Gravitational Wave Detecting Gizmo

Rod
Rod
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Topic 196060

From ArIXiv (Blog)

How Superconductors Can Detect Gravitational Waves

There are some who can live without wild things and some who cannot. - Aldo Leopold

astro-marwil
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Gravitational Wave Detecting Gizmo

Hallo Rod!
That sounds interesting. Let´s wait for a statement of an expert. I hope, they will take more than a look on it.
Martin

Mike Hewson
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Well, I'm not an expert, but

Well, I'm not an expert, but my read is :

- there's quite a few more assumptions involved in this scheme than currently holds for existing IFO's.

- but it's good science because it's testable.

- it is a mix of thoughts from a spread of usually non or barely intersecting fields of interest. That's nice! :-)

- the idea seems to be a diode-like effect ( junctions within substances having different work functions ie. a localised internal energy gradient ) that can distinguish ( that's the plan at least ) the electron motion from the lattice motion.

[ But I really didn't catch the bit about how separable electron motions are from lattice motions. That's quantum, which of course is basically Weird City ie. are models of superconducting phenomena that well settled to extend into this idea? Electrons in materials are typically assigned an 'effective mass' to account for such interactions, and alot is hidden by use of that parameter. So if a tidal effect is operating, that being one way of interpreting the passage of a GW, then is it true that electron behaviour is linear here? Or in equivalent terms, to what ( small ) scale does GR's equivalence principle hold? For me, that's the rub. Would the Hall effect hold true in a centrifuge? Anyway, this is all way more subtle than photons travelling up & down vacuum tubes. Effective electron mass can be a tensor quantity of itself - depending upon which way you are traveling within the lattice - and real materials are rarely pure enough, symmetric enough as it is. So this is my ignorance showing .... :-) ]

- given that, then certain choices of geometry wrt GW polarisation allows conversion to a current flow. A GW to electric current transducer.

- it doesn't seem to operate as null device like the current IFO's, which have active mechanisms to deliberately keep the dark port dark ( so the corrections required to keep it that way are a proxy for the wave action ). A different heuristic applies. I suspect greater confidence would apply if we already knew what GW's sounded like, from the experience of actually detecting.

- you'd still have all the noise isolation problems of existing detectors, but I think is even worse as it would also behave as a tuned EM resonator. Mr Sixty Hertz and harmonics already pollute detector noise budgets as it is. Thus introducing all manner of issues, so what do you do? Cryo for sure, but a Faraday Cage as well? Hmmmm ...

- on the upside it would definitely be a workplace where mobile phones are banned !? :-)

Cheers, Mike.

( edit ) The Hall effect is only truly grasped with QM. So forget the talk, in many text books, about 'holes' being like bubbles in a fizzy drink. That description actually contradicts itself when fully rolled out. The real horror is that in the classic Hall setup whatever 'thing' is inside the material carrying the charge, it must have a negative effective mass in addition to a classical positive charge. Or the voltage gradient would be the other polarity when we perform the experiment. Which it isn't !!

What this effect defines is our ignorance really, or how poorly we can translate a 'electron particle' description that we are fond of for travel in a vacuum, to the situation within a lattice. You can't even begin to localise the electrons in there, and they all look the same! See Fermi etc .....

( edit ) Sorry if I seem obtuse. The relevance of the Hall effect in a centrifuge is that if we model charge carriers in such materials as having a negative effective mass, then if that is truly an inertial ( and per GR thus gravitational too ) property then we can ramp up the spin rate to reverse the polarity of the effect. Statically we use a magnetic field at right angles to the bulk current flow, and measure a voltage gradient along a third axis. Suitably arranged could those negative-mass/positive-charge carriers be encouraged to travel down the other flank of the material? Maybe someone has done this. I don't know.

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

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