Moon's orbit proposed as a gravitational wave detector

Kavanagh
Kavanagh
Joined: 29 Oct 06
Posts: 1567
Credit: 100419559
RAC: 12707
Topic 227218
Mike Hewson
Mike Hewson
Moderator
Joined: 1 Dec 05
Posts: 6534
Credit: 284730859
RAC: 105773

Pretty clever idea ! In a way

Pretty clever idea ! In a way everything resonates with the passage of a gravitational wave, I guess the trick is to make that manifest in a sufficiently precise manner. A nice & probably un-anticipated use of the laser reflectors left on the Moon some fifty odd years ago ( & since ).

Microhertz waves : I gather that means relatively long time duration for one cycle ie. millions of seconds and correspondingly exceedingly long wavelength. One million seconds is ~ 300 billion kilometers of light travel or about 12 light-days ! The reason to calculate that is to compare that with the Earth-Moon separation of about one light second, so the 'detector' here spans only a tiny fraction of the wave. Conversely if the detector spans many ( gravitational ) wavelengths then it can't 'see' the oscillating nature ( it 'blurs' ). For instance your fingertips are very good for feeling spatial waves of the order of the dermal papillae ( hills and valleys in the fingerprints ) but if the spacing is too small - like a sufficiently fine gritted sandpaper - then you can't sense the variation, only an average level.

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

Kavanagh
Kavanagh
Joined: 29 Oct 06
Posts: 1567
Credit: 100419559
RAC: 12707

And it reqires little

And it requires little equipment although the calculations are horrendous.

Richard

Mike Hewson
Mike Hewson
Moderator
Joined: 1 Dec 05
Posts: 6534
Credit: 284730859
RAC: 105773

In GR the calculations are

... said the tax accountant to the doctor. { Boom boom! }

In GR the calculations are always horrendous, this being why Einstein is quoted as saying : 'You know, once you start calculating you shit yourself up before you know it' ! ;-)

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

Kavanagh
Kavanagh
Joined: 29 Oct 06
Posts: 1567
Credit: 100419559
RAC: 12707

Finding the moon's position

Finding the moon's position and velocity using Newton's laws is horrendous. I do not have an adjective in my vocabulary to describe the effort in GR.

Richard

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.