why does e=mc^2? (1 Viewer)

[Riot09]

so i was wathcing a doco on sbs and the colbert report where a guy wrote a book about the question above.the c squared part,why is it there.

professor cox said:that something without mass travels at c so that why it was there.(is intinsic mass the term?) but why?.

so there's like 4 questions i have about this equation.

1.why does e=mc^2?

2.the c squared part,why is it there?

3.if something has intrinsic mass,why does it travel at the speed of light and why is it a constant?

4.mass=energy, if thats how nuclear fission works than why is the energy so large in proportion to the small amount of mass?

 

[pman]

In answer to number 4, mass is to energy as a solid is to a gas...
that is, highly concentrated

 

[Bunzhou]

Why? You don't have to know 'why' just know that it works. Einstein probably just developed mathmetical relationships and came up with E=mc^2.

so i was wathcing a doco on sbs and the colbert report where a guy wrote a book about the question above.the c squared part,why is it there.

professor cox said:that something without mass travels at c so that why it was there.(is intinsic mass the term?) but why?.

so there's like 4 questions i have about this equation.

1.why does e=mc^2?

2.the c squared part,why is it there?

3.if something has intrinsic mass,why does it travel at the speed of light and why is it a constant?

4.mass=energy, if thats how nuclear fission works than why is the energy so large in proportion to the small amount of mass?

 

[pman]

Should prob mention the clichéd crap about how only 4 people on earth understand it!

 

[ibrian]

what? i thoguht it was Emancipation of Mariah Carey to the second power

 

[tommykins]

Mass–energy equivalence - Wikipedia, the free encyclopedia

 

[Bunzhou]

lmao

what? i thoguht it was Emancipation of Mariah Carey to the second power

 

[clonestar]

The answer to these 4 questions cannot be answered in simple HSC level physics.

It requires complex mathematical derivatives.. (See below link). Either way it's proven at a mathematical level but it certainly would be interesting to see the derivative and how Einstein proved it to the world.

The basis of his expression on further reading seems to be a derivative from Maxwell and Hertz equations for velocity of light and Lorentz's equation. Based in that paper he seems to make reference to L as energy so fascinating nevertheless.

EDIT: Here is the paper:
http://www.fourmilab.ch/etexts/einstein/E_mc2/e_mc2.pdf

Furthermore, it is fascinating to think that the mass of all of us can be defined as E/C^2... and surely this should be linked with Newtons F=ma so therefore m=E/C^2 = F/a, therefore the acceleration of all objects is dependant upon a = Fc^2/E.... awesome... this is actually INVALID as Einstein refers to rest mass and this is moving mass with reference to F=ma so therefore F/a ≠ E/c^2.... such a shame...

 

[Cloesd]

I always figured it stemmed from kinetic energy = .5 Mv^2.. where V = C. Where the .5 goes probably has its roots in the difference between kinetic energy and total energy. Probably far far over simplified, but it's a good place holder until uni enlightens me.

 

[heirware]

If you want the basic answer, basically: energy = mass times speed of light squared. The c^2 bit of it refers to a universal constant, invariant speed of light, and thus sets the proportionality of energy mass equivalence. Speed of light is very high, so a little mass corresponds to a large amount of energy and conversely, a large amount of energy corresponds to a little mass

 

[JamieP]

Certain branches are based entirely on postulates. The theory of Relativity is one of them, Quantum Physics is another. Unfortunately more often than not, we can only ask how, but not why. Only geniuses like Einstein, Pauli, Schrodinger etc can come up with those “weird” assumptions which are “proven” by later experiments. Physics are beautified by maths, and physics advances maths. I am also echoing an earlier thread complaining about too much maths in the 2009 HSC physics. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
<o></o>

 

[k02033]

Certain branches are based entirely on postulates. The theory of Relativity is one of them, Quantum Physics is another. Unfortunately more often than not, we can only ask how, but not why. Only geniuses like Einstein, Pauli, Schrodinger etc can come up with those “weird” assumptions which are “proven” by later experiments. Physics are beautified by maths, and physics advances maths. I am also echoing an earlier thread complaining about too much maths in the 2009 HSC physics. fficeffice" /><o>></o>>
<o>></o>>

thats very impressive.. are you currently in yr 10?

 

[JamieP]

thats very impressive.. are you currently in yr 10?

No that was years ago. I was kind of forced to tutor physics and mx1&2 recently by a group of friends, their kids needed some extra push and guidance. I am trying to gauge the level here at BOS. Your reply made me realise I got my profile wrong. Will attempt to correct it.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

 

[ashie0]

riot09. you are the worst.

 

[Amogh]

riot09. you are the worst.

lol why?

 

[Dx_God]

i'm sure the relationship of e=mc^2 can be derived by applying law of conservation of energy and matter. i'm almost certain that Einstein generated the relationship e is proportional to m first as it is very easy to do when u consider mass defect and binding energy. then from experimental data, the constant can be generalized as c^2 when an accurate line of best fit is drawn and the gradient is calculated. but as to how do they know for sure that its c^2, i don't really know but c^2 itself is only an estimation anyway so i think the constant had a value very close to c^2.