Nov 212015


On this date in 1905 Albert Einstein’s paper, “Does the Inertia of a Body Depend Upon Its Energy Content?” was published in the journal Annalen der Physik. This paper explored the relationship between energy and mass via Special Relativity, and, thus, led to the mass–energy equivalence formula E = mc² — arguably the most famous formula in the world. I would also argue that it is the most misunderstood formula in the world, although I notice in researching this post that a lot of physicists in trying to help non-physicists understand it, seriously misrepresent its implications.

The problem frequently in trying to explain physics to the mathematically and scientifically challenged is that scientists and science teachers fall back on analogies – often involving cats for some inscrutable reason. The problem, as I have stated many times in many places before, is that analogies can help, but they can also be misleading.


There is a second problem in that E = mc² does not represent the whole story. That’s the part about theory that non-scientists rarely get. Einstein’s theories of relativity, Darwin’s theory of natural selection, etc. are not complete, hence they are called “theories.” No one is seeking radically new alternatives (although some day they might); scientists are just trying to explain messy bits in the theories that cannot be explained now. That’s how Einstein came to unravel Newton. Newton was not totally wrong; it’s just that his “laws” of motion, for example, are incomplete – as stated by Newton they apply only to mass, force, acceleration, etc. as we encounter them in the everyday world. When physicists started looking at interstellar, and subatomic worlds at the turn of the 20th century, Newton’s physics did not work very well for them. That’s when Einstein came along and added bits to Newton to make his equations more encompassing.

Here’s a couple of provisos before I get into things more. First, for the non-mathematically inclined I am going to have to be simplistic and in doing so I will have to be a little misleading, or, you might say, downright wrong. The only way to understand physics deeply is to understand the underlying mathematics deeply (which, incidentally, I don’t, although I am better at it than most non-scientists). Second, my usual caveat, I don’t find physics per se very interesting. My son switched from being a physics major to an anthropology major a few years ago for precisely the same reason. Physics does very well in helping us build computers, cell phones, and what not, and I use them all the time. Thanks physics. It is useless when it comes to issues that I really care about such as the existence of God, how to mend a broken heart, and so forth. To be sure, philosophers