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caleb
03-05-2008, 02:30 PM
what do you think, im in a rush to crusty demons so il have to explain later.

Lee
03-05-2008, 03:44 PM
Gravity is a force between two masses ie you and the earth, so doesn't have a speed.

skwinty
03-05-2008, 04:55 PM
The force of gravity does not exist. This force was a newtonian construct to explain why apples fall from trees to the ground and why we don't fall of the earth.
The earth is in freefall around the sun (due to the curvature of space time caused by the suns mass) and bodies in free fall feel no "gravity". As far as the earth is concerned it is travelling in a straight line in curved space time.
ie the shortest distance between 2 points which is a straight line.
We dont fall off the earth due to the inertia and acceleration of the earth.
:thumbsup:

Jazza
03-05-2008, 05:06 PM
The effects due to gravity are however felt in such a way as if 'gravitons' moved at the speed of light.
i.e. binary pulsars are used as tests of gen relativity and show that the effect of one pulsar on the other is due to where it was before, not where it is now...

If that made any sense at all... *sigh*

renormalised
03-05-2008, 05:24 PM
Pretty good answer, Steve, but not quite correct. For every day situations, such as an apple falling from a tree, tripping over a crack in the pavement etc, gravity can still be called a force (although, technically, it still isn't....if you like to be pedantic about it:)). However, gravity is really no more than a curvature of the local spacetime field caused by a massive object, Caleb. As Steve said, the Earth and everything else in the Solar System, is in free fall about the Sun and is traveling along straight lines in curved space caused by the Sun's mass.

The reason why we don't feel the Earth's motion about the Sun, or fall off the Earth is due to the fact we're a part of the inertial system which is the Earth and its gravitational well. Really, we're far to small to notice as for all intents and purposes, everything on the planet is just the one object in the system.

However, if you were to produce some sort of rippling effect in the curved space around the Sun (or the Earth, for that matter), you would be generating a gravitational wave, and this wave would travel at the speed of light....it's characteristics are the same as for a light wave except the propagating agent in this case is a graviton and not a photon.

TrevorW
03-05-2008, 07:19 PM
32 feet/sec squared

300,000 kilometers a second

No contest light wins

Entropy
03-05-2008, 07:47 PM
If the speed at which gravity propagates was greater than c. Could this ever be confirmed by experiment anyway?

Wouldn't it be only if the speed of the propagation of gravity was equal to or less than c could we accurately measure it ?

AndrewJ
03-05-2008, 07:51 PM
Nup
It would be finished before you started it.
That would be horribly confusing

Andrew

Ian Robinson
03-05-2008, 08:24 PM
You are assuming that time actually behaves the way Einstein though it might if particles exceeded c. It may not.

Maybe this will be of interest : re superluminary velocity of gravitational effect. http://www.metaresearch.org/cosmology/speed_of_gravity.asp where the Speed of Gravity is ³ 2x10power10 c (ie 20 billion x c) , for all intents and human purposes , that makes the speed of gravity essentially infinite. See Physics Letters A 250:1-11 (1998).


If this true , that's an extraordinary property.

Sorry if the maths is a bit heavy , requiring at least a knowledge of vector calculus and electromagnetism and relativity (2nd and 3rd year uni undergraduate level studies), but well, the proof is in the physics and maths involved in the meta-analysis.

caleb
03-05-2008, 08:41 PM
yes, but i mean. If the sun spontanoiusly dissapeared it would be 8 minutes till we noticed the light source gone. But would the gravity dissapear straight away or 8 minutes after, as the light went.

renormalised
03-05-2008, 08:49 PM
8 minutes later, same as the light...if you follow current understanding in physics.

Ian Robinson
03-05-2008, 08:58 PM
According to the paper below - if the sun disappeared , the earth would "feel" the effect virtually instanteously - there is no delay in the action at a distance of gravity , even if it would take another 8 minutes for us on earth to be aware the sun is not there anymore.:scared:

renormalised
03-05-2008, 10:22 PM
Just had a look at the article, but I haven't read it properly yet. Very interesting and since it's come under the imprimatur of a trusted journal, it means that it holds some veracity....regardless of what pure relativists might think.

acropolite
03-05-2008, 10:24 PM
Sorry Trev, that's simply the acceleration of a body falling within the earths gravitational field.

renormalised
03-05-2008, 10:27 PM
Doesn't work like that.....one is just the gravitational acceleration of an object falling through Earth's spacetime curvature, the other is the velocity of a photon in a vacuum.

What Caleb wanted to know is how fast does gravity propagate at, and is it at the same velocity as light.

renormalised
03-05-2008, 10:36 PM
Which is the really interesting part:)

Sort of throws current thinking into a spin:P

Ian Robinson
04-05-2008, 01:18 AM
It is interesting .

skwinty
04-05-2008, 02:35 AM
Originally Posted by skwinty
The force of gravity does not exist. This force was a newtonian construct to explain why apples fall from trees to the ground and why we don't fall of the earth.
The earth is in freefall around the sun (due to the curvature of space time caused by the suns mass) and bodies in free fall feel no "gravity". As far as the earth is concerned it is travelling in a straight line in curved space time.
ie the shortest distance between 2 points which is a straight line.
We dont fall off the earth due to the inertia and acceleration of the earth.

Originally Posted by renormalised
Pretty good answer, Steve, but not quite correct. For every day situations, such as an apple falling from a tree, tripping over a crack in the pavement etc, gravity can still be called a force (although, technically, it still isn't....if you like to be pedantic about it).

Help me out here renorm.
What part of my statement is incorrect?

My understanding is that Einsteins principle of equivalence states that gravity is equivalent to acceleration.

This implies that we do not realise or feel the earths acceleration as it wends its way around the sun and hence had to invent a fictitious force of gravity to explain the fact of apples falling from trees and rivers flowing downhill.

We choose to ignore the truth that our surrounds are moving relative to us.
Once set in motion, as in a car at a constant speed, our bodies inertia tends to keep us travelling in a straight line at a constant speed until the car turns. If we are not restrained in the car we are jammed against the car door. We attribute this to the force of gravity when in effect it the effect of inertia, or the cars acceleration in a different direction.

Gravity is more of a geometry rather than a force, and the speed of gravity would refer to the speed of the geometries propogation. Herein is the function of the hypothetical "graviton".
Mass tells spacetime how to warp and warped spacetime tells mass how to move and this becomes recursive ad infinitum. This is the origin of gravity, in my understanding.

Now, I suppose this is pedantic semantics but I find that in my attempts at understanding these principles, clarity is impeded by incorrect terms being applied to the fundamentals.

ie is "force" rather than for example "field" the correct word to describe gravitational effects.

renormalised
04-05-2008, 08:30 AM
I suppose it's all pedantic semantics, when you boil it down. I even said that technically, gravity's "force" on the Earth's surface is just a result of the geometry of warped spacetime (well, not in so many words). It may have been the way you worded your original that confused me. However, the main reason why we don't fall off the Earth is that the gravitational field we find ourselves in is much steeper than the one the Earth is in orbit about the Sun. We're sitting near the bottom of ours in a fairly warped spacetime so we feel the effects more so than what we would out in space between the Sun and Earth. It essentially renders us part of the Earth itself, so any change of inertia the Earth might feel in a change of its orbit wouldn't be passed onto us. We'd just "go with the flow".

Essentially we're too small to matter.

Unless, of course, it was a sudden and violent move....like Earth running into a brick wall (built by a Vogon construction fleet, of course:D:P), or some giant goober space entity used us as a golf ball:D.

csb
05-05-2008, 12:34 PM
Skwinty, sorry but I am going to tear your 'assumptions' to bits..in a friendly manner with no malice intended. For you are completely wrong in your whole statement. This is High school stuff.

I haven't backed my answers up but some basic reading will show my understanding is more correct.

What!? How do you come to that conclusion?
Gravity does exist.



The Earth is held to the Sun by gravity. It would actually fall into the Sun except it is moving fast enough to counteract the gravitational pull of the Sun and demonstrates Centrifugal Force.



I'm not sure but I think the curvature is caused by the gravitational force which comes from the Sun's mass.


No, actually Earth is trying to travel in a straight line but due to the effects of inertia(which says Earth should continue in a straight line and not veer away) and the Sun's gravity(which stops Earth from moving further away), Earth travels in a circular pattern - demonstrating Centrifugal Force.


We don't fall off the Earth due to gravity.

bindibadgi
05-05-2008, 12:49 PM
It was high school stuff until Einstein came along. It's not so simple any more, and skwinty hasn't actually got it wrong. It causes many headaches!

Back to the discussion though, if we think in terms of information, we have a problem with the effects of gravity being felt instantaneously. If a huge galaxy suddenly swung by our neighbourhood, and we felt the effect before we could see it, then we have information travelling faster than light. I don't think Einstein would be pleased!

renormalised
05-05-2008, 01:09 PM
Always someone has to spoil the party:P:D

No, all it just means is that the information that's being carried by the gravitational field has arrived earlier than the information brought by its light. One just happens to be faster than the other. It just means that Einstein was "wrong" in thinking that light was the cosmic "speed limit", in so far as any information that was being sent to an observer. He is correct for visual information (light) but not for gravitational information, in this particular case (given the new interpretation in the paper mentioned).

In actual fact, neither condition is in violation of SR or GR, if you don't accept that light is the fastest carrier of information. In both their respective instances, neither light nor gravity can travel at infinite velocity in spacetime. That would be breaking SR and GR. What's being proposed is a modification and extension of SR and GR. People assume that both those theories at present are complete. They're not. Einstein himself never considered them as such.

