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0 pointsmikeash10y ago0 comments

Is there any idea how far away these black holes were? It would be interesting to know the volume of space it can potentially detect evens.

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drx10y ago

TFA says "they had heard and recorded the sound of two black holes colliding a billion light-years away" and "1.2 billion years ago".

And from the paper: "The source lies at a luminosity distance of 410+160-180 Mpcc corresponding to a redshift z=0.09+0.03-0.04.". (https://dcc.ligo.org/LIGO-P150914/public) Which corresponds to 1.337+0.522-0.587 billion ly (or between 750.2 million and 1.859 billion ly).

mikeashOP10y ago

Oops, missed that. Thanks!

Looks like there are roughly three million galaxies within a billion light years. Seems like lots of space for black hole pairs to live in. I suppose over the coming years, these gravity wave observatories will nail down just how common they are.

gradi3nt10y ago

So that's wayyyyyyy outside our galaxy? Any idea how many galaxies fit into a 1 billion ly sphere around the milky way? I'm guessing a shit ton, which makes the detection of a bh merger seem more realistic to me.

That's some serious range!

jballanc10y ago

It was mentioned during the press conference today that gravitational waves are not affected by interstellar/intergalactic dust the same way light is. In theory, once our detectors are good enough we should be able to use gravitational wave astronomy to peer all the way back to the big bang!

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tossaway110y ago

If these waves travel at the speed of light shouldn't the distance and time match up...?

drx10y ago

This would be true in a static universe, but, during the 1.2 billion years the waves have been traveling, the universe was experiencing accelerating expansion.

For example, the edge of the observable universe is about 46.5 lightyears away, while the universe is thought to be 13.8 billion years.

https://en.wikipedia.org/wiki/Observable_universe#Misconcept...

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vanattab10y ago

Not if space time it'self is stretching while the light is in transit.

xenophonf10y ago

That's around 1/60th the diameter of the observable universe!

j / k navigate · click thread line to collapse

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drx10y ago

TFA says "they had heard and recorded the sound of two black holes colliding a billion light-years away" and "1.2 billion years ago".

mikeashOP10y ago

Oops, missed that. Thanks!

gradi3nt10y ago

That's some serious range!

jballanc10y ago

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tossaway110y ago

If these waves travel at the speed of light shouldn't the distance and time match up...?

drx10y ago

This would be true in a static universe, but, during the 1.2 billion years the waves have been traveling, the universe was experiencing accelerating expansion.

For example, the edge of the observable universe is about 46.5 lightyears away, while the universe is thought to be 13.8 billion years.

https://en.wikipedia.org/wiki/Observable_universe#Misconcept...

1 more reply

vanattab10y ago

Not if space time it'self is stretching while the light is in transit.

xenophonf10y ago

That's around 1/60th the diameter of the observable universe!

j / k navigate · click thread line to collapse