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AgoraBasta
2002-Sep-14, 11:27 PM
The idea is quite straightforward. Use the same Walker-Dual scheme as described here - http://www.arxiv.org/PS_cache/gr-qc/pdf/9706/9706082.pdf but with some technological improvements; instead of using two dipoles of macroscopic masses oscillating at a rather low frequency, better use two big quartz crystals of identical resonance frequencies and of very high Q-factor. Put the "transmitter" crystal into active oscillation, then use the other one as a receiver. The Q-factor of 10^11 must be quite realistic for a crystal of a size of about one inch at longitudinal resonance mode, so sensitivity for a non-modulated signal must be very high, thus phase velocity measurements are no problem at all. (In fact, the bigger old-time x-tals really do show very strong parasitic coupling of non-EM and non-acoustic nature.)
To get the group speed we'd need to use some sort of modulation. I'd propose a mechanical or electrical delta-pulse excitation of the transmitter superimposed upon native resonance oscillation, it should produce a phase spike in the receiver crystal output by exciting higher harmonics. The best case for phase-amplitude detector inertiality is about 1/8 of the period of the main resonance, that would be about 10ns inertiality at the detector side; the Q-factor won't be helpful in this case, so it could be better to directly record the burst of higher harmonics in the receiver. If gravity pulse propagates at the same group velocity as light does, then 10ns means 3m. So the sensitivity of the system needs to be sufficient till 1m distance at least for the measured delay to be of the same order as the systematic inertiality, which is quite realistic for big xtals.

So, anyone who's got access to some very old quartz xtals might well try it as a desktop experiment. God knows, it may well turn out very much ftl, after all...

<font size=-1>[ This Message was edited by: AgoraBasta on 2002-09-19 18:04 ]</font>

SAMU
2002-Sep-15, 11:05 PM
I am way behind in the theories of gravitation et al so you will have to forgive me what may be a simplistic question but I have yet to see illustrated the situation of the Earth as to the Sun. Ie. The the Earth revolves around a position in space that is itself moving in relation to the center of the Galaxy and the "center of the universe. So are we revolving around a position by gravitational forces in space where the Sun was, by light speed 7 minutes ago, or are we revolving around the center of gravity as the Sun is "now". Simply put, are we revolving around a place in space where the sun is now or where it was 7 minutes ago?

<font size=-1>[ This Message was edited by: SAMU on 2002-09-15 19:09 ]</font>

Silas
2002-Sep-16, 01:22 AM
On 2002-09-15 19:05, SAMU wrote:
I am way behind in the theories of gravitation et al so you will have to forgive me what may be a simplistic question but I have yet to see illustrated the situation of the Earth as to the Sun. Ie. The the Earth revolves around a position in space that is itself moving in relation to the center of the Galaxy and the "center of the universe. So are we revolving around a position by gravitational forces in space where the Sun was, by light speed 7 minutes ago, or are we revolving around the center of gravity as the Sun is "now". Simply put, are we revolving around a place in space where the sun is now or where it was 7 minutes ago?

<font size=-1>[ This Message was edited by: SAMU on 2002-09-15 19:09 ]</font>


That's the 64,000 dollar question... According to relativity, as currently modeled mathematically, the "speed of gravity" is the speed of light, and so, yes, we are orbiting the place where the sun was seven minutes ago...

Except that the mathematics have corrections built in...

These corrections are what give Tom Van Flandern his support.

The trouble is, if you throw away those corrections, and assume an infinite speed of gravity, all the other equations fall apart, and relativity becomes a wretched mess...

The idea of measuring the speed of gravity using a cyclically moving mass is a good one, but it brings complications...

The perfect method, of course, would be to take a mass and "remove it" instantly. However, that isn't permitted by the laws of relativity (plus, we don't know how to do it in the real world.)

Silas

2002-Sep-16, 02:09 AM
<a name="11 OC 4 CHEN"> page 11 OC 4 CHEN aka 0 yuck 1 barf
ok 1st attack = SPEED { get it straight } its
spectrum or speeeeds { use the plural }
------------------------------------
now back to ScIEnce and I B4E except when after C
and all that "Crap"
whenever theres a big storm off the Oregon coast
those storms do cause a responce to be recorded
on the pSU seismograph:: Well they did untill it went to
the computer? now who can tell [CRAP2.1]

-----------------------------------------
ok so storms of that magnitude "DO" generate
gravity wave inpulses & those do deflect
PSU's seismograph {yes yes like i said B4}

==========================================
so yeah its possibele to do [NOT EASY TO DO]
stupid coMputers anyway
but in theory_MY you could have to Seismographs
say ten or twenty miles apart compare the pattern
and get some results which would be pretty much what
I'd guess P & S ** over again.. now to the Spectral #'s
oppsi out of lines S_n & S_# will just have to wait { yes there was A 4. of the coast No i didn't look .. The S is down {replaced by a C } so 4get this

Senor Molinero
2002-Sep-16, 03:40 AM
If we can determine at any given instant, the tangential direction in which the earth is travelling, then, gravitationally, the sun should be at an exact right angle to that direction. If that point is where we observe the sun to be, then the speed of gravity is equal to the speed of light. If that point is ahead of where we observe the sun to be, then the difference in position can be used to calculate the speed of gravity.
N'est-ce pas?

