Relativity Spinning Laser - The Dot is moving faster than the speed of light- do you see it?- PLEASE HELP!!?

Question

Imagine a laser pointer on a turntable. This turntable spins very fast, so that the point of light on the wall is moving faster than the speed of light. It is in a circular room. If you are standing in the room staring at one point, what do you see? If you are spinning with the turntable, what do you see?

Thanks so much!

Answer 1

Assuming that the laser is still able to escape the end of the pointer (technically, it would be diffused due to the light colliding with the side of the pointer as the pointer changes position), then all that would be seen is a very faint line that would circle the room. the pointer cannot create light at a faster rate, so light that would normally be focused on a single point would instead be spread all around the room, seemingly at once. Since the light coming from any one angle would be a mere fraction of the luminosity that the pointer usually puts out, you likely wouldn't even be able to see the line that the pointer was making.

If you were spinning with the pointer, not only would you not see the line or point, but the all the light of the room would seemingly mix when your eyes picked it up. (Again, assuming that your eye is able to process the information, which it couldn't, since the turn of your eye would cause the light to land against one side of the eye or the other, distorting the image.) What would be seen would likely be very close to white in every direction, assuming that a good mix of colors were in the room. Imagine a color wheel, and you'll see what I mean.

Answer 2

mmmmm....very interesting question.

After a little thought, I have come to the conclusion that the light emitted from the laser will be Constant (186,000 MPS) and if the turntable is spun fast enough so that the dot would exceed the speed of light, the actual photons emitted from the laser will not have time to reach the wall in a uniform, "straight" sweep and the dot will be trailing the beam on the wall along the same line produced at lessor speeds. Even a greater percentage of the light speed at the wall and the individual photons (and waves) will be spread even further behind and lagging behind the beam as they strike the wall at an ever increasing distance behind the conceptional "straight" beam - so there would result no solid entity moving along the wall at speeds exceeding light speed - the dot on the wall would fall further and further behind (at the speed of light) perhaps even being a few laps behind if the turntable were spun fast enough and the diameter of the room was great enough.
On the platter (and still alive?) this phenomenon would necessarily be much to fast for our eyes to process - and we would probably just see a faint streak with no discernible dot what so ever.

Answer 3

according to almighty relativity (compliments of mr. einstein), light will travel at light speed to the view of the observer regardless of the speed of the source which is emitting the light. also, nothing will exceed this speed because it requires infinite amounts of energy to propel something ever faster beyond the speed of light as energy turns to mass as per the famous equation E=mc^2. the "movement" of the dot of light is a consequence of how your eyes function, and is in reality an illusion. What you are seeing when the dot of light moves is a succession of photons striking your eye after being reflected from points on the wall of the room in a sequence determined by the motion of the turn table. Knowing this, regardless of whether you are spinning or not, if the turntable is moving really fast, you will see a thin circle of light around the room. I hope this answers your question.

Answer 4

You wouldn't.

For the table to be spinning fast enough to produce the effect, it would have to either spinning faster than the speed of light (mass can't do that) or distance the light is traveling to reach the wall would be too large to see the result.

That's my take, but then again, other effects would pull your body apart before either happened and I do realize its a thought experiment.

Another way of looking at it would be that assuming a massless table and a small room, nothing is actually traveling faster than light - the location on the wall of the beam isn't the actual light itself.

Nothing in relativity says for instance that space can't expand faster than light, only that mass cannot travel AT the speed of light. Its even mathematically possible for a particle to travel faster than light - a tachyon for instance.

A tachyon, in theory would be a particle that at zero energy, travels at infinite speed. Adding energy to a tachyon slows it down. It can never slow to the speed of light however and that's why we'd never see them from our perspective.

They are mathematical constructs, but still, its possible - physics is weird enough I think.

Heck, I don't know, I'm not a theoretical physicist!

Answer 5

did you know Einstein's theory of relativity? That if any object are to reach (if possible) near the speed of light or at the speed of light, time moves slower as the speed nears that of light. Now, since you know that...I bet you don't know that if anything are to surpass the speed of light, it will gain mass indefinitely and reach infinity as big, plus if you were spinning on that thing....you would've been killed in a second by the centripetal forces that is applied on you while you are spinning

Answer 6

As for the speed of the shadow being faster than the speed of your finger: you can illustrate this by using a flashlight in a darkened room. Shine the light on a wall, and hold your finger right next to the flashlight and wag your finger back and forth. Your finger might be moving at only 1 inch per second, but you'll see the shadow might move by several feet in the same time span. This is really because the ANGLE of the line joining the flashlight and your finger is changing rapidly. If you use a very distant "wall" (like the moon), the shadow could cross the whole face of the moon (2,000 miles) in one quick flick of your finger. If you can manage to flick your finger in about 5 milliseconds, then the shadow's speed (across the face of the moon) would be 2,000 miles/5msec, or about twice lightspeed. With a sufficiently sensitive telescope (theoretically) you could actually see the shadow race from Crater "A" to Crater "B" at faster than lightspeed. This doesn't violate the "faster than light" restriction in physics. That restriction doesn't actually state that NOTHING can exceed light speed; it really just says that no energy or information (no "signal") can exceed light speed. And in fact, there is no way your "shadow" experiment could be used to send a signal from Crater "A" to Crater "B" at faster than lightspeed. To illustrate this, imagine this thought experiment. Say some astronauts living in Crater "A" are baking some cookies, and they wish to inform their fellow astronauts in Crater "B" as SOON as the cookies are done. So their idea is to use the "fast shadow" technique, sending the shadow from "A" to "B" as soon as the bell rings on the oven. But to do this, they have to tell YOU (back on earth) when to wag your finger. So here's what happens: 1. The oven bell rings; 2. The astronaut's in "A" send you a message, "wag now!" but that message takes 1.3 seconds to reach you. 3. You wag your finger. But there's some light from your flashlight that was already on its way to the moon before you began the wag, so that contunues uninterrupted for another 1.3 seconds. 4. THEN the shadow actually begins its superluminal journey from "A" to "B". But now it's already 2.6 seconds since the oven bell rang. So the astronauts' hopes of communicating the signal to "B" at faster than light are already dashed. You can do the same thought experiment substituting an earth-based laser instead of a finger-shadow. In that case, it would still be 2.6 seconds between the time the oven bell rings and the time the laser spot begins to move across from "A" to "B".

Answer 7

When standing on the rooom, I see the objects which are focused by the light.

When spinning with turn table,I see the objects which are focused by the light.

Answer 8

isn't the light speed is moving more faster than speed of laser??
because,as we know,light moving more faster than others.
answer my question,plezz...

Answer 9

It is the same as if you were using a machine gun. That, you can picture. In fact it shows that Einstein was wrong.