Experiments Show Gravity Is Not an Emergent Phenomenon

[MSimon]

Let me also add that high frequencies are easier than low frequencies. To some extent you can filter the noise better by overlaying successive waves. The more waves per unit time the sooner you will see a result. If there is one.

The noise adds as the sq rt while the signal adds linearly. so you gain signal to noise by the sq rt of the number of waves added.

[rcain]

true. but by all accounts, the wavelengths of 'change' associated with heavenly bodies, must be several orders of magnitude longer, (lower frequency), than terrestrial ground noise. various movements of the crust, plate tectonics, etc, perhaps. (perhaps that is indeed a problem - or part of a solution?).

there are also ample 'unambiguous' signatures to look for - eg: sun, moon, eclipses, alignments, etc, that should be unequivocally detectable by similar earth-bound arrays.

also remember this is _gravity_ we're talking about. the signal is very very weak. you're listening for a whisper on a scream.

and even if you just amplify it right off the bat - well then the screams are going to saturate the channel and you'll just get an aperiodic square wave.

the signal strength is another matter (or the flip side of the coin, depending how you look at it).

so far as i can see, all you need, in the limit is a column of water. it will clearly show the sun and moon moving about.

now replace it with a laser beam.

i'm just surprised i haven't heard more of what results this technique 'can' produce already. that is all.

(of course it could well be the 'grumbling' of earths own gravitational field, is causing the noise. hadn't thought of that).

[rcain]

Let me also add that high frequencies are easier than low frequencies. To some extent you can filter the noise better by overlaying successive waves. The more waves per unit time the sooner you will see a result. If there is one.

The noise adds as the sq rt while the signal adds linearly. so you gain signal to noise by the sq rt of the number of waves added.

very good points.

in addition, since we are using high precision lasers and clocks, it is things like 'thermal drift', earth 'rotation effects, etc, that will appear bang in the range of things like planets and stars moving about.

still, i'd like to think we could get pretty good precision from current photonic methods. good enough to hear the big and close-up stuff.

[krenshala]

My problem with the idea is still that both the laser and the detector are going to be affected by changes in the "length" of space due to gravity waves. All of the descriptions I have seen so far describe how the length of at least one of the "arms" will change, causing the recombined laser to change interference pattern, and show the gravity wave.

Am I incorrect that light would be equally effected any any change in local space that would alter the length of the device arm?

[rcain]

My problem with the idea is still that both the laser and the detector are going to be affected by changes in the "length" of space due to gravity waves. All of the descriptions I have seen so far describe how the length of at least one of the "arms" will change, causing the recombined laser to change interference pattern, and show the gravity wave.

Am I incorrect that light would be equally effected any any change in local space that would alter the length of the device arm?

yes. more or less i think. though things like pollutants, thermal, location drift, rotation, etc would probably have particular signatures you could filter out. particularly with some network-bridge of transponders.

i think the general principle is not dissimilar to that used in ring laser gyro's ( http://en.wikipedia.org/wiki/Ring_laser_gyroscope ) - Sagnac interferometer - ( http://en.wikipedia.org/wiki/Sagnac_effect ) - on a much bigger scale.

i'm not sure whether anyone has looked at any use for circular polarisation in such a technique. seems to me it might offer some advantages - eg: some sort of 'vernier' measure.

[krenshala]

My problem with the idea is still that both the laser and the detector are going to be affected by changes in the "length" of space due to gravity waves. All of the descriptions I have seen so far describe how the length of at least one of the "arms" will change, causing the recombined laser to change interference pattern, and show the gravity wave.

Am I incorrect that light would be equally effected any any change in local space that would alter the length of the device arm?

yes. more or less i think. though things like pollutants, thermal, location drift, rotation, etc would probably have particular signatures you could filter out. particularly with some network-bridge of transponders.

i think the general principle is not dissimilar to that used in ring laser gyro's ( http://en.wikipedia.org/wiki/Ring_laser_gyroscope ) - Sagnac interferometer - ( http://en.wikipedia.org/wiki/Sagnac_effect ) - on a much bigger scale.

i'm not sure whether anyone has looked at any use for circular polarisation in such a technique. seems to me it might offer some advantages - eg: some sort of 'vernier' measure.

The difference here is that with a ring laser gyro the Sagnac effect is showing rotation of the gyro in relation to space itself. Space isn't rotating with the gyro.

If space was rotating, and that was the only rotation the gyro was experiencing, I believe the gyro would appear to not be rotating (gyro and space rotating together) as far as the interference pattern is concerned. This is why I believe LIGO (and LISA) will never detect "gravity waves" -- the laser and the device to measure the laser are changing length equally, thus maintaining a consistent interference pattern.

[rcain]

My problem with the idea is still that both the laser and the detector are going to be affected by changes in the "length" of space due to gravity waves. All of the descriptions I have seen so far describe how the length of at least one of the "arms" will change, causing the recombined laser to change interference pattern, and show the gravity wave.

Am I incorrect that light would be equally effected any any change in local space that would alter the length of the device arm?

yes. more or less i think. though things like pollutants, thermal, location drift, rotation, etc would probably have particular signatures you could filter out. particularly with some network-bridge of transponders.

i think the general principle is not dissimilar to that used in ring laser gyro's ( http://en.wikipedia.org/wiki/Ring_laser_gyroscope ) - Sagnac interferometer - ( http://en.wikipedia.org/wiki/Sagnac_effect ) - on a much bigger scale.

i'm not sure whether anyone has looked at any use for circular polarisation in such a technique. seems to me it might offer some advantages - eg: some sort of 'vernier' measure.

The difference here is that with a ring laser gyro the Sagnac effect is showing rotation of the gyro in relation to space itself. Space isn't rotating with the gyro.

If space was rotating, and that was the only rotation the gyro was experiencing, I believe the gyro would appear to not be rotating (gyro and space rotating together) as far as the interference pattern is concerned. This is why I believe LIGO (and LISA) will never detect "gravity waves" -- the laser and the device to measure the laser are changing length equally, thus maintaining a consistent interference pattern.

not if the supposed gravity wave induces some propagation/acceleration along the beam line i'm supposing. particularly if it looks in any way like an 'impulse' signal (or at least a recognized signal).

as to rotation - i am trying to think of ways rotation could be used in the configuration. certainly you might want to cancel it out - so helpful to measure. and point it in various directions. i think that's probably quite important.

apart from that, i think the detection/measurement technologies are quite similar. anyone care to correct me?

[rcain]

ps. how does the rate of precession alter in changing gravity fields? anyone know?

i have on record from the trusty wiki:

http://en.wikipedia.org/wiki/Lense-Thirring_precession
http://en.wikipedia.org/wiki/Thomas_precession
http://en.wikipedia.org/wiki/De_Sitter_precession

amongst the 'relativistic' aspects of precession. so i guess they qualify as 'useful' rotational/gyro effects to study.

just guessing.

[krenshala]

I may be pesimistic, but don't get me wrong. I'm all for the science. What's the line? If at least half your experiments aren't failing, you aren't doing research?