How fast can we go?

[ckam]

orin, zero cant be longer than another zero.

[orin stepanek]

orin, zero cant be longer than another zero.

True! But how do you arrive at 0?

[Wadsworth]

If you were traveling to a star system at the speed of light in the same direction that the universe is moving and returned at the same speed; would the trip there be longer than the return trip, or would the travel time remain the same? Why?
Orin

If your travel velocities are equal (relative to an object outside of the system), but on the way you are approaching something moving away from you, and on the return something moving toward you, of course your return trip is shorter. The key here is keeping an equal (light speed) relative speed.


Zero?

[Orca]

Hello All

I thought the only thing that can go faster than light is the propagation of gravity.

Harry: respectfully, I thought that both GM and QR supported the idea that the propagation of gravity, via gravitons, occurs at exactly the speed of light.

Mind experiment:

If the sun were "plucked" from the solar system in an instant, would the planets instantly travel off in straight lines, even while you still could observe the sun for another 8 minutes or so?

In other words, if something exists outside an object's light cone, that something is not effect by the object's gravity OR light while it remains outside the cone.

[harry]

Hello Orca

There are two conflickting ideas as to the speed of light and the ability for man to generate a speed to go faster than C.

As for gravity, smile the amount of evidence to indicate the speed is very little.

Unless you have evidence rather than hear say.

Look at these links.

http://metaresearch.org/cosmology/speed_of_gravity.asp

Abstract. Standard experimental techniques exist to determine the propagation speed of forces. When we apply these techniques to gravity, they all yield propagation speeds too great to measure, substantially faster than lightspeed. This is because gravity, in contrast to light, has no detectable aberration or propagation delay for its action, even for cases (such as binary pulsars) where sources of gravity accelerate significantly during the light time from source to target. By contrast, the finite propagation speed of light causes radiation pressure forces to have a non-radial component causing orbits to decay (the “Poynting-Robertson effect”); but gravity has no counterpart force proportional to to first order. General relativity (GR) explains these features by suggesting that gravitation (unlike electromagnetic forces) is a pure geometric effect of curved space-time, not a force of nature that propagates. Gravitational radiation, which surely does propagate at lightspeed but is a fifth order effect in , is too small to play a role in explaining this difference in behavior between gravity and ordinary forces of nature. Problems with the causality principle also exist for GR in this connection, such as explaining how the external fields between binary black holes manage to continually update without benefit of communication with the masses hidden behind event horizons. These causality problems would be solved without any change to the mathematical formalism of GR, but only to its interpretation, if gravity is once again taken to be a propagating force of nature in flat space-time with the propagation speed indicated by observational evidence and experiments: not less than 2x1010 c. Such a change of perspective requires no change in the assumed character of gravitational radiation or its lightspeed propagation. Although faster-than-light force propagation speeds do violate Einstein special relativity (SR), they are in accord with Lorentzian relativity, which has never been experimentally distinguished from SR—at least, not in favor of SR. Indeed, far from upsetting much of current physics, the main changes induced by this new perspective are beneficial to areas where physics has been struggling, such as explaining experimental evidence for non-locality in quantum physics, the dark matter issue in cosmology, and the possible unification of forces. Recognition of a faster-than-lightspeed propagation of gravity, as indicated by all existing experimental evidence, may be the key to taking conventional physics to the next plateau.

http://metaresearch.org/cosmology/gravi ... ravity.asp

Abstract. Gravity has no aberration, and propagation delays cannot be used without destroying angular momentum conservation at an unacceptable rate. Even the curved spacetime explanation (“gravity is just geometry”) breaks down when masses and speeds are large, as in binary pulsars. But if gravity or spacetime curvature information is carried by classical propagating particles or waves, a modern Laplace experiment places a lower limit on their speed of 1010 c. The so-called Lorentzian modification of special relativity permits such speeds without need of tachyons. But there are other consequences. If ordinary gravity is carried by particles with finite collision cross-section, such collisions would progressively diminish its inverse square character. Gravity would gradually convert to inverse linear behavior on the largest scales. Curiously, at all scales greater than about 2 kiloparsecs, gravity can be modeled without need for dark matter by an inverse linear law. The orbital motions of Mercury and Earth may also show traces of this effect. Moreover, if gravity were carried by particles, a collapsed ultra-dense mass between two bodies could shield each of them from the gravity of the other. Anomalies are seen in the motions of certain artificial Earth satellites during eclipse seasons that behave like shielding of the Sun’s gravity. Certain types of radiation pressure might cause a similar behavior, but require far more free parameters to model. Each of these effects of particle-gravity models has the potential to lead to a breakthrough in our post-Einsteinian understanding of gravitation. This would also change our views of the nature of time in relativity theory.

