## Orbital period decay and gravitational waves

We know that the orbital period of binary stars decay due to the emission of gravity waves that carry away energy from the system. What is the form of the energy loss of the system: kinetic energy or potential energy?
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 Quote by Ranku We know that the orbital period of binary stars decay due to the emission of gravity waves that carry away energy from the system. What is the form of the energy loss of the system: kinetic energy or potential energy?
It's a combination of the two. The potential energy becomes more negative, while the kinetic energy increases.

 Quote by Chalnoth It's a combination of the two. The potential energy becomes more negative, while the kinetic energy increases.
Can we discern potential and kinetic energy components in the gravitational waves themselves?
When gravitational waves impact an object, say a dust sphere, the effect is not gravitational. That would seem to suggest there is no potential energy component in the gravitational waves themselves, even though the energy loss of the source of gravitational waves may well be a combination of potential and kinetic energy.

Recognitions:

## Orbital period decay and gravitational waves

 Quote by Ranku Can we discern potential and kinetic energy components in the gravitational waves themselves?
I'm not sure that question makes a whole lot of sense. The essential thing is that they transport energy away from the binary system, and can, in principle, deposit that energy elsewhere.

 Quote by Ranku When gravitational waves impact an object, say a dust sphere, the effect is not gravitational.
What do you mean the effect is not gravitational?

 Quote by Chalnoth What do you mean the effect is not gravitational?
When gravitational waves impact a dust sphere, it alternately ellipses in perpendicular directions transverse to the direction of the waves. Gravitational waves do not cause gravitational motion of the dust sphere toward the source of the gravity waves.

Indeed not only are gravity waves not gravitational, primordial gravity waves could actually be repulsive! http://arxiv.org/abs/0909.1922v1

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