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Jul
14
revised BBC radiation: What is it?
deleted 8 characters in body
Jul
14
comment BBC radiation: What is it?
I'm not sure where 'XC' comes from. I merely suspect it is not an acronym, but rather derived from $x_\text{c}$, the sonic (or critical) point distance. I may be wrong about that.
Jul
14
answered BBC radiation: What is it?
Jul
9
comment Why do i see bright red hand when i place flashlight behind my hand?
Plus, the hand spectrum can found here: photobiology.info/PhotobioInArt.html.
Jul
7
comment Physical Role of Batter in Baseball
Here's some related reading: sie.arizona.edu/sysengr/publishedPapers/NewScientist.pdf and en.wikipedia.org/wiki/Coefficient_of_restitution.
Jul
6
comment How to convert physical ligth quantities (frequency, intencity, spectrum) to RGB and back?
See stackoverflow.com/q/1472514/2071794.
Jul
2
awarded  Curious
Jun
21
awarded  Notable Question
Jun
16
revised Why do all elements above $\require{mhchem}\ce{Fe}$ not decay to $\ce{Fe}$?
added 18 characters in body; edited title
Jun
12
comment does there exists a rope such that it takes longer to burn the whole rope from one end?
Something that has an internal structure like this perhaps: en.wikipedia.org/wiki/Chain_sinnet#mediaviewer/….
Jun
12
comment does there exists a rope such that it takes longer to burn the whole rope from one end?
I think that, besides the obvious stuff, there may be an answer that uses some kind of 'directional threading". That is, a way of weaving/braiding the rope that is asymmetrical in direction (but repeating).
Jun
10
revised Can photons have negative energy?
small stuff
Jun
10
comment Can photons have negative energy?
Related: physics.stackexchange.com/q/13654/17609 and physics.stackexchange.com/q/391/17609
Jun
10
comment Why does a large train cause the ground to shake?
Oh, I don't know. I guessed there was a cm or two between each segment to allow for expansion due to hot weather. And also because of the clear rhythm of the noise, which seems slower than the frequency of rotating wheels.
Jun
10
comment Why does a large train cause the ground to shake?
I'm missing the explicitly crossing between two segments, which seems (to me) the key thing that you feel when you are on a train yourself. Also, if the segments would be different-prime-number-lengthed, would the 'problem' be less? :) Or should you just make sure that segment lengths and car lengths don't match (up to some factor)? Like cars should be length 7 and track segments should be length 17.
Jun
10
comment Power delivered by a plug
[This is just the result of a quick Wikipedia search.] With regards to the last part of the question: They use the energy to pump up water, so that they may retrieve most of that power later by letting it flow back down through turbines. en.wikipedia.org/wiki/Pumped-storage_hydroelectricity However, although the UK have such a thing, en.wikipedia.org/wiki/Dinorwig_Power_Station, it is not used for that purpose. I don't know if they use continental facilities or have another solution.
Jun
3
revised The path integral and Feynman diagrams
added 20 characters in body
Jun
3
comment The path integral and Feynman diagrams
I'm not sure about it, because this particular story doesn't mention a conference or a hotel room (in relation to the invention of the diagrams). Maybe you got it somewhere else.
Jun
3
revised The path integral and Feynman diagrams
Feynman's name. Other small stuff.
Jun
3
comment The path integral and Feynman diagrams
Pajamas are in The Pleasure of Finding Things out, p. 198 of the Penguin edition. But this was after the diagrams were already thought up, and before they were called Feynman diagrams. The pajamas are when Feynman wonders if Physical Review would print the diagrams if they were really useful. The actual answer appears one or two pages before the pajamas.