Physics Help Forum What are gravitational waves made of?

 Special and General Relativity Special and General Relativity Physics Help Forum

 Jul 28th 2014, 01:46 PM #11 Senior Member   Join Date: May 2014 Location: Poole, UK Posts: 132 See what Mike said, and see LIGO: "When large masses move suddenly, some of this space-time curvature ripples outward, spreading in much the way ripples do the surface of an agitated pond... Laser light enters the arms through a beam splitter located at the corner of the L, dividing the light between the arms. The light is allowed to bounce between the mirrors repeatedly before it returns to the beam splitter. If the two arms have identical lengths..." Amazingly enough, when the gravitational waves pass through, the arms change length. Because space waves. So what are gravitational waves made of? The same as a gravitational field: space. I don't know why this isn't in the textbooks, particularly since Einstein described a field as a state of space.
Jul 28th 2014, 05:21 PM   #12
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 Originally Posted by Farsight See what Mike said, and see LIGO: "When large masses move suddenly, some of this space-time curvature ripples outward, spreading in much the way ripples do the surface of an agitated pond... Laser light enters the arms through a beam splitter located at the corner of the L, dividing the light between the arms. The light is allowed to bounce between the mirrors repeatedly before it returns to the beam splitter. If the two arms have identical lengths..." Amazingly enough, when the gravitational waves pass through, the arms change length. Because space waves. So what are gravitational waves made of? The same as a gravitational field: space. I don't know why this isn't in the textbooks, particularly since Einstein described a field as a state of space.
I am interested on how the logical thinking works on measuring the space-time curvature ripples to identify gravity wave.

Gravity wave [A] can generate the space-time curvature ripples [B]
A = B, but B is not necessary equal to A
if anyone find occurrence of space-time curvature ripples, then it is possible that Gravity wave is existed, but this ripples could be caused by other factors, so finding Gravity wave by measuring space-time curvature ripples seems again logical thinking, except if they can prove that the occurrence of space-time curvature ripples must exist with gravity wave in the first place. In other words, if someone finds the occurrence of space-time curvature ripples, how can he proves that come from Gravity wave?

Furthermore, does anyone know the minimum requirement on space-time curvature ripples? My body gets weight (mass), when I walk along the street, I should create a bit space-time curvature ripples, do I?

Does anyone have any suggestions?
Thanks, to everyone very much for any suggestions :>

Last edited by oem7110; Jul 29th 2014 at 12:29 AM.

 Jul 29th 2014, 12:55 AM #13 Senior Member     Join Date: Apr 2008 Location: Bedford, England Posts: 668 As I understand it Gravity Waves are a prediction of Einsteins Equations, if you solve the equations for various situations Gravity Waves appear quite naturally in the solutions. For most situations (like walking down the street) the resultant waves are truely tiny (even tiny on subatomic scales). However for truely huge masses in close interactions (like closely orbiting binary pulsars) the consequenses of the gravitational waves are detectable.
Aug 6th 2014, 05:36 PM   #14
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 Originally Posted by oem7110 I would like to know on what gravitational waves are made of, since it can pass through matter, does gravitational waves have any physically property in matter? Does anyone have any suggestions? Thanks in advance for any suggestions What are gravitational waves?
When one is talking about a gravitational wave then what is happening is that the curvature of spacetime is moving at the speed of light. E.g. if a pulse of a gravitational wave is moving through the universe then what's happening is something like this: Let the pulse be at x = 0 at t = 0 and traveling in the +x direction. The pulse will reach the location x = D at a time t = D/c.

What does that mean? It means this: At t = 0 spacetime will be flat everywhere except x = 0. At t = D/c spacetime will be flat everywhere except at x = D.

This assumes that the pulse is localized. I used a localized wave for simplicity.

 Aug 23rd 2016, 05:13 PM #15 Senior Member   Join Date: Aug 2010 Posts: 401 "Water waves" are variations in the height of the surface of water. That is what we mean when we say they are "waves in water". "Gravitational waves are variations in the intensity of the gravitational field. So just as "water waves" are "waves in water", "gravitational waves" are "waves in the gravitational field".