Can gravitational waves INTERFERE with each other?

Thank you, I get this question all the time too.

Stop promoting BetterHelp, please. They've gained a (well deserved) shoddy reputation.

Love the fact this all came from a viewers' question. Shows that you take your community seriously and I love that.

Praying for all these Better Help contracts to run out on Youtube channels. Tired of feeling gaslit by a terrible org being promoted as if they're actually helpful.

Please consider a different sponsor. This one has a pretty appalling data security record.

14:22 - I love the sneaky Doctor Who reference right at the end of a discussion of a highly complex scientific topic! :D

You have the ability to explain the most complex and Difficult subject matter in a way that the general public can interpret. Combine this with a very approachable personality and easy going attitude that you display in your videos and we have something special. I am 62 Years old - I have no real interest in you on a personal level other than what I have said. Having said that, If you were my daughter, I would be extremely proud of your acheivements, and your overall persona. That is why I love your work, and acheive great pleasure in watching these videos.. Thank you, Doctor Becky.

@4:52 is it "deconstructive" interference? I've always heard it as "destructive" interference.

I think you’re conflating interference and self-interaction here a little. In Maxwell’s equation, two light beams will interfere with each other, but they won’t *interact*—if they cross, they will each continue on after the crossing identically to if the other hadn’t been there, with no deflection or scattering. Interference is possible without interaction. Gravitational waves do interact with gravity, as you said, but that’s a different phenomenon from interference.

If a field interferes with itself, it DOES NOT mean that the particle interacts with itself. For example, in pure electromagnetism, light interferes with itself, like any wave, but photons do not interact with photons. In the real world, photons do interact indirectly, but that is an EXTREMELY minor effect, and has nothing to do with the constructive/destructive interferences that we see in lasers. So whether gravitons interfere would not be any indication that they interact with themselves. We do, however, have many other reasons to belive that gravitons self-interact.

Please more videos of answering fan questions! So freaking cool!

Are you sure that interference neccessitates interaction between photons? Interference is a linear effect that also happens in a non-interacting theory. Photon-photon interactions would be a non-linear effect.

Hey, Dr. Becky - I don't quite understand where the 2 sec difference between the gamma ray and gravitational wave signal comes from, if you say they travel the same path and speed?

Hey Becky! Thank you very much for your great science communication! The way you present even the most complex topics to a broad audience is truly astonishing. First of all: I know this is not your main area of research, so hopefully you don't feel like your valuable time is wasted by another one of these crazy theories you will get every day ^^ If this is the case: I'm sorry and please just ignore this... In this video you talked again about the way the path of light is bent by gravity. For the cosmic distance ladder having a good model of it seems essential. Since both my Bachelors and Masters Thesis involved optics/lasers (yeah I was one of those solid state physics guys ^^), it made me wonder if there could be additional factors that might have been unaccounted for. Especially for the basic parallax measurement which by propagation of uncertainty would probably have a major impact on the more distant stages. My best guess of the distribution of the interplanetary medium in the outer solar system is that it is more or less radially symmetric and probably tailors off the more you go outwards (since I left academia I don't have access to many academic journals and (probably also because I was looking for the wrong words) I could not find papers on this for the outer solar system). Because a difference in density will result in a different refractive index this seems very related to gradient-index optics. This is obviously well known in astronomy e.g. with the earths atmosphere acting as a GRIN lens when you can still see the sun even if it is technically already below the horizon (=> unrelated: maybe a nice fun fact to explain in a Night Sky News when applicable). The "Gaia Data Release 2" article/paper [1] does not seem to take this into account. Is this just because the effect is negligible? It is hard to do a back of the envelope calculation because obviously compared to a usual optics lab the gradient in refractive index is minuscule but the distances are gigantic, so a simple ray transfer matrix analysis was basically useless with the data I have. Do you know anything about this from the top of your head? Thank you again for your great science communication! Michael [1] https://doi.org/10.1051/0004-6361/201833051

Great question Larry!

Thank you for the video & the question.

I am enjoying the mavitas with which you talked about mavity. Fantastic!

Thanks!

I just saw the title; this is something I've wondered about a lot! What happens at points of constructive and destructive interference is fun to consider — the nulls ... they're a bit scarier. Haha. The especially fun idea is that if they propagate conventionally, as any acoustic or electromagnetic wave, etc., they'd also be time-reversal invariant. The potential implications for THAT are even wilder (once we can generate them ourselves, that is).

Love your explanations. Thank you!