

Jun 12, 2013
Map showing all galaxies in the local universe color-coded by their distance to us: blue galaxies are the closest, and red are farther, up to 300 million light-years away.

(Phys.org) —An international team of researchers, including University of Hawaii at Manoa astronomer Brent Tully, has mapped the motions of structures of the nearby universe in greater detail than ever before. The maps are presented as a video, which provides a dynamic three-dimensional representation of the universe through the use of rotation, panning, and zooming. The video was announced last week at the conference "Cosmic Flows: Observations and Simulations" in Marseille, France, that honored the career and 70th birthday of Tully.

The Cosmic Flows project has mapped visible and dark matter densities around our up to a distance of 300 million light-years.

The team includes Helene Courtois, associate professor at the University of Lyon, France, and associate researcher at the Institute for Astronomy (IfA), University of Hawaii (UH) at Manoa, USA; Daniel Pomarede, Institute of Research on Fundamental Laws of the Universe, CEA/Saclay, France; Brent Tully, IfA, UH Manoa; and Yehuda Hoffman, Racah Institute of Physics, University of Jerusalem, Israel.

The large-scale structure of the universe is a complex web of clusters, filaments, and voids. Large voids—relatively empty spaces—are bounded by filaments that form superclusters of galaxies, the largest structures in the universe. Our Milky Way galaxy lies in a supercluster of 100,000 galaxies.

Just as the movement of tectonic plates reveals the properties of Earth's interior, the movements of the galaxies reveal information about the main constituents of the Universe: dark energy and dark matter. Dark matter is unseen matter whose presence can be deduced only by its effect on the motions of galaxies and stars because it does not give off or reflect light. Dark energy is the mysterious force that is causing the to accelerate.

The video captures with precision not only the distribution of concentrated in galaxies, but also the invisible components, the voids and the dark matter. Dark matter constitutes 80 percent of the total matter of our universe and is the main cause of the motions of galaxies with respect to each other. This precision 3-D cartography of all matter (luminous and dark) is a substantial advance.

The correspondence between wells of and the positions of galaxies (luminous matter) is clearly established, providing a confirmation of the standard cosmological model. Through zooms and displacements of the viewing position, this video follows structures in three dimensions and helps the viewer grasp relations between features on different scales, while retaining a sense of orientation.

This map shows the currents of galaxies in the universe. The galaxies (white spheres) are like dead branches in a sea. Currents carry them from an island (galaxy cluster) to the closest larger island of galaxies, the Great Attractor region. Red and yellow colors show the islands, and dark blue shows the voids that galaxies avoid by following the currents.

The scientific community now has a better representation of the moving distribution of around us and a valuable tool for future research.

The scientific article, "Cosmography of the Local ," which explains the research behind the video, will be published in a forthcoming issue of The Astronomical Journal. It is now available at http://arxiv.org/abs/1306.0091 .

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Ober
not rated yet Jun 12, 2013
I can't play the embedded video I get an Error Loading Media, File Could Not Be Played message.

I'd love to see this video. It would be nice if there is any evidence of Dark Flow in this video, though I doubt there will be on the scale they have tracked.
Q-Star
3.4 / 5 (10) Jun 12, 2013
I can't play the embedded video I get an Error Loading Media, File Could Not Be Played message..


I couldn't get it play in the browser either. I had to us a video ripper to download it, and then play it with me winamp.

It's pretty cool, but it would be better in an HD large format file.
fmfbrestel
5 / 5 (4) Jun 12, 2013
Works great in Chrome for me.

Makes you feel pretty insignificant as they zoom in on the milky way, and then back out again.
Valentiinro
1 / 5 (1) Jun 12, 2013
The title made me think of A nearby universe, not the nearby area in this universe...
_ilbud
2.9 / 5 (8) Jun 12, 2013
That's the lousiest attempt at English I've heard in a while.
gwrede
4 / 5 (8) Jun 12, 2013
It worked for me in Chrome. But at the end 5:50 the woman is still talking.

I'm really not happy with the video. If they want people to know about their work, they should do their damn homework. That includes checking that people can actually watch it.

And even worse, the narrator doesn't speak English!!! She is a French woman reading a text in English, for frack's sake! Impossible to understand!!

A disgrace.
Howhot
3 / 5 (4) Jun 13, 2013
Really good 3D modeling. I wish the video was better too.
EarthlingX
5 / 5 (5) Jun 13, 2013
Here's a link to the article on University of Hawaii
http://www.ifa.ha...s/flows/
and link to the video, which didn't work for me here either :
http://irfu.cea.fr/cosmography
Ober
5 / 5 (2) Jun 13, 2013
Thanks for the links EarthlingX, Great Video!! This sort of shows the dark flow effect as their is a tendency for Galaxies to flow towards the Great Attractor, or something beyond it. Absolutely amazing to get a hint of how matter moves at such astonishing scales, even though this video represents only a small part of the Universe. Also, what causes the VOIDS, and what cause the ATTRACTORS?? I mentioned the word "hint" as the lady mentions in the video regarding the uncertainty increase with distance, however an overall pattern of motion can be discerned. Amazing!!!!!
fmfbrestel
5 / 5 (3) Jun 13, 2013
Ober -- the easy answer is that differences in the distribution of mass (both dark and regular) accounts for the voids and attractors.

But... thats kinda an unsatisfying answer isn't it? If you want to know why the universe has an uneven distribution of matter in the first place, well that question has a lot more meaning, but is not easily answered. That question is right up there with, "why is there something instead of nothing?"

Personally, I think the answer has something to do with 42. :-)
fmfbrestel
5 / 5 (2) Jun 13, 2013
Hey, it looks like they fixed the video. It doesn't cut out at 5 minutes any more! sweet.
antialias_physorg
3.5 / 5 (13) Jun 13, 2013
"why is there something instead of nothing?"

Personally I think this one answers itself. If there were nothing (I mean truly nothing. Not just empty space. But really an absence of everything - including dimensions)...how long would it exist? In the absence of dimensions (sepcifically temporal ones): no time at all.

Existence doesn't exist because somehow nothingness didn't come about to be. Existence exists because there's no alternative. (Making 'existence' a tautology)

Now why existence exists in the form we observe it to - THAT is an entirely different kettle of fish (and 42 probably comes into it at some point)
fmfbrestel
5 / 5 (3) Jun 13, 2013
"why is there something instead of nothing?"

Existence doesn't exist because somehow nothingness didn't come about to be. Existence exists because there's no alternative. (Making 'existence' a tautology)

Now why existence exists in the form we observe it to - THAT is an entirely different kettle of fish (and 42 probably comes into it at some point)


Many would argue that the anthropic principle is an awfully unsatisfying answer. All you are really doing there is refusing to look at the question at all. It also presupposes a multiverse where universes are poping into and out of existence continually. A cunning interrogator could then merely reform the question and ask why does the multiverse exist?

These are existential questions of course, and the anthropic principle is a convenient way to acknowledge the unanswerable questions without getting caught up in all the Kafkaesque angst.

So enough of the rhetorical dance. I am still amazed by that video.
antialias_physorg
3.2 / 5 (11) Jun 13, 2013
All you are really doing there is refusing to look at the question at all.

Sort of. What I'm actually doing is looking at the question saying: "Does the question make sense?"

The thing is: By using words and concepts in a sentence (in this case a question) we make unspoken assumptions. In this case we make the unspoken assumption that 'nothingness' is a possible state.

But when we think about what a STATE is we find that it contradicts the notion of 'nothingness' - because nothingness can't have a context to be IN (otherwise it wouldn't be nothingness). So the question "why isn't there nothing?" is already a paradox.

And that is why - I think - the question doesn't have an answer...because it isn't a proper question in the first place.

It's also akin to the difference between one and zero (or infinity). One is a number that maps to reality. Zero (and infinity) are concepts that do not map to reality.
indio007
1.7 / 5 (11) Jun 13, 2013
I'm so sick of dark matter being stated as fact. It's existence relies on probably a dozen a priori assumptions.
Q-Star
3.4 / 5 (10) Jun 13, 2013
Here's a link to the article on University of Hawaii
http://www.ifa.ha...s/flows/


Thanks for the link,,,, much better quality.
antialias_physorg
2.8 / 5 (9) Jun 13, 2013
It also presupposes a multiverse where universes are poping into and out of existence continually.

Not really. There may be just one universe - and this one may be it. We really don't know if the values that make up a universe:
1) can be freely chosen (which would argue for a multiverse)
2) are somehow so interrelated that only one combination is possible (which would argue for a singular universe)
3) something in between 1) and 2) (constrained values) - and this universe just happens to be the one generated (which could be used to argue either multi or singular verse, depending on the constraints)

At this point in time we just don't know. The multiverse thing isn't palatable to me because it requires infinite energy and immediate detachment of universes. The singular universe isn't palatable to me because of its reliance on the anthropic principle.

So at this point the answer is up for grabs as far as I'm concerned.
MandoZink
5 / 5 (1) Jun 13, 2013
"There either is or isn't. Since there seems to be, I must assume that there is."

That is a proclamation I seem to recall by P.D. Ouspensky, a century-old Russian mathematician and esotericist at the beginning of a book he wrote in which he attempted to logically make a case for proof of existence. He stated that was the only assumption you were allowed to make, albeit a necessary one.

I don' not recall much more about the book, except that it was a difficult and remarkable read.
El_Nose
2 / 5 (4) Jun 13, 2013
@fmfbrestel

of course 42(hgttg) is just 21 *2 and that of course was expected because 21 + 2 = 23
if you don't understand that joke wiki: 23 enigma

-----

@antialias

i challenge you on that nothingness cannot have a state. the simplest dichotomy of nothingness is existence. Past that fuzzy logic allows us to agree upon degrees of being classified into one state or another. ( fuzzy logic is marvelous at that)

but on our side of nothingness, existence we find in our mundane world that a purely negative state cannot sustain itself. If nothingness can exist ( and it must ) then something must exist as well to give nothingness meaning. If it had no meaning, no information to convey then it cannot exist in the first place. In our state, existence, conceptual abstracts must exist somewhere if it is only on the outside edge of this universe.interacting with everything is not possible, because in our universe that interaction may cause some thing to cease to exist -- like nothingness
antialias_physorg
2.8 / 5 (9) Jun 13, 2013
the simplest dichotomy of nothingness is existence.

See, that's where we already differ in interpretation.
A dichotomy is: two things that have opposite properties.
Nothingness has no properties. If nothingness HAD a property it wouldn't be nothingness.
And the absence of a thing is not the same as the opposite of a thing.

Therefore I'm still convinced that nothingness isn't an attainable state. It's only a concept.

Much like "Having zero elephants" is not an attainable state - since whenever you claim to have achieved that state (by letting your last elephant go) the state you're in also does not have any 'elephantness' about it.
So giving that state the property of "zero elephants" is just attaching a concept to it - and not an actual state (it also doesn't differ from having zero toasters - but you didn't add 'toasterness' to it, either, by giving your last elephant away).
El_Nose
2.8 / 5 (6) Jun 13, 2013
@antialias

I used to believe the same thing you did -- before i took discrete mathematics

as a thougth problem the first two weeks of class we were made to try to define '1' the number -- the concept. we tried all types of arguments of definitions, philosophical and natural and implied and everyone of them were thrown out because the definition was in some way circular. At this point the prof steps up and says that '1' is an axiom in mathematics. We accept its existence without proof because we can only define one in terms of itself. however all other integers require it's existence.

nothingness is the axiom of our existence.as a universe. It must exist. for we are it's negation.
geokstr
1.7 / 5 (6) Jun 13, 2013
"The multiverse thing isn't palatable to me because it requires infinite energy and immediate detachment of universes. The singular universe isn't palatable to me because of its reliance on the anthropic principle."

Are those any more unpalatable than the current theory, which says all the energy and matter in the universe was squeezed into a singularity, smaller than any known particle, then had to expand at faster than the speed of light while conveniently eliminating all the anti-matter?

antialias_physorg
2.8 / 5 (9) Jun 13, 2013
Are those any more unpalatable than the current theory...

