Ask Ethan #74: Gravitational Waves (Synopsis)

“Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.” -Hermann Minkowski

When you think of waves, chances are you think of some type of pressure wave moving through a medium, like sound or water waves, or you think of light, which is an electromagnetic wave that requires no medium to move through. But there's another type of wave that exists, that no one expected before Einstein came along: gravitational waves.

Image credit: Wikimedia Commons user MOBle. Image credit: Wikimedia Commons user MOBle.

It's very counterintuitive how these waves come to exist, and yet, this week -- at the behest of Starts With A Bang reader Adam Rabung -- we do our best to explain just what the heck a gravitational wave is, how we know they exist, and how we plan on finding them.

Image credit: NASA (L), Max Planck Institute for Radio Astronomy / Michael Kramer, via Image credit: NASA (L), Max Planck Institute for Radio Astronomy / Michael Kramer, via

Don't miss this week's Ask Ethan, only on Starts With A Bang at Medium!

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#1: Yes. 42

By MobiusKlein (not verified) on 06 Feb 2015 #permalink

I am thinking that dark matter is actually the mass onto which "perceived reality" is displayed. ( The Movie Screen)
I Think of dark matter as the actual structure of a movie screen. The structure has mass100% Then The information is beamed via photons onto this mass as the photons absorb the mass of FACT, perceived reality arises and we all as digital bits roam around acting as we are prescribed to do in the micro
We Lift OFF The Screen held back by laws.modern physics. But as pioneers we shall break the SLAVE CHAINS OF REALITY..

By Ragtag Media (not verified) on 07 Feb 2015 #permalink

So, I think I understand the concept of gravitational waves. However, when it comes to black holes, I have these questions:
1. How can a gravity wave escape the pull of gravity? If not even light nor space-time can escape it then how can a gravity wave escape it?
2. If light is red shifted by a black hole to the point that it looks to us as if the thing emitting the light looks frozen in time, then would a gravity wave (also traveling at the speed of light), also be "red shifted" to the point that we could not detect it by means of LIGO or LISA?

By John Fruhwirth (not verified) on 09 Feb 2016 #permalink