Faster than the speed of light

[TeleMad]

GAHD: another thought; frequency is the distance between waves, is not the amplitude of those waves(the 'height') actually what dertermins the energy they posess?

 

The energy of a photon is proportional to its frequencey, not its amplitude. This is shown using Planck's ("simplified") equation, E = hf.

[TeleMad]

GAHD: another thought; frequency is the distance between waves, is not the amplitude of those waves(the 'height') actually what dertermins the energy they posess?

 

FreeThinker: The "height" is actually the density. There is a higher particle count in the "higher" parts of the wave and fewer in the lower parts. These waves are made up of oscillations in density count.

 

You appear to be describing compressional (longitudinal) waves, such as sound. But light and sound (and other compressional waves) are two very different things. First, light is a transverse wave whereas sound and other compressional waves are longitudinal. Second, light is an electromagnetic wave and requires no medium in order to propagate, unlike sound and other mechanical waves that do. There is no change in “particle density” for light waves in the sense that there is for compressional waves.

[erKa]

Read Fermi/Dirac light theoryb (Black body light source theory).Light is made of particles called photons having not rest mass. They could exist only by moving at the speed allowed by the media in which they are. Under a certain discrete value of kinetik energy (quantum) they cannot exists, over the quantum threshold they dissipate the surplus energy by "loosing time" (the drag exerted by the media causes this waving.. )in wider and wider wave motions. More the energy, higher the spectrum. There is a trick about the common sense of vacuum and sequentially about speed of light: the vacuum obtained on Earth' s laboratory is billions times more dense than the vacuum among galaxies. Now we know that the intergalactical space is fullfilled of matter, consequently it is not empty. As consequence we don't know what is the real maximum value of c. If I say that c could be twice than the actual reported, probably I am not a liar.

[alexander]

There havent been any hits on this topic for a while, but i got so me information on the speed of light, so i almost want to share...

Ok, it seems to me that a particle can not trave faster than a speed of light according to the current laws of physics, but that doesnt mean that it is not possible at all. Also, Bells therom basically states that interparticle interaction occurs faster than the speed of light. There was an experiment done on that, they took 2 particles rotating in the same direction, separated them, and while one was rotating, the other got charged negatively, and that same exact moment the particle that was not effected started rotating in a different direction. In other words, the sun was to just disappear, we would still see the light that is traveling from it for 8 minutes, but we would immediately stop feeling it's gravity.

[Tormod]

Hm...it was recently determined that the speed of gravity is the same as that of light. Do you have any sources I can check out?

 

We did a story about this research last year:

 

http://www.hypography.com/Article.cfm?id=33083

[Freethinker]

Originally posted by: alexander

In other words, the sun was to just disappear, we would still see the light that is traveling from it for 8 minutes, but we would immediately stop feeling it's gravity.

When Einstein developed General Relativity he asserted that gravity propogates at the speed of light. That it would take about the same period of time for the light and the gravitational effect from the sun to get to us.

 

You can actually see a nice animation of this from the PBS series "Elegant Universe" at:

 

http://www.pbs.org/wgbh/nova/elegant/program.html

 

then watch

 

"A New Picture of Gravity".

[Freethinker]

Tormod, get to bed!

[Tormod]

Yada, yada. Going NOW.

[Bo]

light and gravitons (the 'carriers' of gravitation) travel at the same speed (namely the speed of light);

The effect alexander refers to is called entanglement. And the subtle point there is that no causal influence is transmitted.

 

Bo

[Freethinker]

Originally posted by: Bo

The effect alexander refers to is called entanglement.

Entanglement is a function of particle pairs, is it not? It would not be involved with gravity or the speed of it's information propagation.

[Bo]

entanglement is about speed at which information is transmitted.

Relativity says that no causal information can be transmitted faster then the speed of light. (so also the gravitational influence cannot propagate faster then the speed of light).

But as said this is causal informtaion. By that i mean: some event A can happen, because earlier in time B happened. So B causally influences A. The central point is that upon time reversal, the proces doesn't work (so if A happens first, that doesnt mean that will happen later)

 

Now as for Bell's theorema:

 

Suppose we have 2 particles, A and B. And we know for sure that if one has spin up, the other has spin down and vice versa. (what spin exactly is, doesnt really matter here.)