It does match with observation and makes testable predictions. That tends to make a theory certainly more palatable in my book.

You have a better one? I.e. one that
1) has less assumptions
2) matches observation better AND
3) makes predictions at odds with the current theory so it may be tested

...then I'm certain the scientific world will be all ears. Seriously.

(Please note that "god did it" is by no means a theory with less assumptions because it makes infinitely complex assumptions about a creator (e.g.: "he/she/it can do anything"). It also doesn't make any testable predictions. So it's not a useful theory.)

(and BTW: Spatial expansion isn't bounded by the speed of light. Where do you get the notion that it should be?)
El_Nose
1 / 5 (2) Jun 13, 2013
it never said it was smaller than any known particle -- infact it could have been lightyears across -- science makes no guess at that. the fact is BB theory only goes back to the last part of the expansion -- and not the initail phase of expansion because its untestable and unobservable - but it is spoken about in absolute terms and that becomes confusing to many.

yes BB theory says that everything came from a singularity -- but we have no idea how big that singularity was and there is no guess

i believe me and ant are on the same side today... and its raining while the sun is shining
GSwift7
2.7 / 5 (7) Jun 13, 2013
It's interesting, but somewhat misleading also.

The net motion of all these structures is still expansion above and beyond their 'strange motion'. They all still show redshift relative to us and each other. The video must be based on only the strange motion, with the dominant redshift motion removed. See the second paragraph in the following wiki page on the great attractor:

http://en.wikiped...ttractor

The motions described in the video only represent small deviations in the amount of redshift of each object.

Also, as someone else eluded to above, the great attractor is no longer thought to be "THE GREAT ATTRACTOR". We currently believe it's actually some MUCH larger object beyond the great attractor. Observations in that direction are obscured the our own Milky Way of course, so expect modifications to that theory in the future, as our observational skill improves.
El_Nose
1 / 5 (3) Jun 13, 2013
okay -- BUT -- question

so my math , and it is frquently flawed , points in the direction of we will hit the great attractor in about 75 k - 125 k years. --- around that time the milky way will be very close to a lot of other galaxies and we will all be ripped apart more or less over the next 30k years following. I have not taken into account the universe expanding.

Could someone else check my numbers
Fleetfoot
5 / 5 (2) Jun 13, 2013
okay -- BUT -- question

so my math , and it is frquently flawed , points in the direction of we will hit the great attractor in about 75 k - 125 k years. --- around that time the milky way will be very close to a lot of other galaxies and we will all be ripped apart more or less over the next 30k years following. I have not taken into account the universe expanding.

Could someone else check my numbers


It will take about 4 billion years before the Milky way and Andromeda merge, much longer before our local group reaches the Virgo Cluster and the Great Attractor is beyond that so I think your numbers are a bit out. 75 billion years might be more likely.
TheGhostofOtto1923
2 / 5 (4) Jun 13, 2013
But when we think about what a STATE is we find that it contradicts the notion of 'nothingness' - because nothingness can't have a context to be IN (otherwise it wouldn't be nothingness). So the question "why isn't there nothing?" is already a paradox
Im sure nothingness exists. It must be all over the place. We are just not aware of it because its not really THERE.

Christ. Philosophers.
antialias_physorg
2.1 / 5 (7) Jun 13, 2013
Finally got to a place where I can view the video. Damn...just...damn. Whenever she says "wall of galaxies" the mind just boggles.

75 billion years might be more likely.

Which is well beyond the stage where the universe has run down to a point where life as we know it can be supported. So we shouldn't be unduly alarmed.
El_Nose
1 / 5 (2) Jun 13, 2013
i was off by 6 oreders of magnitude -- HA ... yeah I looked at the distance very hastily and did not notice the Mlyr as Mega - million --- that will through off a calculation in a heartbeat

beleg
1 / 5 (6) Jun 13, 2013
Ay for one...hmmm....

(pssst. Hint. Start over. Use English here. You saw what happen to the french woman with her accent!)

I, for one, am glade the axiom and assumption of, and for, one exists.

The 'Dear John letter' goes to nothingness. Still, zero is the souvenir, lest I forget the affair.

I, for one..............sounds like broken English.....
Ay matey. That it does.
One for all and all for one.
Fleetfoot
5 / 5 (2) Jun 14, 2013
Ay for one...hmmm....

(pssst. Hint. Start over. Use English here. You saw what happen to the french woman with her accent!)

I, for one, am glade ...


You are an open area within a woodland?

http://en.wikiped...raphy%29
antialias_physorg
2.5 / 5 (8) Jun 14, 2013
that every collective motion of multiple galaxies, which are to distant for being able to interact gravitationally,

Lucky then for us that there is no limit on the range for gravitational interaction.
So out the window aerher goes (yet again).
GSwift7
2.7 / 5 (7) Jun 14, 2013
Im sure nothingness exists. It must be all over the place. We are just not aware of it because its not really THERE


Yes, it does. The reason you don't see it laying around all over the place is because I took it all and put it in my checking account.

points to the dense aether model and to the swirling motion of vacuum itself


Rule number three is; We do - not - talk - about dense aether club..
GSwift7
2.3 / 5 (9) Jun 14, 2013
BTW Who is "we"? A plural majesticus? Speak for yourself


You DO know that's a quote from the movie "Fight Club" don't you?

It's about a guy who has paranoid delusions and multiple personality disorder, who ends up forming a terrorist organization and shooting himself in the head. The main character is played by two people and he has fist fights with himself.

BTW Who is "we"?


You know, We, Us, They, Them, etc. As in 'We are watching You'.

BTW, WE had a meeting last week, and if you don't stop making waves about 'certain topics'... well, who knows what will happen. Muahahahaha

See how that works? I can openly admit to being one of THEM, and because I make it sound like I'm making fun of you, nobody believes me (except antialias, who is one of US too, and QStar, who is our Leader).
antialias_physorg
3.2 / 5 (13) Jun 14, 2013
and don't use "we" at places where you aren't approved for it

This from a guy with more than a dozen sockpuppets? Who argues with himself at times? You've got to be choking on the irony...
antialias_physorg
2.2 / 5 (10) Jun 14, 2013
And the physicists already know, that the Great attractor is a gravitational anomaly - they don't expect that the blind textbooks parrots (like you) will disprove it.

Why should anyone disprove it? Dark matter seems to be a reasonable first stab at getting to grips why stuff doesn't move he way it should if only the observable matter were responsible.

What the great attractor is (whether it's 'just' a high concentration of dark matter or something entirely else) we don't know. That's the fun thing about science: some things aren't known and you can try to figure out what it is.

Note that 'figure out' is different from 'make stuff up'. The former always has to mesh with observation, while the latter (like aether) does not.

As a side note why I think gravity is 'faster' than light: If it weren't it couldn't escape a black hole (i.e. the mass inside black holes wouldn't have any gravitational effect at all on the outside).
Fleetfoot
4.4 / 5 (7) Jun 14, 2013
I can openly admit to being one of THEM

This forum is not supposed to be a social club about anybody here. Just keep the subject ...


ROFL, unbelievable, and that from the worst purveyor of pseudo-science, disinformation and technobabble in the forum. There should be a site for quotes like that :-)
Infinum
2.1 / 5 (7) Jun 14, 2013
Awesome!

An interactive 3D model of the flow would be even more amazing!

Great publication :D
Protoplasmix
1 / 5 (5) Jun 14, 2013
Nothing and something are both possible and observed, and even the something is mostly nothing. Nothing's real but we're cautioned not to divide by it. I think our equation for the cosmos adds up to nothing, if I'm not mistaken.

There's plenty of room in the infinitely small to fit the infinitely large, with a 1-to-1 mapping, using a scale factor, no?
Fleetfoot
5 / 5 (4) Jun 15, 2013
There's plenty of room in the infinitely small to fit the infinitely large, with a 1-to-1 mapping, using a scale factor, no?


No, the scale factor would be infinite and the results degenerate. You might look at duality in string theory though.
ValeriaT
1.7 / 5 (6) Jun 15, 2013
And the physicists already know, that the Great attractor is a gravitational anomaly - they don't expect that the blind textbooks parrots (like you) will disprove it.

Why should anyone disprove it? Dark matter seems to be a reasonable first stab at getting to grips why stuff doesn't move he way it should if only the observable matter were responsible.

What the great attractor is (whether it's 'just' a high concentration of dark matter or something entirely else) we don't know. That's the fun thing about science: some things aren't known and you can try to figure out what it is.

Note that 'figure out' is different from 'make stuff up'. The former always has to mesh with observation, while the latter (like aether) does not.

As a side note why I think gravity is 'faster' than light: If it weren't it couldn't escape a black hole (i.e. the mass inside black holes wouldn't have any gravitational effect at all on the outside).

ValeriaT
1.4 / 5 (7) Jun 15, 2013
Why I think gravity is 'faster' than light: If it weren't it couldn't escape a black hole (i.e. the mass inside black holes wouldn't have any gravitational effect at all on the outside).
It violates the general relativity anyway (and it renders the gravitational waves tachyons, i.e. unobservable in deterministic way).
Protoplasmix
1 / 5 (5) Jun 15, 2013
@Fleetfoot Thanks, I'll check on duality in the context of string theory. The scale factor may approach infinity; degenerate results imply processes/interactions have not been likewise scaled if I understand you correctly. To me that means things like the fine structure don't arise from 'nothing'...
vidyunmaya
1 / 5 (7) Jun 15, 2013
Sub:Cosmic Flow--cosmic Function
This is good attempt to understand the cosmic Flow sequence. Many dogmatic terminologies still t persist that confuse the issues. Scientists ,in order to get out of ambiguity, must comprehend- Knowledge base
1. Flows 2. Fields 3. Reflectors and 4 a protective Index all under source.
These are derived from Prime functional concepts. See cosmic function of the Universe , Cosmology Definition and Space Cosmology vedas interlinks- Vidyardhicosmology [dot] blogspot [dot] com. new additions on books include creation of knowledge Base and updated Cosmology Digest-dialogues -May 2013 -application Copyrights.
Welcome East West Interaction
Fleetfoot
5 / 5 (4) Jun 15, 2013
There's plenty of room in the infinitely small to fit the infinitely large, with a 1-to-1 mapping, using a scale factor, no?

@Fleetfoot Thanks, I'll check on duality in the context of string theory. The scale factor may approach infinity; degenerate results imply processes/interactions have not been likewise scaled if I understand you correctly.


In the question you ask, the scale factor would be infinity divided by zero which is infinity. Scaling the small by infinity produces an indeterminate result, it can be anything you like hence any one point maps to all points.

To me that means things like the fine structure don't arise from 'nothing'...


True, but it and all its components are finite. Handling infinity gets tricky.
Fleetfoot
4 / 5 (4) Jun 15, 2013
Why I think gravity is 'faster' than light: If it weren't it couldn't escape a black hole (i.e. the mass inside black holes wouldn't have any gravitational effect at all on the outside).

It violates the general relativity anyway (and it renders the gravitational waves tachyons, i.e. unobservable in deterministic way).


What you say is true Val, I would have given it 5/5 if you hadn't linked to your aether nonsense.
Justsayin
1 / 5 (2) Jun 15, 2013
Link to 2GB avi file http://vimeo.com/64868713 just hit the download tab and pick from four.
baudrunner
1 / 5 (4) Jun 15, 2013
I wonder how they determine the spectral evidence for the presence of Helium in stars, since Helium does not permit the transmission of light. A transparent balloon filled with Helium is black. This makes Helium a prime candidate for dark matter. Matter is energy.

As Jean Bernard Léon Foucault observed in the 1850's, light appears to propagate slower in the presence of a dense medium like water - ergo refraction. In fact, the rate of the interaction of the particles in a medium is the constant that is c, but the presence of more of these in a given distance through water compared to air provides the illusion that light propagates slower in that medium.

Consider the vast distances that light propagates through intergalactic space. The tremendous number of particles interacting through that medium over those colossal distances represent a density that is not being considered when analyzing red shifts.