JS Princeton
2002-Sep-16, 02:15 PM
The Earth is MOVING with the sun. They are, for all intents and purposes, in the same reference frame. Therefore there is no "where the sun was/is" with relation to Earth. The Sun is always in the same separation. This is a consequence of Galilean Relativity.

DaveC
2002-Sep-16, 03:31 PM
On 2002-09-15 21:22, Silas wrote:
The perfect method, of course, would be to take a mass and "remove it" instantly. However, that isn't permitted by the laws of relativity (plus, we don't know how to do it in the real world.)


But we can make mass "disappear" by converting it to energy through fission (or fusion). If the mass could be contained and the energy released, and if we had sufficiently sensitive detectors, theoretically we could measure whether the change in mass was detected before, after or simultaneously with the detection of EM radiation from the fission/fusion reaction.

OK, so there are some big IFs and a few technical hurdles. And one potential problem is that space-time has natural variations in its shape that might be sufficiently large to mask the detection of a minute change in gravity from a point mass as small as 100 kilos of plutonium.

AgoraBasta
2002-Sep-16, 03:55 PM
On 2002-09-16 11:31, DaveC wrote:
...100 kilos of plutonium.


Hey, I proposed using two cheap and safe xtalls along with some conventional electronics, and now you want plutonium?!

DaveC
2002-Sep-16, 06:25 PM
On 2002-09-16 11:55, AgoraBasta wrote:
[Hey, I proposed using two cheap and safe xtalls along with some conventional electronics, and now you want plutonium?!


Apart from being a big fan of impressive displays of fireworks, I was really just responding to Silas's comment that making mass disappear was not possible. Anyway, you got something against plutonium? If so we could use U235.

AgoraBasta
2002-Sep-16, 06:46 PM
On 2002-09-16 14:25, DaveC wrote:
...I was really just responding to Silas's comment that making mass disappear was not possible.


But we don't really need to make mass disappear, all we need is to redistribute mass very fast.

DaveC
2002-Sep-16, 07:44 PM
On 2002-09-16 14:46, AgoraBasta wrote:
But we don't really need to make mass disappear, all we need is to redistribute mass very fast.


Ah - but if gravity propagates at the speed of light, you'd have to redistribute the mass at least that fast. Relativity tells me that we can't move mass fast enough to make an observation of the speed of gravity - unless, for some obscure reason, gravity propagates much slower than c.

AgoraBasta
2002-Sep-16, 07:54 PM
On 2002-09-16 15:44, DaveC wrote:
Ah - but if gravity propagates at the speed of light, you'd have to redistribute the mass at least that fast.

Nope. The start of the process at source is simply felt at the target with certain delay. Just like you don't have to modulate radio wave at the "speed" of the carrier frequency, you just multiply it by a slower signal.

traztx
2002-Sep-16, 11:57 PM
Food for thought...

Consider a binary pair of equal-mass stars in a circular orbit in a far remote place.

If gravity is instantaneous, then the force vector is always in the direction of the sister star. If you draw a line from star to star, you'll see the force vector exactly on the line.

If gravity is at the speed of light, then the force vector points behind the sister star. If you draw a line from star to star, the force vector won't be on the line.

Since the vectors aren't pointing to each other (in the speed-of-light example), will this system of 2 stars experience an increase in total energy over time?

I must be missing something...

Silas
2002-Sep-17, 03:30 AM
On 2002-09-16 19:57, traztx wrote:
Food for thought...

Consider a binary pair of equal-mass stars in a circular orbit in a far remote place.

If gravity is instantaneous, then the force vector is always in the direction of the sister star. If you draw a line from star to star, you'll see the force vector exactly on the line.

If gravity is at the speed of light, then the force vector points behind the sister star. If you draw a line from star to star, the force vector won't be on the line.

Since the vectors aren't pointing to each other (in the speed-of-light example), will this system of 2 stars experience an increase in total energy over time?

I must be missing something...


