the 'new' gravity wave detector'

[bwanaaa]

http://science.slashdot.org/st...or-Gravitational-Waves

The problem I have with gravity waves is the fact that they distort the medium in which they travel. As a result, they should remain undetectable.

If you lived in flatland, and someone was bending your plane, there is no way you would know.

But if you lived in flatland and someone was stretching your plane, you'd see a hubble redshift.

If gravity waves cause pulsatile contraction-expansions, the hubble parameter should vary in sync with the local quasar, black hole or intense gravity source you are observing.

Hasn't that been seen already? or Not? and why will the new method of looking at higher frequency quasars be any better than LISA? I thought longer, low frequency waves traveled better over longer distances with less diffraction.

 

[iCyborg]

Originally posted by: bwanaaa
If you lived in flatland, and someone was bending your plane, there is no way you would know.

I don't think this is true. If your space was being (intrinsically) curved by someone, you could detect that in theory, say by summing up the angles in a triangle and realising they no longer add up to Pi or something...

 

[bwanaaa]

the angles of a triangle add up to >180 deg as curvature increases. A 90 deg bend gives three 90 deg angles for 270 deg for example. However, to measure angles you need to be OUTSIDE OF THE PLANE. So you cannot detect curvature in flatland by this method.

 

[iCyborg]

All the needed quantities are defined within the plane geometry. Why would you need to be outside of the plane?
And don't confuse extrinsic and intrinsic curvature of a space. The latter does not assume any kind of outside space nor higher dimensions. It is defined strictly within the space, and "outside" might not even make any sense.

 

[William Gaatjes]

Originally posted by: bwanaaa
http://science.slashdot.org/st...or-Gravitational-Waves

The problem I have with gravity waves is the fact that they distort the medium in which they travel. As a result, they should remain undetectable.

If you lived in flatland, and someone was bending your plane, there is no way you would know.

But if you lived in flatland and someone was stretching your plane, you'd see a hubble redshift.

If gravity waves cause pulsatile contraction-expansions, the hubble parameter should vary in sync with the local quasar, black hole or intense gravity source you are observing.

Hasn't that been seen already? or Not? and why will the new method of looking at higher frequency quasars be any better than LISA? I thought longer, low frequency waves traveled better over longer distances with less diffraction.

I have a question :

If you have a perfect vacuum and place only 2 particles in it. No matter what the distance, the particles would still attract each other through gravity yes ? This is assuming there is neutral charge and thus not interfering with the gravitational force.

My question is :

Is this correct ?

If it is the case then gravity maybe the result from the same fundament where the so called quantum entanglement of particles is the result of.

If it is not, well back to the drawing board...

 

[firewolfsm]

If gravity is quantized it is possible that a gravitational attraction between particles could be so weak that one "graviton" could only be emitted every so often, and the force may not always exist.

I sometimes think that gravity is not quantized, although it depends on the topic of discussion.

 

[bwanaaa]

Originally posted by: iCyborg
All the needed quantities are defined within the plane geometry. Why would you need to be outside of the plane?

ok, i see my mistake. i was thinking three dimensionally. Here is how I might measure an angle in flatland.

I imagine a flatlander stuck in an equilateral triangle. He could measure the distance to a particular vertex as well as the perpendicular distance from a limb. This would allow him to calculate the angle of the vertex. Finding all three angles would allow him to see how curved his space was as well as how big.
180 degrees= flat
270 degrees =sphere with circumference equal to 4x triangle limb length (imagine a triangle draped over a sphere with one vertex at the north pole and another at the equator.

 

[DominionSeraph]

Originally posted by: bwanaaa
He could measure the distance to a particular vertex as well as the perpendicular distance from a limb. This would allow him to calculate the angle of the vertex.

Except your meter stick is distorted, and 'perpendicuar' doesn't give you two 90 degree angles.

Bisecting one distorted triangle gives you two distorted triangles, not two good ones.

 

[TastesLikeChicken]

If the flatlanders measured their plane in two directions separated by 90 degrees, and calibrated those measurements through the use of laser beams, they could determine when someone or something was stretching that plane in one or more directions unless the stretching was precisely uniform in all directions. Gravity wave detectors work on that same principle. According to theory, gravity waves don't influence an area uniformly and instantly, since they propagate, therefore two separate detectors should be be able to measure any effects from a gravity wave, assuming they have the proper measurement resolution.

 

[Machupo]

wouldn't the flatlanders and their plane of existence also be bent as the triangle was bent, therefore by their frame of reference, nothing had changed?

 

[HibyPrime1]

I don't see how a stretched flatland would be able to detect the stretch with two perpendicular lasers.

If the entire land is stretched, then so are the photons, which will hit the wall earlier due to their stretching, and arrive back at the laser sooner, due to the stretching. All of this would equal out the difference in distance.

You should be able to make any alterations to the flatland, apart from cutting it and making any two parts touch each other (ie. a wormhole), without the flatlanders being able to measure the change

 

[TastesLikeChicken]

Originally posted by: HibyPrime1
I don't see how a stretched flatland would be able to detect the stretch with two perpendicular lasers.

If the entire land is stretched, then so are the photons, which will hit the wall earlier due to their stretching, and arrive back at the laser sooner, due to the stretching. All of this would equal out the difference in distance.

You should be able to make any alterations to the flatland, apart from cutting it and making any two parts touch each other (ie. a wormhole), without the flatlanders being able to measure the change

Light speed is constant regardless of the physical space stretching. Additionally, a gravity wave would propagate along each leg of the detector at different times so each leg's length would be unequal, which would manifest itself in a change in the interference pattern generated by the lasers.