light speed and time travel? Is this any connection betwen?

[radek31]

I wonder about one think, try to imagine situation like this :<br /><br />1 person stands on the moon (or some other planet without any atmosphere) and starts run with some speed around this planet, after some time he will reach the starts point again, right? for now sounds normal <img src="/images/icons/smile.gif" />) but what will be, when he will increase his speed into the point when he will overtake himself....? What will happen?? Does he back in time passing himself and seeing his start which doesn't even act?? what speed he needs to do this? Does it possible to explaine in any science way? <br /> Please, share with me some knowledge about it.<br /><br />Sorry my bad english, it is not my mother language.<br /><br />Radek

 

[kelvinzero]

I typed "Why FTL implies time travel" into google and found of all things a website titled 'Why FTL implies time travel' <img src="/images/icons/smile.gif" /><br /><br />http://sheol.org/throopw/tachyon-pistols.html<br /><br />(FTL stands for Faster Than Light)<br /><br />I also submitted my own explanation in a thread around here somewhere.

 

[qzzq]

Hi radek,<br /><br />You posted: --<i>but what will be, when he will increase his speed into the point when he will overtake himself....?</i><br /><br />Well, at no speed does he overtake himself; running in circles, he'd be speeding away from himself as fast as he would be overtaking himself. He would not be closing in on himself whatsoever. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

 

[wurf]

He could never overtake himself, but at some speed would he be able to look ahead and see the back of his own body?

 

[qzzq]

Well, I think radek's point is; a what point does he overtake the photons bouncing off himself? The photons that make him visible? Of course he can not overtake himself, unless he splits up into two 'selfs'. <br /><br />Say the planet's circumference is exactly the distance a photon travels in a single second: 300,000,000 meters. (We're talking about quite a big planet, about twice the size of Uranus). If he would run that distance in one second, he would travel at the speed of light, and he would be back at the place he started. The photon's bouncing off him at the start would be 300,000,000 meters away though after only that one second - almost the distance from the Earth to the Moon. So he would have to go a lot faster to catch one of those 'bouncing photons'. If he traveled the distance at 300,000,000 times light speed, he would arrive at his starting point in 1/300,000,000 of a second and the 'bouncing photons' would have traveled only a meter. Then he would thus see himself walking in front of him at a distance of 1 meter. The faster you go, the smaller that distance gets. <br /><br />Of course in a single second, and at that (ludicrous) speed, he would travel the circumference of the planet 300,000,000 times. I guess he would see as many images of himself running? Everywhere in his path? Looking ahead and back? <br /><br />Um.... <img src="/images/icons/crazy.gif" /> <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

 

[weeman]

Radek, I give you a big pat on the back for giving your best shot at typing this in english <img src="/images/icons/smile.gif" /><br /><br />The idea of light speed and time travel being intertwined, is one thing that Einstein tried to understand throughout his entire life. <br /><br />If a man runs on the planet fast enough, he may (hypothetically speaking) reach a speed that is faster than light. I say that this is hypothetical because faster than light travel is impossible, with our present day knowledge <img src="/images/icons/wink.gif" /><br /><br />Einstein's equations are undeniable evidence that Mankind will never achieve lightspeed through manmade spacecraft. The reason is this, for an object to reach light speed it must have infinite energy? So, how do you obtain infinite energy? You can't, because it is infinity. Furthermore, even if an object were to reach lightspeed, it couldn't travel faster than light because it already has infinite mass. How can you have a mass that is more than infinity? You can't. <br /><br />Anyways, faster than light travel states that if the man were running faster than light, he would arrive at this destination before he left. So, if he had a starting line on the planet, and traveled faster than light, he could run around the planet and arrive back at the starting line before he even left!!<br /><br /> <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

 

[wurf]

"Anyways, faster than light travel states that if the man were running faster than light, he would arrive at this destination before he left."<br /><br />I've seen this statement often. Why is this so? Light travels fast enough to circle the Earth 7 times in one second. If the man ran a little faster, say fast enough to circle the Earth 8 times in one second, why does that necessarily mean he will arrive where he started before he left? At 7 revolutions per second, light doesn't arrive before it leaves, why would it do so at 8 r.p.s.?