What is the behavior of gravitons

[marcus]

Originally posted by steinitz
What I'm saying is that stars over time radiate away a fraction of their mass that's been converted to energy through thermonuclear fusion, not through the emission of gravitational radiation. However, as their orbits decay the corresponding orbital energy - as opposed to their proper mass - is lost as gravitational radiation. This applies to your binary system as well.

You may be honestly confused about something.

What you seem to be missing is that the system itself has a rest mass which is not equal to the sum of the masses of the individual stars.

The system's rest mass (actually "rest" is redundant)
includes orbital energy.

Just as the sun's rest mass includes thermal energy---it is not simply the sum of the rest masses of component particles.

The binary system can lose mass thru gravitational radiation even though the individual stars do not.

 

[jeff]

Originally posted by marcus

The idea of a star radiating away rest mass is entirely yours,

Indeed I am saying that stars radiate away their rest mass - but as the products of thermonuclear fusion, not gravitational radiation.

 

[marcus]

Originally posted by steinitz
Indeed I am saying that stars radiate away their rest mass - but as the products of thermonuclear fusion, not gravitational radiation.

Now we have something we can agree on!
This is what I say too. The individual stars of a binary pair
would not lose mass thru gravitational radiations but
might thru thermal radiation.
The object in question---the system itself---loses
mass thru grav. radiation. As I hope you will now acknowledge!

 

[jeff]

Originally posted by marcus
You may be honestly confused about something.

What you seem to be missing is that the system itself has a rest mass which is not equal to the sum of the masses of the individual stars.

The system's rest mass (actually "rest" is redundant)
includes orbital energy.

Just as the sun's rest mass includes thermal energy---it is not simply the sum of the rest masses of component particles.

The binary system can lose mass thru gravitational radiation even though the individual stars do not.

Yeah, I think you hit the nail right on the head. If your view that orbital energy is part of the rest mass of the binary system is correct, than so is the rest of you're claim.

My view is that orbital energy is not mass.

 

[marcus]

Originally posted by steinitz
Have you read smolin's book?

Unfortunately I don't know what book you mean?
Do you read many books like The Elegant Universe
and such----popular treatments for the layman?
I stay away from them.

Journal articles and arXiv seem to be an easier and
more reliable way to get information.

Recently I have benefitted from some webreferences
to LivingReviews--- Rovelli's and Thiemann's reviews of LQG.

But I would be curious to know the title of the Smolin
book you refer to----how did you like it? What is it about?

 

[jeff]

Originally posted by marcus
Now we have something we can agree on!
This is what I say too. The individual stars of a binary pair
would not lose mass thru gravitational radiations but
might thru thermal radiation.
The object in question---the system itself---loses
mass thru grav. radiation. As I hope you will now acknowledge!

Yeah, I can live with that... acknowledged.

 

[instanton]

Originally posted by steinitz
1. No, it has two polarizations because it's massless.

Yes. You are right. My mistake.

2. No, they may gravitationally radiate away orbital energy, but not mass.

Are they different? How can you define a mass of binary system?, even say a black hole?

Instanton

 

[instanton]

Let me add a comment on this.
I can not see how to define rest mass in gravitating system. Maybe what Steinitz meant was you goes to the rest frame of each atoms (or what ever), then measure rest mass of them and sum them up. But, this is not obviously the mass of star that will be measured by , say, satelite orbiting around it.

A single static star may not be able to radiate gravitational wave, but unstable wobbling stars like young born neutron star may. This is how collapsing stars loose all the hairs,

Instanton

 

[instanton]

When I have time, I'll be going through you're posts to correct you're errors. No need to thank me. You are a space cadet. [/B]

Ok. I will wait.

Instanton

 

[jeff]

Originally posted by instanton
Let me add a comment on this.
I can not see how to define rest mass in gravitating system. Maybe what Steinitz meant was you goes to the rest frame of each atoms (or what ever), then measure rest mass of them and sum them up. But, this is not obviously the mass of star that will be measured by , say, satelite orbiting around it.

A single static star may not be able to radiate gravitational wave, but unstable wobbling stars like young born neutron star may. This is how collapsing stars loose all the hairs,

Instanton

Proper mass is a property of matter, not radiation, be it gravitational or otherwise.

 

[jeff]

Originally posted by marcus
Unfortunately I don't know what book you mean?
Do you read many books like The Elegant Universe
and such----popular treatments for the layman?
I stay away from them.

Journal articles and arXiv seem to be an easier and
more reliable way to get information.

Recently I have benefitted from some webreferences
to LivingReviews--- Rovelli's and Thiemann's reviews of LQG.

But I would be curious to know the title of the Smolin
book you refer to----how did you like it? What is it about?

The book is "Three roads to quantum gravity" and I enjoyed it, which is saying a lot because I don't ordinarily read popular science books on physics. In it smolin describes the various approaches to QG, but with an extreme bias towards LQG, particularly in it's spin foam formulation. His discussion of the problem of applying quantum theory to closed systems is particularly interesting.

 

[marcus]

Originally posted by instanton
Let me add a comment on this.
I can not see how to define rest mass in gravitating system.

the root meaning of mass (according to contemporary ways of talking about it) is inertia of a body at rest

in astronomy mass is often measured by inference from gravitational effects

suppose the object is a binary pair of neutron stars in tight orbit (period on the order of one day) and picture a distant satellite orbiting the binary system

The binary pair system is at rest although the two neutron stars comprising it are not at rest.

from the perspective of the satellite, the binary pair is essentially a point mass, and the satellite's orbit gives at least a rough measure of the mass of the system.

ORBITAL ENERGY will be included in how attractive the binary system is to the distant satellite

The system will radiate away orbital energy gravitationally and will thus lose mass and become less attractive to the satellite which will drift further away.

GRAVITATIONAL WAVES FROM A SINGLE OBJECT are also
a possibility during violent collapse to a neutron star or black hole.
I believe you pointed to this possibility.
Collapse events are among those which the LIGO experiment is designed to detect, if I remember correctly.

Originally posted by instanton
Let me add a comment on this.
I can not see how to define rest mass in gravitating system. Maybe what Steinitz meant was you goes to the rest frame of each atoms (or what ever), then measure rest mass of them and sum them up. But, this is not obviously the mass of star that will be measured by , say, satelite orbiting around it.

A single static star may not be able to radiate gravitational wave, but unstable wobbling stars like young born neutron star may. This is how collapsing stars loose all the hairs,

Instanton

 

[jeff]

Originally posted by marcus
The system will radiate away orbital energy gravitationally and will thus lose mass and become less attractive to the satellite which will drift further away.

The total energy of any system may be divided into a matter part, and everything else. We can if you like refer loosely to this total energy as the systems "effective mass", but only the material component, which is composed of particles of nonvanishing rest mass - fermions, like electrons etc - has the property of rest mass. Now, the orbital energy is a gravitational potential energy that is radiated away as the binary system decays. However, at no point are electrons and other massive particles transmuted into gravitons - which are bosonic - and radiated away along with the orbital energy as gravity waves. In fact, from a broader view, the only way fermions can transmute into bosons is supersymmetrically, and nothing of the sort is going on here.

 

[Janus]

The bickering stops here.