# Urgent Help : Einsteins derivation of e=mc^2

hi,

This has probably been asked and answered a million times before so sorry but here goes. I urgently need help with a Maths University project about the A-Bomb which will include a chapter on Special Relativity and e=mc^2. I have read loads of books but they treat special relativity from a modern view point whereas I need to know how Einstein "figured out" e=mc^2 as it's a projcent on the impact and development of maths. Can anyone explaine how Einstein derived e=mc^2 or recommend and books/websites. Also, does anyone have any useful mathematical info on the development of the A-Bomb that might help?

Thanks Related Other Physics Topics News on Phys.org
Mk
Where did E^2=m^2c^4+p^2^2 come from?

And why can't users view their own "warnings?"

Tide
Homework Helper
Actually, it's

$$E^2 = m_0^2 c^4 + p^2 c^2$$

and it is the same as $$E = mc^2$$ which uses the "relativisitc mass" whereas the previous expression uses the "proper mass."

Mk
Ummm, which one is rest mass and which one is not? Rest mass is proper mass? Right?

jtbell
Mentor
Tide said:
Actually, it's

$$E^2 = m_0^2 c^4 + p^2 c^2$$
...and you can derive it by starting with the relativistic equations for energy and momentum:

$$E=\frac {m_0 c^2} { \sqrt {1 - \frac {v^2} {c^2}}}$$

$$p=\frac {m_0 v} { \sqrt {1 - \frac {v^2} {c^2}}}$$

and combining them so as to eliminate v.

Mk said:
Rest mass is proper mass? Right?
Right. It's also known as "invariant mass".

Last edited: