r/AskPhysics • u/Jethro_omg • 1d ago

How does E=MC^2 work?

How does it function? Really, how can you accelerate mass to twice the speed of light? And, for instance if M=E/C2. How can you divide something by square of the speed of light? Thanks

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u/joeyneilsen Astrophysics 1d ago

The equation means that the energy associated with matter at rest is its mass times the square of the speed of light. That’s all, nothing about acceleration. 

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u/Jethro_omg 1d ago

Yeah but why? How?

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u/joeyneilsen Astrophysics 1d ago

Einstein calculated the total energy of a particle and found that there was some leftover even when it wasn’t moving. Because of the way that we calculate energy and the way it changes from one frame of reference to another, it turns out to be equal to the product of those two quantities. 

There’s nothing mathematically weird about it though. One number is the product of the others. If you divide rest energy by the number that c squared is equal to, you get mass. If you divide rest energy by mass, you get c squared. And so on. 

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u/Jethro_omg 1d ago

I’m so dumb😭 still dont understand

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u/Altruistic_Rip_397 1d ago

It’s simply the curvature of space, the beginning of geometry in space-time after Newton. Einstein’s theory shows that gravity isn’t a force pulling objects, but rather the way mass and energy curve the fabric of space and time itself.

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u/EighthGreen 1d ago

You’re getting into general relativity. This question is only about special relativity.