To prove if this was correct or not, you could setup an experiment or make an observation of something where this process might be happening.

edwardsdj
05-05-2008, 01:15 PM
In Newton's theory, gravity is a force that acts at a distance between massive bodies. The propagation of this force is instantaneous. Newton was deeply troubled by the fact that he could offer no explanation for the mechanism of action of this force.

Einstein developed a field theory of gravity (much like Maxwells field theory of electromagnetics). In Einstein's theory (General Relativity) matter causes the space-time to warp and it is this warping of the space-time that causes bodies in free-fall to exhibit a curved motion through the space-time. Einstein thus proposed a mechanism for the action of the gravitational force over distance.

In General Relativity, gravity propagates at the speed of light. In much the same way that Maxwell realised that electric and magnetic fields propagate at the speed of light forty years earlier.

edwardsdj
05-05-2008, 01:22 PM
From these statements and those in another thread lately, I feel you would benefit greatly from the study of any first-year physics textbook before generating misinformation and confusion.

Experiments have been done to confirm the prediction of General Relativity that gravity propagates at the speed of light. The experiment involved the study of a distant quasar being gravitationally lensed by Jupiter. The speed of gravity was found to be 1.06 times the speed of light (as I recall) which confirmed General Relativity to within the experimental error.

Gerald Sargent
05-05-2008, 01:54 PM
As a professional geologist/geophysist I see things on a time scale a
bit longer than physics has been around. I do not dispute any of the
experiments that have been done on the speed of light from planet
earth. However as everything is related to fundamental "measuring
sticks" , the so called speed of light being the basic measuring stick
of most of our measures. If however this changes as one passes into
outer space a lot of measure become questionable.
A german pysicist ahs demonstrated a "speed of light" of several
times the accepted speed in passing information through a brass
slug. I gather that he has the greatest difficulty in getting his work
published past the "establishment"
I accept that the accepted speed of light here is approximately
correct, it does however vary in the 4th significant figure as I learned
the hard way some years ago when doing the position fixing for landing
an oil pipeline from the Leman Bank (off East Anglia, UK) when we
pulled the pipe 1/2 miles ashore from the intended position. Research
revealed that this was due to the varying gross electrical resistivy of
the substrate and we actually made charts to enable these errors
to be allowed for in subsequent work.
However back in geologic time that speed may have vaired by a
quite significant amount - I am sure that it, and the value of the
gravitations constant also, varied quite a lot, my twopennyworth
- Gerald.

renormalised
05-05-2008, 02:55 PM
Excuse me....you have no idea what I know or don't know, so before you go casting aspersions upon me (or anyone else for that matter), think carefully about what you say. You might find yourself neck deep in the proverbial.

I'm fully aware of what SR and GR say, and the postulates of both theories. For a start, if I didn't understand them, I wouldn't be doing a masters degree in science (Astronomy and Astrophysics) and averaging 93% in my assessed work. If you read what I have said, instead of going on about the veracity of Einstein, you'd have seen that I prefaced my statements with "if such and such)". There are other interpretations of the observations in the physics journals and whilst they don't always agree completely with the orthodox interpretation, they don't throw the baby out with the bathwater.

If you actually read what I have written before you go interpreting what I have said, you'll see (in this case) that I said "if" something or rather, knowing that experimental evidence needs to be found before something can be declared proven or not. I never said that it was proven that gravity moves faster than light, just that "if" it does, then this or that would happen. But don't think that some scientist haven't questioned Einstein more critically than most would otherwise. Just because experimental evidence appears to confirm his assertions so far, doesn't mean that sometime in the future he will not be proven incorrect. The problem with myopically believing in something is you miss things which may show you that reality could very well be otherwise. Or if you do see them, you just dismiss them out of hand. It happens all too much in science.

In so far as that "other thread" is concerned, I am quite correct in my assertions. Any theory which predicts infinities in its equations is in serious trouble....when it approaches those limits where the infinities appear. That's why renormalisation exists...especially for quantum theories. Infinities are inelegant and theoretical physicists hate inelegant theories. Anything which negates the embarrassment of having infinite values appearing within their equations is seen as a blessing. Infinities generate problems which are extremely hard, if not almost impossible, to deal with.

In so far as your quoted experiment, I find it rather disconcerting that a value of 1.06c was seen as being within experimental error, considering that a 6% error is seen as acceptable when nearly all other experiments in SR/GR have been verified to within 1 part in 10^20 or better as far as error is concerned. I would question their methods and experimental assumptions.

CoombellKid
05-05-2008, 02:56 PM
Gee... dont tell any sky divers

NEWS Flash!!!!
Sky diver made 16km wide crater after his chute failed.

regards,CS

renormalised
05-05-2008, 02:58 PM
Hello, Gerald....from a fellow geologist:)

I feel for those scientist that can't get their papers past the "establishment". It just goes to show you that no matter how rigorous and scientifically sound your paper might be, if you don't agree with the status quo, you might as well go play in the mud. There's so much politics and academic hubris within the scientific community, especially in physics and such, that it's a wonder any progress is made. They deny it, but they're just as myopic and one eyed as priests in any religion.

As a matter of fact, you could say that science has become the new religion.

renormalised
05-05-2008, 03:19 PM
It doesn't....it's just the effect of accelerated motion along a circular path, w.r.t. the mass of an object.

edwardsdj
05-05-2008, 03:23 PM
In another thread you started describing the second law of thermodynamics as the third law.

You then went on to state that the absolute zero temperature state was a state of maximum entropy. The third law of thermodynamics states that absolute zero is the state of zero entropy.

As I say, the chapter or section titled "Thermodynamics" in any first year physics textbook will make all of this clear.

Hope this is of some help :)

Have fun,
Doug

Ian Robinson
05-05-2008, 03:28 PM
Hi Gerald, do you have a link for that (experiment) ?

For the value of c to be variable in a vacuum over cosmological and geological time scales , this requires e0 and mu0 and other fundamental properties to be variable.
It probably also means that everything we know about deep space (and the universial constant is wrong , ie it varies) and perhaps the age of the oldest galaxies is not right.
Interesting hypotheses. These kinds of questions are the spice of life .

PS : (while we are mentioning credentials , not a geologist , I'm but a humble chemical engineer who has recently studied physics and computer engineering , and am now , for want of something better to do , doing a masters degree). :)

renormalised
05-05-2008, 03:41 PM
I made a couple of silly mistakes, so what. Anyone else could. Plus it's been 20 years or so since I did undergrad physics....I'm entitled to make a few faux pas. I remember actually having thanked you for correcting me at the time, but in this particular instance, your repeating of my mistake in order to make a point about my apparent lack of knowledge is the height of arrogance and crassness.

renormalised
05-05-2008, 03:47 PM
Ian, this is something that cosmologist are seriously considering. There's evidence that the fine structure constant, G and a few others are variable and may have been different in the past. I can't remember off hand the actual articles, but they wouldn't be too hard to find if you like to search for them.

(YUUMMM...jelly trifle......way off topic, but I'm tucking into a trifle whilst I type this out:D:D:D)

Paddy
05-05-2008, 03:56 PM
Interesting thread which raises quite a few questions that I've been pondering over. I do hope that all of you learned gentlemen continue to discuss the issue with respect for differences.

Ian Robinson
05-05-2008, 03:56 PM
I think I may have seen them in my travels .... like I said .... they are interesting questions .

If I remember correctly , there is no evidence that the fundamental constants and fundament properties have varied measureably in recent time (which geological time scales (only a few billion years) would be cf cosmological time scale to 14 billion years, in the Dark Ages say where cosmologists are not sure).

renormalised
05-05-2008, 04:00 PM
Very interesting questions, indeed.

From what I can remember, I don't think there's been a measurable change in the constants for the last few billion years...so far as I know. I'll have to catch up with the latest papers and see what they say.

Ian Robinson
05-05-2008, 04:04 PM
I can top that .... got a roast leg of lamb (with garlic and herb rubbing) cooking in the oven) and it smells wonderful. :drool:

renormalised
05-05-2008, 04:15 PM
I defer to your greater culinary droolness:P:D

skwinty
05-05-2008, 04:18 PM
Please glue my assumptions back together again and read them properly this time.:thumbsup:

Jen
05-05-2008, 04:57 PM
:shrug:
:stupid:
:D

skwinty
05-05-2008, 08:21 PM
Here's a thought.
Lets assume that gravity is a geometry, and the carrier of this information is the graviton.
Now liken this geometry to a ruler. When you move the ruler, every point of the ruler will see the move instantaneously unlike a photon which would have to travel the moved distance.

Now, current thinking implies that empty space is not empty but full of dark energy, so perhaps the graviton is part of this dark energy and this dark energy forms the gravitational geometry.

Just a thought, use it or lose it;)

Paddy
05-05-2008, 08:41 PM
Now here I will reveal my naivety. I'm not convinced about gravitons to carry this information, but then I don't know much and might be presumptuous in thinking my naivety might help to avoid a trap. I've just been reading Stephen Hawkings' "a briefer history of time". In his chapter on the unification of physics, he says "if "empty space were really completely empty - that would mean that all the fields such as gravitational and electromagnetic would have to be exactly zero.However the value of a field and its rate of change with time are like the position and velocity of a particle: the uncertainty principle implies that the more accurately one knows these quantities the less accurately one can know the other. So if a field in empty space were fixed at exactly zero then it would have both a precise value and a precise rate of change, in violation of that principle"

He seems to argue that in order to satisfy the uncertainty principle, gravity must be a quantum phenomenon and a quantum theory of gravity is necessary. But if it's not a quantum phenomenon, would it have to satisfy the principle? Is his logic saying that a principle of quantum physics must apply to gravity as an axiom? Maybe gravity is something fundamentally different.

skwinty
05-05-2008, 08:52 PM
Current thinking is that even macroscopic "reality" is a quantum phenomena.
Also note that Stephen Hawking says "if" space is really empty.
I dont believe that it is, but then thats only my belief. :thumbsup:

renormalised
05-05-2008, 09:50 PM
Given the uncertainty principle, spacetime can't be completely empty. No matter if you try to remove all the energy and matter from the system, the fact that you can never know whether you've removed everything means that some energy residual still exists in the fabric of space. It's essentially what they call the residual field, or zero point energy, of spacetime.

