What happens when black holes collide? | EXPERT ANSWERS PHYSICS GIRL QUESTIONS

Diana - Not a critique, just a comment: You didn't touch on the key to how LIGO works: At each LIGO observatory, there are *TWO* laser systems oriented 90° to each other, and any sufficiently strong gravitational waves do indeed 'stretch' the frequency of the light from both of those two different lasers. This means that, unless the source of the incoming gravity waves is at a *PRECISE* angle to the detector complex (exactly at 45° - picture an isosceles triangle bisected by a point from the exact middle of the hypotenuse to the node of the opposite angle), then the gravitational waves will stretch each 90° leg differently - and this means that subsequently combining the signals from *BOTH* laser legs will then yield a 'waving' interference pattern in intensity that can be analyzed to glean MUCH information about that particular event.


I understand and appreciate that you're a popular *EXPERT* at presenting physics to a likely unexposed audience, and I am ever so grateful that you do so, so I get that your omission here was most likely deliberate.


Again - this comment is intended as a clarification, not a critique, and I think it's *AWESOME* both that you do what you do, *AND* how you do it!