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Questions tagged [gravitational-waves]

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How does LIGO detect Gravitational Waves if they bend both space and time?

Please note that this is not an inquiry into the mechanisms of technology that LIGO uses to detect gravitational waves. Also, I am not a flat-earther. I was watching physicists vs. flat-earthers ...
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Pendulum usage in gravitational wave detectors

I've read that pendulums are (or were) used to calibrate the distance between the mirrors in a gravitational wave detector. In principle pendulums are supposed to be moving in just one plane no matter ...
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Has anyone ever tried to derive gravitoelectromagnetic waves equation?

Has anyone ever tried to derive gravitoelectromagnetic waves equation? As we know, there is Maxwell-like equation in gravity. Has anyone here ever formulated gravito electromagnetic waves equation ...
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Could LIGO detect two simultaneous gravitational waves?

Hypothetically if two (or more) gravitational waves were passing through the LIGO detector at the same instant, can the LIGO team deduce from the data that there were two simultaneous waves passing? ...
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What does it mean by $h_{\mu\nu}$ having “gauge symmetry”?

$$\partial^\rho \partial_\rho h_{\mu\nu} - \partial_\mu \partial^\rho h_{\rho\nu} - \partial_\nu \partial^\rho h_{\rho\mu} + \partial_\mu \partial_\nu {h^\rho}_\rho = 0$$ Here $h_{\mu\nu}$ is a ...
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Could a powerful gravitational wave cause electrons to emit light?

I imagine electrons being accelerated by passing gravitational waves, say from a nearby kilonova, so I would expect the electrons to emit light. Am I right?
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What is the experimental evidence for the gravitational field having positive energy density?

Recent direct observation of gravitational perturbations attributed to merging black holes and merging neutron stars has reliably confirmed the existence of gravitational waves. The observed fact that ...
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Redshift z=40 and gravitational waves

Why z=40 is the critical value of the redshift (more or less) to decide find out primordial gravitational waves around it? I have read that is related to the following issue: black hole mergers ...
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Attributing Gravitational waves to a source

At a given time, there would be n number of binary neutron stars or Black Holes or even Super Novae, all of which would be leaving a gravitational wave imprint ..So how do LIGO scientists know which ...
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Lowest 'Order' of Radiation

I've noticed an interesting phenomenon (admittedly from only two data points). In electromagnetism, $A^\mu$ obeys Maxwell's equations: $$\square A^{\mu} = j^\mu .$$ where I've chosen \$\mu_0 = \...
468 views

Do gravitational waves carry energy?

We now know that gravitational waves are real. Do they carry energy? I mean thy are waves and every wave carries energy. If they carry energy, how do they do it? Is there any equation to describe ...
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How to use Ashtekar's variables in classical gravitational physics?

I have often heard of Ashtekar's variables in General Relativity, because of the naturalness with which they would allow a canonical formulation of gravity, useful for a hypothetical quantum gravity ...
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How does a neutron star collision turn mass into gravitational waves?

I heard on the TED Radio hour that in the neutron star collision that LIGO recently detected, some of the mass of the neutron stars was turned into energy in the form of gravitational waves. How does ...
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Determine expansion rate of universe from gravitational waves LIGO?

I heard on the TED Radio Hour that the LIGO team was able to make an independent measurement of the Hubble constant and the increasing expansion rate of the universe when they detected the ...
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How to show that the polarization tensor of the gravitational plane wave in vacuum is transverse

This is Ta-Pei Cheng's book p.254. I am trying to understand (13.28). The Lorentz gauge condition (13.18) is like below. How can I use the (13.18) condition to show (13.28)? I am trying to calculate ...
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What is the wavelength of gravitational waves?

What is the wavelength of gravitational waves? I have looked for an answer but so far not identified one.
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Gravitational waves & cosmological redshift

Are gravitational waves streched by the expansion of the universe in the same way as EM radiation is? In that case how does one differentiate between a gravitational wave from a given event (say ...
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Stochastic versus primordial gravitational waves

I have read differences terms but I doubt if they are exactly the same in Cosmology: Primordial gravitational waves (and their background). Stochastic gravitational waves (and their background). ...
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Gravitational waves' path and interaction with black holes

As a gravitational wave propagates away from its source, how does its path get affected if a black hole is in its way? I was trying to picture it visually and here was my 'before' (with the line being ...
141 views

Could LIGO have detected R'lyeh if it existed?

In Possible Bubbles of Spacetime Curvature in the South Pacific, that R'lyeh might be exist within a bubble of spacetime. (It appears to be a joke paper since some of the references are fictional, but ...
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Observation of Hawking radiation

Is it conceivable that Hawking radiation could be observed using e.g. gravitational waves or imprints in the CMB?
For a wave of the form, say, $$ds^2 = -dt^2 + [1 - A\sin(\omega(t-z))]dx^2 + [1 + A\sin(\omega(t-z))]dy^2 + dz^2$$ how should one orient the detector (that works by monitoring the distance between ...