Acceleration of the expanding universe is an illusion.
baudrunner
1 / 5 (3) Jun 15, 2013
Furthermore, over those vast distances through the medium there is a falloff of frequency resulting from reduction in energy, comparable to the losses encountered over long electrical transmission lines, or the lowering frequencies of audio waves of a car's engine as it drives away from one at a constant velocity. This results in an increase in red shift.
Fleetfoot
5 / 5 (6) Jun 15, 2013
I wonder how they determine the spectral evidence for the presence of Helium in stars, since Helium does not permit the transmission of light. A transparent balloon filled with Helium is black.


Rubbish, it's almost transparent.

This makes Helium a prime candidate for dark matter.


Nope, if it was black, it would be detectable in silhouette like the Horsehead Nebula:

http://apod.nasa....126.html

Dark matter has to be perfectly transparent even through billions of light years of the material.
Q-Star
3.5 / 5 (11) Jun 15, 2013
I wonder how they determine the spectral evidence for the presence of Helium in stars, since Helium does not permit the transmission of light.


Spectroscopy is not based on "transmission", it's base on absorption/emission. (Pssst, Helium is more transparent than O2, N2 or CO2, More transparent than air.)

light appears to propagate slower in the presence of a dense medium like water - ergo refraction.


Propagates slower, in a DENSE medium.

presence of more of these in a given distance through water compared to air provides the illusion that light propagates slower in that medium.


It's no illusion, it's been well measured. It does propagate slower.

The tremendous number of particles interacting through that medium over those colossal distances represent a density that is not being considered when analyzing red shifts.


That is just not true, by many orders of magnitude. Do ya realize just how many particles are in a single cm^3 of water?
Q-Star
3.7 / 5 (12) Jun 15, 2013
comparable to the losses encountered over long electrical transmission lines, or the lowering frequencies of audio waves of a car's engine as it drives away from one at a constant velocity.


Not comparable at all, neither the electrical transmission or the sound waves, entirely different animals both than light.

This results in an increase in red shift.


Wrong, diffraction through a medium, will cause the spectrograph to show each frequency ("colors") falling out at different angles of refraction. Read up on Rayleigh scattering. Redshift due to motion is even across the spectrum,,, every frequency shifts the same amount.

This is how we know gravitational lensing can not be caused by the light being refracted. In gravitational lensing, all frequencies are bent to the same extent, not so when light is refracted in a glass lens, water, or the air.

Protoplasmix
1.8 / 5 (5) Jun 15, 2013
Handling infinity gets tricky.

Good call, I've been careless with the terms. Would've been better to say, "pick *any* arbitrarily large number" instead of "infinitely large".
JRi
5 / 5 (1) Jun 16, 2013
Wonderful video! Now I wish I had a 3DTV and this clip in stereo.
Ober
4.7 / 5 (3) Jun 16, 2013
As a side note why I think gravity is 'faster' than light: If it weren't it couldn't escape a black hole (i.e. the mass inside black holes wouldn't have any gravitational effect at all on the outside).


AntiAlias, I do enjoy reading your posts and the above quote had me in a WOAH moment for a sec. I thought you were onto something, but then I slapped myself around the face and came to a conclusion. Gravity is an additive force (as far as we know). Therefore we can speculate that it is simply a vector which adds to itself. However I think the incorrect assumption you have made is that gravity bends gravity!!!! In a black hole, light is affected by gravity and bent back towards the singularity, hence the event horizon. However I wouldn't assume that gravity travels like light, and that gravity rides the curvature of spacetime like light does. Either way, interesting stuff to think about. Thanks for the insight!!
Ober
5 / 5 (3) Jun 16, 2013
An amendment to the above. Gravity IS the curvature of Spacetime, therefore it is nonsense to assume it RIDES the curvature of Spacetime like light does. Subtle difference, but an important one!!
Fleetfoot
5 / 5 (3) Jun 16, 2013
An amendment to the above. Gravity IS the curvature of Spacetime,..


Exactly. Gravity seems to act instantly, but if you put a ball on a hill and release it, it starts rolling instantly. That doesn't mean that hills travel faster than light, just that the slope (curvature of the landscape) has been there a long time.

It is changes of gravity such as gravitational waves that travel at* the speed of light.

(* In the weak field limit.)
bearly
5 / 5 (1) Jun 16, 2013
They need to add closed captions for the "speaking" impaired.
antialias_physorg
1.8 / 5 (5) Jun 16, 2013
An amendment to the above. Gravity IS the curvature of Spacetime,..

Exactly.

Yes. I think gravity is a geometric effect rather than a particle effect.

Just brainfarting here:
Distances are measured by a 'yard stick' and our current yard stick for astronomy is the speed of light (more precisely: speed of light times some, arbitrary, time constant). Superceding the speed of light we get all kinds of shenannigans with causality.

So a particle (graviton) would have to move faster than photon. If a graviton isn't affected by the gravity (as you rightly point out) we would be witnessing causality problems at black holes IF gravitons carried information.

That's a big 'if' because AFAIK the information in a black hole is currently thought to be (eventually) released via Hawking radiation - which would make the graviton an informationless particle (which sort of contradicts the notion of a particle).

Fun stuff to think about at any rate.
Protoplasmix
1 / 5 (3) Jun 16, 2013
Direct detection of gravitational waves would allow observations of the dynamics inside black holes.

@GSwift7, stop me if you heard this one: I started out with nothing. And I still have most of it.
baudrunner
1 / 5 (6) Jun 16, 2013
Q-Star: Gee, I wish you would know something about physics. You appear to have no ability to understand the concepts I discuss. I won't repeat myself because the concepts are fairly straightforward.

And the rest of you doubters. A transparent balloon filled with pure Helium is black, because HELIUM DOES NOT PERMIT THE TRANSMISSION OF LIGHT. That's basic scientific knowledge, taught when you were all sleeping during your high school physics and/or chemistry classes.

I wish all you pseudo scientists out there would stick to the pseudo science sites.
Q-Star
3.5 / 5 (11) Jun 16, 2013
Q-Star: Gee, I wish you would know something about physics. You appear to have no ability to understand the concepts I discuss. I won't repeat myself because the concepts are fairly straightforward.

And the rest of you doubters. A transparent balloon filled with pure Helium is black, because HELIUM DOES NOT PERMIT THE TRANSMISSION OF LIGHT. That's basic scientific knowledge, taught when you were all sleeping during your high school physics and/or chemistry classes.


Oh really? Then all those hundreds of thousands of times it's been measured in the laboratory to have a refractive index of 1.026 were all wrong? It's that why we use it between elements of telescope lenses?

I wish all you pseudo scientists out there would stick to the pseudo science sites.


Ya mean the ones where they silly things like HELIUM DOES NOT PERMIT THE TRANSMISSION OF LIGHT.?

Nice try for a bluff, but it only shows ya are really stupid. (Can't ya crackpots use the Google before posting?)
ValeriaT
1.7 / 5 (6) Jun 16, 2013
a transparent balloon filled with pure Helium is black
It couldn't be transparent, after then? Helium indeed is transparent.
Ober
5 / 5 (1) Jun 16, 2013
I think Baudrunner is just a Troll. Ignore him.
GSwift7
2.3 / 5 (7) Jun 17, 2013
I agree with antialias about gravitons. Quantum theorists treat gravity as if it were a 'real' force, but we observe that it is only a pseudo-force; a property of space at any time/location. The conditions that result in gravity at any specific location cannot be changed faster than the speed of light, since mass and energy cannot travel faster than that (at macro scales).

I don't think the QT treatment actually represents anything in the 'real' universe, and if I understand QT correctly, I don't think it is meant to. I could be wrong here, but I understand it to be similar to the 'rest mass' of a photon, where it's treated as a force carrying quasi-particle in order to simplify the math. I'd like to clearly state that this 'feels' wrong to me, and I think a more 'correct' version will be found eventually. GR is probably closer to the truth than QT, IMO.

Funny how so few people understand that GR and QT are mutually exclusive, competing theories.
Fleetfoot
5 / 5 (4) Jun 17, 2013
And the rest of you doubters. A transparent balloon filled with pure Helium is black, because HELIUM DOES NOT PERMIT THE TRANSMISSION OF LIGHT. That's basic scientific knowledge, taught when you were all sleeping during your high school physics and/or chemistry classes.


Transparent helium-filled balloons, see for yourself:

http://vanillabli...diy.html
antialias_physorg
3.5 / 5 (8) Jun 17, 2013
C'mon Fleetfoot. Don't confuse the guy with reality and facts. For shame...
TheGhostofOtto1923
1.8 / 5 (5) Jun 17, 2013
Perhaps baudrunner missed the part about ionization while sleeping in class

"...the more free electrons and protons, the more photons interact with them via scattering. This is what being opaque is - ionised gas (free electrons and ions/protons) interacts with photons and doesn't allow them to travel freely.

"In conclusion, the answer is "Doubly ionized Helium (He III) is opaque and traps EM radiation."

-and missed learning about the value of GOOGLE as well for impressing people and winning arguments.
TheGhostofOtto1923
1.8 / 5 (5) Jun 17, 2013
And as far as ftl gravity, science says

"The first effort to measure how quickly gravity exerts its influence indicates that it more or less matches the speed of light...

"We now know that the speed of gravity is probably equal to the speed of light, and we can confidently exclude any speed for gravity that is over twice that of light."

-So much for uninformed, unresearched opinion.
TheGhostofOtto1923
1.8 / 5 (5) Jun 17, 2013
also-

"In December 2012, a research team in China announced that it had produced measurements of the phase lag of Earth tides during full and new moons which seem to prove that the speed of gravity is equal to the speed of light..."
Fleetfoot
5 / 5 (3) Jun 17, 2013
Perhaps baudrunner missed the part about ionization while sleeping in class

"...the more free electrons and protons, the more photons interact with them via scattering. This is what being opaque is - ionised gas (free electrons and ions/protons) interacts with photons and doesn't allow them to travel freely. ...


However, it also depends on the density. Remember that the dark ages ended when the neutral gas was re-ionised.
Q-Star
3.7 / 5 (12) Jun 17, 2013
Perhaps baudrunner missed the part about ionization while sleeping in class

"...the more free electrons and protons, the more photons interact with them via scattering. This is what being opaque is - ionised gas (free electrons and ions/protons) interacts with photons and doesn't allow them to travel freely. ...


However, it also depends on the density. Remember that the dark ages ended when the neutral gas was re-ionised.


The neutral gas was re-ionized as a consequence of the dark ages ending, the first stars and galaxies did the re-ionizing.

By the By: Helium is also transparent as a liquid, and that is pretty dense.
ValeriaT
1 / 5 (5) Jun 17, 2013
The structure of dark matter and the convective cells at the surface of molten gold for comparison. Apparently, some convective flow should be apparent there - and it really is.
GSwift7
2.7 / 5 (7) Jun 18, 2013
"We now know that the speed of gravity is probably equal to the speed of light, and we can confidently exclude any speed for gravity that is over twice that of light."

-So much for uninformed, unresearched opinion


You're talking about the view that gravity is a force, which only applies to quantum theory. From a general relativity point of view, gravity doesn't have a speed any more than length or mass does. Just like the length of your arm is instantaneous, so is the gravity of your arm. The gravity of your arm is an instantaneous and constant property of your arm. You can change the gravity around your arm by placing it next to another object, but the gravity itself surrounds your arm. It is not 'radiated' by your arm according the general relativity. In quantum theory it is treated as a force which is radiated by a force carrying particle, but not in GR. GR and QT cannot both be correct, so either one or both must be wrong about this.
Q-Star
3.7 / 5 (9) Jun 18, 2013
You're talking about the view that gravity is a force, which only applies to quantum theory.


That's not entirely correct. Both GR and QT view gravity as a field.

From a general relativity point of view, gravity doesn't have a speed any more than length or mass does.


The GR field equations DO give gravity wave a finite speed, "c". They won't work without using "c" as the constant.

