Science to ride gravitational waves

BBC News on line ^ | November 8, 2006 | By Jonathan Amos, BBC News science reporter, Hanover

[beezdotcom]

I think we can generate some false positives if we carefully syncronize FReepers in different locales to jump up and down at precisely timed intervals, to create the illusion that a wave has passed through the earth.

Then, we can all go make some crop circles...

[operation clinton cleanup]

The Glasgow University scientist has been chasing these "ripples" in space-time for more than 30 years and feels certain he is now just a matter of months away from bagging his quarry.

Months? or 30 more years?

[VadeRetro]

Alexander Graham Bell's experiment came up empty, so Fitzgerald and Einstein had to figure out something else.

"Michelson and Morley's experiment came up empty," etc. It meant, among other things, that light isn't waves in some medium called "the ether" filling Newtonian absolute space. If it were, the interfermometer would have detected the direction of the Earth's motion against this ether and it couldn't. It also meant that Newtonian addition of velocities didn't apply to measuring the speed of light, although up to then it had applied to everything else.

It was a very upsetting null result.

[RightWhale]

Yet, now, we are confronted with frame-dragging. It's more subtle, but time-space does have some ether-like qualities, just not the ones they were thinking of at that time.

[spunkets]

"No, not practically. You're talking about something with a likely lag time of a second in a system with lags of hours."

The Earth-Moon, or the Sun-Earth system consists of 2 masses. Each of those 2 masses is already responsible for the existence of their respective fields. The fields already exist. That means neither mass can observe gravitational radiation from the other.

Only assemblies of mass radiate gravitationally. The simplest is the mass quadrupole. It can radiate when it rotates and/or vibrates. One of the examples from the article is a rotating mass quadrupole, the mutually orbiting neutron stars. This quadrupole is far enough away that it can be seen as a radiator. Far enough away means that the observer is not a part of the radiating system observed.

[lafroste]

If the velocity of an object changes, then either the distance it traverses, the time it takes to traverse that distance, or some combination of the two changes.

Confusion reigns when I shoot from the hip (often when I don't as well). Velocity requires both distance and time. What I mean to imply is that a changing velocity (as in an object falling into a gravity well) maintains a constant energy (dE_potential = 0) regardless of its apparent dE. This difference in apparent dE can be equated to a function of the object's rest mass and the time differential it traverses. That means that its actual energy change is 0 even though it appears to have accelerated. That apparent energy increase (E=1/2 mV²) is because its overall 5-D energy is at all times constant, and it appears to accelerate in 4-D to maintain the 5-D equality. What this says is that Potential energy, at least as concerns gravity, is an error and is not an actual phenomenon, but simply a mathematical convenience.

The theory says that mass is itself a dimensional phenomenon, and that it is projected into spacetime as mc². That 5-D quantity remains invariant through spacetime and explains why an object accelerates when subjected to a time field. Basically, the object is unchanged, the space around it is changing instead.

Note to all you real physicists: just because I explain it badly doesn't necessarily mean its wrong. I have an open mind on the subject. When it was fresh in my mind a Physics Prof at PSU could not punch holes in it, and ended by saying that I had independently derived relativity from another starting point. I respectfully disagreed because it seemed to me that the theory allowed the definition of an absolute zero in each dimension. I argued that those dimensions could not be "relative" if they possessed an absolute zero. To wit, each of three D's have an absolute zero velocity vector, time has an absolute zero taken as the event horizon of a black hole, and mass has an absolute zero defined as that region of space that has zero time flux.

so please be gentle

[spunkets]

"I thought Einstein came to the conclusion that gravity WASN'T a wave, but a curve in space. After all, if it's a wave, then at what velocity does the wave propagate?"

It is a curve in space. If there's just one object in the universe, the curve is hte same. If there's 2 objects, the curve is the same. Now if the objects are in motion relative to each other, as in vibration, or rotation, the curves will change and the changes propagating through space are the gravitational waves. The propagaiton velocity for the wave is c. See #65.

[jammer]

We already know that ...

Yep. Tom Bethell wrote about (and was vehemently castigated for) this in The American Spectator in, I believe, the mid-80's. I still have the article somewhere. Glad to see one of the best writers anywhere exonerated.

[Right Wing Professor]

Thanks for the explanation.

