Is there anything faster than light?

Then explain what have you understood out of this spacetime stretching ? I must remind you that there are many mainstream papers which say that spacetime is not a physical thing, so pl stretch it now. And let me see how much hardwork is done in this process ?

PS: Pl understand my position, to explain an observation requires theory, proposing and establishing a theory is indeed a very hardwork and I am not taking away that credit from those who are involved. Bigger question is are you supporting from a position of understanding.....beyond literal understanding..

 

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The name of the theory is "General Relativity" as it describes Big Bang Cosmology.

I'm a little shocked that you seem to honestly not have ever heard before heard of this concept which is actually a pretty basic/well known component of modern physics. It's been known for decades.

 

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Correct. Now we're getting into the nitty-gritty. Spacetime is not a physical thing. Stretching is a poor analogy, used as a first-blush attempt to describe the effect to someone who is having trouble grasping the issue at first.

It is more correct to say simply that the distance between things (galaxy clusters) is increasing. It's still inadequate, but such is the nature of physics. All attempts to describe the structure of the natural world using words are, by definition, inaccurate. It is only the mathematics that can describe it accurately. As many scientists have observed, the mathematics is the description.

 

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That is what I call parrotising mainstream ?

What makes you think that others are not aware of this poposcience analogy ?

And can you provide the maths between spacetime expansion and Gravity, like when excatly gravity takes over and vice versa...because at cosmological level gravity is certainly non zero. No mainstream guy will ever do this exercise, because this will be an admission that the expansion is physical (with physical speeds), thus instantly creating problems.

 

You have not understood !! You are just pushing to be with mainstream. Let me try again..

1. Increase in distance between galaxies.....an observation.
2. Explanation is that spacetime is expanding, why not say that the space is expanding ?

Why a mathematical theory cannot be intuitively understood when it is describing a real observation ?

 

How about you don't surmise what others are "just" doing. It's an ad hominem, and therefore off-topic.

That wasn't even true a millennium ago, when people were scoffing at the idea that the Earth goes around the sun. You know better - once you learned how orbits work.

Knowledge is an edifice that, without an adequate foundation, cannot reach any height.

If your argument really is 'if it's not intuitive to me then it probably isn't true', I really can't do much with that.

 

OK, I'll bite. Explain Newton's Bucket. Tell us why if we did that experiment in an empty universe the water would still be pressed against the bottom of the bucket. How can an object "rotate" in empty spacetime if spacetime is not a physical thing?

If you mean it's not a material thing, that is not matter and not energy, OK, that's different from saying it's unphysical. I look at that Ricci curvature tensor and that Riemannian scalar curvature, and I gotta ask, curvature of what, precisely? Certainly it's not curvature of something that's unphysical.

I simply don't believe this. If you can't describe it in terms that most people can understand, I think you don't understand it. You can say all you like that it's indescribable, but it's not. If you use analogies, you need to point out where they fail. If you have to, you can say stuff like, "It's a separate effect that comes in due to GRT; it just behaves some of the same ways that motion as we ordinarily mean it behaves, so we can call it motion and be about as correct as we're ever going to be, but it's not really motion like we're used to, it's an extra thing added into GRT, that doesn't exist in SRT or classical physics, that the universe can do that we can't see here around us, that behaves partly like motion as we normally understand it does." That gets the idea across as much as anything ever will, unless someone gets a little gumption and starts diving into as much of the math as they can handle.

 

No, inability to make correct observation and then proposing an incorrect theory is different.

millennium ago we did not have proper observations, we did not have proper analysis...but once that was done right theories were prposed and understood....I am sure you are not telling that people here are finding problem in understanding the orbital motion..

 

http://arxiv.org/pdf/astro-ph/0310808v2.pdf

The above link was provided by Schneibster in some other thread.

Please find time to go through the contents, you will realise that it is necessary to understand the underlying concept not the literal meaning of what is being stated in words.....You will be surprised at the confusion caused mainly due to mainstream writings itself.

 

Mach, not Newton.

Because the spin zero Higgs field is the quantum spin invariant, in exactly the same way that the rest frame in a particular direction is mathematically defined by the relativistic vector sum of +/- c. The speed of light has no meaning if you cannot define the rest frame. Even the speed of light must be relative to something.

Equal and opposite quantum spin rotations define inertia for a rotating frame because it explains exactly what "zero spin" really means. That, together with light travel time in every direction energy can propagate, defines what is 'space'. It doesn't 'stretch'. It behaves exactly the way Special Relativity says it does, and it is like that everywhere. Space is, and always has been, light travel time. Time does not pass for a photon traveling the bounds of the known universe, nor for energy that is bound in a particle of radiologically stable matter within atomic structure. Time dilation is very important to understand. Much more so than flaky ideas about "space curvature" and/or stretching, with no basis in physical reality.

