132,128 reputation
8221365
bio website ratsauce.co.uk
location Chester, United Kingdom
age 54
visits member for 4 years, 3 months
seen 11 mins ago

Semi retired old time computer nerd who started programming on a Commodore Pet.

Since I'm also active in the Physics forum I should add that I started as a theoretical chemist, moved into solid state photochemistry and finally worked in industry as a colloid scientist. I only became a full time computer nerd in 1997.


2d
comment Do Waves have mass?
Hi Sagnik. Your question has already been answered. See If photons have no mass, how can they have momentum?.
2d
comment What happens in a universe with only two electrons?
@SharonSalmon: have a look at this recent question.
2d
comment What happens in a universe with only two electrons?
@SharonSalmon: decoherence occurs when a quantum system interacts with any big complicated system that has many degrees of freedom. This could be a scientist, but in the slits experiment it's the interaction with the photographic plate that localises the particle. Would you describe the photographic plate as an observer? It's certainly not a conscious observer.
2d
comment What happens in a universe with only two electrons?
The trouble is that the maths for this quickly gets super hard. Follow the link in my comment to give yourself an idea of what decoherence is.
2d
comment What happens in a universe with only two electrons?
@SharonSalmon: The is really a different question, because now you're asking about the mechanism by which superpositions collapse i.e. how is a delocalised particle localised. There are lots of views on this but my favourite is a process called decoherence. This requires a complex system for the particle to interact with, so shove enough particles into your universe and you can start getting decoherence. In the slits the electron is localised when it interacts with the photographic plate and decoheres.
2d
comment What happens in a universe with only two electrons?
@SharonSalmon In the double slit expt the momentum is well defined and the position is almost entirely unknown, so the electron is well approximated as an infinite plane wave. That's why it can go through both slits. If we set up your xpt like that the two electrons would start as plane waves and continue forever as plane waves - all pretty boring really.
Apr
24
comment Electric circuit question
Hi Jenseits and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems.
Apr
24
comment Space Contraction
Yes, it's been done at the RHIC. See the link I've suggested.
Apr
24
comment Space Contraction
possible duplicate of Proof of Lorentz contraction?
Apr
24
comment Determine the speed of balls after collision
Hi and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems.
Apr
24
comment How can the speed of sound increase with an increase in temperature?
I agree with Kyle on this one. Although I still think the question is a duplicate it isn't an obvious duplicate and I can't fault Ravindra for failing to spot the original. And I think it's a perfectly good question - it isn't obvious why the speed of sound should increase with temperature.
Apr
24
comment Has the human race ever done Antimatter experiments in outer space (e.g. on the ISS)?
You're not a tax payer, are you?
Apr
23
comment How can the speed of sound increase with an increase in temperature?
OK, OK, I'll explain why the speed increases with temperature. Sheesh.
Apr
23
comment could the alternating current resistance of a device depend on afrequency?
I'm voting to close this question as off-topic because it doesn't make sense
Apr
23
comment could the alternating current resistance of a device depend on afrequency?
Clicked Post your question too soon?
Apr
23
comment How can the speed of sound increase with an increase in temperature?
possible duplicate of The speed of sound is proportional to the square root of absolute temperature. What happens at extremely high temperatures?
Apr
23
comment Suggestions for Thesis on possible areas of Biophysics
Hi Roshan. I wish you luck with your PhD, but this isn't a question about physics and is out of place on this site. You could try asking in the Physics chat room.
Apr
23
comment Is my window's semi-transparency a consequence of elementary quantum mechanics?
possible duplicate of Why glass is transparent?
Apr
23
comment cosmological red shift significance in terms of success of gr
It's not clear what you're asking. Note that the development of GR predated the experimental discovery of the red shift.
Apr
23
comment When they say the universe was the size of a baseball about a billion billion billion billionth of a second
The point about infinite/finite is that an infinite universe cannot ever have been the size of a baseball because a baseball isn't infinite. I don't understand your point about the density fluctuating. According to the FLRW model the density has been decreasing smoothly since the end of inflation. During inflation the density is determined by the inflaton field, and we don't don't know how this behaved though it probably remained roughly constant during the inflationary era.