I was reading an article in the newspaper today that referred to LIGO (and gravity-wave measurements in general) as "a new type of telescope".

That got me thinking -- as I understand it, LIGO uses lasers to measure the changes in the distances along two pathways, with the output data being in the form of two scalar values.

Is it possible, either in practice (someday?) or even just in principle to use gravity waves to produce viewable 2D images of astronomical objects, the way we currently do with e.g. infrared telescopes?

  • $\begingroup$ Well, you get waveform signals. Gravitational waves don't lie in the EM spectrum, so you can't "see" them like you're imagining. The word telescope is used because it's one of the ways of probing/observing the structure/dynamics of the universe. en.wikipedia.org/wiki/Multi-messenger_astronomy $\endgroup$ – Avantgarde Mar 20 at 1:30
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    $\begingroup$ I'm not sure that lie-ing in the EM spectrum is, on its own, a requirement for making 2D images. For example, consider the common practice of taking "pictures" of a gestating fetus using ultrasound -- no EM involved there AFAIK, and yet parents-to-be get to see a nice (if somewhat abstract) image of their child. $\endgroup$ – Jeremy Friesner Mar 20 at 2:03
  • $\begingroup$ @JeremyFriesner Indeed, I think you could rephrase your question as asking about the possible spatial resolution of LIGO and similar instruments. $\endgroup$ – Rococo Mar 20 at 2:23

If you had enough synchonised detectors then possibly. With just two you only know which side of the Earth the source was at - from which detector triggered first.

If you had three detectors you would know the direction (or one of 2 directions, since the waves pass easily through the Earth).

But all this just gives you a more accurate direction for the single event. If you could detect different signatures from different parts of the event and match them up at different detectors with exact arrival times you could map the source and make a 'picture'.

It's a little like being able to 'picture' where GPS satelites are from the signals recieved at different points on the ground.


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