Break the speed of light
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19-11-2012, 02:53 PM (This post was last modified: 19-11-2012 03:07 PM by Phaedrus.)
Break the speed of light
Take a laser pointer, and go outside after dark. Find the moon. Wave your laser pointer back and forth across the surface of the moon.

The moon has a diameter of 3,475km
Light travels at 300,000km/s

If you wave your hand quickly enough you can traverse the angular section of the moon in 1/100 of a second

3,475 * 100 = 347,500 km/s

347,500 > 300,000

Congratulations, you've just sent one bit of information at faster than the speed of light. Drinking Beverage

E 2 = (mc 2)2 + (pc )2
614C → 714N + e + ̅νe
2 K(s) + 2 H2O(l) → 2 KOH(aq) + H2 (g) + 196 kJ/mol
It works, bitches.
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19-11-2012, 03:00 PM
RE: Break the speed of light
Uh, please show your work. Math - or it didn't happen.

"Whores perform the same function as priests, but far more thoroughly." - Robert A. Heinlein
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19-11-2012, 03:08 PM
RE: Break the speed of light
Edited for math, fixed a mistake, and simplified.


Of course, a typical laser pointer's beam will have spread to around 1000km across by the time it reaches the moon, so you don't get the pretty point of light racing across the surface at faster than light speed, but the principle is the same.

E 2 = (mc 2)2 + (pc )2
614C → 714N + e + ̅νe
2 K(s) + 2 H2O(l) → 2 KOH(aq) + H2 (g) + 196 kJ/mol
It works, bitches.
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19-11-2012, 03:15 PM
RE: Break the speed of light
No you didn't.

The light didn't move from one side of the moon to the other. It's not like there is a separate source of laser light on one side of the moon that is shining toward the other side.

The light actually originated from your laser pointer and moved at exactly the speed of light to one side the moon. You moved your hand and the light now is originating from your laser pointer and moving at exactly the speed of light to the other side of moon. In both cases the light travels from your device to the moon - it never travels from one side of the moon to the other.

I daresay if you conduct this as an experiment, set up two receivers on distant points of the moon with synchronized atomic clocks and build a pinpoint-precise robot to replace your hand with the laser pointer, then have your robot aim at one receiver and then in 1/100 of a second adjust its aim to the other one, you will find exactly the delay that you would expect - the length of time it takes the light to travel from the robot's laser to the moon's receiver, plus the 1/100 second delay as the robot was re-aimed.

"Whores perform the same function as priests, but far more thoroughly." - Robert A. Heinlein
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19-11-2012, 03:22 PM
RE: Break the speed of light
The point is that you move a packet of information from one point to another at faster than the speed of light, not that the photons themselves moved faster than light.

E 2 = (mc 2)2 + (pc )2
614C → 714N + e + ̅νe
2 K(s) + 2 H2O(l) → 2 KOH(aq) + H2 (g) + 196 kJ/mol
It works, bitches.
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19-11-2012, 03:31 PM
RE: Break the speed of light
No you didn't. The information (the red laser dot is information now?) did not move from Lunar point A to Lunar point B. It moved from laser pointer to Lunar point A, then 1/100th of a second later it moved from laser pointer to Lunar point B. Surely you can see that this is true?

"Whores perform the same function as priests, but far more thoroughly." - Robert A. Heinlein
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19-11-2012, 04:01 PM
RE: Break the speed of light
Because the same packet of information moved from the laser pointer to point A and to point B, 1/100th of a second and 3475km apart, the packet did in fact move faster than light. I see what you're trying to say, but the packet still exceeded lightspeed. Drinking Beverage

E 2 = (mc 2)2 + (pc )2
614C → 714N + e + ̅νe
2 K(s) + 2 H2O(l) → 2 KOH(aq) + H2 (g) + 196 kJ/mol
It works, bitches.
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19-11-2012, 04:26 PM (This post was last modified: 19-11-2012 04:38 PM by Aseptic Skeptic.)
RE: Break the speed of light
No, it did not. It only appears that way because you're not seeing the whole picture. In fact, your argument suggests to me that, in your mind, you see that little red dot moving across the lunar landscape at astonishing speeds, maybe with a lunar cat chasing it. I assure you, no such thing is happening (not just the cat, but also not the dot).

