@ACuriousMind :D I just brought it for the anecdote that this one guy in my classes has spilled his coffee no fewer than three times this year. Probably more when I haven't seen.
@ACuriousMind Got in a car wreck in the middle of nowhere... had to hike for days to get help... sat up one night drinking coffee from a portable stove and my hands were shaking so hard I got coffee on my notebook?
A technical question about the electromagnetic tensor, but before that, it is know if, say, instead of being $$F_{\mu\nu}=\partial_{\mu}A_{\nu} - \partial_{\nu}A_{\mu}$$it were $$F_{\mu\nu}=(...)_{\mu\nu}-(....)_{\mu\nu}$$
I am giving an example of the electromagnetric tensor because it is a 2-fo...
I'm personally a bit too lazy, but I think it's worthwhile to explain the difference of the concept of differential forms with the components that we use in physics.
Actually, the comment I wanted to leave is too long so I guess I'll post it as an answer, but I think a better one could be written.
In 1968 NASA, through the assistance of the Israel Program for Scientific Translation, translated from Russian the 1964 book "The Earth in the Universe", with chapters written by top Soviet scientists.
In a chapter written by Prof. A. L. Chizhevskii, who was honorary president of the first Inter...
Recently I came to know from a seminar that where most of the satellites need gallons of fuel to be consumed to get placed in one planet's orbit Mangalyan took 0 fuel and it waited for the 'right time' by using centrifugal force to get placed in the mars's orbit. My question is what principle did...
I recently had a non-multiple of 5 rep points for an answer (specifically, 18). I assume that is due to 2 positive votes and one negative, but there was no comment explaining the down vote.
When I look back at the answer, I see it has a total of +1, but there doesn't seem to be a way to view th...
So I was going through the review queues and noticed a nice comment and tried upvoting it. Turns out the nice comment was mine from last night & I couldn't upvote it.
On http://meta.stackexchange.com/questions/20420/countdown-app-for-devdays balpha comments, "I would be willing to donate 500 rep (on meta) to the first guy who does this with LOGO turtle graphics and this program actually gets used at one devdays venue."
This got me thinking: why not allow peop...
He's asking how we define the present in a very convoluted way. It's relative isn't it? the present is relative to everyone because of inertial reference frames and special relativity?
Most people just leave it at "time is non-simultaneity" but he wants some principle or mathematical model..
@user1667423 Just by glancing at it, a factor of $c^{-2}$ will make things vanish in the classical limit.
Formally the classical limit is $\lim_{c\rightarrow\infty}$.
@user1667423 A note on notation: In special relativity, use the symbol $\partial_\mu$ for partial derivatives. $\nabla_\mu$ is reserved for the covariant derivative of general relativity. The notation $\vec\nabla$ in vector calc is unfortunate.
@0celo7 Of course, thanks. I suppose the relativistic equations still hold with covariant derivatives in GR (ignoring the three-gradients, which happen to have the same symbol)?\