Both GR and QT incorporate the hypothetical particle as the mediator, graviton. In GR it is a massless particle like the photon (the only thing capable of achieving "c" is massless) QT goes further by predicting it is massless, and has spin 2, and it is it's own anti-particle.

Newtonian mechanics is the area where gravity is viewed as a force, and it is valid up to a point.
GSwift7
3 / 5 (8) Jun 18, 2013
On a whim I looked up the wiki page on gravity and gravitational waves.

According to that source, I'm completely wrong. I know it places me dangerously close to cranksville, but I'm willing to challenge that. So far, nobody has actually detected a gravity wave, so it's entirely theoretical, and this isn't exactly a straght forward consequence of GR's equations. It seems to me that you need to assume some aether-like quality of spacetime in order for gravity waves to exist and propogate, and I'm not buying that.

The other consequences of gravity seem to contradict gravity as a force with waves and a finite speed. In the case of a black hole, for example, time slows down as you approach the center, and essentially stops at the middle. If gravity has a finite speed, then how does it propogate past the nearly stopped time inside a black hole? It would take longer than the age of the Universe for it to get out.

The wiki says gravity waves ignore this, but i'm skeptical of that idea
Q-Star
3.7 / 5 (9) Jun 18, 2013
So far, nobody has actually detected a gravity wave,,,


Actually the effects have been detected, in the behavior around rapidly orbiting neutron stars.

so it's entirely theoretical,,,


Of course it is, but the theory is consistent with what we observe. Just as Lamda CMD, GR, and QT.

this isn't exactly a straght forward consequence of GR's equations.


The field equations don't speak of light, but they won't work unless ya use "c" as a constant.

It seems to me that you need to assume some aether-like quality of spacetime in order for gravity waves to exist


Why? Light requires not aether. A massless particle/wave with velocity "c" Gravity wouldn't either, mediated by massless particle/wave with velocity "c".

Q-Star
3.8 / 5 (10) Jun 18, 2013
In the case of a black hole, for example, time slows down as you approach the center, and essentially stops at the middle. If gravity has a finite speed, then how does it propogate past the nearly stopped time inside a black hole?


What goes on INSIDE the black hole is completely unknown to us. There are many speculations, but none that have acquired the status of a working model. The mass of everything INSIDE the black hole determines the spacetime curvature of the OUTSIDE. There is no paradox there. Just as light is effected by the distance from the event horizon, so is the spacetime curvature. What's inside the event horizon is INSIDE.
Fleetfoot
5 / 5 (3) Jun 18, 2013
On a whim I looked up the wiki page on gravity and gravitational waves.

According to that source, I'm completely wrong.


I'm not sure that you are. The key point that seems to be missed in this thread is that changes in gravity propagate with some speed but the static value is just a curvature.

In fact gravitational waves travel at c in a weak field but GR is non-linear so very high values can theoretically have a trailing edge moving slightly slower I believe.

It seems to me that you need to assume some aether-like quality of spacetime in order for gravity waves to exist and propagate, and I'm not buying that.


There is a philosophical argument called "substantivalism" and I can suggest at thought experiment that supports that view, but it can also be explained by non-linear geometry. It's a very complex question! (Incidentally, the Stanford Encyclopedia of Philosophy is a bit naive on this topic.)
GSwift7
2.7 / 5 (7) Jun 19, 2013
Actually the effects have been detected, in the behavior around rapidly orbiting neutron stars


Yes, some effect has been measured which appears to cause the pairs to slow down. However, attempts to measure the actual waves have failed up to now, and we are approaching the limit of theoretical sensitivity.

This is a strange topic, and it gets stranger as I think more about it. It seems at odds with itself in several ways.

Sources claim that gravity waves should pass through a black hole, but that doesn't seem right. If objects are emitting waves that carry real energy, then it would have to obey the laws and be limited to the speed of light, and it shouldn't be able to beat a black hole any better than any other type of information. The rules must apply accross the board, right? I think that once we are able to settle how gravity behaves, we will need to re-think at least one part of that apparent paradox.
TheGhostofOtto1923
2.6 / 5 (5) Jun 19, 2013
You're talking about the view that gravity is a force, which only applies to quantum theory. From a general relativity point of view, gravity doesn't have a speed any more than length or mass does. Just like the length of your arm is instantaneous, so is the gravity of your arm
?? Imagine that your arm was 3 ly long and infinitely rigid. If you pull on one end, the other end would not move for 3 years. This is analogous to the way gravity propagates, force or wave.

This is why one side of the universe cannot ever know what the other side is doing, nor have any effect on it.
Q-Star
3.7 / 5 (9) Jun 19, 2013
However, attempts to measure the actual waves have failed up to now, and we are approaching the limit of theoretical sensitivity.


There in lies the Devil's details,,,, in attempting to measure something 39 orders of magnitude weaker than EM fields. We may be able to do it in the near future, or we may not. Try envisioning the energy contained in a single photon of light. Now place that next to a single "graviton" which has 10^39 times less energy,,,, that is a pretty fine feat of measuring. Which explains why I personally think the "graviton" will only remain a theoretical particle for a very long time.

This is a strange topic, and it gets stranger as I think more about it.


For me the strangest aspect, is deciding what questions to ask.

once we are able to settle how gravity behaves, we will need to re-think at least one part of that apparent paradox.


I don't see a paradox in the standard theories, only limits to our abilities to test all aspects of them.
Fleetfoot
5 / 5 (3) Jun 19, 2013
Actually the effects have been detected, in the behavior around rapidly orbiting neutron stars


Yes, some effect has been measured which appears to cause the pairs to slow down. However, attempts to measure the actual waves have failed up to now, and we are approaching the limit of theoretical sensitivity.


MH Cancri is the best binary candidate known at present while the Crab Pulsar is the best isolated candidate. However, a rotating pulsar is unlikely to generate any waves at all, only asymmetry on the surface would produce waves:

http://www.flickr...6990436/

Until we get LISA, the only hope is probably the lucky detection of a rare neutron star merger.
ValeriaT
1 / 5 (7) Jun 19, 2013
I don't see a paradox in the standard theories, only limits to our abilities to test all aspects of them.
This is an example of your limited ability to test just the aspects of standard theories, which are violating the observations and/or causal logics based on observations.
If objects are emitting waves that carry real energy, then it would have to obey the laws and be limited to the speed of light
In AWT the black hole mergers can emanate the energy in form of gravitational waves, but these waves do manifest itself like sound waves at the water surface, i.e. like the noise. This energy will manifest itself with less or more sudden changes of CMBR noise intensity and/or like the scalar waves, which we discussed recently.
GSwift7
2.7 / 5 (7) Jun 19, 2013
?? Imagine that your arm was 3 ly long and infinitely rigid. If you pull on one end, the other end would not move for 3 years.


Yeah, nice analogy. The question is: Is it correct? That would imply some fairly odd things.

I think it is valid in this case to question whether the rules of causality apply to gravity.

In the special case of a black hole, anything 'inside' the event horizon should be completely isolated from anything further 'down'. There should be no way to get information from anything farther 'down' than you. If gravity waves can propogate out of a black hole, then you're breaking the rules of causality in exactly the same way as if you transmitted information at FTL speed.
Q-Star
3.8 / 5 (10) Jun 19, 2013
I don't see a paradox in the standard theories, only limits to our abilities to test all aspects of them.
This is an example of your limited ability to test just the aspects of standard theories, which are violating the observations and/or causal logics based on observations.


It's not my limited ability Zeph, the present state of technology limits everyone's ablity to detect a "graviton" directly. Unless it's one of those well suppressed secrets like the cheap and easy cold fusion ya keep telling us about.

I for one would appreciate it ya could suggest an experiment to detect a "graviton". A practical experiment with present technology available. Ya could win the Nobel hands down for doing that, and ya won't have to wait 10 to 20 years for the award like everyone else has.

Ya would be counted among Einstein, Dirac, Bohr, Feynman, Planck and Newton. (Sorry, ya still won't measure up to Galileo, the mainstream physics conspirators must draw the line somewhere.)
Q-Star
3.7 / 5 (9) Jun 19, 2013
I think it is valid in this case to question whether the rules of causality apply to gravity.


It's an excellent question.

In the special case of a black hole, anything 'inside' the event horizon should be completely isolated from anything further 'down'. There should be no way to get information from anything farther 'down' than you.


Ya can get any information outside of the event horizon. The total mass of the black-hole (within the event horizon) will produce the shape of spacetime outside of the event horizon. The mass, spin and charge are the only attributes we know of black holes, and our information of these three qualities does not come to us from within, it come from outside measurements.

To be continued.
Q-Star
3.7 / 5 (9) Jun 19, 2013
@ GSwift,,,

If gravity waves can propogate out of a black hole, then you're breaking the rules of causality in exactly the same way as if you transmitted information at FTL speed.


Waves don't propagate OUT of a black hole they are emitted by a black hole. Like photons don't come from WITHIN an electron (or proton) they are emitted by the electron (or proton.)

The mass of the black hole doesn't generate gravity waves, the black hole interacts with the outside universe through gravity fields, an exchange with it's local environment.

The same as with a proton and electron, they interact through a field mediated by the photon. An electron all by it's lonesome won't send out a photon. It must be interacted with by some other particle.

The waves are merely the LOW mass density (outside universe) interacting with a HIGH mass density (the black hole)
antialias_physorg
3.3 / 5 (4) Jun 19, 2013
If gravity waves can propogate out of a black hole, then you're breaking the rules of causality

And i would add that they only break the rules if they carry information from within.
If all the information on them (in the amplitude, phase/frequency) is a direct consequence of the matter outside the black hole while it is falling in then there's 'no harm - no foul'.

But I guess we'll have to wait for the results from Advanced LIGO to come in to get a better picture. For now gravity hasn't divulged its whole secret.
Q-Star
3.7 / 5 (9) Jun 19, 2013
If all the information on them (in the amplitude, phase/frequency) is a direct consequence of the matter outside the black hole while it is falling in then there's 'no harm - no foul'.


Exactly so, the only information we can have any hope of obtaining from the black hole, is provided as a consequence of the matter as it fell in. We can measure the size of the event horizon, but that is done from outside. As matter falls in, it leaves the information outside, by increasing the size of the event horizon. As the matter falls in, it also leaves information outside about it's momentum, because the black hole spin can be measured. Charge is the only other thing we can know about the matter as it falls in, and that is only temporary information, the nature of EM allows that it will become neutral in short order. So the charge is only what is as we observe it, we can't determine what it was or what it will be.
GSwift7
2.3 / 5 (6) Jun 19, 2013
IF gravitational waves are real, and IF they cary energy (they need to cary energy if they slow down a pair of rotating stars), then gravity waves caused by objects inside the event horizon would count as information from inside the event horizon. The waves would transport some enrgy from inside and allow it to do work outside. That is information flow out of the event horizon.

QT allows this by dropping the principle of locality (in some interpretations of QT, but not all), but it is hard to imagine any version of this applied to general relativity.
Fleetfoot
3.7 / 5 (3) Jun 19, 2013
Waves don't propagate OUT of a black hole they are emitted by a black hole.


Be careful here. Under normal circumstances, a BH doesn't emit gravitational waves at all. you would only get GW if the hole was non-symmetrical in which case the waves remove that asymmetry. Remember the Schwarzschild Metric is a static solution. This is one of the reasons behind the "no hair" theorem, any history of the BH's formation is radiated away.
Fleetfoot
3.7 / 5 (3) Jun 19, 2013
IF gravitational waves are real, and IF they cary energy (they need to cary energy if they slow down a pair of rotating stars), then gravity waves caused by objects inside the event horizon would count as information from inside the event horizon. The waves would transport some enrgy from inside and allow it to do work outside. That is information flow out of the event horizon.


Gravitational waves carry energy and travel at the speed of light (as do photons) so they would not propagate from inside to outside the event horizon. They would move towards the centre just like photons.
Q-Star
3.7 / 5 (9) Jun 19, 2013
IF gravitational waves are real, and IF they cary energy (they need to cary energy if they slow down a pair of rotating stars),


Exactly, this is a phenomena we have observed & measured, with many methods.

then gravity waves caused by objects inside the event horizon would count as information from inside the event horizon.


