Moon's orbit proposed as a gravitational wave detector

Kavanagh
Kavanagh
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Topic 227218
Mike Hewson
Mike Hewson
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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
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And it reqires little

And it requires little equipment although the calculations are horrendous.

Richard

Mike Hewson
Mike Hewson
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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
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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

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