Just a quick question.
So does a body lose mass over time due to it radiating gavitational energy?
I guess that it should but at what rate?
Has this been experimentally verified?

have a chat about it if you like, I'm all ears. ;)
Dee Cee

DeeCee, this is an excellent question. I am not a physicist and do not know the answer, but I can see problems raised by either a yes or no answer. I would think
the question would be more suitable in the physics and math forum.

Dee Cee,

I would have a problem with the question in the sense that it infers a strickly Newtonian view. Newtonian gravity is almost passe and is known to not be valid in the macroscopic view.

http://www.astro.umd.edu/~ssm/mond/f5631.gif

The red line is Newtonian gravity. The symbols and blue line are actual observation.

cut and paste from MOND theory:
"Modern cosmological models require copious amounts of nonbaryonic cold dark matter for well established reasons. Yet the existence of CDM has yet to be confirmed. The alternative to dark matter postulated by MilgromM83 (1983), MOND, has long had considerable success in describing the rotation curves of spiral galaxies (Begeman et al. 1991BBS; SandersS96 1996; Sanders & VerheijenSV 1998), a fact which has no explanation in the standard framework. Moreover, MOND successfully predicted, a priori, the behavior of low surface brightness galaxies (McGaugh & de Blok 1998bMBb; de Blok & McGaugh 1998BM), a test which CDM models fail (McGaugh & de Blok 1998aMBa; Moore et al.MQGL 1999). Yet MOND has no clear cosmology.

In this paper, I have attempted to make some predictions for the temperature anisotropies in the microwave background which might potentially discriminate between CDM and MOND dominated cosmologies. In this context, the essential difference between the two is the baryon fraction ( for CDM and fb =1 for MOND). I have used this fact to examine the differences expected for microwave background observations in as conservative and model independent a way as possible.

Upcoming experiments to measure the anisotropies of the microwave background to high precision should be able to distinguish between CDM and MOND. For the simple assumptions investigated here, the observational signatures are surprisingly subtle, requiring high accuracy (i.e., peak position or amplitude to at .) Perhaps the most promising test is the ratio of peak-to-trough amplitudes of the first two peaks, with in plausible CDM models and in MOND.

These predictions are offered in the hope of clearly distinguishing between CDM and MOND in the near future."
http://www.astro.umd.edu/~ssm/papers/cmbpp/node4.html#SECTION00040000000000000000
================================================== ===========

Mac, that paper was written in 1997. The "near future" has already passed. MOND
lost, as I pointed out to you before. MOND was simply a competor to the Cold Dark
Matter theory to explain the mass discrepency proble, i.e., the problem of there not
being enough OBSERVABLE mass to explain how galaxies can hold together without
flying apart and how galaxies lack enough observable mass to be gravationally attracted to each other. WMAP and SDSS solved the problem and established CDM
as the winner over MOND. MOND is invalid.

2Inquisitive,

I am not promoting MOND. It is nothing but an Ad Hoc algorithum. I posted that graph since it shows the gross error in Newtonian gravity.

Also it is worth noting that the "Conclusion" link you provided doesn't actually say what you have just claimed. As I read it it is saying that the ground work to distinguish between CDM and MOND has been established and future testing will be able to determine which is more correct.

It actually shows both sides where MOND suceeded and CDM failed and vice-versa.

So does a body lose mass over time due to it radiating gavitational energy?

Binary pulsars radiate gravitational waves, which carry energy away from the source.
The energy that is radiated reduces the energy of the pulsars, which eventually causes the orbits to decay.
In this scenario, its probably more accurate to say that the energy is reduced and not the rest mass.
Gravitational waves are said to result as a consequence of time dependant quadrupole moment in mass and if this moment were as a result of a nuclear reaction within the radiating mass, then it would lose mass, indirectly, due to the reaction that causes the gravitational waves.
The sun is reducing in mass due to the light it emits, but photons have no rest mass. The fusion process fuels the Emr and indirectly causes a mass decrease.
Its a good question- Looking forward to seeing what others have to say as well. :)

2Inquisitive,

I am not promoting MOND. It is nothing but an Ad Hoc algorithum. I posted that graph since it shows the gross error in Newtonian gravity.