It's not object"s" inside the event horizon. The entire "object" is the event horizon. There is nothing more going on inside that our physics can tell us. All we know of is the "event horizon" that is your black hole. Try imagining it as single object who's shape is the "event horizon".

The waves would transport some enrgy from inside and allow it to do work outside. That is information flow out of the event horizon.


Doesn't transport energy from INSIDE,, but CAN exchange energy with the universe in the form of angular momentum.

GR is as well tested as any theory, it's description of gravitation depends on "c" as THE universal limit.
Q-Star
3.7 / 5 (9) Jun 19, 2013
Waves don't propagate OUT of a black hole they are emitted by a black hole.


Be careful here. Under normal circumstances, a BH doesn't emit gravitational waves at all. you would only get GW if the hole was non-symmetrical in which case the waves remove that asymmetry. Remember the Schwarzschild Metric is a static solution. This is one of the reasons behind the "no hair" theorem, any history of the BH's formation is radiated away.


Ya are absolutely correct. I was too general in my wording,,,, the "field" is what I was trying to express.
TheGhostofOtto1923
1.8 / 5 (5) Jun 19, 2013
Yeah, nice analogy. The question is: Is it correct? That would imply some fairly odd things
It would imply that you could convey information faster than lightspeed, which has been thoroughly explored re entanglement and thoroughly disproved. According to antialias that is.

If the force of gravity exceeded the speed of light you could theoretically use it for ftl communication. Right?
GSwift7
3 / 5 (4) Jun 19, 2013
Exactly, this is a phenomena we have observed & measured, with many methods


We have observed pairs slowing down as predicted, but there's no proof of the mechanism causing it. Gravity waves are the theoretical assumption of cause/effect.

It's not object"s" inside the event horizon. The entire "object" is the event horizon.


No, this is not correct. There is an object inside the event horizon, which is descrete and seperate from the outer event horizon. Two merging black holes of different size will orbit eachother inside their combined event horizon before merging. This scenario should produce distinct gravity waves. It's not the event horizon that produces the gravity, it is the central object(s). Those waves would be radiated from the objects in the middle, not from the event horizon, which has no mass. In the case of a super-massive black hole, it's a LONG way from the central object to the event horizon. Smaller BH's might orbit there for a long time.
Q-Star
3.7 / 5 (9) Jun 19, 2013
We have observed pairs slowing down as predicted, but there's no proof of the mechanism causing it. Gravity waves are the theoretical assumption of cause/effect.


The only explanation we have for the observed orbital mechanics, from satellites to planets to stars,,, include the transfer of gravitational energy.

It's not object"s" inside the event horizon. The entire "object" is the event horizon.


No, this is not correct. There is an object inside the event horizon, which is descrete and seperate from the outer event horizon.


No one can know that, there are no consistent models of anything inside the event horizon. There is not information available beyond the event horizon,,, only speculations. The only observations we have available begin with the event horizon. All models posited for the structure of a black hole fail,,,, we have only the event horizon to work with.
Q-Star
3.7 / 5 (9) Jun 19, 2013
Two merging black holes of different size will orbit eachother inside their combined event horizon before merging.


All we can observe is the event horizon, as a single object,,,, no other information is available with present science and technology.

It's not the event horizon that produces the gravity, it is the central object(s).


The event horizon describes the object. It is not an entity or object in and of it's self. It's a volumetric object. We do not know what is in it. Speculation is all that we say about anything going on inside it. Everything I'm saying only deals with the event horizon and all it contains as single entity.

not from the event horizon, which has no mass.


The event horizon contains the mass, everything within the black hole is contained by the event horizon. Must ya go inside a box to weight is contents? Of course not, ya weight the box, and try to figure out how much the cardboard weighs.
baudrunner
1 / 5 (6) Jun 19, 2013
What a bunch of dumbA***S! Helium is so rare that pure helium is very expensive. it is mined, cannot be manufactured by any process, and I have heard that the recent round the world trip in that helium filled balloon used up 80% of the supply available on the open market. The U.S. has the most Helium in the world in the natural state and probably has the largest supply in reserve, which is not available for general consumption.

The helium used in balloons at county fairs is not pure, by any stretch of the imagination. Those balloons will permit light to pass through them because other elements that contribute to their volume and that do permit transmission of light are also there. The stupid comment made by one poster here concerning the fact that if dark matter were helium then wouldn't it block all the light that we see behind it is evidence of the kind of stupidity that the majority of you here are cursed with. Helium out there is in the company of plenty of other particles.
Fleetfoot
4.2 / 5 (5) Jun 19, 2013
What a bunch of dumbA***S! Helium is so rare that pure helium is very expensive. it is mined,


Garbage, it's extracted from natural gas which contains up to 7% helium.

http://en.wikiped...ribution

The helium used in balloons at county fairs is not pure, by any stretch of the imagination.


The helium I buy at my local shop is N2.0 which means 99% helium, 1% other stuff.

http://www.boconl...des.html

The mix in space is 25% helium, 75% hydrogen, not even on the scale.
Fleetfoot
5 / 5 (2) Jun 19, 2013
.. there are no consistent models of anything inside the event horizon. There is not information available beyond the event horizon,,, only speculations. ..


As long as you use sensible coordinates such as Kruskal-Szekeres, the models are fine:

http://en.wikiped...rdinates

Of course we cannot observe what is within so they remain untested.

On reading various previous posts on gravitational waves carrying information out from inside, the example I thought of would be a tight binary of neutron stars falling through the event horizon of a SMBH such as Sag A*. The gravitational waves emitted by the binary while falling from the EH to the centre would not make it back out but would also fall inwards.

Modelling that would be interesting though.
ValeriaT
1.2 / 5 (5) Jun 19, 2013
it's extracted from natural gas which contains up to 7% helium
Yes, but only at the one place of Earth. Which is why it becomes too expensive for scientific research.
Q-Star
3.7 / 5 (9) Jun 19, 2013
The mix in space is 25% helium, 75% hydrogen, not even on the scale.

Helium is not opaque,


And I, for one am glad it is not, otherwise we wouldn't be able to see as much as we do out there.

and it is not dark matter either.


I'm still glad of that too, otherwise we wouldn't be able to see as much as we do out there.

But being a crackpot pseudo-science guy,,, I'm having trouble with the transparent helium balloons are black except when they contain a contaminate, but the one he saw was pure enough to be black. Am I being too cynical?

I suspect he was witness to a child's birthday party magic act, and the magician didn't want to tell him how he did the "Turn-the-transparent-balloon-black" trick.

After being annoyed by the inebriated dad, the magician finally lied to him and said he used helium to cause it to turn from transparent to black.

I'm also glad of that, otherwise we

Q-Star
3.7 / 5 (9) Jun 19, 2013
Of course we cannot observe what is within so they remain untested.


A model that can not be observed is speculation.

Which is why I keep saying all we have to work with in our experiments, measurements, and observations with the physics we know, is the volume contained in the event horizon as a single object.

Anyone contemplating the idea that gravity is not constrained by "c", must give up GR.

I would suggest they replace "c" with any greater number, (like double it or use infinity), do the maths for objects we can see, and ponder the results.

"c" may be the speed of light. But it's more than that, it is the universal speed limit for everything in our universe, there is just no way around it until we discover something that is more precise than GR on macro-scales. Without "c" being a constant, then EVERYTHING we do in GR & QT fails, all of it would have to be replaced. ALL of our physics would no longer work (Unless we wanted to go back to only Newtonian mechanics
Fleetfoot
5 / 5 (1) Jun 19, 2013
I'm having trouble with the transparent helium balloons are black except when they contain a contaminate, but the one he saw was pure enough to be black. Am I being too cynical?


Nah, he's just clueless. If you have a dark gas and you thin it, it just allows more of the light through but the 1% contaminant in commercial helium would only let about 1% more light through and 1% more thickness would restore that.

Bromine, iodine and nitrogen dioxide are all reasonable opaque but helium is transparent.

http://amazingrus..._big.jpg

A balloon filled with NO2 would be very dark at the centre but nearly clear at the edges. Helium balloons are transparent

http://vanillabli...diy.html

I have no idea why he would think otherwise, though the balloons that last longest are aluminium foil, the gas leaks through the metal more slowly than rubber, and they would be opaque ;-)
Fleetfoot
5 / 5 (2) Jun 19, 2013
Of course we cannot observe what is within so they remain untested.


A model that can not be observed is speculation.


Indeed, though GR is well tested and this is simply an application of it. We have no reason to think the universe will deviate from what it does elsewhere.

"c" may be the speed of light. But it's more than that, it is the universal speed limit for everything in our universe,


In relativity it is just a scale factor for converting units, just as 25.4mm = 1 inch. That's why scientists tend to just as c=1 and forget it, measure distance in light seconds and it disappears.
Q-Star
3.8 / 5 (10) Jun 19, 2013
I have no idea why he would think otherwise, though the balloons that last longest are aluminium foil, the gas leaks through the metal more slowly than rubber, and they would be opaque ;-)


I tried to tell him that it is used in it's purest form as a medium between elements in telescope optics. I guess he didn't want to use the Google to check me on that. I don't know if it is used in high end microscopes but I would think so, because it has a very low refractive index, 1.000036. Less than everything except a pure vacuum. I also tried to tell him it's a clear liquid, which should have given him a clue that in gas form it would not be opaque.

I'm thinking he's a person with a drinking problem and this is what he does when gets to tippling and thinks he smart.
TheGhostofOtto1923
2.1 / 5 (7) Jun 19, 2013
The helium used in balloons at county fairs is not pure, by any stretch of the imagination. Those balloons will permit light to pass through them because other elements that contribute to their volume and that do permit transmission of light are also there. The stupid comment
You dimwit. You dont bother to look things up and you ignore facts when they are posted for you. And so you you end up looking like a dimwit.

You enjoy making things up? Is that it?
A balloon filled with NO2 would be very dark at the centre but nearly clear at the edges
Actually it would look something like this
http://amazingrus..._big.jpg
Q-Star
3.7 / 5 (9) Jun 19, 2013
Indeed, though GR is well tested and this is simply an application of it. We have no reason to think the universe will deviate from what it does elsewhere.


I'm of the mind that we should develop models and theories to describe the reality we witness, to explain phenomena. Rather than "wish" for a phenomenon & model the wish hoping my wish will come true. Newton wondered "how" with the Earth, Sun and apples,,, modeled it with his Law of Universal Gravitation. He didn't dream of the Law & THEN go searching for something to apply it to.

"c" may be the speed of light. But it's more than that, it is the universal speed limit for everything in our universe,

In relativity it is just a scale factor for converting units, just as 25.4mm = 1 inch.


In SR not GR. If ya are measuring gravitation? In GR "c" constrains mass. It's the universal constant for all things real that we can predict with any confidence. I lament that "c" is taught as "the speed of light"
Fleetfoot
5 / 5 (1) Jun 19, 2013
Indeed, though GR is well tested and this is simply an application of it. We have no reason to think the universe will deviate from what it does elsewhere.


I'm of the mind that we should develop models and theories to describe the reality we witness, to explain phenomena.


GR explains gravity and the orbit of Mercury, black holes then appeared as a simple extrapolation, but then we found them :-)

"c" may be the speed of light. But it's more than that, it is the universal speed limit for everything in our universe,


In relativity it is just a scale factor for converting units, just as 25.4mm = 1 inch.


In SR not GR. If ya are measuring gravitation? In GR "c" constrains mass. It's the universal constant for all things real that we can predict with any confidence. I lament that "c" is taught as "the speed of light".


Think of its role in the invariant interval ;-)

http://en.wikiped...ntervals
Fleetfoot
5 / 5 (1) Jun 19, 2013
A balloon filled with NO2 would be very dark at the centre but nearly clear at the edges


Actually it would look something like this
http://amazingrus..._big.jpg


Yep, that was the link I posted with the above comment. Have you mixed up the quotes?
Q-Star
3.5 / 5 (8) Jun 19, 2013
lament that "c" is taught as "the speed of light".