But!!

There are some that think they have proven the speed of gravity to be that of light.

See link
http://curious.astro.cornell.edu/questi ... number=573

In September 2002, two US scientists made some very accurate measurements of the position of a quasar as it passed behind Jupiter. They argued that the exact amount of apparent motion of the quasar (as the path of the radio waves from it was bent in Jupiter's gravitational field) depended on both the speed of light AND the speed of gravity. The measurements they took then proved that the speed of gravity is the same as that of light, ruling out some of the more bizarre modifications to the laws of gravity which have been proposed, and further backing General Relativity (BBC news article on the experiment).

http://www.newscientist.com/article.ns?id=dn3232

Ed Fomalont of the National Radio Astronomy Observatory in Charlottesville, Virginia, and Sergei Kopeikin of the University of Missouri in Columbia made the measurement, with the help of the planet Jupiter.

"We became the first two people to know the speed of gravity, one of the fundamental constants of nature," the scientists say, in an article in New Scientist print edition. One important consequence of the result is that it places constraints on theories of "brane worlds", which suggest the Universe has more spatial dimensions than the familiar three.

But the assumption of light-speed gravity has come under pressure from brane world theories, which suggest there are extra spatial dimensions rolled up very small. Gravity could take a short cut through these extra dimensions and so appear to travel faster than the speed of light - without violating the equations of general relativity.

This response is questionable.

Is faster-than-light propagation allowed by the laws of physics?
http://metaresearch.org/cosmology/gravity/LR.asp
Read this link
Table 1. Overview and comparison of SR and LR.


Something intersting

Speed of light broken with basic lab kit
http://www.newscientist.com/article.ns?id=dn2796

Electric signals can be transmitted at least four times faster than the speed of light using only basic equipment that would be found in virtually any college science department.

Scientists have sent light signals at faster-than-light speeds over the distances of a few metres for the last two decades - but only with the aid of complicated, expensive equipment. Now physicists at Middle Tennessee State University have broken that speed limit over distances of nearly 120 metres, using off-the-shelf equipment costing just $500.

So! does gravity travel faster than the speed of light?

Mate, I wish someone would prove this one way or another.

[Orca]

Me too, harry..

Though it seems to me that it would be really weird if gravity didn't propagate at the speed of light. After all, the other 3 forces have been unified...somewhat...the electro-magnetic force and the weak force were actually referred to as one electro-weak force in one of my textbooks! The strong force is a bit trickier to connect to the other two, but for the most part it is accepted that at some early energetic stage of the universe, the strong, weak and electro-magnetic forces were all unified and indistinguishable; the thought is that if you go back far enough, gravity is also unified with the others. So the other three forces are limited to c, but gravity isn't...what the heck is gravity?

If gravity doesn't propagate at exactly the speed of light, something is very fishy with our model of the universe (to say nothing of both GR and QM).

The discovery of gravity waves would solve this problem. Gravity is just so feeble that it's unlikely a ground-based gravity wave detector would ever actually work.

[harry]

Hello Orca

you said

but for the most part it is accepted that at some early energetic stage of the universe, the strong, weak and electro-magnetic forces were all unified and indistinguishable; the thought is that if you go back far enough, gravity is also unified with the others

You are assuming that there is a start to all this and that the BBT is correct.

In my opinion, there was never a start and there will never be an end. Just a process of recycling and evolution of stages and phases of the objects within the universe.

But! you statement maybe correct within compact star cores and the so called Black holes as ultra dense plasma matter.

[Orca]

Hello Orca
You are assuming that there is a start to all this and that the BBT is correct.

In my opinion, there was never a start and there will never be an end. Just a process of recycling and evolution of stages and phases of the objects within the universe.

But! you statement maybe correct within compact star cores and the so called Black holes as ultra dense plasma matter.

BBT seems to be correct, or at least the best explanation with the data that is available. Almost all of the scientific community now supports BBT and has for decades. So, until data suggests that BBT is incorrect, it seems logical to me to go ahead and use it as the model with which to describe the universe.

Out of curiosity, Harry, what leads you to accept a model that is not supported by the community? Distaste for a finite expanding universe? The lack of a unified theory of gravity so as to understand the first moments before expansion, which we don't have but need to complete BBT?

I don't find it strange that you "fight" BBT. Most physicists have fought the possibility of a finite universe, even when their theories have supported it! It's just that an infinite static universe has so many flaws that can't be accounted for. Not that BBT is a complete theory...yet!

