132,048 reputation
8221365
bio website ratsauce.co.uk
location Chester, United Kingdom
age 54
visits member for 4 years, 3 months
seen 2 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.


2h
comment HOMEWORK HELP! Simultaneous equations (graphical method)
Hi Joseph 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.
3h
comment How to calculate angular velocity given constant tangential acceleration?
Hi Meitar 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.
3h
comment Any disadvantage for sending rocket straight up?
See my answer to this question, which is almost but not quite a duplicate of yours. If you send the rocket and satellite straight up the satellite is going to fall straight back down again!
3h
comment Pinhole Camera Problem!
@InderGill: the diffraction pattern changes with distance from the diffracting object. The equation I give applies to the far field limit, i.e. far from the diffracting object, and in this limit the pattern is known Fraunhofer diffraction. As you move nearer the object the pattern changes and this is known as Fresnel diffraction. So they are the same think, just viewed at different distances.
22h
comment Why is there zero point energy at absolute zero temperature?
Are you asking why the entropy is zero at absolute in spite of zero point energy? Or are you asking why we have non-zero energy at absolute zero? If the latter, your question is a duplicate of this one.
2d
comment Do Waves have mass?
This doesn't seem to address the question of how massless photons can have a non-zero momentum.
2d
comment Does it mean the molecules of all matter above absolute zero temperature are moving?
Why the downvote? Downvoting just because it's a duplicate seems harsh.
2d
comment Does it mean the molecules of all matter above absolute zero temperature are moving?
NB the motion is vibrational not translational.
2d
comment Does it mean the molecules of all matter above absolute zero temperature are moving?
The Q/A I've linked describes how and why motion doesn't cease even at absolute zero. So it answers your question because if motion doesn't cease at absolute zero it is certainly present at temperatures above zero.
2d
comment Working out length of taut rope orbiting the earth remaining straight and radially directed
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.
2d
comment Electric field calculation and its graph vs x
Hi Saood 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.
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.
2d
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.
2d
comment Space Contraction
Yes, it's been done at the RHIC. See the link I've suggested.
2d
comment Space Contraction
possible duplicate of Proof of Lorentz contraction?