You are... And I am too! It has to do with Einsteinian tensor calculus. The nasty fact is that the force tensor "points" toward the "instantaneous" position of the gravitational source. The "speed" of gravity is the speed of light, but the effect of gravity has "instantaneous" elements, as far as General Relativity in concerned.

I've had tensors described to me, but I can't do 'em on paper.

So...to some degree, you have to choose whether you like Van Flandern or Baez.

From all the reading I've done of the public debate between the two, Van Flandern comes off as the loser.

Silas

traztx
2002-Sep-17, 01:42 PM
On 2002-09-16 23:30, Silas wrote:


On 2002-09-16 19:57, traztx wrote:
...I must be missing something...


You are... And I am too! It has to do with Einsteinian tensor calculus. The nasty fact is that the force tensor "points" toward the "instantaneous" position of the gravitational source. The "speed" of gravity is the speed of light, but the effect of gravity has "instantaneous" elements, as far as General Relativity in concerned.


Interesting. I'd like to see how this is reconciled with the conservation laws. Another example would be a proton and antiproton circling each other in deep space. Evidence strongly suggests that charge propagates at light speed. If the direction is instantaneous but the magnitude is not, then we still have energy added (since every 2 points on a circle is closer than 2 points along the diameter).
I'm just glad we have gravity so I can ski in the spring /phpBB/images/smiles/icon_smile.gif
--Tommy

2002-Sep-17, 02:49 PM
[ STANDARD ] FROM 486/100 { disclaimer }
its the same glift as found above

at this time
And that GLIFT is this one [ / / ]
think about it like this
a highway {i'll put in a center line in a version below
in a photograph?of a photograph of a highway ?
(oh never mind}
revised revision of origional revised revision REVISED
[ / | ] picture of a "straight" hiway withe center line included {in the middle
( now pay attention }
A:? If that angle were @B used to devide 1 PIE
how many piecies of pie would I get ?
[ ] i'll make it multiple guess Answer [1] 1
answer #2 [ 2 ] answer 1 [1] is wrong

Tom
2002-Sep-18, 02:03 PM
On 2002-09-15 21:22, Silas wrote:
[quote]According to relativity, as currently modeled mathematically, the "speed of gravity" is the speed of light, and so, yes, we are orbiting the place where the sun was seven minutes ago...


Not exactly. The earth and sun are orbiting a common point in space, which is also constantly moving with respect to each... We never orbit the exact point in space twice. Do the planetary motions carry the frame of reference along?

If so, the speed of gravity is irrelevant.

Tom

Wiley
2002-Sep-18, 04:34 PM
On 2002-09-16 23:30, Silas wrote:
You are... And I am too! It has to do with Einsteinian tensor calculus. The nasty fact is that the force tensor "points" toward the "instantaneous" position of the gravitational source. The "speed" of gravity is the speed of light, but the effect of gravity has "instantaneous" elements, as far as General Relativity in concerned.


I gonna nitpick a little here. The effect of gravity has no "instantaneous" elements. All the terms of the gravitational effect depend only on retarded position, velocity, and acceleration. Retarded means the value at the source when it was emitted, e.g. retarded position is R - c*t. For certain cases, the force vector points towards the "instantaneous" position, but this is caused by cancellations in the terms. Since very few simple geometries have been solved analytically, it is quite a stretch to say it occurs in all cases. I am interested in what the numerical GR people have seen.

We see an analogous effect in electromagnetics. A charge moving with uniform velocity produces a field that also points toward the instantaneous position. The field terms are all functions of retarded position and velocity. It's the cancellation, that produces this effect. Now if the charge changes direction or speed, i.e. accelerates, then the field no longer points toward the instantaneous position. The information that the charge is no longer moving uniformly propagates at the speed of light. For all you familar with systems and controls, it is analogous to a lead-lag network.

Electromagnetic waves and gravitational waves are not complete analogous. Gravity waves radiate from a quadrapole moment while electromagnetic waves radiate from a dipole moment. So a uniformly accelerated mass has no aberration, but would a non-uniformly accelerated mass, e.g. the twin pulsars, have aberration? I suspect the answer is they would indeed have aberration, but I don't know if the problem has been solved.

RadioMike
2002-Sep-18, 04:53 PM
On 2002-09-18 12:34, Wiley wrote:

I gonna nitpick a little here. The effect of gravity has no "instantaneous" elements. All the terms of the gravitational effect depend only on retarded position, velocity, and acceleration. Retarded means the value at the source when it was emitted, e.g. retarded position is R - c*t. For certain cases, the force vector points towards the "instantaneous" position, but this is caused by cancellations in the terms. Since very few simple geometries have been solved analytically, it is quite a stretch to say it occurs in all cases. I am interested in what the numerical GR people have seen.



