Light's constant... isn't constant? Or is it?

According to some work light may be the result of direct violations in relativity, albiet small ones. It was recently published in Arxiv, and a write up is on Physorg.

The new results show that this description of light is a general feature of relativity violations and holds both in empty space and in the presence of gravity. "In this picture, light has a strange beauty, and its origin is tied into minuscule violations of Einstein's relativity in a profound and general way," Kostelecky said.

Miniscule or not, they are still violations. This some pretty interesting work... I haven't read through it all and digested it yet, but this could help explain some things if true.

funny you bring this up, i recently read an article pertaining to the speed of light and how it can be slown down. as a matter of fact two scientists at the stanford university accomplished this task using, nano-crystals to guide the photons through channels which vehimently slowed them. also gravity has a effect on the way light moves through the universe, bending and twisting along the slopes and curves of the distortion of the planets and terrestrial manifestions.

The speed of light is constant, it can neither be accelerated nor deccelerated. Experiments proclaiming to have slowed the speed of light are not pertaining to the speed of light per se, but rather its overall speed within a specific medium. Meaning, as a beam of light hits an atom it stimulates its electrons, causing them to rise from a ground state to an excited state; upon returning to their ground state they release this light energy(in which form whatever) which then proceeds to another atoms' electrons. All "slowing the speed of light" involves is delaying this process (extending the time from reception to emission of the beam of light by an atom's electrons). Again, this all takes place within the atoms. The speed of the beam of light between the individual atoms (vacuum) is always the same, namely ~300,000 km/s.
The experiment done involving certain photons allegedly exceeding the speed of light, which is a while back, had to do with their emergence on the other side of a glass(?) barrier before those not traversing the barrier at all. This was caused by the "detection part" of the -through glass(?) travelling- photon being shifted forward, thus making it seem as if the photon were faster than its non-traversing counterpart. However, even if this quantum tunneling had taken place in the fantastic way we all aspire it to have, the photon would still not have traveled faster than the speed of light intrinsically, as dissappearing on one side of a barrier and intantaneously appearing on the other side does not constitute the conventional definition of delta x(distance). In that context, quantum tunneling would have generally been the same effect as attributed to a wormhole; i.e., you don't travel the distance between two points but simply dissappear at one and appear at the other, instantaneously.
Nevertheless, information has been proven to travel "faster" than the speed of light. Take electron-pairs for example, changing the "spin" of one electron will instantaneously change the "spin" of the other electron within the same orbital, no matter what the distance between them.

[edit on 23-3-2005 by noyhcat]

Riddle me this:

We all know light can be bent by the gravity of stars, can it also be slowed and/or pushed by the same effect??

Example - light leaving our Sun must (should, could??) be affected by gravity of Sun as it leaves the gravity well and the Earth should exert a similar pull - no??

If you can bend it side to side, why can't you pull it for and aft....

My concern is about the constancy of c (the speed of light); as light goes into a denser medium than the medium it was previously travelling in, the light slows down and it bends as a cause of this. This seemed contradicting to me that the speed of light is constant and yet its speed varies in different mediums. Why isn't c constant in all mediums and does this variation of c in different mediums mean in anyway that time flows differently in different mediums

for information about 300 times the speed of light check
www.electrogravityphysics.com...
because it is really possble

Something else to consider - the early universe was much "denser" so the medium had to have an effect on the speed of light back then.... Well maybe that is and even today the universe is not quite an empty medium. For all practical purposes yes, but not quite....

In 1905, at the age of 26, Einstein published five of the most important papers in the history of science--all written in his "spare time." He proved that atoms and molecules existed. He argued that light came in little bits (later called "photons") and thus laid the foundation for quantum mechanics. He described his theory of special relativity: space and time were threads in a common fabric, he proposed, which could be bent, stretched and twisted. And oh, and by the way, E=mc2.

However

in in a book that he revised in 1952, Relativity: the special and general theory [20] on page 76 he makes his important statement - that in General relativity, the law of the constancy of the velocity of light in vacuo, which was a fundamental assumption in Special relativity, cannot claim any unlimited validity. And that Special relativity can only hold when there is no gravity affecting light paths. On page 93 he clarifies it further by saying that in General relativity the velocity of light depends on the coordinates of when a gravitational field is present. And that gravity defines the coordinates.

So, light speed is not constant !

The Einstein Conspiracy

Just a thought I found floating out there in the ether

Because light has no mass it is not attracted by gravity, it only appears to be bent because the medium (by a mass distorted space-time) it is travelling in is bent. Light travels the shortest distance between two points, if at least one of these points lie within bent space then the shortest distance is along this bend.

I read a theory on light a while back that I found very intruiging. I hardly understood it well enough to try to explain it to you guys, but to the best of my understanding, the guy claimed that light was a form of extradimensional energy, formed when the resonant energy of matter reaches a frequency high enough (or hot enough to emit light), it creates a sort of hole in the seperation between dimensions and that has something to do with why is has both properties of particles and waves. But heat from absorbed light is thought to be light trying to resonate the matter it is striking to it's 'escape' frequency. Light passes through our dimension like sunlight does through a clear pane of glass, the transparency of our dimension is caused by resonant, or heat energy, and as it passes through our dimension it leaves heat behind. I wish I had understood and retained the piece I read better. It made alot of sense to me.

Seems like the speed of light would be zero at some point in a black hole. If Black Hole gravity is enough to keep light from leaving it then light must come to a stop at some point before being pulled back inot the singularity. I am of course assuming that their is enough energy and things going on in a black hole were absent the gravity you would normaly have light being produced.


