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Author Topic: Does time seem slower at the speed of light?  (Read 1480 times)

Offline thedoc

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Does time seem slower at the speed of light?
« on: 12/03/2012 09:05:01 »
Robert McDonald  asked the Naked Scientists:
   
Chris,

If someone is on a space ship travelling close to the speed of light, does time seem slower to the person? I am trying to understand if a person on a space ship is gone for 2 weeks and returns to Earth where say 2 years have passed, would it feel like only 2 weeks have passed on the space ship.  

Thank you.

Bob McDonald

What do you think?
« Last Edit: 12/03/2012 09:05:01 by _system »


 

Offline imatfaal

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Re: Does time seem slower at the speed of light?
« Reply #1 on: 12/03/2012 12:02:58 »
Yes it would feel as if two weeks had passed, because only two weeks would have passed on the spaceship!  From the perspective of on board the space ship: All the clocks would have kept normal time, chemical, nuclear, physical, biological processes would have taken a usual amount of time - as a human example, you would sleep about 14 times for 6-8 hours each time, you would eat and drink enough for about two weeks, your wind-up watch would require winding as many times as if you were on terra firma.  Until you looked out of a window and started measuring stuff you thought you knew - you could not tell (barring the time you were accelerating up to the speed and back down again) that you were moving quickly at all.
 

Offline CZARCAR

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Re: Does time seem slower at the speed of light?
« Reply #2 on: 13/03/2012 16:41:58 »
NO, ur metabolism has to maintain or u wouldn't see.........m
 

Offline Ęthelwulf

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Re: Does time seem slower at the speed of light?
« Reply #3 on: 13/03/2012 18:52:33 »
I am going to add a more technical note which will either leave you more confounded, or it will leave you more knowledgable about what is occurring here.

When, according to the postulates of relativity, when you move in any given volume of space, your normal understanding of three-dimensional objects are thrown out the window. Objects which move below the speed of light are called ''Bradyons'' - it has been a collectively acclaimed use for particles which have velocities below the speed of light and therefore having an inertia. These slow moving particles actually move more in the space dimensions more than they spend time in the temperal artefact (and dimension) of the metric of spacetime.

Only at higher speeds, speeds which are in fact significant can we consider pop-math buzzwords like time dilation and time warps. To have a significant effect on time, if indeed time is part of a classical theory, just like what relativity is, then it seems like we need to have either high speeds or high energy densities to achieve local frame dilation.

There is loads of things here which can be discussed but the OP has been answered.
 

Offline yor_on

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Re: Does time seem slower at the speed of light?
« Reply #4 on: 14/03/2012 04:28:20 »
hmm :)

Where ever you are Chris you 'move' in the same arrow locally.
Imagine the opposite.

I'm traveling really fast now (Buck Rogers) and look, I've already finished war and peace?  Tolstoy huh? that's nothing..
And hey, the second hand hasn't moved a iota??  Damn, am I a fast reader or what?

Don't think so :) What exactly would 'speed up' as 'time slows down'?
 

Offline imatfaal

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Re: Does time seem slower at the speed of light?
« Reply #5 on: 14/03/2012 10:28:55 »
I am going to add a more technical note which will either leave you more confounded, or it will leave you more knowledgable about what is occurring here.

When, according to the postulates of relativity, when you move in any given volume of space, your normal understanding of three-dimensional objects are thrown out the window. Objects which move below the speed of light are called ''Bradyons'' - it has been a collectively acclaimed use for particles which have velocities below the speed of light and therefore having an inertia. These slow moving particles actually move more in the space dimensions more than they spend time in the temperal artefact (and dimension) of the metric of spacetime.

Only at higher speeds, speeds which are in fact significant can we consider pop-math buzzwords like time dilation and time warps. To have a significant effect on time, if indeed time is part of a classical theory, just like what relativity is, then it seems like we need to have either high speeds or high energy densities to achieve local frame dilation.

There is loads of things here which can be discussed but the OP has been answered.

The postulates of special relativity are that the speed of light in vacuo is the same when measured from all inertial frames of reference, and the second is Galilean relativity ie that the laws of physics are the same in all inertial frames.  This second postulate directly contradicts what you have claimed.  General relativity is further based on the local factual reality of special relativity and the local equivalence principle.

 As all massive particles travel subluminally then bradyon is of little use except in highly theoretical physics when used to contrast with tachyons which do travel faster than light.  I am not sure what you mean by the last sentence - worldlines are in 4d space time, anything that moves in spatial dimensions only is travelling infinitely fast; this would be against most of modern physics.

Time is never dilated in the local frame so I cannot understand your last paragraph - time is only ever dilated relative to another frame; it is the difference in gravitational potential or the relative velocity between two frames that causes time dilation and never the absolute value in one frame
 

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Re: Does time seem slower at the speed of light?
« Reply #5 on: 14/03/2012 10:28:55 »

 

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