Let's break that down into milliseconds (ms).

Remember, it takes your laser light about 1,278 milliseconds to get from the earth to the moon.

You're aiming your laser at Lunar A (assume you've been pointing at this spot for long enough that your laser dot is on the lunar surface) and now you whip your hand over to Lunar B which takes 1/100th of a second, or 10 milliseconds. What happens in the first ms?

Well, the light that left your laser pointer 1 ms ago is still on its way to the moon. It hasn't reached the moon yet, but older light from before you moved your hand is already there causing the red dot to be visible at Lunar A. Now your pointer is aimed at some part of the moon 1/10th of the way from Lunar A to Lunar B, let's call it Lunar A1. The light leaving your laser pointer at this instant has not reached Lunar A1.

One ms later, the light that left your laser pointer 2 ms ago is still on the way, closer to the moon and Lunar A but not there yet, but older light from before you moved your hand is already there causing the red dot to be visible at Lunar A. The light that left your laser 1 ms ago is still on the way, closer to the moon and Lunar A1 but not there yet. Now you're pointing at a spot 1/5 of the way between Lunar A and Lunar B, let's call it Lunar A2. The light leaving your laser pointer at this instant has not reached Lunar A2.

And so on.

9 ms from the start of your experiment, the light that left your laser pointer 9 ms ago is still on the way, closer to the moon and Lunar A but not there yet, but older light from before you moved your hand is already there causing the red dot to be visible at Lunar A. The light that left your laser 8 ms ago is still on the way, closer to the moon and Lunar A1 but not there yet. Now you're pointing at a spot 9/10 of the way between Lunar A and Lunar B, let's call it Lunar A9. The light leaving your laser pointer at this instant has not reached Lunar A9.

10 ms from the start of your experiment, the light that left your laser pointer 10 ms ago is still on the way, closer to the moon and Lunar A but not there yet, but older light from before you moved your hand is already there causing the red dot to be visible at Lunar A. The light that left your laser 9 ms ago is still on the way, closer to the moon and Lunar A1 but not there yet. Now you're pointing at Lunar B. The light leaving your laser pointer at this instant has not reached Lunar B.

In fact, the light that is leaving your laser pointer right now will not reach Lunar B for 1,277 more milliseconds.

Someone sitting on the moon at Lunar A will still be observing your laser dot still aimed right at Lunar A. He won't even know you moved it for about 1,268 milliseconds. Someone sitting at Lunar A1, Lunar A2, etc., all the way up to and including Lunar B won't even see the dot yet.

Your imaginary information packet is still in transit - at this particular millisecond, it's about 300 KM away from the tip of your laser pointer, still a long, long way from the lunar surface.

"Whores perform the same function as priests, but far more thoroughly." - Robert A. Heinlein
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19-11-2012, 05:01 PM
RE: Break the speed of light
(19-11-2012 03:22 PM)Phaedrus Wrote:  The point is that you move a packet of information from one point to another at faster than the speed of light, not that the photons themselves moved faster than light.
That is a lot of work. You can just watch an episode of Star Trek if you want false information.
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21-11-2012, 11:37 PM
RE: Break the speed of light
(19-11-2012 03:31 PM)Aseptic Skeptic Wrote:  No you didn't. The information (the red laser dot is information now?) did not move from Lunar point A to Lunar point B. It moved from laser pointer to Lunar point A, then 1/100th of a second later it moved from laser pointer to Lunar point B. Surely you can see that this is true?


In this case the point of light can be considered information. Imagine way back before phones. In ancient rome they used fire on the tops of mountains to spread info faster than a human being can travel carrying it. There were many civilizations that did this. Now imagine that you have 2 settlements on the moon. Now imagine that one of our terrorist nations has a nuke heading for one each moon base. We knew it would happen, just not when. The point of light might only be saying "now", but if you aim at the one then drag to the other then that info did just travel across the moon at faster than light speed.
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