Think of its role in the invariant interval ;-)


Excellent.

I think of it as the speed of a massless (virtual) particle when ya need one to make the maths work. Since the maths do work so well then it's useful in predicting our (virtual) reality. But I'm still having trouble incorporating it into the AWT, maybe I'm not properly re-normalizing the opacity of the helium that is mixed up with the aether.

Fleetfoot
5 / 5 (1) Jun 20, 2013
lament that "c" is taught as "the speed of light".


Think of its role in the invariant interval ;-)


Excellent.

I think of it as the speed ...


In that case, you're still not getting it. Instead, try thinking about Pythagoras' Theorem in a world where convention said that all distances north-south are measured in inches but distances east-west are measured in mm. Represent the value 25.4 by the letter 'c' and write down the famous equation as it would be taught on that planet.
Fleetfoot
5 / 5 (2) Jun 20, 2013
GR explains gravity and the orbit of Mercury
GR describes the gravity with Newton gravitational law...;-)


Nope, GR replaced Newtonian law because gravitational bending of starlight is double Newton's value. Repeating something you know to be untrue will only get your error pointed out every time.
GSwift7
2 / 5 (4) Jun 20, 2013
Ooooh, that's an interesting thought:

Could a large black hole tear a smaller black hole apart if they orbit close enough? In other words, is there a roche limit for black holes, and would the math work out just like it does for less compact objects?
GSwift7
1.8 / 5 (5) Jun 20, 2013
No one can know that, there are no consistent models of anything inside the event horizon. There is not information available beyond the event horizon


That was my point. IF contemporary theory is correct, and gravity waves can escape a black hole, then it becomes possible to get information out of the event horizon. A hypothetical person inside the EH could modulate the rotation of a body around the black hole and send gravity waves out.
Q-Star
3.7 / 5 (9) Jun 20, 2013
In that case, you're still not getting it. Instead, try thinking about Pythagoras' Theorem in a world where convention said that all distances north-south are measured in inches but distances east-west are measured in mm. Represent the value 25.4 by the letter 'c' and write down the famous equation as it would be taught on that planet.


I get it just fine. It's just when I "intuit" in my mind, I view it as a "limit" and a "constant" for working the maths. It's also handy for scaling distances/time. If the way ya "intuit" works for ya, that's fine,,, we both get correct answers when use it to do maths.
Fleetfoot
5 / 5 (2) Jun 20, 2013
That was my point. IF contemporary theory is correct, and gravity waves can escape a black hole, ...


My point was that contemporary theory says gravity waves can NOT escape a black hole because it says they travel no faster than the speed of light.
Q-Star
3.7 / 5 (9) Jun 20, 2013
That was my point. IF contemporary theory is correct, and gravity waves can escape a black hole,


This is where we differ,,, I don't interpret "contemporary theory" as indicating that anything escapes a black hole.

then it becomes possible to get information out of the event horizon.


Only if is a priori assume a black hole emits a thing, a gravitational wave. That is not part of conventional theories. Nothing comes out of a black hole.

To be continued.
Q-Star
3.5 / 5 (8) Jun 20, 2013
Cont from below.

A hypothetical person inside the EH could modulate the rotation of a body around the black hole and send gravity waves out.


I can't fathom a priori that "waves" of any sort come from inside a black hole, that is contrary to our physics. The gravity effects of a black hole are not "waves", "particles" or things,,,, it is a field surrounding that black hole.

A black hole doesn't emit EM waves or particles either, but we can measure it's charge by the field around it.

Ya are trying to give gravity some property which no one in conventional physics is giving it. Frame your hypotheses in terms of a phenomena we observe and measure, if it will work there, ya might be on to something.
Fleetfoot
5 / 5 (2) Jun 20, 2013
In that case, you're still not getting it. Instead, try thinking about Pythagoras' Theorem in a world where convention said that all distances north-south are measured in inches but distances east-west are measured in mm. Represent the value 25.4 by the letter 'c' and write down the famous equation as it would be taught on that planet.


I get it just fine. It's just when I "intuit" in my mind, I view it as a "limit" and a "constant" for working the maths. It's also handy for scaling distances/time. If the way ya "intuit" works for ya, that's fine,,, we both get correct answers when use it to do maths.


Well intuition is always a personal thing and if that suits you then go with it of course. I think the way I was suggesting makes it easier to understand the "block universe" and perhaps to move on to GR which sometimes taught in a "coordinate free" manner where you don't define time and space axes so speed has little meaning.
Q-Star
3.7 / 5 (9) Jun 20, 2013
Well intuition is always a personal thing and if that suits you then go with it of course. I think the way I was suggesting makes it easier to understand the "block universe" and perhaps to move on to GR which sometimes taught in a "coordinate free" manner where you don't define time and space axes so speed has little meaning.


I use it more often in thermodynamics, optics and spectroscopy,,,, GR and cosmology are just of an axillary interest, closely tied to but not central to what I do on a daily basis. That's why I "intuit" it best as a limit and a constant.
Fleetfoot
5 / 5 (2) Jun 20, 2013
A hypothetical person inside the EH could modulate the rotation of a body around the black hole and send gravity waves out.


I can't fathom a priori that "waves" of any sort come from inside a black hole, that is contrary to our physics.


You are right on that.

The gravity effects of a black hole are not "waves", "particles" or things,,,, it is a field surrounding that black hole.


That's not completely right. A single black hole produces a static field but an orbiting binary system produces waves like this graphic:

https://upload.wi...Wavy.gif

Ya are trying to give gravity some property which no one in conventional physics is giving it.


No, he is talking of, for example, modulating the rotation rate of such a binary system inside the event horizon while it is falling inwards to produce a GW transmission, but those waves would not escape the event horizon.
Q-Star
3.7 / 5 (9) Jun 20, 2013
The gravity effects of a black hole are not "waves", "particles" or things,,,, it is a field surrounding that black hole.


That's not completely right. A single black hole produces a static field by an orbiting binary produces waves like this graphic:


I'd thought he was talking about A black hole. Of course ya are correct. But in that circumstance,,,, the object is only producing gravitational fields, the interaction of the objects in the fields sets up the waves.

I tried to use an electron as example, but it maybe I blew that. The electron doesn't have photons pop out from inside the electron, the photons emerge from the interaction with another particle's field. If nothing is interacting with it, no waves are going coming from inside the electron, there will be a field waiting for a chance to interact with something.

A gravitational field surrounds them, but don't "send out" things, waves/particles.The waves&"gravitons" arise with the interactions of matter.
Q-Star
3.5 / 5 (8) Jun 20, 2013
but those waves would not escape the event horizon.


Which is why is it usually very easy to explain a black hole,1)Whatever is in it, stays inside the event horizon. 2)The mass is a straightforward attribute.3)The angular momentum is a straightforward attribute (as long as something is going on the neighborhood.) 4)The charge is not so straightforward because it can be positive, negative, or neutral, & is always changing, it can go more positive more negative & back and forth depending on what it might be feeding on.

The real science is not what's going on inside (though it would be a nice thing to know) all the action is outside the event horizon.

Some flaw in my personality causes me to only pursue the things we have a chance of observing or measuring, then only in the area that I'm particularly interested. I've never wanted to be anything more than a generalist in physics, & competent in general astrophysics, & know the specialty I work with intimately.Theorist? I'm not.
Ober
1 / 5 (1) Jun 21, 2013
Space expands faster than light.
Virtual particles are not bound by light speed. Refer to Q.E.D. for details on that. Before you say virtual particles don't really exist, calculations in QED are totally dependent on their existence.

BUT ordinary matter does seem bound by light speed.

Theoretically information CAN be extracted from the interior of a Black Hole. IF you had a satellite orbiting a black hole, and you created entangled pairs, and let one of the pair fall into the BH (without it encountering anything on the way) then the state of your particle on board the satellite would change according to the encounter inside the event horizon. The math for this has been done, and it has been shown (mathematically at least) to be a none zero event, meaning it is possible. The article is here on Physorg somewhere, referred to as Jack and Jill went up a hill.
In my opinion, I'm still baffled by singularities. Can't help thinking they are linked with dark matter/energy some how.
GSwift7
2.3 / 5 (6) Jun 21, 2013
My point was that contemporary theory says gravity waves can NOT escape a black hole because it says they travel no faster than the speed of light.


and

This is where we differ,,, I don't interpret "contemporary theory" as indicating that anything escapes a black hole


Gravity waves take energy from the objects causing them. In the case of neutron stars, we observe the slowing of rotation of the pairs. In the case of two black hole objects orbiting each other inside the event horizon, it would take energy from them in the same way. If you are extracting energy from inside the event horizon and doing work on objects outside the event horizon with that energy, then this is 'information' escaping.

Perhaps black holes are special, but I doubt it. A neutron pair seems to do it, and a massive enough neutron pair will form a black hole if thier combined mass is large enough and orbit small enough. Perhaps they stop emitting gravity waves, but who knows?
Fleetfoot
5 / 5 (3) Jun 21, 2013
That's not completely right. A single black hole produces a static field by an orbiting binary produces waves like this graphic:


I'd thought he was talking about A black hole.


He was talking about gravitational waves produced inside escaping FROM a black hole. You said they weren't emitted BY a black hole. That's why you were talking past each other.

The thought experiment needs a source of GW which is inside the event horizon. A suitable source is a very hard neutron star binary. It can take a couple of hours to fall from the event horizon to the centre of a billion solar mass BH so there's time for a few orbits to generate waves inside.

.. in that circumstance,,,, the object is only producing gravitational fields, the interaction of the objects in the fields sets up the waves.


Exactly, the question then was what happens to those waves. The answer is that they fall to the centre along with whatever produced them.
Fleetfoot
5 / 5 (3) Jun 21, 2013
Space expands faster than light.


Distances expand by 1% in about 130 million years but "1%" is not a distance, you can't really assign a speed to cosmological expansion.

Theoretically information CAN be extracted from the interior of a Black Hole. IF you had a satellite orbiting a black hole, and you created entangled pairs, and let one of the pair fall into the BH (without it encountering anything on the way) then the state of your particle on board the satellite would change according to the encounter inside the event horizon.


Not quite. If you compared the measured values, you would find they were correlated, but if you measure your particle, you get a random value and you don't know whether that was the opposite of the one inside, or if you forced your to take a random value and the one inside was determined by yours. The values are correlated but because they are also random, no information can be sent via that method.
GSwift7
2.3 / 5 (6) Jun 21, 2013
So, you guys both think that pairs of objects inside the event horizon are immune to the gravity wave phenomenon. Keep in mind that the event horizon is actually like a russian nesting doll of event horizons, at any radius inside the event horizon, you should be able to look out just fine, but there would appear to be an event horizon just inside from your location.

According to the math, a supermassive black hole won't tear you apart when you cross the event horizon, so you should be able to get a pair of neutron stars to fall into the event horizon while still orbiting each other. The field gradient at the event horizon of a supermassive black hole isn't that extreme, since its radius is so large.

So, to qstar's point, this may not be observable. If we could ever catch a massive pair of things crossing an event horizon, it might be verifiable, and you would be correct. Or, if we ever detect a gravity wave from a black hole, then you're wrong. It's a testable concept, not silliness
GSwift7
3 / 5 (6) Jun 21, 2013
Not quite. If you compared the measured values, you would find they were correlated, but if you measure your particle, you get a random value and you don't know whether that was the opposite of the one inside, or if you forced your to take a random value and the one inside was determined by yours. The values are correlated but because they are also random, no information can be sent via that method.


He's talking about Hawking Radiation. It's debateable whether it really works like that, but Hawking seems to think so.

As with the gravity wave scenario for extracting 'information' from inside the event horizon, this is testable. If we ever detect black body radiation from the event horizon, then we know it works.

You seem to be confusing 'information' with information like a message. You don't need a 'signal' to qualify as 'information' in this sense. Any measurable from within the event horizon qualifies in this definition of 'information'.
GSwift7
2.6 / 5 (5) Jun 21, 2013
Sorry to flood the thread, but one more thing to add.