Thats the whole problem, Mac. The graph only shows that there would be an
error in Newtonian gravity if the OBSERVABLE mass estimates were all the mass there was. Cold Dark Matter makes up the rest of the needed mass.

2Inquisitive,

I understand that but I also understand CDM is simply made up to account for the Newtonian failure. I'll not drag in the ugly "U" word but there are concepts that don't need MOND, CDM nor Dark Energy to account for the full spectrum of observed gravity in the universe.

BTW: I still anticipate some CDM but not nearly as much when the correct gravity mathematics are used. That is because I suspect there is infact matter we do not see.

But I do expect to see Dark Energy vanish altogether.

Yes, beta, and the question arises in my mind, if mass decreases with gravity emitted,
would not a black hole's singularity eventually evaporate regardless of Hawking radiation? And if mass does not decrease with gravity emitted, where does the
gravitational energy come from?

2Inquisitive,

And if mass does not decrease with gravity emitted, where does the gravitational energy come from?

I hope you are not starting to think "External", GFB. :D

Mac, I am not qualified to offer an opinion on your theory. For one thing, I really don't
understand it well. I do not believe there are enough mathematics to show that it is
consistent, but there are not enough to show that it is invalid either. Hence my caution in earlier thread to not tie it in with MOND to closely, because MOND was
shown to not fall within the cosmological parameters established by WMAP and other
studies. I read the specific paper where MOND WAS considered, but failed to fall
within those parameters. It was a while ago and I don't remember the specific paper,
but MOND was discounted unless vast changes can be made to the theory.

Uh Uh UniKEF....
You boys play nice now.

In this scenario, its probably more accurate to say that the energy is reduced and not the rest mass.
Makes me wonder...

Do objects at absolute zero 'emit' gravity.
I suspect they do.
Which leads me to all sorts of places but lets stick with the topic. :)
If so do they lose mass?

I gotta come clean I'm no physicist but I can grasp most of the concepts (usually) and I can appreciate the power of the math.

Dee Cee

>.. and the question arises in my mind, if mass decreases with gravity emitted, would not a black hole's singularity eventually evaporate regardless of Hawking radiation?

What I was suggesting is that there can be an indirect loss of mass as a result of a process which does cause mass loss and initiates Gravity waves ( which should not carry away rest mass )

>>And if mass does not decrease with gravity emitted, where does the
gravitational energy come from?

There is energy ( gravitational potential energy) in the separation of the binary pulsars to begin with.

>>Do objects at absolute zero 'emit' gravity.
I suspect they do.

Absolute zero is a hypothetical situation- I can't really comment meaningfully.

>>Which leads me to all sorts of places but lets stick with the topic.
If so do they lose mass?

Perhaps indirectly, by the process that causes the quadrupole moment.
I would prefer to say that the energy of the source is reducing, not the rest mass.

2Inquisitive,

Mac, I am not qualified to offer an opinion on your theory. For one thing, I really don't understand it well. I do not believe there are enough mathematics to show that it is consistent, but there are not enough to show that it is invalid either. Hence my caution in earlier thread to not tie it in with MOND to closely, because MOND was shown to not fall within the cosmological parameters established by WMAP and other studies. I read the specific paper where MOND WAS considered, but failed to fall within those parameters. It was a while ago and I don't remember the specific paper,but MOND was discounted unless vast changes can be made to the theory.

Good post. Your honesty is appreciated. Your are correct. The only mathematics to date that have been verified was the initial inverse square, without including the flattening properties of sources inbetween masses as distance increases. But that is being addressed at UTEP. So it has not been verified but it is in the correct direction and I am most hopeful it will perform as anticipated.

And again I do not advocate MOND.

quote:

What I was suggesting is that there can be an indirect loss of mass as a result of a process which does cause mass loss and initiates Gravity waves ( which should not carry away rest mass )
================================================== =====
I'm afraid I don't understand. What kind of mass are you suggesting from a body that
is not moving relativistically from us? Relativistic mass would only appear in different
frames of reference, correct?

quote:
There is energy ( gravitational potential energy) in the separation of the binary pulsars to begin with.

================================================== ===========
Would that not be kinetic energy? But we were speaking of gravity from a single body,
not gravitational interaction with another body.

