[questionposter]

How could a particle decay into a gravitational wave? If matter can only be matter or energy, wouldn't that mean that gravity is energy?

This post has been edited by questionposter: 9 December 2011 - 04:15 AM

[guenter]

This is a weird discussion in a physical forum. It is unphysical to expect matter being radiated away.

Should someone be interested in Physics, this is the right explanation,

Mystery111, on 7 December 2011 - 05:10 PM, said:

http://www.daviddarl...G/gravwave.html

Quote

The Hulse-Taylor pulsar
Take two big masses that are close together, whirl them around their common center of gravity at high speed, and general relativity is clear about what will happen. The orbital energy of the masses will gradually radiate away. They'll give off gravitational waves and, as they do so, their orbits will get smaller and smaller.

which coincides with my post #8.

[questionposter]

guenter, on 9 December 2011 - 10:27 AM, said:

This is a weird discussion in a physical forum. It is unphysical to expect matter being radiated away.

Should someone be interested in Physics, this is the right explanation,




which coincides with my post #8.

So someone predicts that all matter will radiate it's energy away in the form of gravitational waves? But since matter can't travel at the speed of light, wouldn't the gravitational waves from all matter hit matter everywhere else and and thus matter and the universe would continue to have lots of energy? In fact, gravitational waves like that from supernova and things like neutron stars and black holes merging would even trigger the birth of stars in local gases and nebulae.

This post has been edited by questionposter: 9 December 2011 - 01:41 PM

[JustinW]

I heard something about this. That they were trying to detect residual gravity waves left over from the BB, or something to that effect, but have yet to detect them. Which brings up the question, do gravitational waves decay over time? Or does space have a counter effect on gravity? Not to suggest an opposite effect like dark energy, but just some sort of resistance. I'll try to find a link to where I saw that study. It was pretty interesting.

[DrRocket]

JustinW, on 22 December 2011 - 09:02 PM, said:

I heard something about this. That they were trying to detect residual gravity waves left over from the BB, or something to that effect, but have yet to detect them. Which brings up the question, do gravitational waves decay over time? Or does space have a counter effect on gravity? Not to suggest an opposite effect like dark energy, but just some sort of resistance. I'll try to find a link to where I saw that study. It was pretty interesting.

Experiments to attempt to detect gravitational waves from ANY source have been underway since the 1970's, with incrreasing levels of sophistication and sensitivity. To date no gravitational waves have been directly detected.

The best evidence for gravitational waves, as predicted by general relativity, come from measurements of the orbital decay of binary star systems.

[guenter]

Justin, you are right, as reportet here:

Quote

"It would perhaps be the greatest achievement in the understanding of our Universe, that we at Planck would be able to measure the gravitational waves of the Universe, which are directly linked to the Big Bang and cosmic inflation (the extremely rapid expansion of the Universe in the very first moments)", ...

I am not sure what you mean with "decay". Like electromagnetic waves gravitational waves too get redshiftet while the universe expands.

DrRocket, the strongest signals are expected from the merger of massive objects, neutron stars, black holes. Unfortunately such events are rather seldom.

[StringJunky]

guenter, on 25 December 2011 - 05:03 PM, said:

I am not sure what you mean with "decay". Like electromagnetic waves gravitational waves too get redshiftet while the universe expands.

Here's a wiki explaining it.

This post has been edited by StringJunky: 25 December 2011 - 10:53 PM

[guenter]

Quote

name='StringJunky' timestamp='1324853508' post='646948']
Here's a wiki explaining it.

Misunderstanding. Here Wiki explains 'orbit decay', Justin's question however was "do gravitational waves decay over time?" in the context of primordial black holes. There aren't even massive bodies whose orbit could decay.

This post has been edited by guenter: 26 December 2011 - 10:33 AM

[StringJunky]

guenter, on 26 December 2011 - 10:30 AM, said:

Misunderstanding. Here Wiki explains 'orbit decay', Justin's question however was "do gravitational waves decay over time?" in the context of primordial black holes. There aren't even massive bodies whose orbit could decay.

OK...my apologies. I was connecting with Dr Rocket's post about binary stars.

[JustinW]

Sorry guenter,

I was away for awhile. I didn't necessarily mean decay. I was wondering if the wave was somehow less effective over time. Therefore being less detectable.

[guenter]

JustinW, on 26 December 2011 - 08:14 PM, said:

I didn't necessarily mean decay. I was wondering if the wave was somehow less effective over time. Therefore being less detectable.

Justin, interestingly there are two possibilities. In both cases the scientists in this research are relatively optimistic:

Primordial gravitational waves can in principle be detected as a signature in the microwave background (ongoing research of Planck) or as radiation reaching us today by interferometer techniques, e.g. LIGO ect.

The microwave photons have been emitted 380000 years after the big bang (before the universe wasn't transparent for them), primordial gravitational waves however were created very shortly after the big bang (for them the universe is transparent), thus providing hopefully direct information about the early universe.

[JustinW]

Thanks for the explanation guenter.