Derivation of E=mc²

[myaccount3009]

a photon is massless and yet it has energy and momentum. For example, heat is a kind of energy, needs a medium to transfer though: that is understandable. So, is that the photon the only creature that does not interact to gravity so that we cant measure its mass? yet photons somehow respond to electromagnetic fields, as a light beam bends when it passes throughout an electromagnetic field. electromagnetic fields confirmed to create gravity, yet the photon does not respond to it! Kill me 

[myaccount3009]

i wonder why scientists have different derivations for the E=MC^2, i have seen a lot of derivations that are totally different in mathematics, but ending at E=MC^2. So, what is the Einstine's version?! any answer? thanks

[esraretin]

energy kinetic = 1/2 mv^2 so if particules of atom moves with c so formula would be e=mc^2 if u ask for 1/2 i dont know...:) it was just ajoke not serious

[TheDeLoreanFlux]

@esraretin E=mc^2 is actually from a more updated theory (special relativity) than EK=1/2 mv^2.

In relativity EK = mc^2/sqrt(1-v^2/c^2) - mc^2. You need to know calculus to show this, but if you take v as being much less than c, you get EK = 1/2 mv^2 approximately. Wikipedia is pretty good with math/physics stuff, check it out.

[esraretin]

@TheDeLoreanFlux yes i know i investigated derivation of time dilation on wikipedia but i could never fully understand it . e.g. can u imagine the one on train see the ligth beam in an even vertical line? this is a bit strange to me.if we could choose a particular photon , it woud be seen throught the same path as observer and passenger right? so check the beginning part of derivation of time dilation out on wikipedia.i have no problem with triangle calculation but i couldt get its basis

[live4Cha]

Doesn't make sense! We assumed for photon mass m and we can measure the E which is the energy of photon (p = E/c). Now this leads to E = mc^2! funny!!!

[3053767]

E= F x S

E= kgm/s^2 x m

E=kgm^2/s^2

E=kg(m/s)^2

m/s= velocity

speed of pure E = speed of light

hence E=kg(C)^2

i.e. E=MC^2

[professor314]

MC Hawking is the best.

[tonyzero9200]

Actually that doesn't work, damn

[tonyzero9200]

The algebra at 0.57sec is not correct. Simplifying this expression M(^x) = -m(L). I think that ^x should be negative, remember conservation of momentum is equal and opposite, Pphoton = -Pbox. If you make ^x negative, or M(^x) negative the algebra is correct.

[TheDeLoreanFlux]

@tonyzero9200

Well, the symbol is just delta x. Consider the negative sign absorbed into the symbol. It doesn't lose any generality whether I write "-" or not, because it cancels out later.

[polaris2341]

easier than the other derivation using calculus, even a school student with minimal maths knowledge can understand this... useful video

[Kaylaye]

woops, doesn't** that is

[Kaylaye]

i would of thought that at step 0:41 the photon would travel the length of the box fatster than c because the box is moving also? or does the velocity of the box become comparingly negligible that it does get taken into account? delinearization perhaps?

[JasonSilvestri]

This is some funny shit! I rated it a 5

[Deliratio]

I don't get the step at 0:57

[Girl19girl19]

Lose the soundtrack

[dgkjoey]

take that song off.

Its distracting

[TheDeLoreanFlux]

or you could turn the volume down....

[Surfister]

sorry for the ignorance, but how do we know the box stops? thank you

[TheDeLoreanFlux]

if it didn't then momentum wouldn't be conserved.

[Surfister]

thak you! I suggest u reggist this idea fast before anyone does it before you!!!

[TheDeLoreanFlux]

reggist?

[RIP1115]

great video!

[Kunado]

I'm dreading my first terms of Calculus now.

[commodore256]

Did you use the mac text to speech program?

[TheDeLoreanFlux]

No, that is MC Hawking

[ABoffman]

HAHAHAHA

[VColossalV]

nice dude