Reply to post: Re: So . . . . .

Boffins' gravitational wave detection hat trick blows open astronomy

John Mangan

Re: So . . . . .

Scott, bear in mind that I am working from near thirty year old memories here but broadly yes.

I remember seeing graphs with a range of postulated sources; Big Bang, supernovae, merging black holes and others thatI've forgotten. Each had predicted ranges for strain and frequency. I'm pretty sure that the Big Bang was low frequency and amplitude because of the elapsed time/intervening expansion of the universe. The longest wavelength/lowest frequency waves will require a space-based detector with 'arms' thousand of kilometres long, see LISA.

I'll have to dig out my thesis to see compare how the predictions from back then compare with the current thinking on the subject (if I can still understand any significant fraction of it).

Other stuff I remember is that the gravitational waves were quadrupoles with two polarisations usually represented as + and x (similar to photons with l and - ). The 'best' signal would be with the wave travelling perpendicular to the detector (up/down into the ground) with the polarisation aligned with the two arms. This gives maximum 'stretch' to one arm with maximum 'squeeze' to the other alternating as the wave propagates.

Exciting times.

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