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location Utrecht, Netherlands
age 39
visits member for 3 years, 7 months
seen 4 hours ago

Mar
4
comment Photoelectric effect with protons
The nuclear binding energy per nucleon is on the order of a couple of MeVs, while the electron binding energy for the outermost electron is in the tens of eVs. I don't know why you're mentioning the inverse of the fine structure constant here!
Sep
8
comment How do we know that C14 decay is exponential and not linear?
Galileo would be proud! @Ruud: So 2 separate boxes with 500M atoms would decay entirely in 5700y, but if you put them together half would remain. That seems a bit strange, to say the least...
Aug
1
comment The philosophy behind the mathematics of quantum mechanics
@recipriversexclusion: I have a CS background, and those lectures really made it click what quantum computing was about, in terms of computation (as opposed to the physics aspect). I hope it's the same for people coming from physics. Glad you liked them, in any case!
Jul
18
comment Addition of different physical quantities
@Saeed, if you do that, then presumably also 4 oranges + 3 apples = 7 fruits, from which you can derive 1 orange = 1 apple. You might as well call them fruits straight away!
Jun
29
comment Outcomes of earth slowing down spinning on its own axis
Whoops, should have read a bit more. Thank you for the correction, I'll edit it in.
May
25
comment Light travels a straight line write down the principle in which this is manitested
It's also nice to show what you've tried, what did or didn't work with your approach, and a 'please' at the end also help in posing a question.
May
24
comment How fast do I need to go in order to avoid being seen by the Police?
How will you know the cop's there in the first place?
May
24
comment Why are higher generation of matter unstable?
What about a combination of 3 up quarks?
May
12
comment How is the Breit-Rabi formula derived?
@Lubos Thank you! If you answer, I'll accept. In the meantime an arxiv search turned up this paper which also seems relevant, especially sections II and III.a.
Apr
7
comment What is the wavefunction of the observer himself?
For what it's worth, Egan winces at the scientific flaws of the novel and discusses in great detail where he departs from reality here: gregegan.customer.netspace.net.au/QUARANTINE/QM/QM.html
Mar
9
comment Maxwell's Demon - laser cooling
@Peter : Thanks, I didn't know that! Most of my physics knowledge comes, vicariously, from my girlfriend who's doing a Ph.D. on laser cooling of fermions.
Mar
9
comment Maxwell's Demon - laser cooling
@Peter I'd guessed as much, but my intuition was that since the cooling step (presumably) is opto-mechanical, the time scales there would be much larger than the decaying of the atoms. I guess that assumption was wrong, then!
Mar
9
comment Maxwell's Demon - laser cooling
I think Michael means to ask why the energy from the excitation beam (the orange one) doesn't heat up the atoms. My guess would be that they in fact do heat it up, but by an amount that is much less than the amount the gas is cooled down by the subsequent expansion. My question is how can the excited state be stable?