You can readily observe it in the Casimir Effect.

renormalised
05-05-2008, 10:05 PM
You know, Einstein would be upset if he knew this, but there is two things which definitely travel faster than lightspeed....unequivocally.

1. bad news in the media, and
2. Politicians going back on their promises


:D:D:D

edwardsdj
06-05-2008, 01:24 AM
Sorry to have been a bit harsh before. The rise of pseudo-science these days causes me so much concern I find it hard not to speak out sometimes.



The reason we don't feel the gravitational field of the Sun is that the Earth is in free-fall around the Sun. Us inhabitants of the surface of the Earth are not in free-fall around the Earth so we experience the gravitational field of the Earth from our reference frame on the surface of the Earth.

When you go into free-fall (like jumping off a cliff or sitting in an orbiting space shuttle) you cease to feel the gravitational field of the Earth either.

The gravity well of the Sun is actually much stronger than that of the Earth. From a reference frame in free-fall, you just don't feel any gravitational field at all. This was Einstein's great insight (priciple of equivalence).

renormalised
06-05-2008, 08:35 AM
That's true, the reason why we feel it here on Earth is because we're living inside Earth's gravitational well. We feel an acceleration towards the Earth's centre as the "pull" of gravity. The Sun, being so far away, has minimal effect (although tell astrologers that:P)

I wouldn't exactly call jumping off a cliff as being in free fall!!!! The result at the end is never free:P:)

That's a given, greater mass = much larger curvature of space.

I'm just as concerned about pseudo-science as you are, however I'm more careful about whom I address as being one who talks pseudo-science. Much of particle physics and cosmology these days sounds like pseudo-science but you'd never address someone like Neil Turok as being a crackpot!!!! (even if he looks like the proverbial mad scientist:P).

csb
06-05-2008, 10:21 AM
Skwinty, I did read your assumptions again and still I must take a contradictory position.

But as this thread has progressed, I notice the matters as discussed are either too deep for my high school learnings or just too weird (no offence intended to any participants).

skwinty
06-05-2008, 11:25 AM
Hi Craig,
You are still missing the point by not reading the post correctly.
I said the force of gravity doesnt exist. It is a fictitious force like centrifugal force and the coriolus force.
I did not say that gravity does not exist.
Sure, in high school they teach about the force of gravity, but as I said, this is a mathematical construct to explain the effects of gravity. Now the formulae work and produce the correct answers to explain the effect as our inertial frames experience them.
When you are driving your car and you accelerate wildy down the road, your body and senses tell you that you are being forced into the back of your seat.
There is no "force" pushing you into the seat. Your inertia tries to keep your body the way it is and your car pushes into you as its accelerates. As you start to accelerate with the car the feeling of being "forced" into the seat goes away as you have now reached the sames velocity as the car, unless of course you have a special car which does not stop accelerating.

If your car was travelling at a constant speed, but turning then your car would be accelerating whilst turning and so you feel the effects of the "fictitious" centrifugal force. Once again the car is turning into your inertial path and not another force acting on your body.:google:

bird
06-05-2008, 11:56 AM
If this were true then it gives a means for faster than light communication, violating pretty much all known laws of physics :-)

cheers, Bird

edwardsdj
06-05-2008, 12:21 PM
I don't think you understood my resoponse. We are actually much deeper inside the gravity well of the Sun than that of the Earth. The reason we don't feel the effect of the Sun's gravity is that we live on the surface of the Earth which is in free-fall around the Sun.

This is the same reason that an astronaut on the Space Shuttle doesn't feel the gravitational effects of the Earth even though they are only a couple of hundred kilometers above the surface of the Earth - they are in free-fall around the Earth - in Einsien's language they are in an inertial reference frame.

From our reference frame on the surface of the Earth, we are not in free-fall relative to the Earth. In Einstein's language: we are not in an inertial reference frame. The space-time curvature induced by the mass of the Earth is thus experienced in this frame of reference as an acceleration which we call gravity.

To repeat: the gravity well of the Sun is vastly larger than that of the Earth at our position. We just don't experience it from our frame of reference in free-fall around the Sun. Likewise, the gravity well of the galaxy is vastly larger here than that of the Sun: we just don't experience it from this frame of reference because the whole Solar System is in fee-fall around the centre of the galaxy.



Well the example Einstein used himself was being in an evelator car when the cable breaks. He realised that the occupants would be unable to determine if they were in free-fall or in intergalactic space.

In the same way, if you jump off a cliff, you feel weightless as you are in free-fall (neglecting effects of air resistance obviously). When you hit the ground, you are obviously no longer in free-fall. (Einstien himself only bothered to mention this obvious fact in his little book on relativity for the general public: http://en.wikisource.org/wiki/Relativity:_The_Special_and_General _Theory).

This is the fundamental line of reasoning on which the general theory of relativity is based. Einstein realised this in 1907 but it wasn't until 1915 that he had got his head around the math enough to publish a complete physical theory theory of gravity, electomagnetics and motion - the General Theory of Relativity.



You have this correct.



I have never said that Neil Turok is a crackpot. The Chair of Mathematical Physics at Cambridge University is most certainly not a "pseudo" or "fringe" scientist.

All of the things I have mentioned here (and the laws of termodynamics) were covered in a course called PY101 that I studied in my first year at university about 15 years ago. If you are genuinely concerned about psedo-science, I implore you to get your basic scientific facts straight before confronting the more "cutting-edge" areas of physics.

I assure you I am far from arrogant and I mean no disrespect to you. I do have the greatest respect for the scientific tradition as first described by Descartes and perfected by Newton and will jump to it's defense when provoked.

Take care,
Doug

csb
06-05-2008, 02:23 PM
Aha! I understand now, Steve.

I had realised that centrifugal force is actually an effect - from some reading I did before posting yesterday.

And so the same applies to the force of gravity.

I reread the post and I can see what you mean but I still seem to disagree with a few of your statements.

However this discussion is to esoteric for me (but quite interesting for a casual reader of Scientific American) so I will leave you guys to it.

Thanks again, Steve.

And Caleb, if you're still here, will you please edit & correct the typo in the header - what a shocker!:)

Ian Robinson
06-05-2008, 02:49 PM
Not really violating the laws - see the metaanalysis in the article I provided a link to.

The speed of gravity is not infinite while it is very much greater than c .... that's good - in physics infinities are not desireable .
The effect of gravity still obeys causality.
The models of multiple bodies in motion still work.

astroron
06-05-2008, 02:59 PM
i herd that the speed of gravity was the same as light.

He probably thinks we are all sheep for following this thread:rofl::rofl:
Ron

csb
06-05-2008, 04:41 PM
Well, I know I am, what about ewe:jump2::jump2::jump2::jump:

skwinty
06-05-2008, 04:44 PM
Well, Caleb is a good shepherds name;)

renormalised
06-05-2008, 06:34 PM
Doug, you seem to have a rather somber personality. My comment on the free fall off a cliff was prefaced right at the end of my sentence with a twist on words, yet you took it too literally!!!:) You need to lighten up a bit:)

It was meant to be humorous, in that you pay the price for hitting the ground.

I do understand your response. I did almost exactly the same course (PH101) nearly a decade before you did. Actually I finished uni several years before you started:)

Anyway, there's nothing wrong with what you have said except for this. Even though the Sun's gravitational well is much larger than the Earth's, we are subject to a greater acceleration towards the centre of the Earth than we are to the Sun. Sure, as part of the Earth system, we are in free fall about the Sun and don't feel the Sun's curvature of spacetime, but that's precisely the point. We are much closer to the Earth than we are to the Sun and from our vantage point, the curvature of spacetime the Earth generates is more intense than the Sun's. Hence we don't go floating off into space towards the Sun. It's the same for the Solar System. All the planets and assorted debris are well within the Sun's gravitational well. As such they can be considered as acting as one unit when considered w.r.t the Galaxy. The entire gravitational body is in free fall about the centre of the Galaxy. Despite the Galaxy having a vastly larger and more intense overall well, because we are much closer to the Sun than to everything else, we feel the curvature of space generated by the Sun far more so than we do the Galaxy's spacetime curvature. You hit the matter right on the spot with this statement....

We are not in free fall relative to the Earth. We feel the curvature of spacetime near the Earth as the "force" of gravity. We have no inertial frame of reference w.r.t. the Earth. However, the Earth (along with us and everything on it) is in free fall about the Sun and so there is an inertial frame of reference here. It's the same for the Solar System.... the planets feel the acceleration towards the Sun far more so than the presence of the spacetime curvature generated by the Galaxy. There is no inertial frame of reference for the Sun and planets on this scale, however, everything is in free fall about the Galaxy and therefore in an inertial frame w.r.t. the Galaxy.

It's also the reason why satellites and such don't feel the Earth's gravity. They're in free fall about the centre of the Earth because they're constantly in acceleration about the centre. They have an inertial frame of reference w.r.t. the Earth. They're also in free fall about the Sun at the same time, however, if the satellite fired its thrusters and broke the acceleration, it would fall towards the Earth rather than the Sun because at its distance from the Earth it feels a far greater spacetime curvature, hence gravitational acceleration towards the Earth's centre than it does with the Sun.