>>I'm afraid I don't understand. What kind of mass are you suggesting from a body that is not moving relativistically from us? Relativistic mass would only appear in different frames of reference, correct?

What I was suggesting is that it requires energy to create GW's.
This energy, might come from a fusion process (arbitrary choice ) occurring within the mass, which then causes the mass to distort and create a time dependant quadrupole moment.
The mass then radiates GW's, but no mass is lost due to the GW's directly, but it does lose mass due to the fusion process.
Perhaps this is a clumsy way of saying that GW's don't carry away rest mass directly, but the process that cause the mass to radiate GW's can, under circumstances such as I have described.

>>Would that not be kinetic energy? But we were speaking of gravity from a single body,not gravitational interaction with another body.

No, I was referring to binary pulsars - Two orbiting masses, that are the source of GW's.

2Inquisitive & Beta,

How does all this square with the information from the link that 2Iquisitive posted in UniKEF Analysis, that says they found no evidence supporting "Gravitational Waves"?

http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0310/0310723.pdf

That may suggest that gravity doesn't radiate but is an inflow of energy.

What I was suggesting is that it requires energy to create GW's....

GW's don't carry away rest mass directly, but the process that cause the mass to radiate GW's can, under circumstances such as I have described.


I believe you're right - after all the circumlocutory discussion. An object doesn't lose mass simply because it has a gravitational field: that's simply a curvature in the fabric of space caused by the body's presence, which doesn't detract from that body any more than a shadow detracts from the person who casts it.

Massive moving objects produce ripples in spacetime, which leak away the kinetic energy/angular momentum of the objects' motion. In the very long term (10^25 years, perhaps) this could cause the galactic orbits of most stars to decay completely. The stars would not lose mass because of it, though - their gradual loss of mass will be due to proton decay, on a much longer timeframe.

Yes, a gravitational FIELD is described as a curvature of spacetime by General Relativity.
That, however, is a description of the EFFECTS of gravity, not a description of the
mechanism that causes those effects, gravity itself. Newtonian gravity is not described
that way either.
We also are not talking of kinetic energy caused by a body's motion. Binary pulsars
have nothing to do with the original question.

We all know how a vacuum cleaner works , hence due to gravitons falling on mass push the smaller objects towards it hence mass has to increase as gravitons are constantly being added to the mass.

check this out http://www.sciforums.com/showthread.php?t=34490

We all know how a vacuum cleaner works , hence due to gravitons falling on mass push the smaller objects towards it hence mass has to increase as gravitons are constantly being added to the mass.


I don't think gravitons THEMSELVES should be regarded as adding mass to an object. They are the hypothetical quanta of the gravitational force, just as photons are the quanta of electromagnetism - and an adequate quantum theory for gravity has yet to be worked out.

Of course, gravity does result in accretion, thereby increasing the mass of the strongest attractors. This is quite the opposite of transferring mass outwards to smaller objects.

I don't think that gravity is an energy, I mean there is kinetic energy , but for kinetic energy is cancelled out with potential energy.

pardon my ignorance but isn't gravity a force...? and erm... last time i checked... GP didn't radiate.

Jaredster,

Your are correct, gravity "is not energy" but may be the consequence of energy flow. Gravity would be the force created by energy absorbtion.

Jadedflower,

pardon my ignorance but isn't gravity a force...? and erm... last time i checked... GP didn't radiate.

You too are correct; however, It is upon you to tell us just HOW it is that mass curves time-space. You have no understandable cause for the affect.

If everything leaks away angular momentum, wouldn't that mean that not only planets come closes to their suns but that this process will repeat on larger scale, like our stars going closer to the center of our milkyway and cluster of galaxies getting closer to a common center, just makes you wonder how much energy is conserved in the angular momentum of our whole known universe....

If everything leaks away angular momentum, wouldn't that mean that not only planets come closes to their suns but that this process will repeat on larger scale, like our stars going closer to the center of our milkyway and cluster of galaxies getting closer to a common center, just makes you wonder how much energy is conserved in the angular momentum of our whole known universe....

The slowing of orbits by gravitational radiation should not be considered beyond the scale of the stars in a galaxy, simply because clusters of galaxies fo not orbit one another; they are either mutually gravitating into superclusters, or receding from one another because of the general expansion of the Universe.

