5 ms·
Hence I said my friend was being a bit “interpretive”. He really meant that though photons have zero rest mass, they nonzero inertial mass (E=mc^2)
by JWKennington 7y ago
Hence I said my friend was being a bit “interpretive”. He really meant that though photons have zero rest mass, they nonzero inertial mass (E=mc^2)
- kgwgk 7y agoMaybe you could write “because photons have energy that can be viewed as (relativistic) mass” then. Or maybe he did really refer to the “rest energy” of photons? That seems weird even for an experimentalist ;-)
- JWKennington 7y agoIt was weird - I've reparaphrased that to be "momentum" now for improved clarity. thanks for feedback
- typothrowaway 7y agoThat still does not make any sense. I'm sorry to be so direct, but I'm really worried laypeople here are going to think that this is correct.
- dschuetz 7y agoA layperson here. Don't.
- JWKennington 7y agoPhotons have momentum. momentum is analogous to mass in special relativity (specifically, mass is the 0 component of the four-momentum)
- deleted 7y ago[deleted]
- filmor 7y agoThat's not how it's written in the post though. If you just swap out the "inertial mass" at the end and the "rest energy" somewhere in the middle it makes more sense: > because photons have rest energy (=> kinetic energy) that can be viewed as mass in special relativity > [...] > impact the gravitational field despite having no inertial mass (=> rest mass)! Speaking of "mass" in context of relativity is always a bit tricky. The term "inertial mass" for example is really saying something about how an object behaves under the influence of a force (F = ma), not how it behaves relativistically (that would be "relativistic mass", E = mc2).
- JWKennington 7y agoI've cleaned up the last paragraph, and replaced my friend's reasoning with the term "momentum" to avoid confusion. thanks for feedback