Gravity Waves: Energy Transfer from Observation

Click For Summary

Discussion Overview

The discussion revolves around the implications of observing gravity waves, particularly whether energy is transferred from these waves to the observing instruments. Participants explore the mechanisms of this energy transfer and the historical context of related arguments in physics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Historical

Main Points Raised

  • Some participants propose that gravity waves, when observed, imply a transfer of energy to the observing instruments, albeit a very small amount.
  • One participant describes how gravity waves pass through matter similarly to sound, suggesting that they cause slight changes in the length of the interferometer arms without altering the matter itself.
  • Another participant asserts that the oscillations of the interferometer arms due to gravity waves possess kinetic and potential energy.
  • A historical reference is made to Feynman's "sticky bead argument," which is cited as a demonstration that gravitational waves carry energy and can do work on an antenna.
  • There is an anecdote regarding Feynman's frustration with the abstract mathematical approaches of other scientists, emphasizing the need to focus on the physical implications of gravitational waves.

Areas of Agreement / Disagreement

Participants express varying views on the nature of energy transfer from gravity waves, with some agreeing on the existence of energy transfer while others focus on the mechanics of how it occurs. The discussion does not reach a consensus on the specifics of this energy transfer.

Contextual Notes

Participants reference historical arguments and anecdotes that highlight the complexity and nuances of understanding energy transfer in the context of gravity waves. There is an acknowledgment of potential confusion in the scientific community regarding these concepts.

NC_Seattle
Messages
12
Reaction score
7
I'd be interested in hearing some thoughts on this.

Does the fact that a set of gravity waves were observed imply that some energy, presumably a very small amount, was transferred from the gravity wave to observing instruments? If so, where in the apparatus and how did this transfer occur?
 
Physics news on Phys.org
NC_Seattle said:
If so, where in the apparatus and how did this transfer occur?
The gravity waves simply pass through matter similar to how sound passes through matter. As the waves passed over the interferometer arms it changed the length ever so slightly but enough to be measured then they returned to their normal length. I don't think gravity waves "change" matter or "change" back into matter, they just dissipating energy.
 
NC_Seattle said:
Does the fact that a set of gravity waves were observed imply that some energy, presumably a very small amount, was transferred from the gravity wave to observing instruments? If so, where in the apparatus and how did this transfer occur?

Yes, the waves caused the arms of the interferometers to oscillate in length. Those oscillations had kinetic and potential energy.

Historically, there was a lot of confusion on this point. Feynman came up with an argument called the sticky bead argument to demonstrate that gravitational waves would carry energy and could donate energy to an antenna: https://en.wikipedia.org/wiki/Sticky_bead_argument
 
  • Like
Likes   Reactions: jerromyjon
bcrowell said:
Feynman came up with an argument called the sticky bead argument

As an amusing historical note, Feynman apparently came up with this out of frustration with other scientists at the Chapel Hill conference, who he felt were stuck in abstract math instead of looking at the physics, and as a result were confusing themselves unnecessarily. In a letter he wrote from the conference (to his wife Gweneth, IIRC--I read about this in the foreword to the Feynman Lectures on Gravitation), he said something like "This is what comes of looking for conserved tensors, etc., instead of asking: can the waves do work?"
 
  • Like
Likes   Reactions: jerromyjon

Similar threads

  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 169 ·
6
Replies
169
Views
9K
  • · Replies 58 ·
2
Replies
58
Views
6K
  • · Replies 73 ·
3
Replies
73
Views
7K
  • · Replies 33 ·
2
Replies
33
Views
3K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 0 ·
Replies
0
Views
2K
  • · Replies 39 ·
2
Replies
39
Views
4K
  • · Replies 7 ·
Replies
7
Views
3K