Once again, Doug, you too what I said took literally....about Neil Turok. In actual fact, he does look like the typical madscientist. Rather gorky and awkward looking and so he can be stereotyped in this fashion. Nerdy you could say. That's where the "crackpot" moniker comes into it. I agree, he's far from being crackpot, only because we can understand what he's on about, however most people would find him rather "out there".

The problem I see here, Doug, is that we have two completely different people. You seems to be very literal and orthodox in your way of thinking. Very analytical and "step by step" in your train of thought. In contrast, whilst I can think very literally, I can also think and visualise at tangents and sometimes I interpret things differently to you. To put it in another way, the both of us are in orbit about Einstein, but the only thing we have in common is the fact that the light from his torch reaches us at the same velocity, despite our differences:)

Karls48
06-05-2008, 07:02 PM
Ian Robinson has posted very interesting link to the paper that doesn’t go well with currently accepted theories. Why all of you who disagree with it read the article and then explain why it is wrong or right in it instead constantly quoting the BOOK. Regardless how intelligent and innovative Einstein was he was not the God and as anyone he could be wrong in some of his assumptions. I take my hat off to the people like Renormalised and Ian Robinson because they can think for themselves. Forget what you learn in Uni 20 years ago, I have done it 40 years ago and lot of what I learn is not accepted truth today. Actually it is better to forget most of what you learn in any kind of school. The main reason for the education is to teach you how to conform and for some – how to think. If you want know definite answers to everything join one of thousands of religions that are around. Read the BOOK and it will give you all the answer to the mysteries of life and Universe.
How dare anyone to assume that we are even close to understood how the Universe works. Imposing limits on the speed and the information at our stage of civilisation is ridicules. We are just primitives who just few thousand years ago run around hitting each other with simple club The only think that make as progress were wars as we needed to invent better club. Well we still do it( hit each other) when we run out of bullets.
It has been discussed many times before that Scientists are not really free and impartial, they depend on funding and if they come up with some idea that is not in the line with current thinking, they will get none (unless it is of some use for military).
We are all amateurs. There is no economical pressure on us to influence our thinking. So keep questioning current theories when you come upon something that does not make sense in relation to something else.
To me Darwin was much greater scientist then Newton or Einstein as he plotted the path as where we come from, what we are and where are we going (and is a PUB going to be still open when we get there?) .
Again big thumbs up to the people such as Ian Robinson, Renormalised and others who are able to think for themselves.
Don’t get me wrong, is Einstein was right I got no problem with it. Its just there are too many inconsistencies in his theories. And I just don’t believe that we can place finites on anything at our stage of civilisation.

Bassnut
06-05-2008, 07:21 PM
I dont understand the details, but one thing puzzles me.

An outside observor sees infalling matter into a black hole slow down to a stop at the event horison (and its "information" be preserved, smeared over the event horison, as Hawkings has postualted recently). This implies that time, to an outside observor, at the event horison slows to a stop (matter is traveling at C). To the black hole then, the passage of time of the outside universe is instananeous, as it is to a photon. How can a black hole actually grow in mass beyond the event horison then, it hasnt got time to. Is the space inside the event horison empty?. Is all its mass smeared over the event horison?.

skwinty
06-05-2008, 07:35 PM
Hi Karl
For clarity, which book is constantly being quoted?;)

renormalised
06-05-2008, 07:47 PM
That's what I was wondering??

Karls48
06-05-2008, 08:11 PM
Sorry, I was referring GR and SR as it has become holy bible of physics. Any descent and you are excommunicated. It does not matter what kind of argumed someone will come up with. Einstein said that nothing can travel faster then light and that’s it.

skwinty
06-05-2008, 08:27 PM
Hi Fred
For any spinning black hole, there exists an invisible boundary, known as the stationary limit. Within the stationary limit, nothing can escape being dragged around the black hole - unless it can travel faster than light, currently an impossible condition. At the limit itself, a visitor could avoid being dragged around (and remain stationary), providing that he could travel at the speed of light.
Now, if you can't maintain the speed of light, its off to the event horizon and the singularity.:eyepop:

renormalised
06-05-2008, 08:35 PM
And then it's "spaghettified", "crushified" and nullified for you:jawdrop:

Bassnut
06-05-2008, 08:37 PM
Ahh, OK, that makes sense, thanks Steve.

Bassnut
06-05-2008, 08:42 PM
LOL, but how "nullified" ?, is its "information" preserved?.I may have this wrong, but I understand it must be or some fairly important Physics theories fall apart ,or is that covered in "Hawkings radiation") ?.

sjastro
06-05-2008, 08:45 PM
Fred,

A black hole cannot grow beyond the event horizon because the horizon is a function of the mass of the black hole. As the mass of the black hole increases the event horizon will also increase. Conversely as a black hole evaporates the event horizon will shrink.

Because information cannot be retrieved beyond the event horizon what happens beyond that boundary is speculation.

Steven

skwinty
06-05-2008, 08:48 PM
No preservation of information and as you approach infinite gravity and zero volume, all known laws of physics will break down as will space time.
So the current thinking goes.
As for Hawking Radiation the current thinking is about 43% of the mass escapes as radiation, so black hole wins by a large margin, bearing in mind that mass and energy are one and the same thing.
Or so the thinking goes!;)

skwinty
06-05-2008, 08:54 PM
Thanks for clearing that up.
One point to remember however.
Einsteins theories although incomplete, have been thoroughly tested and proven beyond any doubt although they may be replaced by more complete theories in the future. String theory looks like it may be the contender but as yet cannot be tested in any form whatsoever. So until then, Einsteins theories reign supreme.:P:thumbsup:

Bassnut
06-05-2008, 09:12 PM
43%?, that implies black hole remnants last for ever. I read somewhere black holes evaperate altogether in something like 10*250 years?. 43% over what, a period of time?.

And, if information is not preserved, doesnt that stuff causality. I thought if time was reversable, you could recreate any state in the past?.

edwardsdj
06-05-2008, 10:09 PM
I agree with you completely on this part: we are subjecft to a greater acceleration towards the centre of the Earth than we are to the Sun (by about 3 orders of magnitude).

I have never said otherwise. This is why I was careful to refer to "gravity well" and not "gravitational acceleration" or "force".

Escape velocities give a good feel for the size of the gravity wells:

Escape velocity of Earth = 11.2 km/s
Escape velocity of Sun = 618 km/s



This is not the reason we don't fall off the Earth though. As the Earth is in free-fall around the Sun, we don't feel the gravity of the Sun directly. We do feel it's massive curvature of the space-time in our vicintiy through tidal effects.

Take care,
Doug

Ian Robinson
06-05-2008, 10:23 PM
Time required for a blackhole to evaporated is governed by it's mass.

There's an equation for it : see http://library.thinkquest.org/C007571/english/advance/core8.htm

is t = M^3/3K seconds , I'll leave others to plug the numbers in for K and a given mass of blackhole.

dugnsuz
06-05-2008, 10:30 PM
yeee-haaah!!!!!

dugnsuz
06-05-2008, 10:32 PM
oops, sorry - wrong thread!

renormalised
07-05-2008, 12:16 AM
"As Doug yells in wild abandon, his trusty starship dives headlong across the event horizon of the black hole, never to return. Only, Doug gets spat out as a virtual particle.":P:D

Ian Robinson
07-05-2008, 12:21 AM
Only to discover .... he'll never get there Doh !!!

renormalised
07-05-2008, 12:36 AM
Then realises the answer to the question about life, the universe and everything isn't 42..... it's the SQRT(-0/2pi x 10^-22)/v x G.... whatever that is!!!!:P:D

edwardsdj
07-05-2008, 01:13 AM
:lol:

skwinty
07-05-2008, 01:53 AM
Sorry about the delayed answer, i was delayed by the black hole called work.
As i said earlier the radiation emitted by blackholes is about 43% of the in falling matter.
Matter has two varieties matter and antimatter. When these twins meet they annihilate with 100% mass to energy conversion.
Now if matter crosses the event horizon without its twin antimatter, then the antimatter outside the event horizon will not be able to pop out of existence via the annihilation process. It then gets promoted from virtual particle to real particle and this is the essence of the Hawking radiation. The result of this loss of energy is the weakening of the black holes gravitational field as the energy of annihilation cannot occur within the blackhole. This is the 43% deficit. Now obviously as time progresses the gravitational field gets weaker and weaker until eventually the blackhole evaporates. (as the gravitational field gets weaker, less matter falls in so its a compounding problem):P

Or so the thinking goes;)

Jen
07-05-2008, 05:29 PM
:screwy::screwy::screwy:
:stupid:
:D

skwinty
08-05-2008, 09:57 PM
Hi Fred
Here is an article from Scientific American about this issue.
:thumbsup:

Bassnut
08-05-2008, 10:48 PM
Excellent, thank you Steve

xelasnave
16-05-2008, 01:56 PM
What an interesting thread...gravity interests me and I have specific views on the accumulation of truths we hold up as the final word on the subject..but for my investigations I say no one really knows zip and as such I add my thoughts to this thread even though it is now old and expired.
Newton ..the man who discovered gravity:eyepop: notwithstanding his apparent scientific approach to the subject and the extraction of many usable and relevant formulea when pressed for an explanation as to the force of gravity presented his view...the force of gravity is due to God:eyepop: ...most scientific observation prompted by a recognition that the Church was very jealous about taking power away from God....
Is there anyone reading this who is content to accept Newtons idea that gravity is due to the force of God???
So all is well...at the time Newton was working on gravity he was exposed to the "push" concept of gravity..an associate shared this view and Newton was aware..rather than endorse a push force or a force of attraction (horrors) Newton still left grqavity to God... interestingly the Church hunted down the push gravity guy and finished him off..for the reason he lead a band of children ...this was the reason cited by the church for the hunt however I feel it was this chaps determination to attribute gravity to a force other than God that got the church after him....and so who is next on the gravity subject...Dr A of course...and do we get Dr A buying into the force aspect of gravity..no way..Dr A's genius was in the fact that he provided knowledge of gravity that in no way erroded God's power to provive it... So we now ask someone who understands general relativity about gravity and are told there is no force..it is as if the sums make the objects move..force who needs a force..the sums make it work..I feel that view misses a realtiy which should no have to be explained but to those who need explaination can not see that gravity needs a force..the sums are not enough to make gravity work...
Gravity I feel can be expalined as an external pushing force perhaps due to particle pressure... dark energy can only work as an external pushing force and I suspect that gravity is an extention of what we now call dark energy.

