Originally Posted by
dead_pan
How many conspiracy theories start with these four words?
Talking of which, I recall attending an energy conference in the US a few years back during which an esteemed professor from a prestigious US uni ended his lecture with an entirely serious and non-ironic comment that, "according to Ben Rich", Einstein had got his famous equation all wrong, that it was in fact e=mc^2.5. Cue fits of giggles from us assembled Brits.
Actually, MC^2 is an approximation. Near enough for all of us, but it is not quite correct. Einsteins T-Shirt looks better than a value other than 2.00000000000
(E^2=mC^2 + pC^2 is more accurate). The proof of the T-Shirt does work, but it is for a specific condition which is why the additive gets put into the equation for all cases.
or:
whether it is close depends...
- For E at rest, for a mass it is correct, if the mass is invariant
- For a photon it is incomplete
- For other cases, it is an approximation
Was a great presentation from Fermi Labs that made the point neatly.