:eek: Within an individual cluster, the galaxies may orbit one another: but at the present age of the Universe, they can't have completed more than a few orbits - those orbital paths are mostly unstable anyway in the long term, without having to invoke gravitational radiation effects. The Milky Way & M31, for example, are schedualed to collide in a few billion years.

While looking at Stanford's Gravity Probe B website, I came across the original question
in their Q&A section, question no. 75. I thought I would give a copy & paste:

"Don't objects steadily evaporate over time by emitting gravity waves?
Although the mass of every body includes the energy stored in its gravitational field, the only way to get a body to loose energy by gravity is by way of gravitational radiation. This is produced by accelerating the body, however, in order to get large mass losses, you need to accelerate the body enormously because gravity waves are so weak. The acceleration felt by two dense neutron stars orbiting around each other every minute at a distance of a few hundred kilometers is the most extreme acceleration known. It is not very effective in causing the bodies to loose much mass compared to the feeble mass lost by the electromagnetic radiation leaving their surfaces."
http://einstein.stanford.edu/

With regard to the explanation given by Stanford's GP-B site - Its correct, as long as you realize they are not talking about the 'rest mass' of the source as decreasing.

All bodies are in motion, there is no universal rest frame. All massive bodies therefore
radiate gravity, they are in an accelerating frame, a non inertial frame. Mass loss due
to gravitational radiation is slight, but it is present. What mass are you saying is
decreasing? If you mean the rest mass of a body in a universal rest frame is not
decreasing, where do you find such a body?

>>All bodies are in motion, there is no universal rest frame. All massive bodies therefore radiate gravity, they are in an accelerating frame, a non inertial frame.

I don't understand what you are referring to. Inertial FoR's do exist and not all mass radiates GW's.
Gravitational radiation requires a time dependant quadrupole moment in mass.
Can you explain what your idea of gravitational radiation is.

>>Mass loss due to gravitational radiation is slight, but it is present.

Do you have evidence for 'rest mass' loss due to GW's.

>What mass are you saying is decreasing?

Energy is lost from the source ( we see it in pulsars orbit decay).
There is some validity in calling this energy loss as 'mass', but not 'rest mass'

I believe gravity is produced at the atomic level, by the nuclear processes and energy
contained within the atom itself. A loss of energy in a system is a loss of mass, period,
but it does, of course, take a huge amount of energy to equal a small amount of mass
as evidenced by e=mc^2. A copy and paste and a link to one paper which you may
not agree with, but there are others also:

Gravitational Radiation from Quantum Systems
Like electromagnetic radiation, gravitational radiation could be emitted by quantum transitions. We introduce
this concept with the simple analogy to the well known binary pulsar GW source. By this analogy the ideal
laboratory source of gravitational radiation could be a couple of almost identical orbiting objects with nuclear
matter density and with electric charge, which will give us the ability of controlling them with an
electromagnetic field. Being the scale factor in principle not relevant for the efficiency of the EM-GW
converter, and looking for a high frequency array of such objects, we could reduce the scale factor reaching, for
instance, the size of Cooper’s pairs, which certainly satisfy our initial requirements.
At atomic scale the emission of a quantum of gravitational radiation, the graviton, is accompanied by a L=2
transition in the quantized angular momentum of the emitting system.
In (Halpern, 1964) the investigation of the interaction of the gravitational fields with microscopic systems has
been extended to the nuclear and molecular phenomena, with the interesting result that the gravitational
interactions have here a greater significance than at a macroscopic level, where gravitational radiation is
extremely difficult to generate and detect. The multipole expansion of the gravitational radiation field resulting
from periodically oscillating sources has been performed in full analogy with the method used for the
electromagnetic fields, thus formally reproducing a successful and experimentally tested methodology.
According to (Halpern, 1964) and (Halpern, 1968) atomic transitions for which the orbital quantum number L
changes by + or – 2, and for which the total quantum number J changes by 0 or + or – 2 are gravitational
quadrupolar transitions and are permitted for the emission of gravitons, while the emission of photons is
forbidden. It has been found that atomic transitions from orbitals 3d to 1s, 3d to 2s and 3d to 3s are possible
candidates for transitions, which may be applicable for the generation of gravitational radiation by atoms of a
suitable material. The material could be pumped by photons and let decay gravitationally.
http://arxiv.org/ftp/physics/papers/0110/0110042.pdf

>>I believe gravity is produced at the atomic level, by the nuclear processes and energy contained within the atom itself. A loss of energy in a system is a loss of mass, period, but it does, of course, take a huge amount of energy to equal a small amount of mass as evidenced by e=mc^2.

