3 ms·
Why Einstein’s E = mc² is only half of the equation
- hkwerf 3y agoThe 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.
- garbagecoder 3y agoThat might be his most famous equation, but his most important equation is G_{\mu\nu} + \Lambda g_{\mu\nu} = kT_{\mu\nu}
- ysleepy 3y agoAngela Collier's youtube channel had a Video exactly about this topic: https://m.youtube.com/watch?v=6HlCfwEduqA https://m.youtube.com/watch?v=6HlCfwEduqA Her Videos are amazing and I love her ability to tell interesting stories with a lot of context and insight. I hope more people will enjoy watching her channel, give it a try. Her video is a month old and seeing this article immediately made me think the author saw it too and did a write-up. It is about the paedagogy of E0 = mc² and how telling people there are two masses etc. leads to a lot of misconceptions with people not going on to get a Phd in physics. (She has one)