G18 - you've sparked my interest and curiosity. Could you give me a link or an article that will delve into this proven, "traveling faster than light", phenomena that you speak of. I've read most of the theoretical BS out there and none of it moves me. Any solid information along these lines would be appreciated, Thanks j6.
j6p, The NEC Research Institute in Princeton, New Jersey conducted experiments in which pulses of light, in this case a laser, was sent racing through a chamber of gas about 300 times faster than the speed of light. It moved so fast that it appeared to exit from the chamber before it entered. God18 posted a couple links to it already in the first post, but there are many others if you look in a search engine
After looking into it further, the light can leave the chamber before it has finished entering because the cesium atoms change the properties of the light, allowing it to exit more quickly than in a vacuum.
"That which is great becomes greater after being less."
Posted 15 September 2003 - 12:24 AM
This is an interesting topic...
I just want to point something out to do with Homer's refutation to the gun being fired in the car.
Anyone who's taken Grade 12 physics should know a bit about vector relations; the fact that velocities are cumulative. What that means is this: say I can throw a ball at 70km/h, and I can run at 15km/h. If I run at top speed and then throw the ball, the total velocity of the ball relative to the ground will be the speed at which it is thrown, PLUS my running speed: 85km/h.
So, in fact, if we go with the car analogy, a gun fired from within the car would have a normal gunshot velocity relative to the car, but relative to the road its velocity would be the sum of the two. Theoretically, then, your headlights would be moving at twice the speed of light (however, they would not be - see below).
This also works the other way. If I run at 15km/h, and throw the ball behind me at 70km/h, its total velocity relative to the ground will be 55km/h.
This is the basic tenet of relativity (notice I say the speed of the ball *relative* to the ground/road). What makes a finite, fixed speed of light so important is that Einstein says that this phenomenon does *not* apply to light. No matter how fast you are moving in relation to a photon of light, it will *always* move at C, 180 000 m/s. Put another way, if you attach a searchlight to the nose of a rocket that moves at a speed close to C, the total velocity of the light form the searchlight is still C - NOT C + the speed of the rocket.
Also; God18 says that it's been proven that we can accelerate information faster than light. Am I right in presuming that you're talking about quantum engtanglement? For those who don't know, quantum entanglement describes a phenomenon where two quanta (photons, electrons, quarks and the like) are "entangled" such that a given property will be shared between the two.
Putting it simply, Quantum A and Quantum B each have a property called "spin". It can have one of two values: left, or right (for example). After having entangled the two quanta, if we measure the spin property of one quantum we will know the property of the other, because the two are entangled and thus always equal. So, if we learn Quantum A's spin property is "left", then automatically we know that B's spin is left as well.
The cool thing is that it doesn't matter how far apart the quanta are - because of the entanglement phenomenon we will always know one property by learning the other. Essentially this implies that if Quantum B is 5 million light-years away, we can gain the information of its spin property indirectly, and pretty much instantly, by measuring the spin of Quantum A.
While it seems that the information telling us the spin of Quantum B must be travelling faster than light (a lot faster, in this case) to get to us, that is in fact not the case. Because we're not measuring the spin of Quantum B directly (that is, we're not doing anything to B to figure out its spin), the information that tells us its spin valus is not in fact originating from the position of Quantum B. It's coming from Quantum A, which is right here in our lab where the speed of its information fully respects the laws of relativity.
It's good to realize that in these experiments, the only thing that's moved faster than C is light. So, if light can move faster than light, what does that change about relativity? Essentially nothing yet. We may find that we can move light at any arbitrary speed, but that we can never reduce its *apparent* speed by increasing ours.
Personally, though, I'm gonna wait and see where this goes before I decide what I think of it.
Occam's Razor, It's good to see another member who enjoys discussions on physics
God18 wasn't refering to quantum entanglement. He was refering to photons being manipulated to going beyond light speed. Even that isn't accelerating information faster than light speed, as he stated. If God18 would have actually read the articles he posted links to, he would have understood that it is energy that has gone faster than light, and not information.
Although my examples/explanations aren't as technical as yours, they are as accurate. I was trying to avoid being too technical, and have been known to confuse others in the past. Hopefully your explanation can clear things up a bit better than mine.
"That which is great becomes greater after being less."
Posted 15 September 2003 - 06:33 AM
Merci beacoup, for the warm welcome, Homer.
