How do bar detectors work in gravitational wave detectors?

[Josiah]

TL;DR

How do bar detectors work

Hi, I was just wondering how bar detectors work. From what Ive read, the electrons act as one, thus accentuates the effect of a single gravitational wave.

 

[Josiah]

Or do the electrons in this state absorb more gravitational waves, thus the effect is magnified and can be detected

 

[PeterDonis]

From what Ive read

What have you read? Please give specific references.

 

[Ibix]

Don't they just change length when a gravitational wave passes through them? And you should be able to detect the induced strains with sufficiently sensitive strain gauges. Not sure where electrons come into this.

Unless there's some other kind of bar detector I've not heard of.

 

[AlexB23]

Don't they just change length when a gravitational wave passes through them? And you should be able to detect the induced strains with sufficiently sensitive strain gauges. Not sure where electrons come into this.

Unless there's some other kind of bar detector I've not heard of.

I think our guy is talking about Weber Bars. A precursor to LIGO, without lasers.

https://en.wikipedia.org/wiki/Weber_bar

 

[renormalize]

I think our guy is talking about Weber Bars. A precursor to LIGO, without lasers.

Yes, and I think that's exactly what @Ibix is talking about as well. To quote his post #4, with some clarifications in brackets added by me:
"Don't they [Weber bars made of metal, e.g., aluminum] just change length when a gravitational wave passes through them? And you should be able to detect the induced strains [in the block of metal, caused by the passage of the wave] with sufficiently sensitive strain gauges. Not sure where electrons come into this [i.e., the block is just ordinary, room-temperature metal involving no special electron states other than standard conduction]."

 

[Ibix]

I think our guy is talking about Weber Bars. A precursor to LIGO, without lasers.

https://en.wikipedia.org/wiki/Weber_bar

As @renormalize says, I know that. Interferometric detectors like LIGO have mirrors that are free to move independently, so they don't resist length changes and you can use interferometry to detect those changes as the gravitational wave passes through. Solid bars do resist length changes, so should ring (similar to the way they do when tapped by a hammer, but much, much weaker) when a gravitational wave passes through. But electrons don't really enter into the discussion any more than they do in any other material science topic.

Maybe you need to worry about electrons in terms of thermal noise. Or maybe the OP is talking about some other kind of detector. It's hard to tell. Hence the general requirement for references for discussion, and Peter's specific request for same.

 

[AlexB23]

Yes, and I think that's exactly what @Ibix is talking about as well. To quote his post #4, with some clarifications in brackets added by me:
"Don't they [Weber bars made of metal, e.g., aluminum] just change length when a gravitational wave passes through them? And you should be able to detect the induced strains [in the block of metal, caused by the passage of the wave] with sufficiently sensitive strain gauges. Not sure where electrons come into this [i.e., the block is just ordinary, room-temperature metal involving no special electron states other than standard conduction]."

What I do know is that the OP was vague. Bar detector does not return any results, unless one specifies Weber Bars.