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Faster than the speed of light?
 Posted: 15 October 2007 09:42 AM [ Ignore ]
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Nothing can travel faster than the speed of light. Right? I imagine sitting on the sun and discovering that in about one minute the sun will explode and disappear. Now, it takes about eight minutes for light to travel to earth, and nothing, not even gravity, can move at a greater speed. This gives my fellow humans a little over eight minutes to act (eight minutes + the several seconds before the explosion). Can I warn them? No, I can’t. Any kind of communication would take more than eight minutes. But! What if I had a pencil long enough to reach the earth? (Already in place, ready to start writing.) The humans can read my message as I am writing it. Would this work? Could we say that in this case a thought would travel faster than the speed of light?

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 Posted: 15 October 2007 09:56 AM [ Ignore ]   [ # 1 ]
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Wouldn’t work. As you move your end of the pencil, a wave is created along its length. That wave can’t move faster than light.

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 Posted: 15 October 2007 10:03 AM [ Ignore ]   [ # 2 ]
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Why is there a wave created along the pencil’s length? What kind of a wave?

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 Posted: 15 October 2007 10:06 AM [ Ignore ]   [ # 3 ]
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Well, I’m not a physicist, but I imagine it’s a sort of pressure wave. If you hold a long piece of rubber, wood or even metal and move one end, you create a wave that propagates along its length. It’s easiest to see with string, because string is less rigid than wood or metal, but the result is largely the same.

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 Posted: 15 October 2007 10:15 AM [ Ignore ]   [ # 4 ]
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Okay.

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 Posted: 15 October 2007 12:01 PM [ Ignore ]   [ # 5 ]
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I think I would find it rather difficult to write anything that could be read with a pencil of that size. And I’m not sure how the different gravitational forces (and at ponts, lack of) would effect its movement.

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 Posted: 15 October 2007 12:06 PM [ Ignore ]   [ # 6 ]
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morgantj - 15 October 2007 12:01 PM

I think I would find it rather difficult to write anything that could be read with a pencil of that size. And I’m not sure how the different gravitational forces (and at ponts, lack of) would effect its movement.

Well, yes. There are lots of other insurmountable problems here. But I was using it as a sort of thought-experiment. There is no material so rigid as to move at the same time along its entire length. Motion has to propagate from molecule to molecule along its length, and the molecules are pulled along by electromagnetic forces between themselves. It wouldn’t propagate faster than the speed of light.

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 Posted: 15 October 2007 12:27 PM [ Ignore ]   [ # 7 ]
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what if the pencil is made of titanium?

PS: how is george avoiding the heat and radiation from the sun?

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 Posted: 15 October 2007 02:07 PM [ Ignore ]   [ # 8 ]
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dougsmith - 15 October 2007 12:06 PM

Motion has to propagate from molecule to molecule along its length, and the molecules are pulled along by electromagnetic forces between themselves.

This is interesting. Does this mean that the movement of my hand on sun, while writing the message, and the movement of the pencil’s end on Earth, while writing the message, wouldn’t happen simultaneously?

truthaddict - 15 October 2007 12:27 PM

what if the pencil is made of titanium?

PS: how is george avoiding the heat and radiation from the sun?

This is irrelevant, TA. There are millions of reasons why this wouldn’t work. What about the Earth spinning around its axis?

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 Posted: 15 October 2007 02:11 PM [ Ignore ]   [ # 9 ]
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George - 15 October 2007 02:07 PM
dougsmith - 15 October 2007 12:06 PM

Motion has to propagate from molecule to molecule along its length, and the molecules are pulled along by electromagnetic forces between themselves.

This is interesting. Does this mean that the movement of my hand on sun, while writing the message, and the movement of the pencil’s end on Earth, while writing the message, wouldn’t happen simultaneously?

Right, that’s what I’ve been saying. The motion would propagate in a wave along the length of the “pencil”, just like when you move a long rope or string, it doesn’t all move simultaneously, the bit in your hand moves first, it moves the stuff next to it, and so on and so on until the motion gets to the far end.

It’s all molecules pulling on each other.

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 Posted: 15 October 2007 02:18 PM [ Ignore ]   [ # 10 ]
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George - 15 October 2007 02:07 PM

What about the Earth spinning around its axis?

Whoa! Settle down there, Galileo. What are you trying to say?

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 Posted: 15 October 2007 02:18 PM [ Ignore ]   [ # 11 ]
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dougsmith - 15 October 2007 02:11 PM

the bit in your hand moves first, it moves the stuff next to it, and so on and so on until the motion gets to the far end.

It’s all molecules pulling on each other.

Thanks, Doug. I needed the explanation for a 5-year old to understand this. At least I can now tell about it to my kids. :grin:

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 Posted: 15 October 2007 08:57 PM [ Ignore ]   [ # 12 ]
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George, even if you could go through a wormhole so you ended up on earth instantaneously, what the hell are they going to do in eight minutes?  Besides, who’d believe you?

Occam

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 Posted: 16 October 2007 12:16 AM [ Ignore ]   [ # 13 ]
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Who would believe me? The Peruvians would: Behold Inti! The sun god. Our source of warmth and light and a protector of the people. After we would all run to Nazca, get out the rocket ships, and take off. (And Joe Nickell and Doug are not coming.)

[ Edited: 16 October 2007 12:20 AM by George ]
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 Posted: 16 October 2007 01:13 PM [ Ignore ]   [ # 14 ]
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This is incorrect, the movement of all points along the pencil would (more or less) simultaneously since the electrostatic attraction exchange particles are gamma photons generated as one charge moves within the field of another.  since the particles at your end are moveing, they move their neighbouring particles by means of exchange gamma photons travelling between them.  However, those particles are also moving relative to their nearest and are generating exchenge particles with them almost simultaneously.  The generating pairs will altenate along the length of the pencil simultaneously rather than sequentially because when a pair is repelling, the individual atoms that make up this system may be either attracting or repelling a neighbour on a different face.  So, yes George, in theory you could communicate faster than light in this way.

Incidentally some people think tacheons travel faster than light, but they tend to be people who think tacheons actually exist, whereupon I don’t have much time (no pun intended) for them.

As to gravity, I don’t think its wise to say that it travels, given the fact that the jury is still out as to what gravity actually is (mechanistically speaking).  However, the effects of gravity do appear to have no measurable delay at all; except in road runner cartoons when someone goes over the edge of a cliff.

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 Posted: 16 October 2007 01:19 PM [ Ignore ]   [ # 15 ]
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narwhol - 16 October 2007 01:13 PM

This is incorrect, the movement of all points along the pencil would (more or less) simultaneously since the electrostatic attraction exchange particles are gamma photons generated as one charge moves within the field of another.  since the particles at your end are moveing, they move their neighbouring particles by means of exchange gamma photons travelling between them.  However, those particles are also moving relative to their nearest and are generating exchenge particles with them almost simultaneously.  The generating pairs will altenate along the length of the pencil simultaneously rather than sequentially because when a pair is repelling, the individual atoms that make up this system may be either attracting or repelling a neighbour on a different face.  So, yes George, in theory you could communicate faster than light in this way.

Sorry, you’ve lost me there. And color me skeptical, since I don’t believe faster-than-light communication is possible.

How fast are these “gamma photons” moving along the pencil? Aren’t they moving at the speed of light? If so, then the “signal” (of motion) will travel down the pencil at the speed of light.

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