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Old Jul 27th 2014, 04:09 AM   #1
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What are gravitational waves made of?

I would like to know on what gravitational waves are made of, since it can pass through matter, does gravitational waves have any physically property in matter?
Does anyone have any suggestions?
Thanks in advance for any suggestions

What are gravitational waves?
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Old Jul 27th 2014, 07:28 AM   #2
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Originally Posted by oem7110 View Post
I would like to know on what gravitational waves are made of, since it can pass through matter, does gravitational waves have any physically property in matter?
Does anyone have any suggestions?
Thanks in advance for any suggestions

What are gravitational waves?
Keeping things simple: You know how water waves transmit energy? Gravitational waves transmit a gravitational field.

The reality is a bit more complicated...water waves travel in water. What do gravitational waves travel in? The really don't have to travel in anything...light doesn't either. It's a Quantum Mechanical thing and it commonly creates all sorts of difficulty in explaining things.

If you like I'll give you a more "rigorous" explanation. But the water wave concept is probably one of the better ones out there, without invoking some odd ideas.

-Dan
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Old Jul 27th 2014, 09:31 AM   #3
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Originally Posted by topsquark View Post
Keeping things simple: You know how water waves transmit energy? Gravitational waves transmit a gravitational field.

-Dan
Water wave seems not related to gravitational waves at all, since water wave transmit energy through particles, but particles does not play any role for gravitational waves at all.

Do you have any suggestions?
Thank you very much for any suggestions :>
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Old Jul 27th 2014, 10:49 AM   #4
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Originally Posted by oem7110 View Post
Water wave seems not related to gravitational waves at all, since water wave transmit energy through particles, but particles does not play any role for gravitational waves at all.

Do you have any suggestions?
Thank you very much for any suggestions :>
Quantum Mechanically speaking if there is energy then there are particles to carry that energy. In this case the changing gravitational potential makes gravitons.

-Dan
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Old Jul 27th 2014, 02:43 PM   #5
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Nobody Knows

I think that, at a fundamental level, nobody knows.
This is one of the key issues being attacked by theoretical physicists.
String Theory promises much in this area, but people are starting to get a bit impatient for some form of delivery on that promise.

The only experimental evidence (that I know of) for gravitational waves comes from certain binary pulsars where Cosmologists have found that the change in the orbits of the pulsars match the predictions of gravitational wave theory.
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Old Jul 27th 2014, 03:35 PM   #6
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Originally Posted by topsquark View Post
Quantum Mechanically speaking if there is energy then there are particles to carry that energy. In this case the changing gravitational potential makes gravitons.

-Dan
Could you please describe more on how changing gravitational potential make gravitons?

Thanks, to everyone very much for any suggestions
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Old Jul 27th 2014, 05:42 PM   #7
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Originally Posted by oem7110 View Post
Could you please describe more on how changing gravitational potential make gravitons?

Thanks, to everyone very much for any suggestions
It's a wave-particle duality thing in QM. When you heat an object it will glow at a certain frequency. Well, a whole lot of them all at once, but you can measure the color with a meter and use that as a frequency. This is because the heated object is at a high energy and it releases photons...electromagnetic energy. Similarly when a gravity wave is emitted from an object (more likely a distribution of objects), the energy is carried off by gravitons.

It's a little hard to explain. According to QM space is filled by all sorts of fields, the EM field for one, and energy fluctuations will produce a particle that the field represents. The larger the fluctuation, the larger number of particles will be given off. So the heated object is giving off particles of the EM field...in this case photons. If all that seems a little strange, consider the more mundane reference to an "electric field." The electric field fills all space and is a fundamental part of basic Physics. The Quantum fields act in a similar manner.

Too much? Too little? Not clear enough?

-Dan
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Old Jul 27th 2014, 06:18 PM   #8
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Originally Posted by topsquark View Post
It's a wave-particle duality thing in QM. When you heat an object it will glow at a certain frequency. Well, a whole lot of them all at once, but you can measure the color with a meter and use that as a frequency. This is because the heated object is at a high energy and it releases photons...electromagnetic energy. Similarly when a gravity wave is emitted from an object (more likely a distribution of objects), the energy is carried off by gravitons.
...

Too much? Too little? Not clear enough?

-Dan
Gravity wave can get through matter (physical particles) with no problem, does protons have the same properties too?

Does Gravity wave contain photons...electromagnetic energy?
Can Gravity exist without energy?

Furthermore, on Earth, mass creates Gravity, if we look for gravity wave from Big Bang, since most of the mass was gone for far far away, can we still able to look for gravity wave from Big Bang without mass existed?


Does anyone have any suggestions?
Thanks, to everyone very much for any suggestions :>

Last edited by oem7110; Jul 28th 2014 at 06:00 AM.
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Old Jul 28th 2014, 08:53 AM   #9
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Gravitational waves are propagating, time-varying ripples in the curvature of spacetime. They DO affect matter when they pass through matter ... the matter experiences a variation of tidal forces. Go buy a copy of Kip Thorne's "Black Holes and Time Warps" ... he spends a lot of time in the latter part of the book talking about gravitational waves. The whole book is exceptionally good.
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Old Jul 28th 2014, 09:51 AM   #10
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Originally Posted by oem7110 View Post
Gravity wave can get through matter (physical particles) with no problem, does protons have the same properties too?

Does Gravity wave contain photons...electromagnetic energy?
Can Gravity exist without energy?

Furthermore, on Earth, mass creates Gravity, if we look for gravity wave from Big Bang, since most of the mass was gone for far far away, can we still able to look for gravity wave from Big Bang without mass existed?


Does anyone have any suggestions?
Thanks, to everyone very much for any suggestions :>
Gravity waves do not produce photons. I've been using the EM field as a simpler example than gravity. I hope that didn't confuse you. You see, the problem with gravity is that the field is "non-linear" in the sense that gravitons can actually produce new gravitons. This is why it is so hard to come up with a theory of gravity at the Quantum scale. I've been using the EM field because it is simpler to work with.

Okay, your questions.

Yes, gravity waves can move essentially freely through any object as the object is made out of mass and energy. An EM wave can only move through transparent objects. (Metals are a gray area in this sense. I'm ignoring those for the moment.)

An area with a gravitational potential has either mass or energy (or both!) in the vicinity. Gravity waves carry energy just like any other wave.

There was a recent report that gravity wave effects have been measured in the Cosmic Microwave Background. I'm haven't been keeping up with the study but I think I heard they have to recalibrate something so they have to do it again. Don't take my word for that, though. But in principle, yes, we should be able to measure the effect of gravitational waves in the Background.

I'm not sure what you mean by "without mass." The early Universe had just as much mass/energy as the current Universe does.

-Dan
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