Why does e = mc^2?

Question

why can't the squareroot of e/m = c?

i was just seeing if people came up with stupid replies. read them and judge for yourself.

Answer 1

Here's the proof to e=mc^2

It is very clear.

http://www.drphysics.com/syllabus/energy/energy.html

Answer 2

Excellent question, but no easy answer. The speed of light squared is a big number, and I think the answer comes out in ergs or joules, or some such measure of energy. Without going into a lot of math (which I couldn't anyway, even if I wanted to), it's like the inverse square law. The brightness of a light bulb 2 feet away appears only 1/4 as bright (not 1/2 as bright) if you're 4 feet away. It just works that way. E=mc^2 has to do with the ratio of mass to energy. All mass is energy and if you convert mass to energy, the ratio is such that if you square the speed of light (in centimeter units/second) and multiply that times the mass (in grams), you get the energy amount (in ergs). I don't know how many ergs make a watt, or whatever, but you get the idea.

Answer 3

The equation is trying to figure out 'e', which is energy, not 'c', the speed of light. So, it is a better format to have 'e' be alone on one side of the equal sign. That way, when people want to calculate 'e', or energy, they don't have to do extra work to move numbers over. Your equation would work, but its format would make it harder to plug numbers in. So, the equation is e=mc^2 just to make it easier to use and more 'nice-looking' I suppose.

Hope this answers your question!

Answer 4

Are you asking for the mathematical derivation of Einstein's famous equation? If so, I think you need to Google or ask a univerisity level physics professor.

Or are you saying that you disagree and that the formula is not right? If so, what makes you say so? I think a lot of mathematicians have checked out Einstein's work without finding any mistakes....

As for your second question, I think c _is_ the square root of e over m, as you suggested. That's what I get when I get c by itself in the equation.

Answer 5

Because e = mc^2 is the precise way to express in a formula what Albert Einstein said in plain words.
He wanted to express energy in terms of mass, not the speed of light in terms of mas and energy.

Try to set up the wording for sqr of e/m = c.

Answer 6

E = mc2 is one of the most famous equations, even to non-physicists, and which states a relationship between energy (E), in whatever form, and mass (m). In this formula, c², the square of the speed of light in vacuum, is the conversion factor required to formally convert from units of mass to units of energy, i.e. the energy per unit mass. In unit specific terms, E (joules) = M (kilograms) multiplied by (299792458 m/s) 2.
The equation was first published in a slightly different formulation by Albert Einstein in 1905 in one of his famous articles. He derived it as a consequence of the special theory of relativity which he had proposed the same year.

Answer 7

This equation states a relationship between energy (E), in whatever form, and mass (m). In this formula, c², the square of the speed of light in vacuum, is the conversion factor required to formally convert from units of mass to units of energy, i.e. the energy per unit mass

Energy = Mass x (speed of light)²

The equation means the maximum amount of energy "obtainable" from an object to do active work, is the mass of the object multiplied by the square of the speed of light.

That's why....

Answer 8

You'd have to ask Einstein and his wife. They worked on that theory together. Too bad he got all the credit. Does anyone even KNOW that Einstein's wife was a physicist?

OK, I'm getting off my soap box now. I don't know the answer to your question so I thought I'd rant like a raving lunatic just for fun.

Answer 9

Kinetic energy of other things is E = !/2 m* v^2

no rest mass of a photon so it mass is from the kinetic energy
it moves at speed of light v = c
the 1/2 is from the integration and can be dropped with the right units

Answer 10

It does. Its called changing the subject of the formula. e=mc^2 is just more popular because thats how einstein introduced it to the world.

Answer 11

well that other way would be correct as well.

but c is equal to the speed of light, which we already know. Usually when people use this equation they are trying to solve for "e" or "energy". Since "c" is already a constant, and we are usually given mass, then it makes more sense to solve this equation in terms of "e"