140,739 reputation
9242395
bio website ratsauce.co.uk
location Chester, United Kingdom
age 54
visits member for 4 years, 5 months
seen 10 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.


1h
comment How fast can a fluorescent lamp flicker
@Mehdi: oops, that's a typo. At 5hKz one half cycle is 100$\mu$s (I originally wrote ms instead of $\mu$s) and all the lifetimes are consirably greater than this.
1h
comment dependence of dipole moment on charge of dipole
Hi Bhawana 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.
6h
comment Shapes of ionic compound
I'm voting to close this question as off-topic because it should be on the Chemistry Stack Exchange
9h
comment Buying books that are out of print
I'm voting to close this question as off-topic because it's about buying books not physics
9h
comment Is there any evidence against the Cosmological Principle?
Hi Lance. A good answer would in effect be a review article and I think that makes the question too broad. I found an interesting paper on the Arxiv that includes a literature survey. This would be a good start. A brief answer is that there is some tantalising evidence that the universe may not be as homogeneous and isotropic as we have assumed, but nothing concrete yet.
1d
comment Doesn't dating the universe violate the concept of spacetime's inseparability?
@JimsBond: actually I've just spotted that the Wikipedia article I linked uses the term "comoving time". So yar boo sucks!!! :-)
1d
comment 't Hooft–Polyakov and Dirac monopoles, instantons and solitons
There are loads of articles on these subjects out there in Googlespace. I think you should read around the subjects a bit before posting here. If there are some aspects that you don't understand please come back to us and post a question explaining what you do understand and what you don't.
1d
comment Throwing the object around the Earth
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.
1d
comment Doesn't dating the universe violate the concept of spacetime's inseparability?
Well, it's the time component of the comoving coordinates. Is abbreviating this to comoving time such a sin? You are of course correct that it is also the proper time of a comoving observer.
1d
comment Are magnetic orbits possible?
The magnetic fields of the Sun and Earth have a negligably small effect on their mutual orbit. The orbit is dominated by gravitational forces.
1d
comment Firing a blank vs live round from a gun
I'm voting to close this question as off-topic because it's about firearms not physics
1d
comment Doesn't dating the universe violate the concept of spacetime's inseparability?
@AlanMonroe: by editing the question you have rendered my answer pointless. Ideally you should revert the question to its original form then post a new question as a follow-up.
1d
comment How to emulate 40ft (12 m) of water?
To be fair, the OP specifically asked what weight would be needed. Otherwise I wouldn't have mentioned putting a weight on top of the tank. As for using a 40 foot header pipe, I can't see why that's functionally any different from using a compressor. It wouldn't have to be a big deal one, even my bicycle pump can generate 60 psi.
2d
comment Cleaning a dirty jar
Hi Simeon. I've suggested a duplicate question, though my answer to that duplicate is far from quantitative. If someone would like to post a really rigorous discussion of the problem here I'll remove my duplicate vote.
2d
comment Cleaning a dirty jar
possible duplicate of Fluid Dynamics - Water Bottle Drink Mix: Air or No Air?
2d
comment How to emulate 40ft (12 m) of water?
@LightnessRacesinOrbit: in practice there is some compliance in the walls of the tank and that's where most of the pressure is stored. It's like inflating a balloon with water - the water is under pressure even though it hasn't been compressed because you've stretched the walls of the balloon. In effect you would be inflating the metal tank slightly.
2d
comment Why can't gravitons be created in traditional particle accelerators?
@GennaroTedesco: I would guess John's point is that virtual particles are just a mathematical trick used in a perturbative description of electromagnetic interactions. Real photons obviously do exist but virtual photons do not exist in the sense of being distinct particles.
Jun
30
comment I tried to solve circuit analysis problem but it failed
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.
Jun
30
comment Flow Rate Calculation from a drain tank through a pipe
Hi Loris. The question I've linked isn't an obvious duplicate at first sight, but the answers to it explain how to calculate flow rates in a pipe given the pressure difference.
Jun
30
comment Flow Rate Calculation from a drain tank through a pipe
possible duplicate of Calculation of pressure from flow rate of water