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  • 04-07-2008 8:58pm
    #1
    Kevster
    Closed Accounts Posts: 2,980 ✭✭✭


    Hi,

    I consider myself well-up on most cosmological concepts but there is one that I just CANNOT understand; and I'd appreciate any insight from anyone who knows here. Basically, it's the concept that states that if you travel at near to the speed of light away from Earth and then return, the time that you will have recorded as passing will be sbstantially less than the actual time that has passed on earth.

    I simply don't see how this can be AT ALL. For me, true time is universal, and has no bearing on how fast you travel here or there.

    I'm puzzled.

    Kevin


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    #2
    Spear
    Moderators, Computer Games Moderators, Technology & Internet Moderators, Help & Feedback Category Moderators Posts: 25,271 CMod ✭✭✭✭Spear


    Kevster wrote: »
    Hi,

    I consider myself well-up on most cosmological concepts but there is one that I just CANNOT understand; and I'd appreciate any insight from anyone who knows here. Basically, it's the concept that states that if you travel at near to the speed of light away from Earth and then return, the time that you will have recorded as passing will be sbstantially less than the actual time that has passed on earth.

    I simply don't see how this can be AT ALL. For me, true time is universal, and has no bearing on how fast you travel here or there.

    I'm puzzled.

    Kevin

    It's an effect or relativity called time dilation.


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    #3
    Kevster
    Closed Accounts Posts: 2,980 ✭✭✭Kevster


    I know that it's a consequence of relativity and, indeed, I have read much about it. I just don't see how it's possible at all though. I was hoping someone might be able to explain it to me in a different way.

    Kevin


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    #4
    Spear
    Moderators, Computer Games Moderators, Technology & Internet Moderators, Help & Feedback Category Moderators Posts: 25,271 CMod ✭✭✭✭Spear


    Kevster wrote: »
    I know that it's a consequence of relativity and, indeed, I have read much about it. I just don't see how it's possible at all though. I was hoping someone might be able to explain it to me in a different way.

    Kevin

    In much the same way as the three spatial dimensions, time is also relative to the observer.


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    #5
    Kevster
    Closed Accounts Posts: 2,980 ✭✭✭Kevster


    ... ...I know but I just can't imagine that. If I spend one hour on a spaceship tearing away from Earth at 50,000 km/h - and then turn back at the same speed - two hours will have passed for me and the same should have passed for you. If we had two timers, both would show two hours.

    Whilst time fits neatly into the equations as a dimension, I just don't see how it's a dimension, practically-speaking.

    ...grr, sorry! :p

    Kevin


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    #6
    slade_x
    Moderators, Science, Health & Environment Moderators Posts: 1,425 Mod ✭✭✭✭slade_x


    Kevster wrote: »
    ... ...I know but I just can't imagine that. If I spend one hour on a spaceship tearing away from Earth at 50,000 km/h - and then turn back at the same speed - two hours will have passed for me and the same should have passed for you. If we had two timers, both would show two hours.

    Whilst time fits neatly into the equations as a dimension, I just don't see how it's a dimension, practically-speaking.

    ...grr, sorry! :p

    Kevin

    Time slows with motion, but its only apparent to an observer not in motion relative to the object in motion

    One of the easiest examples i can see to grasp these concepts are to check out Special Relativity articles, once such article is sourced from howstuffworks

    In the section below an example like yours is given, someone travelling away from earth but with a reference at a speed where the dilation is obvious thanks to the doppler effect.

    Fun with special relativity:
    http://science.howstuffworks.com/relativity14.htm

    Its best if you skim the entire article but if you dont want to read it all go from the section i just linked to right down to the twin paradox using simultaneous events


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    #7
    bogwalrus
    Registered Users Posts: 1,454 ✭✭✭bogwalrus


    good article. Simple enough for me to get my head around. Now i finally know what that whole "frame of reference" thing is about.:)


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    #8
    Nutlog!!!
    Closed Accounts Posts: 59 ✭✭Nutlog!!!


    Hi, I'm a newbie to this forum, but have always had a fasscination with special and general relativity, and the concept of relativity in general. Here's another way of visualising the process of time dilation:

    http://www.squidoo.com/relativity_explanation

    Scroll down for to the 'time clock' section! :cool:

    An interesting topic is also how time dilation affects the principle of the conservation of energy. Quanta of energy travel at or near the speed of light, therefore time relative to them is slow. I know that relativity has a tendancy to break down at the quantum level, but just a random thought...any other random thoughts?


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