Do gravitational waves propogate slower when blocked by mass

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Discussion Overview

The discussion revolves around the propagation of gravitational waves in the presence of massive objects, exploring whether their speed is affected similarly to electromagnetic waves when passing through different media. Participants consider the implications of spacetime geometry on gravitational wave propagation and the potential observable effects, such as the Shapiro delay.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether gravitational waves slow down when blocked by massive objects, drawing a parallel to the behavior of light in different media.
  • Another participant notes that gravitational waves are influenced by spacetime geometry, suggesting that there is a tiny effect on their propagation speed.
  • A further inquiry is made about the noticeable effects of gravitational wave propagation speed when dealing with very large masses, specifically in a hypothetical scenario involving VY Canis Majoris.
  • One participant mentions the Shapiro delay, estimating it to be on the order of 1 millisecond for a very massive star.
  • A participant seeks clarification on the mechanism that causes gravitational waves to slow down, comparing it to the bending of light waves in a gravitational field.
  • Another participant clarifies that the Shapiro delay is not due to bending in space but is an effect of curved spacetime.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and interpretation regarding the effects of mass on gravitational wave propagation, with some agreeing on the existence of the Shapiro delay while others seek further clarification on the underlying mechanisms. The discussion remains unresolved regarding the specifics of how gravitational waves are affected by massive objects.

Contextual Notes

The discussion includes assumptions about the nature of gravitational waves and their interaction with spacetime, which may not be fully explored or defined. The potential discrepancies in speed relative to light are not quantitatively established, leaving some uncertainty in the claims made.

NotJimmy
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I'm not sure exactly how to phrase this question, but I was thinking earlier about electromagnetic waves being absorbed by atoms and 'slowing down' the speed of light.

Do gravitational waves propagate slower when blocked by, say, a really massive object? In the same way that light slows down when blocked by a medium like water or gas?

If not, why?
 
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Gravitational waves are influenced by the spacetime geometry, so in general there is an effect. It is extremely tiny, however.
 
Is it noticeable at all when you're dealing with very large masses?

Like, let's say I had a 'transmitter' on one side of VY Canis Majoris moving around an object with great mass and generating gravitational waves. On the other side, I had a 'receiver' that filters out all of the noise and detects my transmitter's gravitational waves. How big would the discrepancy be between the speed of those gravitational waves and the speed of light?
 
You would get the Shapiro delay, something of the order of 1 millisecond for a very massive star.
 
What's the actual mechanism that slows down the gravitational waves though? I think I can understand how light waves slow down in a gravitational field, since they get bent on their path (correct me if that's the wrong interpretation), but how does that work with gravitational waves?

I'm just a non-physics student trying to sate my own curiosity, so sorry if I'm mangling some of the theory here.
 
The Shapiro delay is not a bending in space, it is an effect of (4D-)curved spacetime, the same in both cases.
 

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