GR, and the parts of GR traceable to Minkowski and Hilbert simply have too much of the static timeless geometry of Euclid and Pythagorus in them. When someone tells you that inertialess space has curvature (like a Euclidean solid) and that time dilation is simply an unimportant side effect, that's a problem in a universe of energy transfer events where time dilation depends on the mode of propagation of energy as well as its magnitude.

Keep E=mc^2. Ditch those useless past / future light cones and Minkowski's version of relativistic rotation. GR was not supposed to be a throwback to absolute space and/or absolute time. The only reason it works at all is because it manifestly deals with processes that are slow. To make it compatible with QM, it must be extended to explain why the speed of entanglement appears to be >>c. Subsume that into SR and GR.

It would probably help if I could find any SCRIPTURE to support these ideas, but this is something I refuse to do. Do it yourselves if you wish. Good luck with that. Would space "stretch" if there were nothing in it? G-d only knows, and why would I even care? To thine own self be true or something.

 

A quick course in relativistic vector addition:

c + c = c (the speed of unbound energy like a photon in the vacuum)
c - c = o (at rest for bound energy, matter or antimatter in a particular direction)

I couldn't care less if mathematicians have trouble understanding this. It is what it is, and I didn't make it up. Apply the Pythagorean theorem and / or complex numbers or rotations in higher Euclidean dimensions any way you wish. It won't help. This is not a Euclidean vector space and no part of it, other than the inertialess field itself (and the exact centers of bound particles) is static. The passage of time (dilation) is different anywhere in the proximity of energy or states of relative motion of matter or antimatter.

Nothing curves. Nothing stretches, other than my patience with the purveyors of unnecessary fancy pants geometry to explain something as simple as a lack of inertia. To curvy hell with all of them.

Understanding that space is light travel time helps.

 

However, space is. You can read about this in the Einstein digital papers and elsewhere. Space waves, a field is a state of space, and so on. Space isn't nothing. It's like this gin-clear ghostly elastic. Einstein talked about the stress-energy tensor, so it's like stressed elastic. And stress is directional pressure, so it's like compressed elastic. When you appreciate this it's even more surprising that Einstein didn't predict an expanding universe.

I disagree with that Dave.

 

This is an inaccurate description of space.

 

You are saying exactly what I'm saying. We are in agreement.
One cannot simply intuit how nature works. One must understand.
Mainstream writings may or may not be confusing to the reader, but that does not take away from their accuracy.

 

Ok, you understand, then please explain..

1. what is this stretching of spacetime ?
2. Can you say that space stretches ? If no then what stretches ?
3. when excatly expansion takes control from gravity and vice versa ?

 

danshawen, I was responding to DaveC; you couldn't tell because you have him on ignore and it takes his quotes out of everyone's posts so you don't have to see them.

Also, you haven't responded to my posts to you.

No, Mach claimed that without other matter in the universe there would be no way to define rotation. But there is; there is the gravity field, even if it's zero.

I couldn't connect the rest of your post with anything. It looks like you're claiming that GRT is wrong, and the problem with that is that GRT works.

 

Fixed that for you.

 

As stated previously, these are poorly-formed questions.

Spacetime does not stretch; it is not made of anything. What happens is that the distances between objects that are not gravitationally bound increases over time.
The mechanism by which this happens is currently an active area of investigation.
The description by which it happens is beyond the scope of this thread and would be better facilitated with a good book on the subject.

Finally, the fact that it may not make sense to you, or even that it has not been adequately described to you here is not a valid refutation of its veracity. To claim so, would be a logical fallacy called argument by incredulity. The onus is on you to refute the findings of cosmological expansion, not on me to back up that which has been modeled already.

 

Couldn't have put it any better, and that is precisely what I am saying.. Static fixed coordinate systems are a good approximation to what happens with gravity for most intents and purposes. But not for describing precisely what inertia (gravitational or otherwise) is.

When a particle physicist like Matt Strassler says "inertial mass has nothing to do with E=mc^2, has nothing to do with gravitational mass, has nothing to do with GR's Principle of Equivalence", well then someone who puts more credibility in some sketchy and inconsistent math needs to think about what physical reality informs us about inertia. He is trashing relativity in favor of some dicey math in the Standard Model. Every day it operates, the LHC proves E=mc^2. Trashing relativity like that negates the use of math that works most consistently. Dogs have better sense.

No one seems to have paid any attention to the most important thing I wrote. Posit zero mass/energy for the entire universe. Now tell me again, what exactly is it that causes space to stretch or bend anywhere? If you cannot answer this, why would anyone wish to assume that it does, much less that it would do so in a manner to allow for FTL motion of anything? What does it accomplish, other than to trash relativity? If no configuration of inertial/gravitational mass can produce velocities >c, adding space to the equation avails nothing.

Relativity deniers are not worth the water in the bidet nor the paper needed to wipe us clean of them.

 

What makes you think the expansion of space 'trashes relativity'? General Relativity completely is in line with the expansion of space. General Relativity clearly revealed that space must either be expanding or contracting!