Please excuse an interjection from a rank less-than-amateur, but isn't the objection to gravity being equal to the speed of light merely perceptual?

In other words, I have no issue that if the Sun "magically" winked out, I wouldn't see it wink out for what, 8.31 minutes or something.

It seems to make sense to me that the Earth would still be influenced by the effects of its gravitational pull for the same amount of time. Just because the Sun is gone, its light still is streaming (?) or traveling toward Earth. Wouldn't its gravity do the same thing?

In other words, we'd still be in free-fall due to the gravitational force still being felt, even if the body was gone.

Probably doesn't sound very convincing coming from me.

If an Astronaut in communication with the Earth while in orbit around Saturn suddenly was zapped by...the Vatican, for example - we'd still hear his or her voice 12 or so minutes after, even though the astronaut was...no more. There would be nothing "instantaneous". You can't put the cart before the horse.

I do hope this was the gist of the argument.

Apologies to A.C. Clark for the "Vatican" line. /phpBB/images/smiles/icon_smile.gif

Mike

AgoraBasta
2002-Sep-18, 05:16 PM
On 2002-09-18 12:34, Wiley wrote:
So a uniformly accelerated mass has no aberration, but would a non-uniformly accelerated mass, e.g. the twin pulsars, have aberration? I suspect the answer is they would indeed have aberration, but I don't know if the problem has been solved.

Wiley, the funny little "paradox" here is - whether the strong equivalence principle or gravitational waves, but not both simultaneously...

Wiley
2002-Sep-18, 05:28 PM
On 2002-09-18 13:16, AgoraBasta wrote:
Wiley, the funny little "paradox" here is - whether the strong equivalence principle or gravitational waves, but not both simultaneously...


Eh? Can you say that again but with an active verb? /phpBB/images/smiles/icon_smile.gif

AgoraBasta
2002-Sep-18, 05:40 PM
On 2002-09-18 13:28, Wiley wrote:
Eh? Can you say that again but with an active verb? /phpBB/images/smiles/icon_smile.gif

Here's your verb - "you get" (with a gratis pronoun) /phpBB/images/smiles/icon_smile.gif

<font size=-1>[ This Message was edited by: AgoraBasta on 2002-09-18 13:43 ]</font>

Silas
2002-Sep-18, 05:46 PM
On 2002-09-18 12:53, RadioMike wrote:
In other words, I have no issue that if the Sun "magically" winked out, I wouldn't see it wink out for what, 8.31 minutes or something.

It seems to make sense to me that the Earth would still be influenced by the effects of its gravitational pull for the same amount of time. Just because the Sun is gone, its light still is streaming (?) or traveling toward Earth. Wouldn't its gravity do the same thing?



The problem is that the sun's gravity bends the space through which the gravity is streaming... If the sun magically popped like a bubble and its mass was gone, you have a lot of bent space that's violating a bunch of laws...

The question is perfectly valid... But it involves doing something what the equations of General Relativity do not permit...

(You can block light almost instantly, just by putting something opaque in the way. But there isn't any way to block gravity...)

Again, think of the standard example of a mass bending space as if a weight is set on a stretched rubber sheet. The weight causes the sheet to bend, causing a dimple. Larger masses cause greater bending, and deeper dimples. (A black hole is so massive, it tears right through the sheet...)

How do you cause a weight to disappear so quickly that the dimple remains? That would be, in effect, moving the weight faster than light...

Silas

Wiley
2002-Sep-18, 06:00 PM
On 2002-09-18 13:40, AgoraBasta wrote:


On 2002-09-18 13:28, Wiley wrote:
Eh? Can you say that again but with an active verb? /phpBB/images/smiles/icon_smile.gif

Here's your verb - "you get" (with a gratis pronoun) /phpBB/images/smiles/icon_smile.gif

<font size=-1>[ This Message was edited by: AgoraBasta on 2002-09-18 13:43 ]</font>


Seriously, I don't understand what you're trying to say. Are you saying that the SEP and gravitational waves can exist together without causing paradoxes?

traztx
2002-Sep-18, 06:02 PM
On 2002-09-18 12:53, RadioMike wrote:
Please excuse an interjection from a rank less-than-amateur, but isn't the objection to gravity being equal to the speed of light merely perceptual?


Once the speed is measured it will enter the realm of perceptual. Until then, it is only theoretical.



On 2002-09-18 12:53, RadioMike also wrote:
It seems to make sense to me that the Earth would still be influenced by the effects of its gravitational pull for the same amount of time. Just because the Sun is gone, its light still is streaming (?) or traveling toward Earth. Wouldn't its gravity do the same thing?


