Why Not Just E=mc?by thykingdombutt Tags: None 

#1
Jan614, 11:07 AM

P: 3

I know E=mc^{2} essentially means energy = mass. One might think why not just say E = m?
But I also know that: Every object travels through space and time at the speed of light. So now one might think why not just E=mc? That's essentially where I'm stuck at now. I'm not sure why it's necessary to ^{2} the c. I know that light waves only travel at right angles, but I don't know if that has any relevance to the formula. 



#2
Jan614, 11:21 AM

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Look at the units and tell me what happens with E=mc.




#3
Jan614, 11:50 AM

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#4
Jan714, 09:40 PM

P: 53

Why Not Just E=mc?
Common misconception: Everything does not necessarily travel at the speed of light. Everything's proper velocity's magnitude is c (under only the influence of gravity? I think).
E=mc^2 wasn't a guess. It was derived by a thought experiment of Einstein's and described in his paper "Does the Inertia of a Body Depend upon its Energy Content." There he found that with a discrepancy between the measurements of mass between multiple inertial reference frames is that the measured difference is E/c^2. In other words m=E/c^2 or E=mc^2. 



#5
Jan814, 02:17 PM

P: 3

Another thought I had that might help me understand this, what does Einstein mean by "energy"? Energy is defined different based on type (kinetic, potential, mechanical, electric, etcetera). I read his paper but he refers to it mostly in general.




#6
Jan814, 02:32 PM

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#7
Jan814, 02:33 PM

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#8
Jan1014, 03:29 AM

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#9
Jan1414, 03:17 PM

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Sorry for taking so long getting back to this thread. I wanted to do a lot more research and come back with more confidence. I'll discuss my current thoughts now.
I think the reason mass is multiplied by the speed of light (as opposed to the speed of sound or some other variable) is because light in a vacuum is constant and so can give you precise reliable numbers to work with. I think the reason the speed of light is squared has to do with the nature of momentum: To move a given object twice as fast for example, wouldn't take twice the energy/work but rather 4 times, thrice as fast 9 times, etcetera. 



#10
Jan1414, 03:40 PM

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See, for instance dimensional analysis http://en.wikipedia.org/wiki/Dimensional_analysis. Then try visiting Google calculator, and typing in the expression kg * (meter per second)^2 = 



#11
Jan1514, 02:38 AM

P: 1

Isnt it because the energy released is equivalent to e=mc^2



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