[Southack]

"The Earth-Moon, or the Sun-Earth system consists of 2 masses. Each of those 2 masses is already responsible for the existence of their respective fields. The fields already exist. That means neither mass can observe gravitational radiation from the other."

That **might** be true in a static system, but it certainly isn't true in a dynamic, moving system...and make no mistake the Moon does indeed move around the Earth.

This movement matters, at the very least, because the force of Gravity is dependent upon distance. The Moon's gravitational force on one ocean is not the same as on any other ocean at any given moment simply because the Moon is closer to one than another when it is on the opposite side of Earth.

As the Moon orbits around the Earth, its gravitational force will be temporarily stronger on the area closest to the Moon at the time. This causes tides, among other things.

[mikrofon]

1

It's not just a good idea...

It's ze Law!

[Lonesome in Massachussets]

Carefully note the precise lag between the tide rising compared to the overhead orbital position of our Moon.

Any lag is swamped by the lagging response of ocean. Besides, tides are caused by a inbalance in centrifugal force and gravity, the earth moves through the already arrived gravitional field of the moon.

A more sensitive test of gravitional/inertial interaction is available in measuring physical libration on the moon. The moon's rotation is tidally locked to its sidereal orbital period, 27.3 days. However, because of the eccentricity of the moon's orbit, its orbital motion varies as it comes closer and further from the Earth, but its rotation is more uniform, so she presents a slight different aspect to the Earth during the month.

Copyright Antonio Cidadao.

As the aspect varies, the Earth pulls more strongly on the heterogenous lumps in the moon, effecting a torque. This results in an actual change in the rotational speed of the moon, with respect to the distant stars, called physical libration. (The effect above is overwhelmingly apparent libration, caused by the non-uniformity of the moon's orbital speed.)

There are corner reflectors on the moon whose displace should exhibit the effects of this torque far more accurately than anything we might be able to do with tides. The laws of propagation of errors are against you I fear. While it is possible to tease out the measurement of physical librations, these measurements probably cannot ever be sensitive enough to reveal lags associated with the speed of gravity.

[Southack]

"There are corner reflectors on the moon whose displace should exhibit the effects of this torque far more accurately than anything we might be able to do with tides. The laws of propagation of errors are against you I fear. While it is possible to tease out the measurement of physical librations, these measurements probably cannot ever be sensitive enough to reveal lags associated with the speed of gravity."

Interesting.

[spunkets]

The field you see from the Earth, or from the moon appears fixed. The field from either of those objects is static. The field from a binary neutron star system appears varied. It's the fact that you see the waves coming from a point source that's important.

You can't see the energy radiated away from the Earth-Moon system. From here it's too small too see. Gravity looks conservative here, except for frictional losses from the Earth creaking and the water flowing. If you had a sensitive enough device and were far enough away that the Earth-Moon system looked like a point source, then the you could see the waves. Else, you'd need the same sensitivity to account for frictional looses well enough, to determine the decay in Moon orbit due to gravitational radiation. That would be as difficult as sensing the gravitational waves from the Earth, due to the rotating Earth's surface being lumpy. It can't be done.

[Southack]

No. The fields **may** be fixed, but their "shape" or scope reduces over distance...and the Moon is closer to one ocean on one side of the World than to an ocean on the opposite side at any given moment of the Moon's orbit around the Earth.

This means that the Moon exerts more pull on the ocean directly below it at the time than on an ocean on the opposite side of the planet...and this peak pull is constantly moving as does the Moon move.

[AndrewC]

Looks like Michelson - Morley without the mercury bearing.

Just what I thought. I wonder if the results will be the same?

[RunningWolf]

Sorry, you don't get the 10B grant unless you can work global warming into the proposal.

We can do this! I've got Steve working on some of the technical details, and now you will conduct a benefit analysis, and through that somehow discover our project will cure global warming in a dramatic way.

Wolf

[woofie]

This lady has defied gravity for years

[steve8714]

I need more funding to complete my computer modeling, but preliminary results look promising. Grant application to follow.

[spunkets]

" The fields **may** be fixed"

The fields are fixed.

"This means that the Moon exerts more pull on the ocean directly below it at the time than on an ocean on the opposite side of the planet...and this peak pull is constantly moving as does the Moon move."

The subject is the propagation of gravitational waves, not the motion of bodies in fixed fields.