Is Gravitational Radiation the Key to Unlocking Cosmology's Secrets?

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Discussion Overview

The discussion revolves around the significance of gravitational radiation in cosmology, exploring whether the detection of gravitational waves is essential for the validity of cosmological theories, particularly general relativity (GR). The conversation includes various perspectives on the implications of not finding gravitational radiation and its impact on cosmological models.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that cosmology does not solely depend on the detection of gravitational radiation, suggesting that the field can continue regardless of such findings.
  • Others argue that if gravitational radiation is not detected where expected, it could challenge the validity of general relativity, which predicts gravitational waves.
  • A participant suggests that mainstream cosmology is fundamentally based on general relativity, implying that the detection of gravitational waves is crucial for its verification.
  • There is mention of two different approaches to detecting gravitational waves: direct detection methods (e.g., LIGO, VIRGO) and indirect detection related to the cosmic microwave background (CMB), with implications for different cosmological models.
  • One participant expresses excitement about the indirect detection methods and their relevance to cosmological theories, despite not fully understanding the mathematics involved.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of gravitational radiation for cosmology, with some asserting that cosmology can persist without it, while others maintain that its detection is critical for validating general relativity and, by extension, cosmological models. The discussion remains unresolved regarding the implications of not detecting gravitational radiation.

Contextual Notes

There are unresolved assumptions regarding the foundational role of general relativity in cosmology and the potential consequences of failing to detect gravitational waves. The discussion also highlights the complexity of the relationship between gravitational radiation and cosmological theories.

wolram
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Please excuse the naivety of the question, i guess the whole of cosmology hinges on the finding of G Radiation, is this a proper assumption?
 
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wolram said:
Please excuse the naivety of the question, i guess the whole of cosmology hinges on the finding of G Radiation, is this a proper assumption?
Of course not.

Cosmology is a field of science not a theory. Even if we assume for a moment that no gravitational radiation will be found were we would expect it, then that does not mean cosmology is dead. As long as there is a cosmos and humans to ponder it there will be cosmology.

However, if we would not find gravitational radiation where we logically expect it then the general theory of relativity would become a questionable theory since this theory predicts the existence of gravitational radiation.
 
Last edited:
MeJennifer said:
Of course not.

Cosmology is a field of science not a theory. Even if we assume for a moment that no gravitational radiation will be found were we would expect it, then that does not mean cosmology is dead. As long as there is a cosmos and humans to ponder it there will be cosmology.

However, if we would not find gravitational radiation where we logically expect it then the general theory of relativity would become a questionable theory since this theory predicts the existence of gravitational radiation.

OOps, i did not want feathers to fly, of course cosmology will continue, but without GR?
 
wolram said:
OOps, i did not want feathers to fly, of course cosmology will continue, but without GR?
Why not? No theory is sacred in science.
 
MeJennifer said:
Why not? No theory is sacred in science.

Oh my, give me one the other.
 
wolram said:
Please excuse the naivety of the question, i guess the whole of cosmology hinges on the finding of G Radiation, is this a proper assumption?

Hi wolram, I interpret your question differently from how Jennifer hears it, so I answer differently (without contradicting any of J's facts)

I think the whole of mainstream cosmology is built on a foundation of classic Gen Rel.

To verify Gen Rel, gravity waves must be detected. Otherwise the theory is falsified.

So I would say in answer to you YES finding waves in geometry is crucial.

If it turned out there were no waves, then GR would be out and the theory of spacetime geometry would have to be rebuilt and then standard cosmology would have to be rebuilt on the new foundation.

So it is fair to say, I think, that standard cosmology hinges on the wave issue.

It would not necessrily be BAD to have to rebuild our model of the universe on a drastically changed foundation, however :smile:
 
Thank you Marcus.
 
Two searches for gravitational radiation

Wolram,
There are two radically different efforts to detect gravitational waves going on. One is direct detection ala LIGO, VIRGO, GEO, TAMA and later LISA in space. If these gravitational waves are not found it would be a very big surprise and seriously challenge GR, which is fundamental to cosmology (and a lot of other things).
There is another effort to detect gravitational waves from the time of inflation near the beginning of the universe indirectly by the effect of the tensor gravitational waves on the B mode of the polarization of the CMB. See the last paragraph of http://xxx.lanl.gov/PS_cache/astro-ph/pdf/9706/9706147v1.pdf for example.
This indirect detection is much more directly related to choosing between different cosmological models.

Jim Graber
 
I have read some of the papers, i do not under stand all the maths, but
can under stand the idea, these tests are far more exciting to me than GPB.
 

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