Now QM says, that as long as we dont make the measurement, both particles are Both spin up AND spin down. (this is a typical QM effect; think also of schrodingers cat that is alive and dead at the same time)

 

So QM says that if we make a measurement on particle A we have 50% chance of measuring spin up and 50% of measuring spin down. But the same holds for particle B.

Now the point is, if we measure A(up) then IMMEDIATLY (so faster then the speed of light) the outcome for the measurement on B becomes B(down) instead of the 50-50 chance.

 

Many has been written on this subject (the so called EPR paradox) and i personally think the most sensible explanation uses the difference between causal influence and 'ethereal' (as my QM book calls it, i would prefer: 'the other one') influence.

As where relativity is about causal influence (events giving rise to other events), in the EPR paradox we dont have a causal influence. since causal influence is defined by the fact that the influence would be lost on time reversal, entanglement still works on time reversal. Because if we had first measured B(down) that would have forced A(down). this subtle difference with 'normal' influence makes entanglement special.

 

Bo

[Tormod]

Originally posted by: Bo

entanglement is about speed at which information is transmitted.

 

Good post, Bo. However I think it is important to point out that it is as yet impossible to transmit information via entangled particles. No one has managed to to this AFAIK, and any success in this area would dramatically revolutionize long-distance communication. Plus, as you mention, it would violate the speed of light.

[Bo]

hmm i think i have read something somewhere that they used entanglement to teleport the information of one atom to oanother one...

 

have to look that up

 

Bo

[Tormod]

Yes, what entanglement means is simply that any change made to one particle is instantly made to the second particle as well. The problem is to know which change has been made (polarity, spin, color, charge), and as you point out there are problems with reference (you mention up/down, which was discussed in an article in New Scientist recently).

 

Since information cannot travel faster than light (according to our current knowledge) entanglement is not the same as teleportation. It *looks* like it but it is not...it is, however, a mystery.

[Freethinker]

Originally posted by: Bo

entanglement is about speed at which information is transmitted.

...

Suppose we have 2 particles, A and B.

For clarification, my point was the particles A and B would need to be a quantum pair. Not just any two particles at random. I am not aware of any entanglement between non-pairs.

Now QM says, that as long as we dont make the measurement, both particles are Both spin up AND spin down. (this is a typical QM effect; think also of schrodingers cat that is alive and dead at the same time)

As far as the cat, is it not more correct to state, not that the cat is BOTH dead and alive, but it's state is not known? Not that the cat IS both, but that the probability of either is the same.

 

And as far as spin, is this a non-issue in a wave and like the determination of the cat, is not KNOWN/ established until wave collapse/ particle form?

[paultrr]

There is a bit of a term problem here when one defines FTL for entangled states. Yes, the correlation seems to exist at least at local testable scales where whatever information is being shared by the entangled pairs seems to communicate faster than normal C limited signals. However, an interest aspect of this comes with looking at the wavefunction spread at the Planck scale. At that scale, by quantum theory the wavefunction spreads out to infinity. If we define the local lightcone for any event by that wavefunction spread then C has become infinite at such a scale. As such, the signals being transfered are not actually exceeding C for the quantum frame of reference at all. I believe when one examines quantum theory the Planck scale rather forms a secondary frame of reference in which for all intents this frame acts like every point in space is connected with zero time passage for the frame itself.

 

To answer the question does this lways involved pairs created out of one particle I would refer one to certain articles on entangled particles being formed by not only Blackhole horizons, but also, motion itself in certain cases. These particles thus entangled are not one partricle forming two entangled pairs at all.

 

The real problem when it comes to entanglement is that all measurments of information being entangled has to be checked via normal lightcone limited paths(C limited). If one requires error correction through normal means then entanglement is not a path to send real information FTL. The only information usable via this path at the current time is what we would define as quantum information like spin, etc.

[paultrr]

The reference here to secondary frame is simular to that found in articles on DSR or Double Special Relativity. Yes, the idea underlines some aspects of the variable speed of light debate at present. But, here, its more of a quantum level frame versus our normal space-time frame. In the quantum frame information transfer speed is directly related to the wavefunction spread at the Planck scale, while in our frame C in a local vacuum state with a specified stress energy condition remains constant. At close examination one finds that even though signals there seem to transfer faster we can only general observe those signals via normal C limited paths.