Questions about Gravitational Waves: Answers Here

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Discussion Overview

The discussion centers around the existence of gravitational waves (GWs), exploring both the mathematical predictions and the challenges associated with their detection. Participants examine indirect evidence for GWs, particularly in relation to binary pulsars, and discuss the difficulties faced in achieving direct detection.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question the existence of gravitational waves, noting that while they are mathematically predicted, direct detection has not yet been achieved.
  • Others argue that there is indirect evidence for the existence of GWs, citing changes in the orbital parameters of binary pulsars as consistent with predictions from General Relativity.
  • A participant highlights the challenges in directly detecting GWs, suggesting that the weak nature of the waves requires extremely sensitive detectors that must be isolated from disturbances.
  • Concerns are raised about noise problems affecting detection efforts, particularly in relation to ongoing projects like ALIGO.

Areas of Agreement / Disagreement

Participants generally agree that while there is indirect evidence for gravitational waves, direct detection remains unresolved and challenging due to technical difficulties and noise issues. Multiple views on the status of detection efforts are present.

Contextual Notes

Limitations include the dependence on indirect evidence and the unresolved nature of the technical challenges in detecting gravitational waves directly.

Bassirou
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Hello. I would like to ask if really gravitational waves (GWs) exist? Mathematically they are predicted to exist. However despites the intense efforts invested to detect them so far they cannot be detected.
 
Physics news on Phys.org
Thanks in advance for any reply.
 
There is indirect evidence that gravitational waves exist, yes. The best evidence is changes we have observed in the orbital parameters of binary pulsars, which can only be explained as loss of energy in the binary system due to the emission of gravitational waves. The orbital changes observed are consistent with the predictions of General Relativity for gravitational wave emission.

The binary pulsar with the longest time series of observations is the Hulse-Taylor binary pulsar, described here:

http://en.wikipedia.org/wiki/PSR_B1913+16
 
Thank you PeterDonis for your kind answer and for the link. So, so far we just know from an indirect evidence that GWs exist. Now I have another question, please. Why GW cannot be directly detected? Their are many workgroups working on that such as ALIGO, but if I am not wrong they seem stuck to noise poblems. Is that (one of) the reason why GWs cannot be directly detected?
 
Bassirou said:
Why GW cannot be directly detected?

It's not that they "cannot" be; we expect to eventually detect them directly. The problem is that the GWs we could potentially detect here on Earth are so weak that it takes an extremely sensitive detector that has to be isolated extremely well from all other disturbances. That's very hard to do, which is why we aren't quite there yet.
 
Alright, Thank you for the information. It is very helpful. I hope I will hear from you again at my probable future questions on this topic.
 

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