4 ms·
The article's math is fine, but it completely omits that in E = mc^2, m is the relativistic mass, i.e. the rest mass m_0 * gamma? They even perform the exercise
by hkwerf 3y ago
The article's math is fine, but it completely omits that in E = mc^2, m is the relativistic mass, i.e. the rest mass m_0 * gamma? They even perform the exercise of extracting gamma there. If m is interpreted as the relativistic mass, the term is complete again and the premise of the article breaks down.
Sure, it's interesting to see the math, but the main take-away should not be that E = mc^2 is somehow incomplete. It should be that there are different kinds of masses.
- evanb 3y agoNo professional physicist I know thinks natively with relativistic mass. They much prefer m to mean the rest mass, a relativistic invariant, and to include explicit factors of (v/c) or γ when they're talking about frame-dependent quantities. Anecdotally, this is also good pedagogically: the mass is an inherent, invariant property; avoiding the relativistic mass helps students. Just make sure to drive home that E^2 = (mc^2)^2 + (pc)^2 is a statement about a four-vector magnitude.