
#1
Jan913, 07:07 AM

P: 47

So when a moving object reaches the speed of light time dilates so I assume if an object that has mass somehow achieves the speed of light time stops moving (since it is travelling slower and slower) and once the object exceeds the speed of light time becomes negative so does that mean the object travels backwards in time? (I know this is impossible because we cannot create an infinite amount of energy but assume it is achievable)




#2
Jan913, 07:24 AM

P: 1,098

Would need to read about SR and specifically about metrics. Going "back in time" is just going back in coordinate time. Not same as travel back in time to 1905, like time travel scifi. In other words the clock on board your spaceship wouldn't start ticking backwards...just think of the paradox there you would just keep being forced back in time to the point you started to travel ....back in time. lol oh imagination 



#3
Jan913, 09:31 AM

Sci Advisor
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P: 2,957

You might, however, try searching the web, wikipedia, and this forum for "tachyons", which are hypothetical fasterthanlight particles with many interesting properties. Just be skeptical about the sources; there's a lot of oversimplified junk out there. 



#4
Jan913, 09:38 AM

P: 47

Question about travelling faster than light. 



#5
Jan913, 09:45 AM

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#6
Jan913, 09:52 AM

C. Spirit
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It depends on if you want to talk about observed reality as we know it now or possible pathological examples and also what you mean by "time travel". In a non time  orientable space  time you have point(s) where one cannot differentiate between future and past for example.




#7
Jan913, 10:12 AM

P: 266





#8
Jan913, 12:45 PM

P: 1,098





#9
Jan913, 12:52 PM

P: 266





#10
Jan913, 01:05 PM

P: 1,098





#11
Jan913, 01:29 PM

P: 849





#12
Jan913, 01:56 PM

P: 47





#13
Jan913, 03:38 PM

P: 849





#14
Jan913, 03:59 PM

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#15
Jan913, 04:13 PM

P: 849

Perhaps... I have never heard either of those as claims for why FTL in SR allows for time travel. Neither really is time travel. Not in the sense of the original post.
The notion I get from people and nonphysics students is that they take the fact that time dilates as you approach "c" and conculde that time stops at "c" and then goes backwards when you are over "c". This is an error of course and is usually how I see the time travel idea in SR justified. Look at the original post, "once the object exceeds the speed of light time becomes negative ". Confusing imaginary time with negative time is the source of his error. 



#16
Jan913, 04:17 PM

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FYI: I've never heard any other explanation than the above. Reputable books would never mention the nonsense argument you refer to. The above argument goes back a 100 years. 



#17
Jan913, 04:20 PM

P: 266





#18
Jan913, 04:20 PM

P: 849

I'm not talking about reputable books. I'm talking about nonreputable people (no offense to the original poster :P)



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