If gravitational effect propagates at the same speed, then yes. If not, then it's more like lightning vs thunder. Just because you get an image of lightning at light speed does not prove that all information about the event should reach you at the same speed.



On 2002-09-18 12:53, RadioMike also wrote:
In other words, we'd still be in free-fall due to the gravitational force still being felt, even if the body was gone.


Yes. If the propagation is at light speed, then the Earth would continue orbiting the sun until the effect reached it. When the effect reached the Earth, the sun's tidal effect would vanish from one end of the Earth to the other at the speed of light.

When the tidal effect is gone, all of the potential energy from the tidal effect would transform into kinetic energy. I don't know how much. Would we feel the ground suddenly lurch? Perhaps the world would quickly become too hot to handle?

If gravitational effect is instantaneous, then the loss of tidal effect would occur while the sunlight is still streaming down on us.

I think the Earth would be moving too fast to be captured by Jupiter, but we could enter a collision course or close flyby if conditions were just right.



On 2002-09-18 12:53, RadioMike also wrote:
If an Astronaut in communication with the Earth while in orbit around Saturn suddenly was zapped by...the Vatican, for example - we'd still hear his or her voice 12 or so minutes after, even though the astronaut was...no more. There would be nothing "instantaneous". You can't put the cart before the horse.


Right.

However, if gravitational effect is faster than light, and if we somehow figured out how to transmit information over gravity, then we would stop hearing the astronaut on the gravidio before we saw the explosion in our telescopes.

AgoraBasta
2002-Sep-18, 06:11 PM
On 2002-09-18 14:00, Wiley wrote:
Seriously, I don't understand what you're trying to say. Are you saying that the SEP and gravitational waves can exist together without causing paradoxes?

I say that, in case of radiation, gravity is not equal to acceleration.

RadioMike
2002-Sep-18, 06:16 PM
Great answers folks! Thanks!

Now all I have to do is scratch my head, read some more, and make sense of them /phpBB/images/smiles/icon_smile.gif

Wiley
2002-Sep-18, 06:48 PM
On 2002-09-18 14:11, AgoraBasta wrote:
[quote]
I say that, in case of radiation, gravity is not equal to acceleration.


GR is consistent. There is nothing wrong with having SEP and gravitational radiation. It's like "parallel lines never meet" and "the sum of the angles in a triangle are 180". The latter is a consequence of the former. They are perfectly consistent. You may have issues with the postulate, SEP, but gravity waves are direct result of the postulate. If you accept SEP, you will have to accept gravity waves. And any "paradoxes" are resolvable.

<font size=-1>[ This Message was edited by: Wiley on 2002-09-18 14:50 ]</font>

AgoraBasta
2002-Sep-18, 07:33 PM
Wiley,

The only thing that I would insist on, is that gravitational wave can be distinguished from non-radiative field no matter how small the testing area. Just like periodic EM wave can always be distinguished from Coulomb field. And the reason for that is spin.

<font size=-1>[ This Message was edited by: AgoraBasta on 2002-09-18 15:47 ]</font>

Wiley
2002-Sep-19, 09:11 PM
On 2002-09-18 15:33, AgoraBasta wrote:
The only thing that I would insist on, is that gravitational wave can be distinguished from non-radiative field no matter how small the testing area. Just like periodic EM wave can always be distinguished from Coulomb field. And the reason for that is spin.

<font size=-1>[ This Message was edited by: AgoraBasta on 2002-09-18 15:47 ]</font>


A gravitational wave can be radiating or non-radiating. If you want to distuingish between a radiating field and non-radiating field, that's quite possible. If you want to discrimnate a field in a vanishingly small spatial area, again, quite possible. If you want to do the same in a vanishingly small spacetime area, impossible.

2002-Sep-19, 09:36 PM
<a name="20020919.5C"> page 20020919.5C aka 2.5C
On 2002-09-18 15:33, AgoraBasta wrote: To: C HUb's 5

http://www.badastronomy.com/phpBB/viewtopic.php?topic=2264&forum=1&0#JD2452537.5C

this was only a test,
HAD THIS BEEN AN ACTUAL MESSAGE
it would have an edit line below

AgoraBasta
2002-Sep-19, 09:58 PM
On 2002-09-19 17:11, Wiley wrote:
If you want to do the same in a vanishingly small spacetime area, impossible.

Could you please elaborate a bit? I have a problem visualizing the case... Do you say I can't distinguish spin-1 and spin-2 fields in a point??

