Did Einstein discover E = mc^2?
One thing that bothers me about the “somebody had mc^2 and only had the proportionality constant wrong” arguments is that it ignores one very important point: whatever you come up with, the units have to be that of energy. So it’s not like the Far Side cartoon where Einstein has written E=mc^3, E=mc^7 and various other powers and the cleaning lady says “Everything’s squared away. Yessir, squaaaaaared away!” (and Albert has a wonderful look on his face). Funny, for a cartoon, but in reality you need a speed squared term to go along with mass in order to get units of energy. E=mc^7 doesn’t have units of energy. E=mc^2 does. So, really, showing what the proportionality factor is is really the majority of the battle.
If I recall there has been several papers in the past that had E ~ mc^2.
So I doubt it was a “surprise” when Einstein wrote it down, but he got the numerical constant correct by his reasoning based on special relativity. As far as I know, older claims that E ~ mc^{2} were not based on such a paradigm shift and various numerical factors have appeared.
In my opinion E = mc^2 is not really that important in this context, what is important is that it is understood in the context of special relativity. I will allow science historians to argue as much as they like about this!
Many times something is running in many people’s head at the sametime.
And the one who understands it better first wins. So Einstein won!
Nike shoes cheap, I don’t think you feel strongly about it at all.