How Do Electromagnetic Stellar Gravity Waves Simulate Sound at LIGO?

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Discussion Overview

The discussion centers on the relationship between gravitational waves and sound waves, particularly in the context of the LIGO observatory's detection of gravitational waves. Participants explore the nature of these waves, their propagation mediums, and historical experiments related to gravitational wave detection.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Historical

Main Points Raised

  • Some participants question how gravitational waves, which are detected by LIGO, can be analogous to sound waves given that sound requires a medium to propagate, while gravitational waves are changes in the geometry of spacetime.
  • Others clarify that gravitational waves are distinct from sound waves and electromagnetic waves, with gravitational waves being waves in spacetime rather than in a physical medium.
  • One participant references Einstein's work, suggesting that he equates gravity with electromagnetic fields, while another counters that Einstein's equations are invariant across coordinate systems and do not imply that gravity is electromagnetic.
  • Historical references to Weber's experiments are made, noting that he detected gravitational waves at a frequency of 1662 Hz, but there is contention over whether these waves can propagate through a vacuum.
  • Some participants assert that sound cannot propagate in the vacuum of space, while others argue that the vibrations detected in Weber's experiments were not sound waves traveling through space.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of gravitational waves and their relationship to sound waves. There is no consensus on whether gravitational waves can be considered analogous to sound waves or if they propagate in a similar manner.

Contextual Notes

Participants highlight limitations in understanding the propagation of gravitational waves versus sound waves, including the dependence on definitions of waves and the conditions under which they are detected. There are unresolved questions about the implications of historical experiments and the interpretations of Einstein's equations.

carl susumu
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https://en.wikipedia.org/wiki/LIGO#/media/File:Simplified_diagram_of_an_Advanced_LIGO_detector.png

The axis on the bottom of the graph depicts frequencies between 20-1000 Hz which are sound waves. Again, how can a sound wave (gravity waves) propagate in the near vacuum of stellar space that is vacuum?

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"On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10^−21." (Abstract).Abbott, B. P. Observation of Gravitational Waves from a Binary Black Hole Merger. Physical Review Letters. 116, 061102. 2016

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Can you explain how electromagnetic stellar gravity waves (GR) form the effects of sound waves at the LIGO observatory?
 
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carl susumu said:
The axis on the bottom of the graph depicts frequencies between 20-1000 Hz which are sound waves. Again, how can a sound wave (gravity waves) propagate in the near vacuum of stellar space that is vacuum?

Sound waves which are audible to us have frequencies from about 20-20,000 Hz, but other waves exist with these frequencies which are not sound waves. For example, EM waves at this frequency are used for communications.

As for what these gravitational waves use as a medium, the answer is that they are waves in the metric of spacetime. They are, in short, a propagating temporary change in the geometry of spacetime.

carl susumu said:
Can you explain how electromagnetic stellar gravity waves (GR) form the effects of sound waves at the LIGO observatory?

These waves are gravitational waves. Gravity waves, electromagnetic waves, and sound waves are all something different. Gravity waves are waves on the surface of a fluid, such as the wave on the surface of the ocean, while EM waves are waves in the electromagnetic field (light, radio waves, x-rays, etc) and sound waves are a certain type of wave within a physical medium such as water, air, or even rock.
 
In Einstein's paper, "The Foundation of the Generalised Theory of Relativity" (1916), Einstein represents gravity with Maxwell's electromagnetic field using Maxwell's equations.

dh/dt + rot e = 0.........70div h = 0............71rot h - de'/dt = i.........72div e' = p"..........73

(Einstein5, § 20). Einstein is representing gravity with Maxwell's electromagnetic field that is based on Faraday's induction effect but a small stone that is affected by gravity yet unaffected by a magnet of Faraday's law and a three inch lead plate does not produce anti-gravity which proves gravity is not an electromagnetic phenomenon. Stellar gravity waves are electromagnetic waves. The same waves as a radio wave.
 
Weber experimentally detected gravitational waves that have the frequency of sound (1662 Hz). "Further advances are necessary in order to generate and detect gravitational waves in the laboratory." (Weber, Conclusion, 1960). "A description is given of the gravitational radiation experiments involving detectors at opposite ends of a 1000 kilometer baseline, at Argonne National Laboratory and the University of Maryland. Sudden increases in detector output are observed roughly once in several days, coincident within the resolution time of 0.25 seconds. The statistics rule out an accidental origin and experiments rule out seismic and electromagnetic effects. It is reasonable to conclude that gravitational radiation is being observed." (Weber, Abstract, 1970). "EXPERIMENTS AT 1662 HERTZ" (Weber, Intro, 1970).Weber detected gravity waves with the frequency of 1662 Hz using the acoustical vibration of a 750 lb aluminum beam but sound cannot propagate in the vacuum of stellar space.
 
Precedence--------Weber
 
carl susumu said:
In Einstein's paper, "The Foundation of the Generalised Theory of Relativity" (1916), Einstein represents gravity with Maxwell's electromagnetic field using Maxwell's equations.

No he isn't. To quote Einstein, from paragraph 814 on his translated paper at wikisource:

The equations (60), (62) and (63) give thus a generalisation of Maxwell's field-equations in vacuum, which remains true in our chosen system of co-ordinates.

He's setting up Maxwell's equations in a form which remains invariant regardless of your coordinate system choice.

carl susumu said:
Stellar gravity waves are electromagnetic waves.

That is incorrect.

carl susumu said:
Weber detected gravity waves with the frequency of 1662 Hz using the acoustical vibration of a 750 lb aluminum beam but sound cannot propagate in the vacuum of stellar space.

The "acoustical vibration" is in the aluminum beam, which is being stressed at the frequency of the passing of the gravitational wave (or would be if he had actually detected a gravitational wave, which he did not), it is not in the vacuum. No sound is propagating through space.
 

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