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Thread: Noob questions ^^'

  1. #1 Noob questions ^^' 
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    Hi all,

    First of all, i have to tell you that i'm in my first year of engineering studies, so I'm a bit noob, OK ? ^^'. And the second thing is that i don't speak English very good, so excuse me if i speak strangely ...

    Well , i was studying a few days ago relativity, and today, i was thinking, (please correct me if I'm lost ^^):

    Radioactive atoms have a sort of "life", they're losing mass and we approximately know in how much time. So we can use them as a clock:

    With the modern instruments we can accelerate an atom to nearly speed of light,
    so if we take two radioactive atoms with exactly the same life, and we accelerate one of them at nearly speed of light, relativity tell us that the one who traveled at high speeds, will return "younger", with lower emitted radiation, that means it'll have traveled to the future.

    Is that correct, i mean, m I telling a stupidity xD ?
    And if it is; has this been done done yet ?


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  3. #2  
    Moderator Moderator Dishmaster's Avatar
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    In principle, this has been tested already. The test particle is a muon that has a well known half life as measured in the lab. It is produced in the Earth's upper atmosphere as a part of a reaction chain caused by cosmic particles.



    The experimental setup is shown here:
    http://hyperphysics.phy-astr.gsu.edu...iv/muonex.html
    http://hyperphysics.phy-astr.gsu.edu...ativ/muon.html

    Without relativistic effects, the life time of a muon is too short for it being able to reach the surface of the Earth. If you calculate the time it takes to reach the ground, it should have been decayed before it can be detected. But the fact that we do measure quite an amount of muons, it tells us that relativistic effects prolong its half life when being observed from our reference frame. If seen from the muon's perspective, the distance from its production in the upper atmosphere to the ground appears much smaller than we measure it.


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  4. #3  
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    Quote Originally Posted by Dishmaster
    In principle, this has been tested already. The test particle is a muon that has a well known half life as measured in the lab. It is produced in the Earth's upper atmosphere as a part of a reaction chain caused by cosmic particles.



    The experimental setup is shown here:
    http://hyperphysics.phy-astr.gsu.edu...iv/muonex.html
    http://hyperphysics.phy-astr.gsu.edu...ativ/muon.html

    Without relativistic effects, the life time of a muon is too short for it being able to reach the surface of the Earth. If you calculate the time it takes to reach the ground, it should have been decayed before it can be detected. But the fact that we do measure quite an amount of muons, it tells us that relativistic effects prolong its half life when being observed from our reference frame. If seen from the muon's perspective, the distance from its production in the upper atmosphere to the ground appears much smaller than we measure it.
    This same phenomenon recorded daily in particle accelrator experiments as well.
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  5. #4  
    Forum Masters Degree Twit of wit's Avatar
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    Quote Originally Posted by Dishmaster
    ... as measured in the lab.
    how?
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  6. #5  
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    Ok, thank you for your answer ^^. But can you tell me please what is the results?
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  7. #6  
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    Quote Originally Posted by Mentak
    Ok, thank you for your answer ^^. But can you tell me please what is the results?
    Exactly as predicted by special relativity.
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  8. #7  
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    Well, thank's a lot =) .
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  9. #8  
    Moderator Moderator Dishmaster's Avatar
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    Quote Originally Posted by Twit of wit
    Quote Originally Posted by Dishmaster
    ... as measured in the lab.
    how?
    Muons are produced in accelertor experiments in ample amounts. Their half life relative to their velocity can be measured with high accuracy.
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