Wiley
2002-Sep-23, 09:20 PM
On 2002-09-19 17:58, AgoraBasta wrote:


On 2002-09-19 17:11, Wiley wrote:
If you want to do the same in a vanishingly small spacetime area, impossible.

Could you please elaborate a bit? I have a problem visualizing the case... Do you say I can't distinguish spin-1 and spin-2 fields in a point??


At a point in spacetime, you have no information of the derivatives, either spatial or temporal. Without derivatives, you can't glean information about the source.

AgoraBasta
2002-Sep-23, 09:26 PM
On 2002-09-23 17:20, Wiley wrote:
At a point in spacetime, you have no information of the derivatives, either spatial or temporal. Without derivatives, you can't glean information about the source.

Without derivatives, the idea of "physical laws" loses any sense, and SEP becomes a tautology.

Wiley
2002-Sep-23, 10:26 PM
On 2002-09-23 17:26, AgoraBasta wrote:


On 2002-09-23 17:20, Wiley wrote:
At a point in spacetime, you have no information of the derivatives, either spatial or temporal. Without derivatives, you can't glean information about the source.

Without derivatives, the idea of "physical laws" loses any sense, and SEP becomes a tautology.


What you have written is meaningless and misses the point. The point is the smaller area of spacetime you have, the more difficult it is to obtain information about the derivatives of the field. At a point, no matter how good your measurement technique is, you won't be able to obtain any information about the derivates of the field. And without this information, you can't say anything about the source of the field. If you recall, you wrote


The only thing that I would insist on, is that gravitational wave can be distinguished from non-radiative field no matter how small the testing area.

I am saying if by area you mean spacetime area, then what you have written is incorrect.

AgoraBasta
2002-Sep-23, 10:49 PM
On 2002-09-23 18:26, Wiley wrote:
I am saying if by area you mean spacetime area, then what you have written is incorrect.

What I say is that you can't use such reasoning in a classical theory. "Free fall" in spin-2 radiative field can't reduce the effects of spin.

Wiley
2002-Sep-23, 11:35 PM
On 2002-09-23 18:49, AgoraBasta wrote:


On 2002-09-23 18:26, Wiley wrote:
I am saying if by area you mean spacetime area, then what you have written is incorrect.

What I say is that you can't use such reasoning in a classical theory.

Sure, you can. I just did. /phpBB/images/smiles/icon_smile.gif Oh, and string theory is a quantum theory, not a classical theory. GR and electromagnetics are classical theories.


"Free fall" in spin-2 radiative field can't reduce the effects of spin.

I am not sufficiently knowledgable on string theory to comment. But I can say the same fundamental measurement limit exists. As spacetime becomes a point, you lose ability to discriminate your tensor field. You won't know your contravariant from your covariant.

SAMU
2002-Sep-24, 04:19 AM
Say you mounted a sensitive spring type weight scale (accelerometer) on a tower 1/4 of a light second high attached to a small asteroid with 1/100th g gravitatinal attraction on the scale. You then fire rockets on the asteroid so it accelerates away from the scale at 1/100th g. Of course you have telemetry on both the asteroid and the scale transmitted to a point equidistant to both. If gravity is instantanious the scale should register an instantanious zero g. condition at the moment the mass is accelerated away. That is the scale would accelerate along with the asteroid at 1/100th g so the scale would register 0 acceleration. If gravity is less than infinite then there should be a delay between the time the mass accelerates and the accelerometer registers the 0g condition. Obviously that sort of experiment, although expensive, would yield certain results. Although expensive the equipment is crude. Some more sensitively refined equipment should be possible to be devised to achieve the same experimental contitions at lower cost? For example were the accelerometer sensitive to 1/1,000,000th g the mass could be smaller and need less thrust to accelerate and if the time measureing device between the mass and the accelerometer measure very small variences in signal then the tower can be shorter also. Should an array of towers and accelerometers with varying distances and angles from the mass be created shouldn't this produce an outline of the shape of the gravitational wave if in wave form?

I point out what may be interesting, as the mass accelerates and the accelerometer accelerates the accelerometer gains kinetic energy. This kinetic energy is applied to the mass by the rockets and transmitted to the accelerometer not by electromagnetic means but by gravitation.

There are some paradoxes that arise with regard to either infinite or non infinite gravitational effects according to the above illustration but I have yet to describe them in a suitable form. But I have posted the above to allow some of the nimble minds here to play with it.

traztx
2002-Sep-24, 04:45 PM
On 2002-09-24 00:19, SAMU wrote:
If gravity is instantanious the scale should register an instantanious zero g. condition at the moment the mass is accelerated away.