That paper is a hypothesis, regarding possible methods of utilizing GW's to create propellant- less thrust.
They do not claim that gravity ( the usual curved spacetime as we understand it in GR) is produced by quantum transitions, but they are presenting possible methods of GW generation, primarily by energy emitted ( they assume it could be a graviton ) during a transition from an excited quantum state to a stationary quantum state.
While their approach is based on some GR formalism, it is very speculative.
If you are going to claim a loss of mass, you should qualify it as rest mass or frame dependant mass, then offer some supporting evidence.
I would not classify that article as supporting evidence.

Here is a link to a description of the loss of energy in a system due to gravitational
radiation. Mass is more or less just a concetrated form of energy, correct? I do not understand why you insist their would be no loss of rest mass. Do you think the
mass would be regained if the system stopped orbiting?
"In recent months there has been an upsurge of interest in the theoretical prediction of gravitational radiation in general relativity following observations by Taylor et al. (1) on the binary pulsar PSR 1913+16. (2,3) They have found a systematic decrease of the orbital period of the system that is consistent with energy loss due to gravitational radiation as predicted by Einstein's general theory of relativity. The compact nature of the participating objects is such as to rule out convincingly significant contributions from other mechanisms such as tidal interaction. These observations represent the first tests of general relativity outside the solar system and also constitute the first convincing experimental evidence, though indirect, for gravitational waves."
http://www.davis-inc.com/relativity/

Celestial mechanics are well described by both GR and Newton, but no one has an
exact model explaining how gravitation is produced. Most models I am aware of are
concentrating on the atom itself. Gravitons and gravity waves are both supported
by theory, but there is no direct evidence for either. Both may be possible, just as
there is support for both photons and EM waves. How would I or anyone else know
now?

>...I do not understand why you insist their would be no loss of rest mass. Do you think the mass would be regained if the system stopped orbiting?

Rest mass is not frame dependent.
A massive source of GW's has rest mass which remains constant as well as it's frame dependent energy.
When it radiates GW's, it losses energy, or the mass equivalent to this energy, but the rest mass does not change.
Once the binary pulsars orbit has decayed and is no longer a radiating source, it's rest mass is unchanged, but it has lost energy.
This is why I just prefer to say it has lost energy. (it should save confusion ?)

Sorry, beta, I guess the following is where my confusion arises.
quote:
"They have found a systematic decrease of the orbital period of the system that is consistent with energy loss due to gravitational radiation as predicted by Einstein's general theory of relativity. The compact nature of the participating objects is such as to rule out convincingly significant contributions from other mechanisms such as tidal interaction."

I understood that to mean the mass loss was NOT due to kinetic energy (tidal interaction) or any forces other than by gravitational radiation. I thought it would
indicate the rest mass WOULD change. Where am I going wrong?

>> I understood that to mean the mass loss was NOT due to kinetic energy (tidal interaction) or any forces other than by gravitational radiation. I thought it would
indicate the rest mass WOULD change. Where am I going wrong?

I haven't referred to the article, but my interpretation from that paragraph is-

*The observation is a decrease in orbital period.
*Is this due to Gravitational radiation, or some other reason.
*Perhaps the other reason may be tidal interactions between the masses.
*However, the two massive bodies in the pulsars are too small to lose the energy needed to explain the observed orbit decay by tidal effect.
*Why do they reach this conclusion- Energy will be lost due to tidal interaction, but with the expected size of the mass, the gravitational potential difference across the mass due to tidal interaction is too small to create an energy loss of sufficient magnitude.
*Therefore, gravitational radiation is still the most probable cause for the observation.

I can't see any inference that rest mass should change, just the above observations.
I suspect you may be misinterpreting the reference to tidal interaction.