X

fairly sure that the distance from a black hole where this occurs is called the Schwartzchild radius.

BTW, the whole preceeding discussion about the constancy of the speed of light could be easily clarified if someone out there would pick up a modern physics or optics textbook (though Noyhcat already answered it quite well). Just look up 'n', the index of refraction. But hey, that's just me thinking out loud.

No matter how in depth we discuss this.....all theories relating to mass, time, space etc break down at the time of the big bang.........

Ultimately we know SQUAT.....

End of story.......

Not being an expert in this field, I defer to those stronger in this area than myself.

But in my opinion, the jury is still far from done with deliberations. Here is just one example. There are many more.

13 things that do not make sense

Not-so-constant constants
IN 1997 astronomer John Webb and his team at the University of New South Wales in Sydney analysed the light reaching Earth from distant quasars. On its 12-billion-year journey, the light had passed through interstellar clouds of metals such as iron, nickel and chromium, and the researchers found these atoms had absorbed some of the photons of quasar light - but not the ones they were expecting.

If the observations are correct, the only vaguely reasonable explanation is that a constant of physics called the fine structure constant, or alpha, had a different value at the time the light passed through the clouds.

But that's heresy. Alpha is an extremely important constant that determines how light interacts with matter - and it shouldn't be able to change. Its value depends on, among other things, the charge on the electron, the speed of light and Planck's constant. Could one of these really have changed?

No one in physics wanted to believe the measurements. Webb and his team have been trying for years to find an error in their results. But so far they have failed.

Webb's are not the only results that suggest something is missing from our understanding of alpha. A recent analysis of the only known natural nuclear reactor, which was active nearly 2 billion years ago at what is now Oklo in Gabon, also suggests something about light's interaction with matter has changed.

The ratio of certain radioactive isotopes produced within such a reactor depends on alpha, and so looking at the fission products left behind in the ground at Oklo provides a way to work out the value of the constant at the time of their formation. Using this method, Steve Lamoreaux and his colleagues at the Los Alamos National Laboratory in New Mexico suggest that alpha may have decreased by more than 4 per cent since Oklo started up (Physical Review D, vol 69, p 121701).

There are gainsayers who still dispute any change in alpha. Patrick Petitjean, an astronomer at the Institute of Astrophysics in Paris, led a team that analysed quasar light picked up by the Very Large Telescope (VLT) in Chile and found no evidence that alpha has changed. But Webb, who is now looking at the VLT measurements, says that they require a more complex analysis than Petitjean's team has carried out. Webb's group is working on that now, and may be in a position to declare the anomaly resolved - or not - later this year.

"It's difficult to say how long it's going to take," says team member Michael Murphy of the University of Cambridge. "The more we look at these new data, the more difficulties we see." But whatever the answer, the work will still be valuable. An analysis of the way light passes through distant molecular clouds will reveal more about how the elements were produced early in the universe's history.

When you hear the constant "c" as the speed of light, that's meant the speed of light in a vacuum. It moves slower when moving through media such as air, water, glass and diamond for example.

Originally posted by djohnsto77
When you hear the constant "c" as the speed of light, that's meant the speed of light in a vacuum. It moves slower when moving through media such as air, water, glass and diamond for example.

Yeah thats what I've always found very interesting about Photons. I wonder if there is a medium which would effectivly "speed" the Photons up? It seems that they are constrained by the medium in which they are travelling.

Listen, light does move slower through a medium. But its velocity is still 300,000 km/sec. Light always has the velocity of 300,000 km/sec. The only thing that makes it appear to have a lesser velocity, when moving through a medium, is the fact that it gets absorbed by the medium's atoms' electrons.
Picture this: A beam of light enters a meduim, it gets absorbed by the elctrons of an atom of this medium, these electrons rise to a higher energy state, then return to their previous energy state, thereby emitting the beam of light (again). This process is the only thing that takes the time to "decrease" light's velocity of c! Keep folowing me! "Decrease" because light's velocity in a medium is measured over a distance, which includes at least one atom of this medium. In the time light causes the elctrons of this atom to rise, and subsequently fall, it is not traveling! Thus atoms act as a sort of stopper for light. When the beam, then, gets emitted by the electrons of the atom that absorbed it, it travels to another atom of the medium which then absorbes the beam of light. After this atom's electrons have risen and fallen the beam of light gets emitted once again to travel to another atom of this medium, this process continues until the beam of light has traversed the medium. Now, when the beam of light is actually traveling, from atom to atom (or atom's electron(s) to atom's electron(s), doesn't matter) of the medium, it is traveling in a VACUUM (Yes in between atoms of any medium exists a vacuum!!!), so when tavelling from atom to atom light travels at 300,000 km/sec. "In fact light always travels at 300,000 km/sec", says noyhcat, I'll quote myself thank you very much.
An analogy: Think of a line of, let's say 10, people whose task it is to get a small rubber ball from one end of their line to the other. No. 1 starts and throws the ball to no.2 at 10mph, no.2 throws the ball to no.3 at 10 mph........These people take time to catch, turn, aim and throw, right? This is what atoms(of a medium) do; this is what happens in a medium; they catch, turn, aim and throw. Well, atoms don't turn and aim, but you get my drift. Now compare this to no.1 simply throwing the ball to no. 10. at 10 mph, this is what happens in a pure vacuum. While the ball is still traveling at 10 mph it gets to no.10 before the ball that is being thrown from no.1 to no.2 at 10 mph, from no.2 to no.3 at 10 mph,......Why you ask? Because you don't have the people inbetween that have to catch, turn, aim and throw! I hope this helps to clear up things.



[edit on 29-3-2005 by noyhcat]