Interesting idea, but wouldn't the tower itself mess up the results? I think it would begin to lengthen the moment the base falls away, since there is no longer a load compressing it.



On 2002-09-24 00:19, SAMU also wrote:
Some more sensitively refined equipment should be possible to be devised to achieve the same experimental contitions at lower cost?


I think the method of measuring the g-lensing from Jupiter as it passes stars is a lot cheaper, and the telescope you measure it with can be used for lots of other science.

SAMU
2002-Sep-24, 11:22 PM
traztx
Quote:
"Interesting idea, but wouldn't the tower itself mess up the results? I think it would begin to lengthen the moment the base falls away, since there is no longer a load compressing it."

As a practical matter you are correct. The tower would lengthen. However the least amount of compression is at the top where the accelerometer is and the greatest amount of compression is at the base on the asteroid. The decompression you mention can only propogate up the tower at the speed of light. But if gravity is infinite then the accelerometer (and the entire tower)should begin accelerating at asteroid g in the same direction as the asteroid as a unit and register the reduction of g to 0 due to the accelerating asteroid instantly.

SAMU
2002-Sep-25, 05:45 AM
Lets say we have an object in orbit around a small mass. The object orbits in a circular orbit until the mass accelerates away from the object. The orbital path of the object must then change from circular. If the speed of gravity is infinite then the path must change instantly. If not the path changes later in the circle. Since any part of a circle can be expressed as an angle the two paths are at angles to each other. By a simple calculation the path expected from either situation can be calculated and the observed path will give the speed of gravity.

AgoraBasta
2002-Sep-26, 08:32 PM
On 2002-09-25 01:45, SAMU wrote:
By a simple calculation the path expected from either situation can be calculated and the observed path will give the speed of gravity.

That's not so simple, because the field of the greater (near-static) body is already there where you push the much smaller one. Thus the effect, if any, is delivered by the gravitational field of the smaller object further relayed back by the reaction of the greater mass, i.e. possible non-instantaneous part of reaction is smaller, by a factor of M^2/m^2, than the full near-instantaneous reaction.

<font size=-1>[ This Message was edited by: AgoraBasta on 2002-09-26 18:17 ]</font>

badactor
2002-Sep-26, 10:08 PM
Can the gravitational effects of a coronal mass ejection be measured? If so, compare the time of arrival of a CME event spectrally and gravitionally.

AgoraBasta
2002-Sep-26, 10:27 PM
On 2002-09-26 18:08, badactor wrote:
Can the gravitational effects of a coronal mass ejection be measured? If so, compare the time of arrival of a CME event spectrally and gravitionally.

I don't know if such attempts were ever made. Yet there's enough evidence of very suspicious correlation between sun's magnetic activity and interactions of small masses in laboratories on Earth. The magnetic activity is associated with the spots on the sun. I'm afraid, those two different effects will overlap in experimental data.

SAMU
2002-Sep-26, 10:59 PM
AgoraBasta,

You eroniously rewrote the illustration I gave.

Quote:
"the field of the greater (near-static) body is already there where you push the much smaller one."

My illustration does not apply any "push" to the smaller object. The push is to the larger mass.

While the small object's path is a circle in space centered on the center of the larger mass, it cannot continue in the same circle if the center of the larger mass is no longer there because that circlular path is caused by the gravitational effect of the larger mass. When the gravitational effect of the change of position of the center of mass of the larger mass reaches the smaller mass the path must change.

AgoraBasta
2002-Sep-26, 11:33 PM
On 2002-09-26 18:59, SAMU wrote:
You eroniously rewrote the illustration I gave.

Sorry, that was unintentional.
Well, it seems to me, you're quite right. Your scheme must work out quite easily. It might even be possible to detect the effect watching debris orbiting the space station while vibrating a large enough mass nearby.

SAMU
2002-Sep-27, 02:38 AM
That might work. Possibly monitoring the change of orbiting debris as they relate to the acceleration of the space shuttle as it departs the vicinity of the space station. Though I suspect that the masses are too small to and too near the planetary magnetic fields of the Earth to have a stable enough path to discern a difference between a mass caused change in path or a magnetosphereicly caused change to the tolerence required. Deep space at least 20,000,000 miles from a small planet like the earth would probably work. And I suspect that beyond the orbit of Mars would be needed to sufficiently minimize the effect of the Sun. In fact just around the asteroid belt might be the break off point. Might be one of the reasons that the Asteroid belt formed there. That is that the sort of stable microgravity systems required for the experiment free from the magnetic perturbations of the Sun are also what causes the belt (and the outer planet's rings for that matter) to be stable there.



