# Tag Info

14

Yes, it is possible to calculate (within an error range) the distance of observed gravitational wave events. It is known that a variety of parameters will affect how the amplitude and frequency of the observed gravitational waves will change over time as recorded in the "chirp" event from the interferometers: the parameters include distance of the event, ...

12

Yes, it's possible, but less straightforward than for "normal" objects. If the optical counterpart of the GW signal is located, as in the case of GW170817, the distance can be inferred by standard methods of observing the redshift of its host galaxy. If not, the luminosity distance $d_L$ can still be inferred because the amplitude of the GW signal scales ...

8

To answer the question in your title (by following the links in the other answers): GW170817 (two neutron stars): 40 Mpc GW150914 (two black holes): 410 (+160 or -180) Mpc antlersoft's link (GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs): distances range from ...

5

The answer is, of course, that a singularity can't exist. The fact that General Relativity predicts that singularities are inevitable under certain conditions is proof that GR is wrong. A singularity is an infinity and a place where the equations of GR literally break down and become meaningless. (Infinities are decidedly unphysical!) When (if!) a more ...

4

The thermal eccentricity distribution was first calculated by Jeans 1919. The probability density function is indeed $$f(e) = 2e.$$ See this blog post for a nice derivation of this beautiful result, which is independent of the "temperature". The derivation relies on a small 'swindle' by assuming a population of only binaries and not any single or trinary ...

3

As you say (although you phrase it slightly wrong), time slows down closer to the horizon, as seen from a distant observer. That means that, in the reference frame of a distant observer, matter never crosses the event horizon, but instead "piles up" at the horizon, creating a thin shell of matter. In the reference frame of the falling matter, however, it ...

2

This is additional to the other answers. We now have three GW detectors (LIGO x2 + VIRGO). This allows the direction of the event to be deduced, by the relative timing of the arrival of the chirp, which is an effectively planar wave passing through the Earth at the speed on light. More accurately, deduce one of two possible directions: towards the event ot ...

2

Disclaimer: this is speculative, since no images of a black hole have been taken with enough resolution in visible light. The black hole represented in the movie Interstellar is moderately realistic with the knowledge we have at present. In fact, the movie makers asked astrophysicists to contribute. From the article Gravitational lensing by spinning black ...

1

Remember that there are millions of stars in that central hub between the black hole and us. We are seeing their light. The fact that there is a black hole behind them is not relevant.

1

Not quite the answer but little more than a comment. Singularity, as pointed out by Stan Liou (a note about geodesic incompletness), can be understood as a point beyond which you cannot extend geodesic (shortest path between two points). This can be illustrated on conic singularity (like corner on a cube) on 2D sheet of paper. If you pick two points on the ...

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