[harry]

Hello Orca

Mate, If you think that the Big Bang is it so be it. By next year the theory will be exposed. Its onlly a matter of time.

until than read these links
I have been reading these papers on the Big Bang

The Big Bang Theory Under Fire by William C. Mitchell
(As Published in Physics Essays Volume 10, Number 2, June 1997)


Cosmology: The Big Bang Theory
On the Problems of the 'Big Bang' Theory of Cosmology
http://www.spaceandmotion.com/Cosmology ... Theory.htm

The Metaphysics of Space and the Wave Structure of Matter (WSM) explains how our Finite Spherical Universe Exists within an Infinite Eternal Space
http://www.spaceandmotion.com/Cosmology.htm


Read the above papers and draw your own conclusions.

[ckam]

orin, zero cant be longer than another zero.

True! But how do you arrive at 0?

flying through space with c, you could arrive anywhere at no time (literally).

[orin stepanek]

orin, zero cant be longer than another zero.

True! But how do you arrive at 0?

flying through space with c, you could arrive anywhere at no time (literally).

Than if we had a machine [ship?] that could bend the space time continuum; [literally create our worm holes;] we could own the deepest reaches of the universe? But what would happen to the time everyone else lived in while we were [maybe weren't] gone? If that's true then the photons life across the universe is 0 time. Interesting!
Orin

[Orca]

Mate, If you think that the Big Bang is it so be it. By next year the theory will be exposed. Its onlly a matter of time.

Exposed? You make it sound like a conspiracy!

If BBT is found to be inaccurate, and the tests that prove it to be inaccurate can be replicated throughout the community, then a new more accurate theory will be formulated that will take its place. This is scientific progress. It just seems to me you are too eager to jump on to the "newest thing" and accept a new hypothesis before it is a working theory.

I think it's great that there are scientists trying to crack BBT's armor. This is what keeps science from stagnating. But I will not simply swallow every new thesis that comes along.

I seriously doubt BBT will be tossed out completely. More likely, it’s missing elements will be completed as it is refined. But that’s just my guess.

The main problem with BBT, methinks, is the actual singularity from which the universe supposedly expanded. The problem is, classical GR (GR without the effects of Quantum Mechanics) mathematically predicts the singularity. But, when you toss in the effects of QM, do singularities actually exist? This is the point at which classical GR “breaks down” in terms of making predictions about the behavior of such an event. So again, when GR and QM are combined in a quantum theory of gravity, perhaps these answers will be found and BBT will be completed.

True! But how do you arrive at 0?

flying through space with c, you could arrive anywhere at no time (literally).

Than if we had a machine [ship?] that could bend the space time continuum; [literally create our worm holes;] we could own the deepest reaches of the universe? But what would happen to the time everyone else lived in while we were [maybe weren't] gone? If that's true then the photons life across the universe is 0 time. Interesting!
Orin

But a ship and its crew are made of matter, which has rest-mass, and therefore can't travel at c.

EDIT: Mathematically, yes, at the speed of c you'd travel anywhere in the universe in 0 time. I am just pointing out that in terms of practicality for space travel, it won't do us material folks any good.

[orin stepanek]

I may not be wording this right; but theoretically if you can compress space in front of you and expand it behind you; you can travel faster than the speed of light and still inside your machine time would remain normal. A lot of space gas I know; but I read about it somewhere. I'll try to find it somewhere and post it sometime.
Orin

[orin stepanek]

http://www.usd.edu/phys/courses/phys300 ... e/dave.htm

Not that I believe it; but it is intriguing; and who knows; with technology improving all the time?
Orin

[harry]

Hello Orca

Like I said.

The Big Bang theory is only a theory. As a theory it is not a fact.

Until I see evidence to prove the theory as a fact, than I may consider it.

So far all the info supplied by the scientists is in dispute.


People who wish to draw their own conclusions

Big Bang links supporting:

http://map.gsfc.nasa.gov/m_uni/uni_101bblimit.html
http://www.umich.edu/~gs265/bigbang.htm
http://www.nasa.gov/vision/universe/sta ... ather.html
http://hubblesite.org/newscenter/archiv ... s/2006/44/

http://hubblesite.org/newscenter/archiv ... s/2006/49/
http://lanl.arxiv.org/PS_cache/astro-ph ... 604561.pdf
http://www.smh.com.au/news/science/big- ... 22240.html
http://people.cornell.edu/pages/jag8/spacetxt.html

http://cosmos.swin.edu.au/lookup.html?e=bigbang

http://wmap.gsfc.nasa.gov/m_or/PressRelease_03_06.html
http://map.gsfc.nasa.gov/m_uni/uni_101bblimit.html
http://nedwww.ipac.caltech.edu/level5/G ... tents.html

http://hyperphysics.phy-astr.gsu.edu/hb ... fy.html#c1
http://www.astronomycafe.net/qadir/q55.html

One more point, many people think that the big bang started from one point. That is a mistake. If the the big Bang did occur it would have occured at the same time in many spots.

