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E=mc^2, but nothing can travel faster than light? 
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#1
Dec1111, 11:28 AM

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I tried to find an answer to this here, but may have missed it.
There must be a flaw in my understanding here, since it seems to be contradictory. Mass times the speed of light squared = Energy, and yet (according to Einstein), nothing can travel faster than the speed of light? I'm just curious also if anyone has a link handy, what is the equation that led to the famous e = mc^2 formula or are there a series of equations? 


#3
Dec1111, 11:48 AM

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Of course the speed of light squared is much faster than the speed of light, and yet nothing can go the speed of light (much less that speed squared). If c^2 is impossible, what is the use of the famous equation?
But I must be misunderstading something (or everything! :D). 


#4
Dec1111, 11:55 AM

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E=mc^2, but nothing can travel faster than light?
1. c^2 is not a speed. It has units of m^2 / sec^2, whereas speed has units of m/sec.
2. Even if it were a speed, simply because c^2 appears in an equation does not mean that anything is actually traveling at that speed. 


#5
Dec1111, 12:06 PM

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#6
Dec1111, 12:44 PM

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You're looking at an intermediate step in a calculation, not the input value. The input value is the speed of light, not the speed of light squared. You can also enter any actual speed into the equation and get the energy equivalent  but entering 10 m/sec means your object is moving at 10 m/sec not 100 m/sec (or m^2/s^2).



#7
Dec1411, 06:31 AM

P: 3,187

http://en.wikipedia.org/wiki/Electro..._wave_equation http://en.wikipedia.org/wiki/Impedance_of_free_space PS. the first (?) paper that precisely led to the massenergy equation is rather complex, but even reading it diagonally may give you a feeling for how it was done: http://www.fourmilab.ch/etexts/einstein/E_mc2/ 


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