<p>When photons pass through matter, they do tend to get absorbed by that matter to some degree depending on the properties of the photon and and the matter. Even the brightest light is at least somewhat obscured by matter in its way.</p>
<p>Similarly, while neutrinos interact very little with normal matter, they are eventually absorbed as well: you just would've need a whole lot of matter for that to be efficient (such as one light year of lead to capture 50% of neutrinos)</p>
<p>Does matter have an effect on gravitational waves and their propagation, or do they just pass through the matter unaffected? If there is no effect, where does the energy needed to actually move things around come from (we can detect them due to this movement!)? If matter can block gravitational waves, how much matter we would need to block GWs from typical BH merger detected by LIGO / VIRGO (say 30 + 30 solar masses)?</p>

CC BY-SA 4.0
2021-04-05T10:07:18.593Z
See [physics.se]  question https://physics.stackexchange.com/questions/490866/do-gravitational-waves-disperse-refract-like-em-waves-in-a-prism
James K
CC BY-SA 4.0
2021-04-06T02:17:41.187Z
Thanks for pointing that out. The question linked above did state that matter seems to be transparent to GWs, but did not elaborate on the subject. I added a related question at Physics.SE https://physics.stackexchange.com/questions/627384/why-matter-is-transparent-to-gravitational-waves
tuomas
CC BY-SA 4.0
2021-04-06T02:31:54.070Z
Great question! Answers to [Transfer of energy from gravity back to other “more familiar” forms of energy?](https://physics.stackexchange.com/q/262926/83380) ("beads on a string") and [Do gravitational waves impart linear momentum to objects? (e.g. Quasar 3C 186)](https://physics.stackexchange.com/q/321166) ("very small") may be informative here as well. I think that one can develop an answer that *blocking* gravitational waves is not likely by mere thousands of galaxies, you'll need something much, much bigger :-)
uhoh
CC BY-SA 4.0
2021-04-06T02:35:09.683Z
Oh, and [How much energy does the Earth absorb when a gravitational wave passes through it?](https://physics.stackexchange.com/q/237168/83380) found in [this answer](https://physics.stackexchange.com/a/627386/83380) to your different but related question in Physics SE.
uhoh
<gravitational-waves>
Does matter absorb/scatter gravitational waves?
tuomas
# Does matter absorb/scatter gravitational waves?

(Asked by: username_0 on 2021-04-04)

When photons pass through matter, they do tend to get absorbed by that matter to some degree depending on the properties of the photon and and the matter. Even the brightest light is at least somewhat obscured by matter in its way.

Similarly, while neutrinos interact very little with normal matter, they are eventually absorbed as well: you just would've need a whole lot of matter for that to be efficient (such as one light year of lead to capture 50% of neutrinos)

Does matter have an effect on gravitational waves and their propagation, or do they just pass through the matter unaffected? If there is no effect, where does the energy needed to actually move things around come from (we can detect them due to this movement!)? If matter can block gravitational waves, how much matter we would need to block GWs from typical BH merger detected by LIGO / VIRGO (say 30 + 30 solar masses)?

**Tags:** gravitational-waves
> **Comments:**
> **username_1**: See [physics.se]  question https://physics.stackexchange.com/questions/490866/do-gravitational-waves-disperse-refract-like-em-waves-in-a-prism  
> **username_0**: Thanks for pointing that out. The question linked above did state that matter seems to be transparent to GWs, but did not elaborate on the subject. I added a related question at Physics.SE https://physics.stackexchange.com/questions/627384/why-matter-is-transparent-to-gravitational-waves  
> **username_2**: Great question! Answers to [Transfer of energy from gravity back to other “more familiar” forms of energy?](https://physics.stackexchange.com/q/262926/83380) ("beads on a string") and [Do gravitational waves impart linear momentum to objects? (e.g. Quasar 3C 186)](https://physics.stackexchange.com/q/321166) ("very small") may be informative here as well. I think that one can develop an answer that *blocking* gravitational waves is not likely by mere thousands of galaxies, you'll need something much, much bigger :-)  
> **username_2**: Oh, and [How much energy does the Earth absorb when a gravitational wave passes through it?](https://physics.stackexchange.com/q/237168/83380) found in [this answer](https://physics.stackexchange.com/a/627386/83380) to your different but related question in Physics SE.  

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