# Questions tagged [gravitational-waves]

For questions about the propagation of waves carried by space-time, for instance as described by general relativity. Not to be confused with gravity waves, such as ocean surface waves.

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### Non-test-particle dynamics from inside a black hole horizon

It seems to me that most arguments in favor of impossibility of communication from beyond black hole horizon region are based on "test-particle" scenario, where the falling object is (very) light with ...
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### Different perturbations?

In Newtonian gravity and gravitational waves the metric ($g_{\mu\nu}$) changes. The metric tells us how to measure distances in a spacetime (in this case the flat $\eta_{\mu\nu}$), and is correlated ...
1 vote
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### Newtonian fields interaction

Newtonian gravity is a linear approximation of a very weak field, such as gravitational waves. But why do gravitational waves interact with each other while Newtonian fields don't?
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### GW luminosity depends on the 3rd time derivative but quadrupole formula depends on the 2nd time derivative?

The quadrupole formula for GW emission (see here) states that the metric perturbation is given by: \begin{align} \bar{h}_{ij}(t,r) = \frac{2G}{c^4 r} \ddot{I}_{ij}(t - r/c) \end{align} This ...
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### Tensioned string and gravitational wave

Potential energy of the spring/string is a square of deformation. It is way better to add deformation to tensioned resonator. In existing gravitational wave resonators wave deforms antenna some 10^-20 ...
1 vote
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### What does "DC" mean in gravitational physics?

I have came across a few works in gravitational physics using the term "DC" without further explanation of its meaning. For example, consider Strominger's 1703.05448, which states in p. 2 ...
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### What is the difference between Hawking radiation and a black hole laser?

While reading this paper (https://arxiv.org/abs/1409.6550), I got a little bit puzzled: what is the difference between Hawking radiation and a black hole laser? Is it the same thing? From my ...
1k views

### Gravitons with negative mass?

I have been reading several papers on massive gravity. All of them have equations that involve the square of the graviton mass, rather than graviton mass itself. See for example, equations 43 and 44 ...
1 vote
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### Do particle physics experiments need to take a possible gravitational wave background into account?

As I understand gravitational waves, we can barely detect them, because their strength is so small. On the other hand, they are presumably able to move individual particles like electrons. Does this ...
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### Is LIGO flawed by the identical expansion of laser wavelength and arms in presence of a gravitational wave?

LIGO, Laser Interferometer Gravitational-Wave Observatory, is a large-scale physics experiment aiming to directly detect gravitational waves. The device measures the phase shift laser beams. If I ...
379 views

### Particles Associated With Gravitational Waves

I've been reading about linearized GR and the study of gravitational waves, and an odd thought popped into my head. According to wave-particle duality (admittedly, usually used in quantum mechanics!), ...
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### How can a pulsar slow down?

I saw in some astronomy textbooks that pulsars gradually slow down due to the loss of energy by its radiation. I wonder why this is possible? Although the radiation is now not thermal but in the form ...