However my point is General Relativity certainly describes gravity as not needing a force however such an approach I feel fails to appreciate sums alone do not govern the Universe they can merely interprete matters that are in play...
alex

TrevorW
17-05-2008, 10:37 AM
The speed of light is constant in a vacumn light consists of photons, electromagnetic particles that can either act as as a particle or as a wave depending on the observer. Gravity is a force or wave, the effects of gravity can change depending on the mass of an object and diminish with distance. Gravity is a product of the distortion of time and space caused by the mass of an object.

xelasnave
18-05-2008, 06:57 PM
Thanks Trevor for that:thumbsup:....you said.......

"Gravity is a product of the distortion of time and space caused by the mass of an object."

My statement is that there must be more at work than the sums of general relativity which raises the question in my mind...

"how does mass distort time and space?:shrug:..... there must be a machinery in real terms.. an interaction of particles perhaps?..a communication of "waves" between masses...it is an interesting question ..the very one avoided by Newton and Dr A.;)

Or how does the force of gravity (remembering GR does not speak of a force) get from one place to another...

Neither Newton or DrA speaks of how the force may work:) ...

Gravity must be more than the force of God one could expect.

alex:):):)

skwinty
18-05-2008, 08:25 PM
Gravity is classically characterised by space time geometry as a gravitational field.

General Relativity holds true when the distances involved are greater than the Planck-Wheeler Length. (This is the shortest distance that can be accurately measured).

When distances are shorter than the Planck-Wheeler Length then General Relativity breaks down, hence the search for a quantum gravity theory.

Now, the holy grail of physics is the unification of Gravity, Weak, Strong Nuclear Force and the Electromagnetic Force.

Now, Gravitational Waves or perturbations in the gravitational field is the domain of the graviton. This hypothetical particle has zero rest mass ( I didnt know they non catholic )

Gravitational waves can be detected by 4 methods.

1. Extremely low frequency gravitational waves left their imprint on the microwave cosmic background.

2. Very low frequency gravitational waves influence radio waves propogated by pulsars.

3. Low frequency gravitational waves influence on radio transmissions between earth and interplanetary space craft. This will be replaced in 2012 by LISA or Laser Intereferometer Space Antenna.

4 High frequency gravitational waves measured by earth based detectors ie LIGO or Laser Interferometer Gravity Obsevatories.

Seems as though the Michelson-Morley apparatus has grown up and forgotten about the ether

edwardsdj
18-05-2008, 10:07 PM
Hi Alex,

The first part you raise is the issue. In metric theories of gravity (the class of theories to which the General Theory of Relativity belongs) matter/energy is put in by hand. GR is not a theory of matter. This is what quantum theory is all about.

It is important to understand that in GR space and time do not have an independant existance. It is the "spacetime" that is warped by the presence of matter/energy as per the Einstein equation.

It is the warping of the spacetime that causes bodies (like the Earth) to appear to follow a curved path. All bodies are actually following a straight line in a curved spacetime geometry.

In this way Eisteins theory explains the action of gravity at a distance (unlike Newton's theory). What GR doesn't explain is the mechanism by which matter causes the spacetime to curve. This is what quantum gravity is all about.

The first fairly comprehensive theory of matter that we humans have developed (quantum theory) doesn't include gravitational effects. It is played out in the flat spacetime of special relativity.

Have fun,
Doug

xelasnave
19-05-2008, 07:21 AM
Thanks for the interest fellow travellers:thumbsup:

Steve mentioned......"Now, the holy grail of physics is the unification of Gravity, Weak, Strong Nuclear Force and the Electromagnetic Force."

Steve I think about this all the time... and if you take this in confidence and dont spread it around I can tell you that the push gravity approach that I have subscribed to certainly has the opportunity to do this....:lol::lol::lol:
At one stage Hawking said he received at least one paper a day claiming the grail was contained therein;).


Doug said..........
It is important to understand that in GR space and time do not have an independant existance. It is the "spacetime" that is warped by the presence of matter/energy as per the Einstein equation.

Yes I understand this...... a pythagoras therom with a "fourth" ..side or arm... time....which time "changes" as space bends from an influence of local mass...

What I do not grasp is why mass needs to seek a "straight" path which is in point a line of the least resistence (of space) conecting to the most local "bent" space.... or what is it that tells the Sun to follow its "straight" line to where ever it seems to be headed...

I see a space/time grid as geometry that seeks to describe "space" in a way we can measure and relate our presence within it (space)....why that grid dictates that a section of the grid describing space say near the Sun becomes "small" and as such masses in a part of the grid with bigger squares (less space curve) are bound to move..in a straight line..to the point where space is bent more...is the aspect I miss...what dictates this within the grid or the math??? I get to a point where I can see a grid much like a weather map showing highs and lows (of gravity or intensity of space curvature) but can see no rule that says the high must move to the lower pressure areas....

Dont worry about trying to field my concern I am reasonably happy with all that I can understand of the way current science approaches the matter..

Thanks for all the neat information....

alex:):):)

xelasnave
19-05-2008, 07:41 AM
As to eather..however it is spelt?...
I find it strange that given the regular new findings of various particles..nuetrinos alone could fit the bill of eather...and of course they are not the only candidates...
I feel some science is guided by fashion and I detect the fashion was to get rid of the old Greek thinking... eather was tossed..but the atomists continued..which offers some authority that some of their thinking openned doors to a greater wider truth..
So fashion removes the eather/.. loyalist will point to the Morely experiment.. but how does this answer the nuetrino abundance and stll say ..there is no eather...
I know this is a contentious matter.. but I think its time for fashion to make a move to perhaps idenify space as containing stuff..lots of stuff... billions upon billions of particles..all of which I feel rasonably be grouped to be called "space" (a no longer "empty" medium) or indeed..eather..the group of the billions of particles we now recognise as being there in abundance.
I like the eather because I feel it will provide the particle pressure required by a push gravity approach...

Why do galaxies hold together...dark matter we currently believe... is dark matter or dark energy a candidate for the eather??? but it is clear that dark energy acts as an external pushing force as a galaxy can not be bound simply by internal forces of attraction.. the distances prevent sensible relays of gravity messages...they are limited to the speed of light and thereofre take over one hundred thousand years for actions to be noticed on the other side of the gallaxy....an external force will work an intrnal force will not...or so I believe...
Sorry for the unsolicited rambling:whistle:
alex:):):)

edwardsdj
19-05-2008, 09:31 AM
Hi Alex,

It is important to understand that in GR space and time do not have an independant existance. It is the "spacetime" that is warped by the presence of matter/energy as per the Einstein equation.

What one observer perceives at space, another in a different frame of reference may perceive as time. It is only be considering the spacetime (often written space-time but never space/time - they are not separate in any physically meaningful way) that the physical nature of the situation can be understood.

The notion of time being a "fourth" side or arm is Netwonian theory. I cannot stress enough that it is not the "space" that is warped by matter/energy in GR: it is the "spacetime".

In this way a body in an inertial reference frame (in free-fall like the Earth in orbit around the Sun) moves in a straight path through the spacetime which from the frame of reference of the Sun appears to be an ellipitical path though the space over time (to a good approximation anyway).

I seem to recall first reading something like the "push" concept of gravity in Richard Feynmann's little book "The Character of Physical Law" as effort to show the reader a possible physical explanation of Newtonian gravitation. As I recall, it was a concept he held up as a straw man in order to shoot it down. Unfortuantely I cannot find an online copy of this great little book :(

Take care,
Doug

xelasnave
19-05-2008, 11:51 AM
Thank you Doug.
I have a morosophic attachement to the push concept..in part because when I first thought of the idea I was unaware that it was already a very old concept (1745 is the date attached to LeSage having the idea)... thinking it was my original idea I worked on it for a long time before I realised it was already out there... I focussed upon it because it was the only way I could make gravity work..assuming I was left to build that part of the Universe... but right or wrong trying to engage the subject of gravity has seen me reading all sorts of stuff I never would have bothered with... and with each question answered being replaced with more questions.

Many will not accept the push concept and our mate is not the only man to have argued against it..assuming reasonably that as you say he held it up to tear it down........and I respect the chap particulary for his surprising statement given his profession....

"love nature..hate mathematics.."

For a moment I felt he could be converted but I suspect the statement held deeper meaning ..perhaps that nature was indeed the embodiment of mathematics.

If gravity pushes the space craft that leave our solar system will get "stuck" they will appear to slow, finally stop and then appear to race away at approx 350 kms per second....
I dont think I cut across GR as I can not see that it says gravity pushes or pulls no could it if the underlying aspect of the theory is that there is no force attached to gravity.

So there is a prediction to maybe escalate the idea to a theory;)..

