Thread: Does E=mc2 really make sense?

We had learn to calculate nuclear energy in science school using E=mc2 equation and the answer in joules. but does it really make sense that the real energy level it emited? Albert Einstein write this equation just to amaze the people how intense the energy of the nuclear atomic particle can give out. He just simply put the equation as enormous as possible by using the speed of light because he just thinking the long number of speed of light it can given in meter length, then raise the power of 2 to make it even astounding.

If you really wanted to find the exact answer of energy in joule the atomic energy can give out, E=mc2 really cant give you the correct or exact answer, unlike 1+1=2 , E may not given by mc2. it all depends on particle quality, temperature, pressure, humidity level, source of origin, impurity content, ways of particle interaction with each other,proximity or distance of particle, speed of particles and so on.

needless to say more, Albert Einstein also can put E=mc3 or even mc4 as he like to indicate the powerful energy it emit, it just a symbolic, it doen't intended to give accurate energy level. If one really wanna to find the real energy the particles can give out, there must be a very long complicated equation that God knows.

So just forget it to put in the school text book to let the student calculate the energy level, it just waste of resource and make student more stupid. Just like we all have studied that our solar system have 9 planet and it proven wrong when Pluto is not a planet recently. the knowledge we acquired may not true, perhaps some more planet wil join in from outer space when its path stray within our solar system in distant future.

just tell you all frankly, even Albert Einstein don't use E=mc2 to calculate the atomic bomb energy in joules that bomb Japan... so how dare you all using that equation so seriously in school to calculate energy?

im sorry. where did u get the idea that he didnt? and no, he was not the one who proposed nor i doubt the one who did the equations. he's being linked to the atomic bomb was due to his clout back then with the US and the scientist who thought of the bomb needed someone with great credentials to support his idea. hence the common mistake of linking einstein with the A bomb. i think u can check this idea up with history texts and several science texts (like how i did).

secondly. was not conceived out of thin air. may i first ask at what level are u studying? the equation is just a summary of a very long series of proofs which he did. hence the very short equation. though i may not be a physics student (at this juncture i recommend that u divert this to the physics forum) im very sure each physics equation has its relevant proofs and are not abstract in themselves.

that said, i cant comment on the units in question (and energy can be stated in many ways as concentration too in chemistry terms) but i think that ure points raised regarding the environmental/surrounding factors would have some effect in the calculations.

and im hoping the 'famed' WM does not happen to chance upon this post least another barrage of nonsense...

What is taught in science today is probably in no way close to being 100 % correct. I guess that’s the nature of science, it’s to be challenged. But what is true is that what is being taught has been credited and is most of the time been peer reviewed and is the best we have at the moment of going to print.

Your argument is that the equation is not valid, am I right? I’m no physicist and I probably never will be, but what I have been taught about the equation has been credited and shown to be right (or so I assume, if I was to research everything I am taught I’d never graduate ). Until that time, when a bright spark shows other otherwise we have to assume its right. Your argument can’t be based on much scientific proof or else I would have seen it on the news over breakfast.

I suggest you look at the theory and come back and try to argue with the physics crew if you still think you can.

If it’s your argument about teaching science you want to talk about, and I guess your point regarding teaching material in class rooms is somewhat valid, then I suggest you repost (a more clear and to the point) topic in the education section.

Damien

Originally Posted by albert chong

given in meter length, then times 2

It's not multiplied by 2, it is raised to the second power. Do the units make sense now?

Originally Posted by albert chong

We had learn to calculate nuclear energy in science school using E=mc2 equation and the answer in joules. but does it really make sense that the real energy level it emited? Albert Einstein write this equation just to amaze the people how intense the energy of the nuclear atomic particle can give out. He just simply put the equation as enormous as possible by using the speed of light because he just thinking the long number of speed of light it can given in meter length, then raise the power of 2 to make it even astounding.

If you really wanted to find the exact answer of energy in joule the atomic energy can give out, E=mc2 really cant give you the correct or exact answer, unlike 1+1=2 , E may not given by mc2. it all depends on particle quality, temperature, pressure, humidity level, source of origin, impurity content, ways of particle interaction with each other,proximity or distance of particle, speed of particles and so on.

needless to say more, Albert Einstein also can put E=mc3 or even mc4 as he like to indicate the powerful energy it emit, it just a symbolic, it doen't intended to give accurate energy level.

Your idea of how science works is obviously very screwed up. Do you really think that Einstein just threw out "E=mc^2" without explaining exactly how he got it, and everyone just took his word for it?

Of course we all realize that "2+2=4" was only meant figuratively. It's amazing how many people take it literally when counting their money.

E=mc^2 does calcuate energy accurately, what reason do you have to think it doesn't? It is used to accurately calculate the energy given out during nuclear reactions, and recently the success of 'lattice qcd' also points to einsteins equation being bang on.

Read 'Asimov's new guide to science', by Isaac Asimov, pages 876-884. There is a decent explanation as to how the rule was worked out.

is it just me, or are there a bunch of small mistakes in the equations in that book? It generally makes sense, but every now and then he has something random thrown in, that isnt there in the next line of working...

I'm pretty sure mass is lost in fusion reactions, and probably fission reactions. If the amount of energy gained from these reactions were not equal to c^2 multiplied by the mass lost, that would seem to be a refutation of the this equation. That said I think we'd know if it was false (because it seems pretty simple to disprove).

Originally Posted by Golkarian

I'm pretty sure mass is lost in fusion reactions, and probably fission reactions. If the amount of energy gained from these reactions were not equal to c^2 multiplied by the mass lost, that would seem to be a refutation of the this equation. That said I think we'd know if it was false (because it seems pretty simple to disprove).

This is what they use e=mc^2 to calculate, and it gives the right answer. It calculates the energy difference before and after a nuclear fusion reaction. The excess is the amount of energy given out, say when a nuclear fusion bomb goes off.

When mass travels faster than the speed of light - since the speed of light is as fast as anything can go - it will be converted into energy, due to Einstiens theory of relitivity. (there's a book called E=mc^2 that explains all of this in detail - by David Bodanis) anyway, the fact of the matter is, that when you actually measure the total energy is given off, and compare it to the equasion, you will get the same answer.

Originally Posted by albert chong

Albert Einstein write this equation just to amaze the people how intense the energy of the nuclear atomic particle can give out. He just simply put the equation as enormous as possible by using the speed of light because he just thinking the long number of speed of light it can given in meter length, then raise the power of 2 to make it even astounding.

This is not correct - see below

Einstein also can put E=mc3 or even mc4

No, absolutely not, it is a requirement of the mathematics.

Look. I paraphrase your man

Consider a material body B with energy content . Let B emit a "plane wave of light" for some fixed period of time = t. One easily sees that the energy content of B is reduced by , which depends only on t.

Let (i.e.the light energy "withdrawn" from B).

Now, says Einstein, consider the situation from the perspective some observer moving uniformly at velocity = v with respect to B. Then, evidently, by Lorentz time dilation, L' depends only on t', which is .

The difference between L and L' is simply . By expanding as a Taylor series, and dropping terms of order higher than 2 in v/c, he finds that

.

Einstein now says something like this: the above is an equation for the differential energy of a body in relative motion; but so is , the equation for kinetic energy - these can only differ by an irrelevant additive constant, so, by simple substitution, set

and then .

But, says he, L is simply a "quantity" of energy, light is this case, that now depends only on m and so......

.

To see the man in action, look here http://dbserv.ihep.su/~elan/src/einstein05c/eng.pdf

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