While I grant that we needn't all be Physics majors to participate in this forum, I would personally welcome any attempt by any one of you to educate me in something I am not wholly familiar with - so too, I hope, is the general attitude here.
At the risk of treading on toes a bit early in the game, I have to again stress that your relativistic assertion regarding the car and the bullet are in fact incorrect.* Removing the consideration of light-speed from the example (and thus all scientific complications of that vein that may arise), if we were moving in ANY vehicle that was travelling significantly faster than a bullet, the bullet still would not be overtaken by us unless we are taking air-resistance into consideration. However, if we're considering air-resistance, then we would, in our self-powered vehicle, eventually catch up to the bullet regardless of how fast we are moving, because eventually the bullet would stop. In a vaccuum, though, the bullet's velocity would forever be that of the muzzle-velocity of the gun being fired PLUS the velocity of our vehicle.
Relating this to the topic of the discussion, the headlight example is equally incorrect, at least within the tenets of relativity (it would be premature to argue on the basis of these new discoveries just yet). I will be most happy to provide you with Einstein's original paper on Special and General Relativity, in PDF format, if that interests you at all. But once more, the special case of light is that its velocity is the same in all reference frames - whether I'm standing still, or moving at near-light speed, the speed of light in a vaccuum will always be C (and when you think about it, this has yet to be disproven even in the wake of these recent experiments). Thus, if we could accelerate a car to light speed and then swith on the headlights, they would illuminate nothing, because in order to get ahead of the car and thus shine ahead of it they would first have to accelerate faster than it.
Again, I do hope I'm not causing offense by choosing to differ; and if I am in fact mistaken in my own assertions, I would be quite interested to hear the underlying logic behind your own. Perhaps we can share ideas privately, if you feel the discussion is too technical for everyone else here - but then, who knows. They may be interested.
*The basic gist of your comment, that a bullet fired from a car moving at light speed would not outpace the car, IS correct, I do grant that.
Occam's Razor, No need to provide me with any materials, as they aren't neccesary at this time, but I do appreciate the offer.
I concede the bullet example to you. You are correct, and I am, in fact, incorrect. I failed to take into consideration that the bullet would never decelerate in a vacuum, and the idea was that the vehicle was traveling at the speed of light in a vacuum. Thank you for pointing that out to me, as I was considering wind resistance.
But in the headlights example, you didn't contradict anything I previously posted. In fact, what you said backed up what I said, only your wording is a bit more technical than mine.
if you turned on the cars headlights, since those lights would travel at the speed of light--ahead of the car. However that light would travel at the same speed as the car, and not any faster.
Please don't feel you are treading on toes here. This is very interesting stuff, and we are all interested in, and can learn from, your input. I'm sure your explanations weren't too technical, as mine are just not worded very good. I look forward to further discussions with you about this and other topics as well. Again, thank you for clearing that bullet example up for me.
An experiment in which a pulse of light shot into a tunnel went thorugh it so fast that it appeared to exit before it even entered. It was sent through 300 times faster than the speed of light. This all took place 3 years ago.
Since the speed of light is constant in a vacuum, the photons from the headlights can't 'outrun' the vehicle.
......and there lies the crux of the argument. The problem here is that we are basing our theories on the assumption that nothing can travel faster than light. If we fly a jet fighter at Mach 2....and then fire its nose mounted cannon, the bullets will leave the gun at a considerably higher velocity (relative to the Earth itself) than if they were fired from a static test stand.
Ok let me try to clear this up. Light travels at a constant speed in a vacuum, no more no less but it does slow down when confronted by an object. For the sake of brevity I'll refer you to the Michelson-Morley experiments and to Einstein's Special Theory of Relativity. I can give you a little tid bit here and it has to do with the property of matter and time. The faster you go the slower time travels for you and the more (condensed/flattened) you will get. So if I shine a light beam from a static position and you travel at two thirds the speed of light in the direction of the light beam time will slow for you so that one second elapses for me and 1/3 of a second elapsed for you. So the light will reach a point at the same time for both of us. Add to this that a moving object and space compresses along their direction of motion, you get that relative thingy. As for the faster than light experiment. I've read it and as I've said before it's too ambiguous. The way I interpret it is if you and I are running to a destination with a message and we are exactly the same speed but I am running against a head wind and you are not. You will reach the destination ahead of me but that doesn't make you faster even though you got our message there first. The key word in the example for me is: "the beam "appears" to leave the chamber before it enters." I'll stick with my belief that, "you can't get there before you leave here."