I reckon the Corona of the Sun is due to the out flow of the Sun's energy meeting the inflow of the particle pressure I associate with what makes up gravity...and I feel that is reasonable in principle as certainly that approach does not require systems that are not apparent to supply the vast energy to have the Corona so much hotter than the Sun's surface. I do not see the suggestions that hot gas is transfered "up there" as viable...and even those speculations say that only one 10,000th of the energy can be taken up that way...sorry drifting off a little.... but push fits so well.:whistle:

I also feel push gets rid of the need for dark matter and push explains the motions of outter stars orbital speed... and to me I think a Universe where we can see most of the matter more desirable than one where we need unsceen matter to make up the greater percentage of all that is....

However at this point in time I feel my views have some way to go before they are generally accepted:lol::lol::lol:

I do say however it is the flow of particles that "bend" the space time grid... so I see no conflict:D ..I should be able to use most of the GR stuff to finally support my ideas;)

Have a great day I must get back to the Lab;)
alex:):):)

sjastro
19-05-2008, 03:25 PM
Unfortunately any gravitational push theory violates the principle of equivalence, that states that gravitational mass and inertial mass are the same.

Try performing Einstein's elevator experiment in the gravitational "shadow" between two bodies that are being pushed towards each other.

Regards

Steven
http://users.westconnect.com.au/~sjastro/small (http://users.westconnect.com.au/%7Esjastro/small)

xelasnave
19-05-2008, 05:18 PM
Thanks for the opportunity to consider something specific Steven.
Maybe I am missing something but I fail to see there need be any problem in the areas you suggest.
Let me think about it.
Thanks this is very exciting.
alex:):)

xelasnave
20-05-2008, 10:45 AM
To think one must focus on the issue.. and so I state the equivalence principle that would be the foundation of General Relativity:).

It states that ``there is no experiment a person could conduct in a small volume of space that would distinguish between a gravitational field and an equivalent uniform acceleration''

I lifted the following and changed it slightly so as not to infringe copyright;)...



Consider two elevators ..you in one and one``at rest'' outside your elevator way out in space.. the other traveller shines a flashlight horizontally into your elevator and toward the far wall of the elevator.

At rest, then you will see the beam of light travel in a straight horizontal line.

If your elevator is moving at a constant velocity upward relative to the other elevator the beam of light shall travel in a straight-line path angled downward.

The other person sees the beam travelling in a horizontal direction.

If the elevator is accelerating upward the beam will follow a curved path downward relative to you.

If the beam of light curves in the accelerating elevator, then the equivalence principle says that the beam of light should also follow a curved path in a gravitational field.


So this what we face!!!

Personally I question the experiment...it is a thought experiment and clearly if we conducted such an experiment I wonder what "bend" in the light path one could actually observe...lets say our elevator is 12 feet wide and so our beam is that length... at what rate of acceleration could we detect a upward or downward trend in the beam... light travels 300,000 klms per second... to cover a distance of 12 feet we can determine but even without the sums I suspect any variance would be impossibvle to detect.... I wonder if the elevator was doing near light speed could we get a readng...maybe? ..in theory because in reality the elevator will never whislt humans are trying to move it get to a speed within a small fraction of the speed of light....

IT is a thought experiment... so facts the we seize upon issuing in our belief from this thought experiment must keep such in mind....

So Steven I have thought about how push gravity can offend the premise I can not... and so I must ask of you specifically where you see a difficulty say if we seek to establish the "observed" facts within a context of a push gravity approach...

I am sorry to have to ask but I am clearly missing something and although embarrassed because of my ignorance must ask you to point out what you feel could deal a lethal blow to push gravity.


alex:):):)

xelasnave
20-05-2008, 03:58 PM
I have tried the experiment in the shadow as you suggest ..at first run seems ok but I will think more and get back here with my thoughts.
alex

sjastro
20-05-2008, 06:26 PM
Hello Alex,

I'm not into debunking any theory.

Particles colliding into larger bodies as a mechanism for push gravity only requires the inertial mass of the body to be defined.

One of the early criticisms of push gravity theory is that the gravitational mass seemed to play no role what so ever. The size of the gravitational shadow in conjunction with colliding particles overcoming the inertia of each body determined the gravitational effects.

This clearly violated both GR and Newtonian physics.

One way of bringing gravitational mass into the picture was by eliminating the shadow effect. Particles were allowed to penetrate each body. Some of the particles would undergoe inelastic collisions. The change in KE before and after collision allowed bodies to move towards each other.

The main question now is what has happened to the converted energy? Has been converted to heat, has mass accretion occurred or both. There is no supportive evidence.

Regards

Steven

xelasnave
20-05-2008, 08:13 PM
Thanks for your views Steven.

You asked....
The main question now is what has happened to the converted energy?

Well that is a good question... in the case of the Sun it converts into the Corona:D as I said above the out flow runs into the "gravity" flow ... now these particles travel at near C and although of little mass can produce a lot a energy ..via the famous equation...I think the Corona gets its energy this way...


I have thought that maybe it is the missing energy you enquire about that "powers" an atom.... when you think of it atoms seem to carry infinite energy in so far as they last a very long time for such a small item...where do they hide their power pak???... maybe their energy is being topped up by the flow??? maybe they get energy from the interaction with the "flow" (the gravity push stuff:)).... maybe the electrons orbit because every time a particle from the flow hits them they are kicked along.....

Like wind driving a windmill.....mind you this idea may need a little more support than that given here:lol::lol::lol:

I thank you for engaging in such deep matters..
have a great day
alex:):):)

sjastro
21-05-2008, 11:25 AM
While the high temperatures of the Corona has never been satisfactory explained, the dimensions of the Corona vary according to the solar cycle. I can't see why the Corona dimensions would vary if it is caused by the inelastic collisions between gravitational particles and the sun.

Regards

Steven

Karls48
21-05-2008, 05:48 PM
Equivalence principle experiment using the elevator as example is flawed for at least two reasons. Such a thought experiments belongs to the human thought domain and human imagination and got very little to do with actual physical reality.
If you are put in the elevator in under influence of gravitational field you will experience gravity imminently. However if the equivalent weight of you (apparent gravity) is due to the acceleration, such an apparent gravity will build over the period of time. As far we know no mass can accelerate from 0 to n speed in instant. Therefore you would know if the apparent gravity you are experiencing is due to acceleration or gravity.

If by some magical means (ala Scotty beam me up) you can be put in the elevator that is already under influence of either gravitational field or acceleration (what happen to causality?), then over the period of time if you are under influence of gravitational field (orbiting a star) your weight will remain constant. However if your apparent gravity is due to the acceleration, you will eventually come to gravitational field of some star somewhere in the universe. Then you can measure acceleration or de-acceleration due to the gravitational influence of such a star.

Now here comes fudge factor. People who will disagree with this will say, “if there are not any stars”, “if you can get to the elevator that is already under influence of gravity or acceleration”. My answer to this is that what my grandma used to tell me when I started with IF. “If you could catch fish on the road you would not need to go the river”.

Alex’s assumptions regarding space and the aether seems to display a lot of thought or intuition. If we assume that Big Bang theory is correct and the space and the time was created at moment of Big Bang, it is very reasonable to assume that the space is just some kind of conversion of matter or energy. The time itself is not real physical entity being just property of the space. This would explain the problem of electromagnetic waves propagating via medium without any substance. It may even provide answer to dark matter assumption, the dark matter being the space itself.

Again I have to point out that this tread started with link to the article that presents good arguments for speed of gravity being faster then speed of light. So far no one presented any reasonable argument as why it cannot be. The only answer seems to be that nothing can travel faster then light – why? Because Einstein say so.

skwinty
21-05-2008, 06:15 PM
Hi Karl
Herewith a post by Hans de Vries with regard to this issue.
Also remember, as I have said before, Einsteins postulates have been tested and verified many times over and until they can be disproved or some other theory has the same credentials then Einsteins postulates remain valid and relevant. It seems as though you have some doubt regarding Einstein.

Tom Van Flandern also claims that mars was inhabited by humans or human like beings....

Maybe you understand why your link (to his website) was removed. As far as the 1998
paper concerns, it is wrong. It has been discussed here multiple times as well as on
sci.physics.research (with Steve Carlip (http://xxx.lanl.gov/abs/gr-qc/9909087) and John Baez)


Where does Tom Van Flandern go wrong?

He assumes that the direction of the force, gravitational or electric, is always pointing
to the place where the source was at the moment that the force field was emitted.

This assumption, as we now know more than a century (!), is wrong. The Electric Field (http://www.physicsforums.com/library.php?do=view_item&itemid=2)
of a moving charge points to the place where the charge will be if it continuous
moving in the same direction during the time the force field needs to propagate.

The same is true for gravitation. In practice this means for the dynamics of the solar
system that the force is towards the location where the planet or sun is at that moment.

This can be measured and Van Flandern erroneously concluded that this means that
gravity must be instantaneous. Because the force is directed to the location where
the object is and not to where it was. His conclusion is a beginners error which
unfortunately made it into a peer reviewed journal.


For the math in case of the electric field, see for instance the links to my book in the
post I made on this thread here (http://www.physicsforums.com/showpost.php?p=1717519&postcount=39).

sjastro
21-05-2008, 08:17 PM
Many scientific theories do begin with thought experiments including GR.
The chemical structure of the Benzene molecule was worked out from a dream involving snakes....

The elevator experiment is not flawed because there is no violation of Newtonian physics. Einstein used Newtonian physics as a special case for GR.
The elevator experiment uses CONSTANT acceleration hence there is no "buildup" of force. Seems to me you are confusing acceleration with velocity.


