Questions about the Speed of Light

[tarchon]

Not sure I will sleep better to have learnt that though...

My main point was to reveal some major secret of the universe that has escaped the attention of the scientific community so far: at the speed of light time and space don't exist, and thus our universe is a vast holographic illusion with no substance.

Not exactly - velocity in Einsteinian relativity is essentially an interchange of space and time, so the speed of light is in some sense just the pivot point between being spacelike and being timelike for the direction of motion. Many things move at the speed of light and yet they're perfectly happy in spacetime. Einsteinian spacetime has 4 dimensions, and your velocity determines which dimension you see as time and which 3 you see as space, but observers in other reference frames pick a different time direction, even though they're still in the same overall spacetime.

 

[Gidien]

Unfortunately, Turanil, these are not new realizations (though they are pretty cool). I myself had these thoughs a few years ago and discussed them with my physics professor last semester. Just to add some more weirdness into the mix, as my prof pionted out: things that move fast get shorter, length contracted, as has been discussed. From the point of view of a photon going at the speed of light, it is standing still and the universe is the one that is moving (that's the whole point of relativity, you can claim to be the one standing still and all the laws of physics still work). In this case, it is the universe who's passage through time has slowed to nothing, and on top of that the whole universe is length contrated into a single 2D plane... so in the direction it is moving, the photon really would fill up the entire universe, instantaneously, which really isn't that hard anyway, since the universe no longer has size in that direction.

 

[azmodean]

You know, it would be an interesting day if we came to learn that the core concepts and ideas of physics we cling to end up being wrong and that the universe really isn't logical or rational at all...with Cthulhu and the Elder Gods out there waiting on us.

Actually this has happened to quite a few mathematicians when they were convinced of the... I think it's called the incompleteness theorem that states that no axiomatic system can prove itself. (sorry if my summary is innacurate, don't have the theorem in front of me) IIRC, many of them eventually killed themselves, and the initial cause can be traced back to the incompleteness theorem.

 

[bolen]

As an aside Mr. Hawking postulates that due to the Heisenberg Uncertainty Principle it is possible for subatomic particles, which have mass, to travel faster than the speed of light within the swartchchilde(sp?) radius of a black hole.

No Hawking radiation is NOT faster then light. It is caused by virtual pair production a the event horizon of the BH.

Or are you talking about the fact spacelike vectors change into timelike vectors inside the Schwarzschild radius?

 

[RangerWickett]

Hm. Do you recall the discovery in the past few years that, if you take two particles who have a matched, opposite spin, and you caused one to change direction, the other would change direction also, immediately, regardless of how far away it was, like the information was traveling faster than light?

What happens when you have one of these particles on earth, one on a spaceship, and the spaceship hypothetically reaches light speed? Time has stopped on the ship, so does the particle change or not? Can you change the particle on earth, or will it somehow become timeless? If the particle on the ship were set to turn off the light speed drive when it changed rotation direction, could you use that to return the ship to time?

 

[Warrior Poet]

All of which reminds me of one of my favorite bumper stickers:

186,000 miles per second: it's not just a good idea, it's the law!

Sorry. I have nothing intelligent to add to the conversation. I'm enjoying it, though. Thanks for the interesting posts!

Warrior Poet

 

[bolen]

Hm. Do you recall the discovery in the past few years that, if you take two particles who have a matched, opposite spin, and you caused one to change direction, the other would change direction also, immediately, regardless of how far away it was, like the information was traveling faster than light?

What happens when you have one of these particles on earth, one on a spaceship, and the spaceship hypothetically reaches light speed? Time has stopped on the ship, so does the particle change or not? Can you change the particle on earth, or will it somehow become timeless? If the particle on the ship were set to turn off the light speed drive when it changed rotation direction, could you use that to return the ship to time?

You are talking about entangled quantum states. go to http://en.wikipedia.org/wiki/Quantum_entanglement or
http://plato.stanford.edu/entries/qt-entangle/ as to what would happen if you go at light speed this is not an interesting question because physics forbids this and if you say "well physics could be wrong". I'd reply "well if your going to violate physical laws and then ask me what would happen. I would have to raise my shoulders and shrug"

 

[Ankh-Morpork Guard]

I'd reply "well if your going to violate physical laws and then ask me what would happen. I would have to raise my shoulders and shrug"

...but I thought laws couldn't be violated

Its an interesting idea, really. We set so much into these laws and what we say IS right, yet we really don't have anything beyond theory when it comes to the universe as a whole. Kind of seems to me that claiming these are unbreakable laws of physics would be like having lived away from rivers and natural water sources one's entire life and claiming that, due to this, the entire world is covered in land.

 

[Umbran]

Hm. Do you recall the discovery in the past few years that, if you take two particles who have a matched, opposite spin, and you caused one to change direction, the other would change direction also, immediately, regardless of how far away it was, like the information was traveling faster than light?

It isn't new at all. The Einstein-Rosen-Podolsky Paradox was recognized back in 1935.

Your description is a bit lacking in detail. IIt makes it sound as if you should be able to manipulate one particle, and have the other respond. That's not at all what happens. the "paradox" is instead that if you haven't yet made a measurement of a pair of entangled particles, and then you measure one of them, that information gets transmitted to the other particle seemingly instantaneously.

What happens when you have one of these particles on earth, one on a spaceship, and the spaceship hypothetically reaches light speed? Time has stopped on the ship, so does the particle change or not?

Another tree in the forest - if time is stopped on the ship, the people upon it cannot report what has happened with their particle, because making an observation and reporting it reporting takes time. Until they slow down, they cannot communicate with you, at which point they aren't moving at lightspeed, thus ruining the experiment.

 

[bolen]

Its an interesting idea, really. We set so much into these laws and what we say IS right, yet we really don't have anything beyond theory when it comes to the universe as a whole. Kind of seems to me that claiming these are unbreakable laws of physics would be like having lived away from rivers and natural water sources one's entire life and claiming that, due to this, the entire world is covered in land.

No relativity (both special and General) has been shown to be real in experiments.

- Atomic clocks have been placed in aircraft and shown to run slow

- Relativistic corrections are required for GPS satellites to work

- Accelerators require special relativity to work

- Black holes (while they obviously can not be seen directly) have been observed by their effect on other objects

- Gravity waves while not measured directly, have been shown to exist in the binary pulsar experiment.

If you are interested in this read Was Einstein Right by Clifford Will