<font size=-1>[ This Message was edited by: SAMU on 2002-09-26 23:00 ]</font>

badactor
2002-Sep-27, 02:23 PM
"I don't know if such attempts were ever made. Yet there's enough evidence of very suspicious correlation between sun's magnetic activity and interactions of small masses in laboratories on Earth. The magnetic activity is associated with the spots on the sun. I'm afraid, those two different effects will overlap in experimental data."

Electromagnetic effects travel at the speed of light. Even if the gravity measuring device is sensitive to electromagnetic effects, you should still be able to get some useful info out of it. For instance, if gravity waves travel faster than c, you would get two pulses(one of which arrives before you "see" the CME). If the gravity waves travel at the speed of light, there would be one pulse.

AgoraBasta
2002-Sep-27, 02:33 PM
On 2002-09-27 10:23, badactor wrote:
For instance, if gravity waves travel faster than c, you would get two pulses(one of which arrives before you "see" the CME).

Chances are, there's always a succession of "pulses"... Too much noise. And you never know where's the start of CME, since the process is most likely to start inside before erupting.

2002-Sep-27, 03:04 PM
486 disclaimer
On 2002-09-27 10:33, AgoraBasta wrote: To: HUb'


On 2002-09-27 10:23, badactor wrote:
For instance, if gravity waves travel faster than c, you would get two pulses(one of which arrives before you "see" the CME).

Chances are, there's always a succession of "pulses"... Too much noise. And you never know where's the start of CME, since the process is most likely to start inside before erupting.
HUb'says? From my experiences (Whatching Gramps pour coffee staight up, riding a GW, and sea stories}
its my guess also ther must be a precursor to arouse human awareness
in those who are aware of such things.. ANYWAY my methode for detecting the speed of gravity would be to establish an alias log on called GRAVITY with a pass word called GRAITY also SO THAT ANYONE COULD log in as GRAVITY and change any prior GRAVITY entry? Comprenda?

AgoraBasta
2002-Sep-28, 10:40 AM
HUb',

Your method guarantees a prompt lockup /phpBB/images/smiles/icon_smile.gif

2002-Sep-28, 11:54 AM
On 2002-09-28 06:40, AgoraBasta wrote: To: 4:45 A.M. PST
HUb', :: yeahhhhh mmmm Maybe next month?

Your method guarantees a prompt lockup /phpBB/images/smiles/icon_smile.gif

now back to astrON0my see clock #3 of 5 clocks
libk here later?

2002-Sep-29, 09:49 AM
<a name="20020929.2:34"> POST 20020929.2:34 aka
On 2002-09-28 07:54, HUb' wrote: To: 20020929
.1 links are more likely to come from 386/20
2: one reson Snipper2 does not work here
3? any HELP in how to pluck text with a 486 ?

Your method guarantees a prompt lockup /phpBB/images/smiles/icon_smile.gif
A. And maybe not? clearly You do sound Athorative
B: But consider WHAT might be the result of coLABeration
c: cant remember the Question {just a minute}
oh yeah the rate of travel I found was [DISTANCE2SUN]/(50EarthHours)? I think it was in terms of Miles per second

2002-Sep-29, 09:50 AM
<a name="20020929.2:34"> POST 20020929.2:34 aka No Link ?
On 2002-09-28 07:54, HUb' wrote: To: 20020929
.1 links are more likely to come from 386/20
2: one reson Snipper2 does not work here
3? any HELP in how to pluck text with a 486 ?

Your method guarantees a prompt lockup /phpBB/images/smiles/icon_smile.gif
A. And maybe not? clearly You do sound Athorative
B: But consider WHAT might be the result of coLABeration
c: cant remember the Question {just a minute}
oh yeah the rate of travel I found was [DISTANCE2SUN]/(50EarthHours)? I think it was in terms of Miles per second

2002-Sep-29, 10:26 AM
<a name="20020929.3:10"> POST 20020929.3:10 aka GENERAL gw
On 2002-09-29 05:50, HUb' wrote: To? HUb' 3:11 A.M. PDT
.1 having just returned from GENERAl
{yes its that dull} this point1 Could it be
that in Clock3[D3} the fastest EM_wave catchable = C
and any EM_wave going fasters just to fast to catch?
[JUST A THOUGHT] now back to Gravity_waves
when exchange of energy (ergs) from clock3{D3}
to clock4[D2} I "think" theres plenty of time
for the transport to occure and theres just no hurry..
SO "when the Moon" {UM c flat minor please}
"in your eyes" {G7th} "passes the stars in the skys" {Sharp F}
does there arise (well neber mind gravity) Back to TV
Yeah it Ken Burn & the C.War just over Maybe 3:20 A.M. PDT