If light requires a propagating medium like sound waves, the speed of light will no longer be constant to all inertial observers. In that case SR is completely wrong as would be GR. Our understanding of particle spin in Quantum mechanics would be compromised as would be the associated theories of chemical bonding and the pairing of protons and neutrons in nuclear physics.
The Michelson Morely experiment has been performed many times over a hundred years and the result is still the same.............



Yes I read the article. The paper came out in 1998. The first experimental data on the speed of gravity came out a few years later. The results were anywhere between 0.8c to 1.2c. No where near the 2 X 10(10)c predicted by the paper.
The experiment incidentally was slammed by the scientific community.

Finally on the subject of Einstein, perhaps you are unaware that Einstein lost credibility towards the end of his career over his opposition to the probabilistic nature of Quantum Mechanics. The fact is QM did not come to a standstill because of Einstein's opposition. Science is bigger than any individual including Einstein.

Einsteins theories of SR and GR are accepted simply because of the supportive experimental data.

Regards

Steven

xelasnave
21-05-2008, 10:00 PM
Once I saw space as static and empty however as we learn more it is clear that things are perhaps rather more complex and certainly not static...
I doubt if conditions are inelastic or rather free from fluctuations...
Consider a gravity wave explained via push gravity.. an increase in the flow of particles from say a super nova area.. push and GR agree that there will at least be what each would define as at least a ripple....and so given the frequency of super novas and similar lesser or greater events may well provide the fluctuations in the presure of gravity..maybe there are times when the inflw is raised (or lowered by distant super nova or events that may vary the particle flow upon which I speculate...an alternative explanation my be that the out flow of the Sun varies such that the energy interchange in the region I suggest can be related to variations in the Sun's output.

Maybe the center of the Earth is hot as a result of the energy loss you mention..I have thought this would be a consequence ...

I have also wondered if indeed things were this way what would be the consequence of the energy exchange we both ask about upon say a block of lead in remote space...one would think if large enough that if push be valid that such a lead block should be able to build heat in its center not withstanding it bein in cold dark space....

And if the lead gets hot that way does an atomic chain reaction need to be viewed different...I am not up to speed on atomic reactions but from what I see suspect a large block of lead may act similar...well it may do if push rules...

I spent 4 hours on my back (recovering still from the hernia op) and thought about the lifts over and over... man you would have to be slick to conduct that experiment at the speed of light....
I was trying to do the simple math as to how far the beam would get across our elevator and at one point reasoned it may well hit the floor...mmm now if it did and the floor was a mirror what then.... the mind is a wonderful playground ... one thing for sure timing would have to be spot on so the light beam met the lift if it went by at C...mmm if it went by at C how big would it look? in fact how could we tell it was coming our way if it was travelling at c..it would be on us and past before we could turn on the torch....

mmm first day without pain killers..does it show:lol::lol::lol:
alex

xelasnave
21-05-2008, 10:57 PM
My point re eather is simply the description seems to be of a space that is full of particles... we now look at space and we acknowledge billions of particles...
if we now find this to be so is not eather a fair and reasonable description of space...
I feel the belief that light requires no medium may well be flawed... if one considers the double slit experiment it has no explanation unless we reach for a medium.... if we have a medium it is easy to infer how two wave patterns can appear from the firing of one electron...mmm maybe we should use one electron in the lift experiment fired thru two holes in the lift wall and think about what we may see...one electron??? crossing the lift or multiply wave patterns (in the eather:lol::lol::lol:)...anyways in the double slit I bet it matters not where you place the slits a wave pattern will appear behind because the one electron creates a wave (in the eater) that propogates to any screen set up to show such...
I guess what i believe is that even the emptiest part of space has billions of particles..as it does..there is not one point in this Universe where a little light (rather EME) from every part of the Universe does not reach... if you think of the billions of objects each putting out "stuff" will not space be full of this stuff..does this stuff not fit what was called eather... but the word is a hot one.. but where the eather disagrees with the reality I do not know...

Can these particles have mass... yes the dust and such of corse but even the sub atomic particles ..some have mass.... and at near C little mass still means relatively big energy... suffu=icient energy to run a push Universe...sufficient to whack the outflow of the Sun and produce mind numbing quantities of heat where there should be none...
And if push dark matter is not needed..rather the dark matter if it can be attached to anything as Karl said it is seeing each bit of space as containing its share of the particles from everywhere.

AS to speed of gravity the interesting thing about a push approach is although the particles presumably travel at or near C the overall effect of pressure may well be "simultaneous"..... consider the external push upon a gallaxy (like they believe dark energy may work)... it acts on the whole body (galaxy) for these purposes instantly all over... and it does this because it is external..an internal force (attraction) takes time at C to be read within the galaxy....

The problem with dark matter as I see it is this... they see the outter stars going too fast..why because there is additi0nal matter outside that does this...but as you add more matter outside you get run away effect that you need more and more and so we end with what must be an unrealistic conclusion that 70?80 90? percent of stuff is a mysterious stuff we can not see.... as I admitted once that we can not see it I guess is fair..we can not see air.. but this stuff we can not see it..at all no way..zip..we can infer its presence but implied gravity influences.... we must work this way if we use attraction as the force direction of gravity... but if push how different.. even with ut sums we can see we get away from the need to add more and more mass to balance the wheel that is our galaxy..and every other galaxy..

Why is the Universe expanding..push gravity... the force of each object radiating its presence to the rest of the Universe... give light or part of the electro magnetic spectrum just a little mass and the thing will work... or so I believe..

The flow (of particles making up the gravity pressure) is space... and is the machinery that bends the space time grid.... assuming I have the grid correct one fits and complements the other... but those fond of GR will think I have a bit of hide to suggest any relationship...but it works..push from my approach dos not offend GR (given I see GR as geometry laying 3d ...er 4d graph paper out onto which we can instal mass and objects to describe how they impact space... bend or curve...

Mind you that raises another sore point you may know I have... the ball and the blanket thing is not the way GR says space is bent... and I still dont know if I am right or not but I say the ball is definitely on the wrong side of the blanket...space is bent toward it not around it.... and this is very important if you work out how gravitational lensing really works.... yes they have that wrong too... but when you see the way gravitational lensing really works it is so neat ...not much different to the way a refractor works...

Anyways folks thanks for your inputs...as most know I know zip about this stuff but enough to talk nonsence with little provocation... I admit some is tounge in cheek is an attempt to be outrageous but most miss that side of me..
Thanks again..I hope something herein has been entertaining for my part:D.

alex:):):)

Karls48
22-05-2008, 04:40 AM
No I’m not confusing acceleration with speed. If the elevator was travelling at constant speed there would not be apparent gravity on board. This thought experiment is assuming conditions that doesn’t exist in real universe. It violates causality. In the event that would let scientist (lets say 80kg of mass) to appear miraculously in elevator it would require infinitive force to keep acceleration constant.
“The experiment incidentally was slammed by the scientific community”

The scientific community is no different to the politicians, used car salesmen or any other group of people in our community. They are exposed to same social and economical pressures as the rest of the community. And probably more so then most of the community groups. The times of free thinking “gentleman of independed means” are long gone.

xelasnave
22-05-2008, 07:29 AM
The times of free thinking “gentleman of independed means” are long gone.

Thats my role:lol::lol::lol:

alex:):):)

sjastro
22-05-2008, 08:57 AM
Astronauts train in weightless conditions in aircraft in free fall. The only difference to the thought experiment is that Einstein used a free falling elevator instead of an aircraft. How do astronauts violate causality and more importantly exist in conditions that supposedly do not occur?

Steven

xelasnave
22-05-2008, 12:32 PM
As to the Michelson Morely experiment lets be clear it has been rated as the best failed scientific experiment there was... because of what it failed to prove...the presence of a eather wind....

Needless to say the experiment could never prove what it set out to do ...there is no monodirectional eather wind...

That is what they were looking for... why did they have it fixed that there was a single direction for the flow of this "eather wind"....
I say they were always looking for something that was a mere human misconception of what is really there....

The eather (or the assembly of all the particles flying thru space)must flow in every direction at once and as such requires an approach beyond that enlisted in the famous experiment....

Have I got it wrong??? if not can no one see the premise of a single direction being attributed to ther eather flow is horribly simplistic of the sea of particles that are out there.... and on that point would the equipment and method used be able to identify a direction of that particle flow or any of its members...

You have to be real smart to figure how to measure something that comes from everywhere and is the fabric within which we exist...

I can not say to my mind many have thought thru the folly of buying into this one direction trip... why was this so? where did they think this wind came from.... so far it looks very primitive and I seek others views or additional input that may raise the credibility of the experiment from where I suspect it lays.

alex:):):)

xelasnave
22-05-2008, 12:43 PM
Man its like standing at the side of the freeway with your back to the traffic and happily report you were unable to observe any passing trucks... a single direction ???? talk about having your back turned against reality... I going way out here .. but I defy anyone to call me on this one... let reason wash over you folks... one directional eather wind???... we didnt find it... I wonder why... just means you had no concept of the eather (my current updated eather..or if you like "open space")

I am flabagasted this can be held up in such high regaurd...

AND I wont be ticked off if anyone decides their science is better than mine.
alex

xelasnave
22-05-2008, 12:53 PM
I think I get it..the direction coming from the Earth path thru it.. so something travelling at 350 klms per second approx against an environment where things happen at C... what thepercentages??? .001??? anyways I see the approac..still its a little better as I have a wind sorce as it were..still the problem remains I feel that the experiment could not do what they expect....

mmm I am going to throw 4 hours of on the back time at this.
alex

edwardsdj
22-05-2008, 06:13 PM
Hi Alex,

The point of the Michelson-Morley experiment was to detect the motion of the Earth through the ether. The Earth moves around the Sun at about 30 km/s relative to the Sun. It was thought (prior to Lorentz and Einstein) that the speed of light measured in the direction of the Earth's motion would be about 30 km/s less than that at right angles to the direction of the Earth's motion.