[Qev]

One more point, many people think that the big bang started from one point. That is a mistake. If the the big Bang did occur it would have occured at the same time in many spots.

Actually, the Big Bang theory states that it happened everywhere at the same time. It's just that 'everywhere' happened to be much smaller at the time.

There you go saying "just a theory" again. Everything in science that isn't an observation is a theory, and no theory can ever be proven, only supported or falsified.

[harry]

Hello Qev

Actually, the Big Bang theory states that it happened everywhere at the same time. It's just that 'everywhere' happened to be much smaller at the time

There you go again adding a comment like

It's just that 'everywhere' happened to be much smaller at the time

The first part I garee with, but not the add on. What does smaller mean in an infnite universe.

[Orca]

There you go saying "just a theory" again. Everything in science that isn't an observation is a theory, and no theory can ever be proven, only supported or falsified.

Exaaaactly! Nicely put, Qev!

[Orca]

The first part I garee with, but not the add on. What does smaller mean in an infnite universe.

Is the universe infinite? Is it also static? If so how does it avoid gravitational collapse? Remember, even before Newton this was a struggle...people 'wanted' the unvierse to be infinite, but there are too many logical traps!

[harry]

Hello Orca

What logical traps?

[Orca]

Hello Orca

What logical traps?

Well, it all goes back to Newton and before, when they were kicking around the idea of gravity and a static universe. Now this is before they knew about galaxies.

The mind experiment went something like this: if you have an a static universe full of stars, gravity would, over time, cause them to come together. So the universe would end up with one big ball of stars. An infinite static universe would have an on-going cascade of such "star balls" constantly crashing together. So what if you had an infinite universe where you had an equal distribution of stars, so no one star was any more distant than another. Well, for one, the whole sky would appear white, as any line of sight would eventually fall onto the surface of a star. Another problem is that if any one star moved the slightest bit, you'd again have a difference in forces, and clumps of stars coming together.

But remember, these people also thought of the universe as an empty void with stuff bouncing around in it. It wasn't until Einstein and Hubble that mainstream science got a taste of an expanding 4 dimensional universe.

[orin stepanek]

http://curious.astro.cornell.edu/questi ... number=575

Here's an article of galaxies moving apart at faster than the speed of light. It's kind of confusing. If galaxies moved apart that fast than they would eventually disappear from each other.
Orin

[harry]

Hello Orca

The mind experiment went something like this: if you have an a static universe full of stars, gravity would, over time, cause them to come together. So the universe would end up with one big ball of stars. An infinite static universe would have an on-going cascade of such "star balls" constantly crashing together. So what if you had an infinite universe where you had an equal distribution of stars, so no one star was any more distant than another. Well, for one, the whole sky would appear white, as any line of sight would eventually fall onto the surface of a star. Another problem is that if any one star moved the slightest bit, you'd again have a difference in forces, and clumps of stars coming together.

The universe is endless and recyclic. Through observations we see clusters of stars, clusters of galaxies, cluster of clusters of galaxies.
There is no way that you can have an equal distribution of stars. We see star formations in different stages and galaxy formation in different stages and we also see stars and galaxies colliding and so on.

As as for the "All" sky showing all stars. If you focus for 1 minute you will find many stars, if you focus for a day you will find lots and lots. Imagine if you focus for a month and so on. Work this logic.

[harry]

Hello All

I have read
http://curious.astro.cornell.edu/questi ... number=575

THat is total rubbish.

[Orca]

Yep Harry, that article is indeed Rubbish. Someone needs to read up on GR.

As for the model I was describing, it's just some of the 'logical battles' early astronomers wrestled with their limited knowledge of the universe.

But, I don't buy into the idea of an infinite universe, or one that somehow conjures up matter for new stars. Harry, in your model, if the universe is infinite, does it have infinite matter and therefore infinite energy? Or is it an infinite universe with a finite amount of matter that is created at a given rate (this rate, is it static or does it change?)

If it was an infinite universe with finite matter, I would imagine that without your "magic matter creation" mechanism, you'd end up with an infinite universe that suffered from heat death.