In the case I mentioned above, where a neutron pair crosses the event horizon of a supermassive black hole while orbiting eachother, would the pair continue to orbit, or would they be annihilated? As I said, the math says that you should be able to fly in a spaceship and cross a SMBH's event horizon without even noticing, except for the absolute red shift/blue shift when you look out the windows. It shouldn't tear you apart. You don't reach the Roche limit until you get much farther 'down' towards the center, and you don't get speghetification until you get past the Roche limit.

So, you would have a bulge in the event horizon due to the mass of the infalling pair, correct? It should stick out near them. That bulge would fluctuate due to the wobble of their rotation. This is a gravity wave. Is that a better explanation of what I was trying to say? I'm sure you can see the implication, if that scenario is real.
Fleetfoot
5 / 5 (2) Jun 21, 2013
According to the math, a supermassive black hole won't tear you apart when you cross the event horizon, so you should be able to get a pair of neutron stars to fall into the event horizon while still orbiting each other. The field gradient at the event horizon of a supermassive black hole isn't that extreme, since its radius is so large.


That's correct and is the basis of the thought experiment I suggested, good start.

So, you guys both think that pairs of objects inside the event horizon are immune to the gravity wave phenomenon.


No. What I said is that the binary system continues behaving the same way so still generates gravitational waves as it falls, I do not disagree with you there either.

However, those gravitational waves travel at the speed of light so are subject to the same rules that apply to light, they fall inwards towards whatever might be at the centre and do not emerge from the black hole, that's where our difference lies.
Fleetfoot
5 / 5 (2) Jun 21, 2013
IF you had a satellite orbiting a black hole, and you created entangled pairs, and let one of the pair fall into the BH (without it encountering anything on the way) then the state of your particle on board the satellite would change according to the encounter inside the event horizon.


The values are correlated but because they are also random, no information can be sent via that method.


He's talking about Hawking Radiation.


No, he specifically discussed creating an entangled pair and then dropping one of them into the BH to extract information.

You seem to be confusing 'information' with information like a message. You don't need a 'signal' to qualify as 'information' in this sense. Any measurable from within the event horizon qualifies in this definition of 'information'.


So if I create an electron-positron pair and drop the electron into the BH, have I "extracted" the information that the BH is now more negatively charged? This may be semantics.
Fleetfoot
5 / 5 (1) Jun 21, 2013
So, you would have a bulge in the event horizon due to the mass of the infalling pair, correct? It should stick out near them.


Yes, temporarily.

That bulge would fluctuate due to the wobble of their rotation. This is a gravity wave.


No it isn't, just as a spinning disc with voltage isn't an EM wave, but it creates one. A gravitational wave is the ripple in space which travels away from the BH, and the effect of that radiation of energy is to flatten the bump in the horizon.

Is that a better explanation of what I was trying to say? I'm sure you can see the implication, if that scenario is real.


I think the point Q-star is making is that those waves are radiated from the distortion of the horizon, not from inside. While that is happening, the binary system is separately still radiating waves but those remain inside so neither carries information outside, across the boundary.

Incidentally "gravity waves" are completely different, but you probably know that.
ValeriaT
1 / 5 (5) Jun 21, 2013
Q-Star
3.3 / 5 (7) Jun 21, 2013
This is where we differ,,, I don't interpret "contemporary theory" as indicating that anything escapes a black hole


Gravity waves take energy from the objects causing them.


Are ya trying to apply fluid mechanics to gravitation as set forth in GR? I'm lost on what ya are pursuing with this.

In the case of neutron stars, we observe the slowing of rotation of the pairs.


Only when they are NOT inside the event horizon of a BH.

In the case of two black hole objects orbiting each other inside the event horizon, it would take energy from them in the same way


Energy is conserved,,,, the system retained the energy. And the system is everything INSIDE the event horizon.l

If you are extracting energy from inside the event horizon and doing work on objects outside the event horizon with that energy, then this is 'information' escaping.


Ya can not extract energy from inside the event horizon.
GSwift7
1.7 / 5 (6) Jun 21, 2013
I think the point Q-star is making is that those waves are radiated from the distortion of the horizon, not from inside


The event horizon cannot radiate anything, it's not an object. The mass which causes the event horizon effect is the source. If gravity waves are emitted from the event horizon, they must get their energy from the source of gravity, the massive object causing it. The event horizon is not an object and has no mass. It cannot emit a gravity wave, and it has no energy to be lost. Gravity waves cary energy, and cannot simply be produced by a field. They must be produced by an object acting in the field.

The whole idea of a gravity wave may not be correct. Binary neutron stars slowing down can have alternative explanations, such as the pair gaining mass.
Q-Star
3.3 / 5 (7) Jun 21, 2013
Perhaps black holes are special, but I doubt it. A neutron pair seems to do it, and a massive enough neutron pair will form a black hole if thier combined mass is large enough and orbit small enough.


Yes but everything they do will be contained within their mutual event horizon if they merge. If separate their event horizons may overlap, but only for a time, they will merge, until they do, they will produce gravitational waves we might observe, but nothing we detect will be emanating from "inside" the event horizons. Only from the spacetime around and between the event horizons.

Perhaps they stop emitting gravity waves, but who knows?


Gravity waves can only be generated in a fluid medium, please tell me that ya haven't joined the aether wave group.
Q-Star
3.3 / 5 (7) Jun 21, 2013
The event horizon cannot radiate anything, it's not an object.


And neither is a gravitational wave, it's not a form of radiation. It is a fluctuation of a gravitational field.

If gravity waves are emitted from the event horizon, they must get their energy from the source of gravity, the massive object causing it.

Gravitational wave are emitted. They form when massive objects interact in spacetime.

The event horizon is not an object and has no mass


No one has said it is any more than a boundary created by mass, the point where the escape velocity exceeds "c".

It cannot emit a gravity wave, and it has no energy to be lost.


Except for a single special case, the BH with everything between it and the event horizon can not lose energy.
GSwift7
1.8 / 5 (5) Jun 21, 2013
wwoah, wait a minute here.

You guys have forgotten that I started as asking a question, and proposing what it would mean if the answer were yes versus no.

If we ever observe a gravity wave from a black hole, then it must originate from inside the event horizon. That's a big if, since we've never observed a gravity wave from any source at all, so who knows.

Ya can not extract energy from inside the event horizon


I agree that this is the Universe as we know it.

If we ever observe a gravity wave from a black hole, that has to change. Gravity waves cary energy (if they exist), and as such are taking energy from the objects inside the event horizon. That would break the rules as we know them. That's all I was suggesting, and I tried to suggest a scenario that should allow that idea to be tested. It would be a neat thing to see.
Q-Star
3.3 / 5 (7) Jun 21, 2013
Gravity waves cary energy, and cannot simply be produced by a field. They must be produced by an object acting in the field.


That is what I've been trying to tell. A single black hole which has no spin, has a GRAVITATIONAL field in spacetime around, but produces no waves, especially "Gravity waves". If a massive object gets near enough to it the field , the local spacetime will undergo field fluctuations (waves). But they won't be gravity waves exchanging energy, they will be disturbances in spacetime.
GSwift7
1.8 / 5 (5) Jun 21, 2013
Yes but everything they do will be contained within their mutual event horizon if they merge. If separate their event horizons may overlap, but only for a time, they will merge, until they do, they will produce gravitational waves


You're assuming that the two neutron stars must merge into a single object before the event horizon forms. Two neutron stars of sufficient mass would form an event horizon before becoming a single object if they get close enough to one another. Whether they would immediately self-seek to the center is a good question, but I don't see any reason to think they would immediatly implode when the event horizon formed. I think it is more likely that they would continue to orbit one another inside the event horizon until the eventual merger happened. That could take millions of years, or nerver happen. If you're correct that no energy can leave the system, then the pair would have no way to shed angular momentum. Nothing should be able to cause a merger.
Q-Star
3.3 / 5 (7) Jun 21, 2013
Gravity waves cary energy (if they exist),


They only exist in a dense medium. A fluid medium. There is no aether.

and as such are taking energy from the objects inside the event horizon.


Okay I'll pretend that there is a dense medium,,,, that would mean, the waves have to move through a sea of mass at greater than the speed of light to escape the event horizon.
That would break the rules as we know them.


That is exactly what we are saying. ANYTHING leaving an event horizon breaks ALL the laws as we know them.

That's all I was suggesting, and I tried to suggest a scenario that should allow that idea to be tested. It would be a neat thing to see.


Once it crosses into the event horizon there is nothing more to see. All the action, all the observational science starts at the event horizon and outward.
Q-Star
3.3 / 5 (7) Jun 21, 2013
You're assuming that the two neutron stars must merge into a single object before the event horizon forms.


I'm not assuming that, BUT I am saying no event horizon will form until ya have one or more black holes. That is the definition of event horizon.

Two neutron stars of sufficient mass would form an event horizon before becoming a single object if they get close enough to one another.


That's not correct, one or both must become a BH to create an event horizon.

If you're correct that no energy can leave the system, then the pair would have no way to shed angular momentum. Nothing should be able to cause a merger.


Energy is conserved. So is angular momentum. The system is conserved, one object will gain momentum, and the other will loss momentum, the total does not go up or down. One object may transfer energy to the other. But it is still conserved. Conservation is even better tested than GR.
GSwift7
1.8 / 5 (5) Jun 21, 2013
They only exist in a dense medium. A fluid medium. There is no aether.


What?

We're trying to detect gravity waves with experiments right now. I don't see where you get aether from. I certainly didn't suggest that there's any kind of aether. Neutron star pairs in tight orbits are suspected of producing gravity waves, correct? Where did you get aether from, and where did you get the idea that gravity waves would only exist in a dense medium? I'm not following you there. The only medium needed is spacetime.

You certainly need a medium to detect it, but the waves propogate regardless of whether you detect them or not. (assuming the whole theory is correct in the first place)
Q-Star
3.3 / 5 (7) Jun 21, 2013
We're trying to detect gravity waves with experiments right now.


Surfers detect gravity waves. Barometers can detect them also.

I don't see where you get aether from.


Because fluid mechanics is the field where one would study gravity waves.

Neutron star pairs in tight orbits are suspected of producing gravity waves, correct? Where did you get aether from, and where did you get the idea that gravity waves would only exist in a dense medium? I'm not following you there. The only medium needed is spacetime.


Ah, ya mean gravitational waves. Gravitational waves are the result of the interaction of massive bodies in space, It's a fluctuation of the fields, a ripple in spacetime.

Gravity waves are what ya see in at ocean, water waves created and fashions by the Earth's gravitational mass interacting with the moon.
Ober
3 / 5 (2) Jun 21, 2013
Oh QSTAR don't get into semantics, gravity waves vs gravitational waves, we all know what is being discussed here.

Anyway, I'm enjoying reading the discussions here. Seems we have come along way from the shit slinging sessions that used to occur. Good to see intelligent people can have a different opinion and discuss it in a civilised fashion. We should be proud of ourselves for turning physorg threads around, back to being "good reads". After all science is about discussing different points of view, providing there is some logic to follow.
Q-Star
3.3 / 5 (7) Jun 21, 2013
Oh QSTAR don't get into semantics, gravity waves vs gravitational waves, we all know what is being discussed here.

But gravity waves play a very important mechanism in astrophysics.Particularly those caused by BH's and neutron stars.Their gravity field induce fluctuations in the clouds of gas and aid in new star formation, whenever one chances by a particularly rich field of gas. Because of the different mass of the various particles, they can set up a wave, much like in the ocean, it gives gravity a boost, an instability that enhances a cloud's ability to radiate away heat and under go further (star forming) collapse. Like water piling up sand at the shore when the waves hit the shore.