The experiment was more than sensitive enough to detect this effect though none was detected.

Take care,
Doug

xelasnave
22-05-2008, 07:19 PM
I went off half cocked when I saw the directional thing and the poor choice of words..eather wind...

Anyways its not much of an experiment if it cant prove the eather:lol::lol::lol:....

I met a mathematician tonight and he had a mate even more into math... we had a time;)
They were just like real people and we seemed to share a common thing ....we all spoke as if we were right without absorbing the merit of each others case... so good ... no offence taken or given...

anyways I have yet to have my think time..

alex:):):)

edwardsdj
23-05-2008, 04:23 AM
Hi All,

This thread started with a 15 year old who was just attempting to get his first view of Jupiter (to which myself and others were kindly willing to give him practical advice):

http://www.iceinspace.com.au/forum/showthread.php?t=31433

asking the simple question: does gravity propagate at the speed of light?

He has had on the order of 10 pseduo-sciece (at-best), speculative answers for every one that has given a reasonable response based on accurate, measured, scientific understanding:

Yes, the overwhelming view of the scientic community based on factual evidence is that GRAVITY DOES PROPAGATE AT THE SPEED OF LIGHT.

In my view every single person speculating otherwise in this thread has demonstrated through their posts a complete lack of understanding (or even an attempt to understand) basic high school/first year level physics.

Had I read these speculative responses at age 15 I may well have become too confused to be judged as one of the top 23 physics students in the country at age 15 and invited to attend the National Physics Summer School where we were taught physics to a first year university level at this age.

I am forever endebted to Professor Rodney Jory for providing me with this opportunity at ANU in 1988. I am also deeply endebted to Professor Jory for teaching me the valuable lesson in life that "people are more important than things".

I again (though I'm sure in vain) point people to Einstein's great little book written for the general public on the matter (here is yet another online reference):

http://www.bartleby.com/173/

Einstein revered Netwon and Mawxell (among others like Plank): those great scientists that had paved the way before him. I would greatly appreciate it if armchair speculators would take the time to fully understand at least a first-year course in physics and then at least taking the time to comprehend this highly accessible work before undermining the work of the Great Man.

I implore moderators to start a Forum entitled "Pseduo-science" or more accurately "Armchair speculation" or "The New Age" where matters like the bulk of what has been raised in this thread could be promptly refered.

This would do a great service to the scientific education of young people participating in this forum.

Best regards,
Doug Edwards

skwinty
23-05-2008, 06:08 AM
Hi Doug
Good link to a comprehensive sysnopsis of Einstein's way of thinking. Should be considered as compulsory reading!!:P (My Einstein icon)

xelasnave
23-05-2008, 07:38 AM
Are you looking at me???:lol::lol::lol:

Doug all you say is somewhat valid however to hold up our science as conclusive suggests an inflexibility that I would not wish to see instilled as an ingredient in a young mind.

And to hold up our science and to be happy to sign off on matters that are beyond full current explaination... black holes and dark matter..as proven facts by inference or extrapolation of a math premise seems to fail to recognise that it is not all over. For goodness sake take the time to read the stuff the headlines day in day out re the dark matter chase for example...mostly wild speculation ..designed to be sensational to attract a looker....
And to entertain many multiple universes with such conviction... as they do because the math can speculate this way.... an onlooker could easily feel that such facts presented are absolute evidence of such a proposition... and of course they are not... most folk will not comment because they are intimidated by someone with a degree and funding in the area... but I doubt if you can look at the press releases and not conclude that speculation is abundant and yet presents as science.

DrA perhaps stood out because he did not hold the course in many respects but struck out to find something new..and he did... I imagine at the point where his speculations were a mere idea, he would have found that if he shared them with others I expect he would have been laughed at ... and indeed many exciting discoveries come from someone asking questions that the then current science says should not be asked.

What would you have said to this young man when that chap came forward with the idea that ulcers were not caused by stress but rather by a germ or virus... would you suggest that the proponent of the idea go back and read all the books written by great and wonderful men with practices in Macquarie street where they traded upon their mistaken approach to treatement centered on a mistaken belief..lets face it he was regarded as a fool...but he was right notwithstanding all the accumulated knowledge he faced in opposition to his valid approach.

Most folk can accumulate other folks knowledge but without free thinkers such as Dr A and our ulcer chap who have the courage to offer more from their consideration of all they have learnt I question upon what basis discovery may move forward.

I would think on the positive that the young man who started this thread may learn something of the real world from the drift of this thread... there will be many opinions offered to you on your journey thru life and you will need to make your mind up as to what you will accept.

I dont accept gravity works without a force as dictated by Dr A nor do I accept that gravity is due to the force of God as presented by Newton....and I point to the possible influence of those determined not to erode God's power ...otherwise why would these smart men cop out on applying their capable brains to the machinery of gravity... those who are happy to accept the current field of play will continue doing the same old sums but if we are to answer that question we will have to accept that Newton on this aspect was wrong and that Dr A's genius lay in the fact he could take gravity forward and still not buy into a fight to take gravity away from God.

AND so does this make me wrong because I wont accept Newton's view or Dr A's side step??? In the mind of the converted of course it does... I am impertinent because I dare to think upon such matters and not accept what great men have laid down as truth...well I will be the judge of what I accept as fact and what I do not...

I do not accept as fact..black holes, dark matter, multiple Universes, and resent someone presenting such as scientifically inescapable conclusions... for they are not... and I know NASA has maps of all the black holes.. but I want to see one in the flesh if I am to treat it as a fact....

Doug I know where you are coming from and I have no difficulty in reviewing your view here ..you are the embodiment of establishment and that gives you the right if not the duty present your last post...
But how could I let it pass without comment... I am not even sure in what specific area I am at odds and can only add the thoughts I have set out above.

AS to gravity as you know I like the idea of push and I arrived at this position because I concluded that there was no way the force we call attraction can work..on my limited understanding of particle physics... and so I sought a system that would work... I think it works, it offers reasonable approaches and does not take wild shortcuts... I am happy to be its advocate because I believe it offers an explaination where really there is none... GR observes a lot and explains nothing of a machinery...

If GR is the end of it we must leave the force of gravity to God and I will never be happy with that.... and certainly wont stop thinking about the matter because I do not have formal science education.... I have read what I have of Dr A's (translations not his original notes) and frankly there is stuff I dont buy... but it does not mean I have not read it... I have read all the NSW Uni 4th year particle physics course for example... but I dont run around saying so to make me sound expert or to build my castles upon the ideas accepted as fact ..I am not expert and cant talk to sound proficient but I do know about all they talk about... understanding may vary but all students will have that problem..

I hope you dont think I am upset.. on the contrary statements like yours and indeed mine must have some merit it is not as though we are preaching the virtues of global warfare ..
.
I enjoyed this reply and I hope you are not one of those folk that find folk like me simply frustrating ..I also hope you do not think I am too ignorant of the matters I talk about... but I like a lite style of expression to retain my public impression of humility.

MMMM a new section for alternative science.. although that is condecnding I like the idea...

alex:):):)

xelasnave
23-05-2008, 10:26 AM
I thought I had the following in the above..I place it here rather than edit hours after


.............
Einstein considered the "Schwarzschild singularity" and black holes as bizzarre constructs, resisting the logic of his own theory right up to his death in 1955.

And so when I reject black holes I doubt many folk thought about Dr A's position.

alex
alex

Karls48
23-05-2008, 11:52 AM
"Are you looking at me???:lol::lol::lol:"
:thumbsup: for Alex, although I don’t embrace his gravity push theory. But he thinks for himself.

As someone had pointed out previously in this tread, for some people science has become religion.

sjastro
23-05-2008, 02:57 PM
It's not wind, it's drag. If ether did exist, the earths motion through the ether would create a drag effect. The speed of light would increase in the direction of the Earth's motion and slow down in the opposite direction. Very simple physics.

The Michelson Morely experiment was designed to split a light beam in two, send one beam in the same direction as the Earth's motion and the other beam in the opposite direction. The beams were then recombined. If there was any difference in the velocity of the split beams an interference pattern would be observed.

The fact that a null result was obtained was the death blow to the ether theory.

The drag effect also kills off push gravity. The motion of a body through space would result in the gravitational particles in front of the body having a higher KE energy than the particles behind the body. That will effectively turn gravity into a repulsive force.

Steven

xelasnave
23-05-2008, 03:38 PM
Yes Steven you are right on the direction etc... I went off half cocked..I did confess above someplace...
I spent a lot of time looking at stuff on the experiment and finally I must say I thought it was very clever...using the wave length of light as a ruler was so smart.

I dont agree that push is dead on this basis but must say you have the advantage in the arguement... I conceed that so as to be clear.

Still I am not put off ..

I was reading about the difficulties with establising data from the Gravity B probe(from years ago) and it made me realise that whatever you want to establish you need fine gear ... it also made me think the mass of the Earth may distort the eather in such a way that a flow direction could not be percieved on Earth..just a hunch but a more reasonable place to run the experiment would be in orbit...er like the gravity B probe...actually they are using a very similar approach to the MM light split... I better have another look at it...and come to think of it a lot of gravity experiments have the beam of light thing going to obtain variations.

And sorry again for being so hot headed on my dealing with "the eather wind":sadeyes:

alex:):):).

edwardsdj
23-05-2008, 11:55 PM
I really wasn't talking about anyone in particular. Just the entire nature of the thread.