LIGO gravity waves

Bye Jack

Yeah I heard there are rumors....

George H.

A simple way to have the high sensitivity of a long arm length interferometer for high frequency gravity ways would be to have the laser beam bounce back and forth many times between two mirrors at a tiny angle so that after possibly 1000 bounces the laser beam until it can return back to the beamsplitter having travelled 1000x or more distance of the interferometer arm length.

The short overall arm length would still make the interferometer sensitive to high frequency gravitational waves.

I guess the thermal/quantum uncertainties of the mirror surface would be also magnified by 1000x times though, so this technique would require a near perfect mirror reflective surface, ie probably not possible without some crazy mirror chilled to almost absolute zero that can withstand the high power laser bouncing off it 1000 or more times and still stay cold, maybe liquid helium pumped through channels in the mirror if it is a zero viscosity superfluid maybe it has no vibrations to destroy the interferometer measurement too :D

cheers, Jamie

cheers, Jamie

One last idea:

LIGO is not direction sensitive, so to improve the detector to allow it to sense gravity waves vector, it should have a 4km deep hole drilled for a third arm on the interferometer, so that there are a total of 3 X, Y, Z coordinate arms orthagonal, and then three different frequency lasers used, one for XY, XY, YZ arm measurements, this should allow the difference in interferometer intensity to give the source vector for the gravitational wave source.

cheers, Jamie

Jamie, no offense, but there are ~1,000's of physics types working on this. All thinking hard... many much smarter than you or I.

Try this... (with 2-axis detectors.) If you put one in Italy (say) and another over on the west coast of the US, then you've got the three dimensions pretty much covered. (The up/down in the US is the same as E/W in Italy.)

George H.

And they are looking for changes in length that are potentially only a fraction of an atom across. It is right at the limited of experimental science. They are already exploiting almost every trick in the book. They only really stand a chance because they can to some extent predict the sort of signal that a black hole swallowing something will produce.

You can dream up many experimental scenarios but building them and making them work reliably is another matter entirely.

A bit like neutrino detectors in the day having several different ones across the world using slightly different methods and seeing a signal in all of them tends to indicate a real external signal. Some of the early detections were just a few hits but in more than one detector.

You are absolutely right that is it far simpler to build on the surface and exploit the fact that the Earth is a sphere.

I built this gravity wave detector from Radio Electronics mag. Some kind of integrator. I hooked it up to a strip chart. Sounded interesting. Well it was interesting. I was getting slow wave shapes over time. The interesting thing was, I was getting symmetrical wave shapes. I never pursued futher. Down the page with other crazy stuff.

Greg

Maybe I'm dim, but can someone enlighten me on this? Given that according to GR, gravity just warps spacetime

Jeroen Belleman

That is a worrying opening gambit to a question given that you are as I recall at CERN. I'm a bit rusty on GR these days - gravitational radiation really only came of age with the discovery of the first binary pulsar which helpfully did just what it was predicted to do.

Ask one of your local tame physicists to explain...

AIUI the passage of the wave through the spacetime in the etalon affects the transit time for the shortest path as it goes past. I hope all will become clear when they make the announcement this afternoon.

Related to the Shapiro time delay seen in signals from pulsars that pass very close to Jupiter (and it found a mistake in the computer generated VSOP ephemeris for planets - ISTR for continuation cards).

Interestingly all the LIGO weblinks are offline today.

BBC radio was broadcasting a simulated going down the plughole chirp signal this morning (and if they have seen that it would clinch it).

Xray satellites have seen a corresponding signal for a feeding BH

That is with a classic accretion disk and ordinary matter.

But a BH BH merger is something else and much more violent.

A moving mass alters the spacetime around it in a subtle way. It is astonishing if they have grabbed one though - their intrinsic noise to signal ratio makes radio astronomy look easy by comparison.

What figures do you masters come up with IF the gravity waves are traveling slower than light speed?

Ever stop to think that they might know more about what they are doing than you do? Perhaps you missed a few tricks in your brains.

Perhaps it it the transition which is detectable.

What causes the Earth's poles to flip?

Are there feral physicists?

Only in the back woods of Idaho, you've got to be real careful approaching them. They will take your Lagrangian with out warning. :^)

George H.

Some of us are only potentially energetic. ;)

Cheers

Phil Hobbs

Did you see the live press conference? Looks like they have nailed it with a mind boggling peak strain of 10^-21 at both detectors and a waveform signature that is pretty much exactly what GR would predict.

Truly an impressive achievement - Nobel prize stuff!

No but someone said to look here,

George H.

Then you'll surely fall into that sink hole and make it all the way to the Earths core, where you will be trapped in a pendulum swing back and forth for just about ever. At least until the entropy doctor arrives.

Do a google on "KIT CFN rdax"

Nice little slotted nanodevice there.

On Thu, 11 Feb 2016 08:26:36 -0800, George Herold wrote: snip

Hey look! It's Ringo Star!