I just didn't realize which phenomena. Gravity waves can only exist in the context of a medium to transmit them a gas, a liquid, see? Gravitational waves aren't waves of energy, they are fluctuations of spacetime, and they don't by the fact of their existence HAVE to transfer energy but CAN.
ValeriaT
1 / 5 (5) Jun 21, 2013
But gravity waves play a very important mechanism in astrophysics.Particularly those caused by BH's and neutron stars.. Like water piling up sand at the shore when the waves hit the shore.
We never observed such a mechanism, so I doubt it's "very important". Interstellar gas is often subject of various Bloch and shock waves, but these effects were never attribute to gravitational waves (i.e. the metric deform of space-time). Please, don't invent stuffs which don't fit the observations.
they don't by the fact of their existence HAVE to transfer energy but CAN
Such a "fact" doesn't actually exist, as the gravitational waves are derived with energy balance of gravitational field equation (in form of Einstein pseudotenzor) - so they MUST transfer an energy, because they're defined with mass-energy equivalence principle. The twaddling about physics is not so free game as you probably believe...
Fleetfoot
5 / 5 (1) Jun 22, 2013
You're assuming that the two neutron stars must merge into a single object before the event horizon forms.


No, I specifically talked of the two continuing to orbit while falling inside the EH of a SMBH.

Two neutron stars of sufficient mass would form an event horizon before becoming a single object if they get close enough to one another.


Yes.

I think it is more likely that they would continue to orbit one another inside the event horizon until the eventual merger happened. That could take millions of years, ..


Two neutron stars would have a combined mass of less than 3 solar masses so the time to the centre is in the microseconds. they will reach the singularity in far less time than it would take for a single mutual orbit. Of course they will be beyond the Roche Limit and spaghettified rather than remain as spherical objects anyway.
Fleetfoot
5 / 5 (1) Jun 22, 2013
I think the point Q-star is making is that those waves are radiated from the distortion of the horizon, not from inside


The event horizon cannot radiate anything, it's not an object.


You have to remember that a black hole is a vacuum solution to GR and the distortions of the field are very complex during a merger.

Gravit[ational] waves cary energy, and cannot simply be produced by a field.


They are an outwardly-propagating part of the overall curvature of the field and carry both energy and momentum.

They must be produced by an object acting in the field.


The mass(es) create the field and changes in the field propagate through the vacuum as distortions of its geometry.

The whole idea of a gravit[ational] wave may not be correct. Binary neutron stars slowing down can have alternative explanations, such as the pair gaining mass.


Try working out how much mass PSR B1913+16 would need to be gaining. Where is it coming from? That doesn't fly.
Q-Star
3.3 / 5 (7) Jun 22, 2013
But gravity waves play a very important mechanism in astrophysics.Particularly those caused by BH's and neutron stars.. Like water piling up sand at the shore when the waves hit the shore.


We never observed such a mechanism, so I doubt it's "very important".


Gravity waves & gravitational waves are two different things Zephyr.

Please, don't invent stuffs which don't fit the observations.


Gravity waves are observed. At the beach, and out in the cosmos whenever a very massive object is moving near a cloud of dense matter (No, not aether, actual matter.) The moon's tidal pull aids in the formation of gravity waves at the beach. And a massive cosmic object will also produce actual real observable waves in rich clouds of gas. The more different kinds of particles in the cloud, the more pronounced will be the waves.

Gravitational waves don't do that.
Q-Star
3.3 / 5 (7) Jun 22, 2013
they don't by the fact of their existence HAVE to transfer energy but CAN
Such a "fact" doesn't actually exist, as the gravitational waves are derived with energy balance of gravitational field equation (in form of Einstein pseudotenzor) - so they MUST transfer an energy, because they're defined with mass-energy equivalence principle. The twaddling about physics is not so free game as you probably believe...


Such a fact does exist Zephyr, the gravitational waves may possess energy. But they don't HAVE to transfer energy. We will not know that they are required to transfer energy until we are able to detect the "particle" (hypothetical particle) that mediates that transfer, ie the "graviton". Until then the most we can say is we observe situations where energy is transferred, and we also observe situations we don't observe the transfer of energy. So it a MAY phenomenon, not a MUST phenomenon.
Q-Star
3.3 / 5 (7) Jun 22, 2013
Please, don't invent stuffs which don't fit the observations.


P.S. By the By: I will take those words of the Zephyr as an indication I am on the right track. Thanks Zeph, ya have removed any doubts I was having.

Maybe ya could help me by putting all this into longitudinal electron superluminary water waves in the transverse aether,,,, then we wouldn't have to worry about any "invent stuffs which don't fit the observations" creeping in.
ValeriaT
1 / 5 (5) Jun 22, 2013
But they don't HAVE to transfer energy
So far the gravitational waves were found just with the energy, which they mediate (Hulse–Taylor binary pulsar as an iconic example). BTW to call something a wave without release of energy is an oxymoron. This is the only way, how some wave can manifest itself - with spreading of its energy at distance. In dense aether model the gravity waves manifest with CMBR noise, but they still spread an energy, just not in deterministic way in our limited set of dimensions.
I will take those words of the Zephyr as an indication I am on the right track..
If you're considering the lack of evidence as an evidence, then you can consider way more irrational stuffs, than just some non-radiative waves and it may be possibly relevant to consider more effective medication.
Q-Star
3.3 / 5 (7) Jun 22, 2013
If you're considering the lack of evidence as an evidence, then you can consider way more irrational stuffs, than just some non-radiative waves and it may be possibly relevant to consider more effective medication.


Uuh, are ya trying to say that ALL waves TRANSFER energy? (It's kind of hard to tell when ya mix your comments into the AWT.) Be that as it may be, if that is what ya are saying, I disagree. Not all waves transfer energy from one place to another place. If ya meant that all waves "possess" a certain energy, then I agree. Think careful before ya reply, ya are already wrong on some very very basic physics here.

Oops, I almost forgot. By the By: Ya would probably be a person with some experience to ask. What particular medication do ya think would work best in my case? If ya have no empirical first-hand experience, don't bother, anecdotal suggestions I don't trust.
ValeriaT
1.5 / 5 (6) Jun 22, 2013
When you say, that gravitational waves may not spread an energy, then I'm just asking you for observational evidence and/or theory, which applies to it. Random ad-hoced idea doesn't count here.
Q-Star
3.3 / 5 (7) Jun 22, 2013
When you say, that gravitational waves may not spread an energy, then I'm just asking you for observational evidence and/or theory, which applies to it. Random ad-hoced idea doesn't count here.


Google is your friend Zeph. Give it ago. (Or maybe not, ya will have to read through some stuff that is counter to every aspect of the AWT.) I will warn ya though, it's not ad hoc, as a matter of fact, it's pretty, uuh, mainstream, so ya will have to Google with an open mind.
Q-Star
3.3 / 5 (7) Jun 22, 2013
When you say, that gravitational waves may not spread an energy, then I'm just asking you for observational evidence and/or theory, which applies to it. Random ad-hoced idea doesn't count here.


I've got to run now Zeph, so I can't go back and forth with ya tonight. But read up on waves in general and gravitational waves, and gravity waves until I can get back.

By the By: If ya force your ad-hoced AWT on me, why can't use conventional mainstream tested ad-hoced ideas and theories? It's only fair.
GSwift7
2.3 / 5 (3) Jun 23, 2013
OFFS, yes gravitational waves. 1000 characters, yes? The discussion was about gravitational waves, I just shortened it for simplicity.

As for surfers, no they do not use gravity waves. Ocean waves are caused by wind, which is a product of convection, which is a product of static gravity. You don't need tides in order to have waves. If you're going to be silly about semantics, then I can too. That's really got nothing to do with what we were talking about though.

The point at hand is that if we detect gravitational waves from a black hole, then we will need to rethink things. But, as I said earlier, I think I agree with fleetfoot. I don't think you would see gravitational waves from a black hole. The objects inside might create them, but they shouldn't propogate out.

I disagree that you can treat the EH as an object. It has no physical properties of its own.
GSwift7
2 / 5 (5) Jun 23, 2013
Farther up the thread I suggested that you might be able to cross the EH of a supermassive black hole without noticing, but I have re-thought that.

Inside the EH, nothing can propogate outwards, so the atomic bonds should break down. The atomic forces shouldn't be able to propogate outwards, so I guess you would disintigrate at that point. There shouldn't be any way to hold an atom together inside the EH, right? The atomic forces would propogate inwards, but there'd be no opposite attraction going the other way. There'd be no like force repulsion either I guess. Orbits of subatomic particles would stop, since they could only travel inwards too. Maybe it would all immediately go zipping inwards to the center? There seems to be no other choice.
Q-Star
3.5 / 5 (8) Jun 23, 2013
I disagree that you can treat the EH as an object. It has no physical properties of its own.


That's what I've always said, it's a boundary. There is everything within that boundary, and it stays in. And there is everything outside that boundary, it can go in, but once in, it is lost to us by all the rules of physics as we know them.

What is within the event horizon has a gravitational field that extends beyond the horizon. For us it begins at the event horizon. There will be no gravitational waves, until that field (outside of the event horizon) interacts with another another gravitational field. The ripples (waves) in space with manifest.

No gravitational waves come from inside. If ya detect them, they are created outside of the event horizon.
Q-Star
3.3 / 5 (7) Jun 23, 2013
Ocean waves are caused by wind, which is a product of convection, which is a product of static gravity. You don't need tides in order to have waves. If you're going to be silly about semantics, then I can too.own.


My silly semantics are correct,,, yours are wrong.

Ya seem fond of wiki,

Gravity waves:

In fluid dynamics, gravity waves are waves generated in a fluid medium or at the interface between two media (e.g., the atmosphere and the ocean) which has the restoring force of gravity or buoyancy.

When a fluid element is displaced on an interface or internally to a region with a different density, gravity tries to restore it toward equilibrium resulting in an oscillation about the equilibrium state or wave orbit.Gravity waves on an air–sea interface are called surface gravity waves or surface waves while internal gravity waves are called internal waves. Wind-generated waves on the water surface are examples of gravity waves, and tsunamis and ocean tides are others.


Fleetfoot
5 / 5 (1) Jun 23, 2013
Farther up the thread I suggested that you might be able to cross the EH of a supermassive black hole without noticing, but I have re-thought that.

Inside the EH, nothing can propogate outwards, so the atomic bonds should break down. The atomic forces shouldn't be able to propogate outwards, so I guess you would disintigrate at that point. ..


At what point would that happen? The event horizon is observer-dependent. The one we usually talk about is the location for a distant observer at rest but as you fall towards the hole, the event horizon according to you is always some distance ahead of you.

Someone recently talked of a black hole being like the layers of an onion but it's more like a moving target, or Zeno's Paradox, no matter how close you get to the centre, the horizon is always between you and it.
Fleetfoot
5 / 5 (1) Jun 23, 2013
When you say, that gravitational waves may not spread an energy, then I'm just asking you for observational evidence and/or theory, which applies to it. Random ad-hoced idea doesn't count here.


Actually guys, Val is right in this instance. Gravitational waves have never been observed directly but they are predicted by GR. If GR is correct, then they will carry energy and momentum at the level it predicts. If GR is wrong, they may not exist. What we can say though, is that there is no theory which predicts the existence of a gravitational wave that doesn't carry energy or momentum, and there are no observations of such waves either.

In fact if a wave didn't carry energy, it's hard to see how it would be detectable.
Fleetfoot
5 / 5 (1) Jun 23, 2013
As for surfers, no they do not use gravity waves. Ocean waves are caused by wind, which is a product of convection, which is a product of static gravity.


Gravity waves are waves on a surface where gravity provides the restoring force for any displacement from the mean. Ocean waves are gravity waves.

You don't need tides in order to have waves.


That is correct, the tides alter the local mean level, it is the waves which are deviations from that mean that are gravity waves.

If you're going to be silly about semantics, then I can too.


Let's just agree to use the correct jargon. We all use abbreviations because of the character limit (I use GW in this context) but "gravitational waves" and "gravity waves" are two distinct phenomena.

The point at hand is that if we detect gravitational waves from a black hole, then we will need to rethink things.


GW are expected to be emitted during the creation of a black hole but those come from outside the horizon.