Question about the nature of light including relativity...?

Question

.. of course it seems to be a known fact that the speed of light c~299.000 m/sec is the ultimate speed limit of things.

Now regarding the outcome of experiments like the double-slit experiment which was like:
'obviously the photon knows which slit is open, and where the detector is'.. i would like to ask wether it's a little different.
Lets assume something CAN travel >c lets disregard and leave open WHERE and HOW .. but ...
Wouldn't be something travelling at >c would make us believe we observe something traveling at a finite speed in the opposite direction ?
Possibly making us believe it acts like knowing the setup, cause it already passed through in the opposite direction for example ?

yes i know about Quantumn entanglement, i know Feynmans QED, i therefor know about retarded and advanced particles.
about information cannot travel in excess of c i disagree, this was already shown by Niemtz et al. but this wasn't my question. I just rememered something i saw on BBC where a car approached a traffic light. And they showed what would happen if it would travel faster than light thus making it appear travelling backward, for the outstanding observer. This makes me think photons (or better photons as tachyons) could do the trick in a similar way. I'm fully aware that this possibly hurts any standard physics, but i see physics as i kind of playground for ideas and this one does not seem too bad, not to clue around on it, na ? sooo any idea ?

Answer 1

First, it's 299,000 KM/sec, not m/sec.

Then, stranger things than that occur in quantum mechanics. And light photons (and all the other EM quanta) are the packets of one of nature's four fundamental forces. So light is truly a quantum force in our universe.

Have you heard of quantum entanglement for example? This is really strange stuff where two quanta meet one night, dance and fool around with each other for a brief moment, and then separate and go on their merry way.

But now you can't tell one from the other...they are identical in every way...including by what they do and experience. They have become like the identical twins in SciFi where one twin feels what the other one feels, and vice versa. And like these twins what happens to one quantum instantaneously happens to the other one...no speed of light limitation. Ah ha...v>c.

Now let's look at another little strange stuff from the world of quantum mechanics...jitter. Quanta are nervous little bits that keep popping into and out of places. When we try to measure where they are, we cannot measure their momenta. When we try to measure their momenta, we can't measure their location. They are skittish.

Some physicists posit that quanta can come and go anywhere in the universe. Imagine, a quantum, like a light photon, might blink out on Earth, and reappear instantaneouly on the planet Mongol half way across the universe. And that too is instantaneous ... faster than light speed.

By the way, quantum entanglement is more than just theory. Physicist have recently done a kind of teleportation using quantum entanglement. [See source.]

So who knows, what you suggest might someday become fact. We are just beginning to scratch the surface of our universe and its mysteries.

PS: When information is exchanged instantaneously del t = 0 and since velocity = del S/del t, where S is some distance over which the info is exchanged, velocity is undetermined (aka infinite). To my way of thinking, infinity >>>> c, the speed of light.

Answer 2

I myself am not so sure that the speed of light is the stops limit on travel ;) but to answer your question something traveling at faster then the speed of light would be very hard to detect and im not really sure how you would observe such a thing. Maybe it would leave behind a boom of light so 2 speak and that wave would look diferent depending on where you looking at it from. Lets say you look at it from behind the object moving faster then the speed of light. All the light infront of this object would get pushed or actualy Really Really rammed into a somewhat forward direction going away from where you are looking. Of course this would probably also make a light sucking vaccume causeing some of the light around the objects path to be pulled somewhat backwards and in on itself making the object apear to be traveling backwards kinda like a stream. So the object would apear to be moving backwards and fowards inwards outwards in all directions at the same time depending on where your viewing it from. Heh sound like warp speed 11 on star trek or something.

Answer 3

Think of c as the speed limit on information, whether it be classical or quantum. If we abandon this assumption, we are introducing a number of unphysical paradoxes (like time travel).

Someone also mentioned teleportation. This is just a fancy name from a protocol in which someone can transmitted a bit of quantum information by transmitting two bits of classical information. No faster than light signalling here.