94,260 reputation
3125233
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 6 months
seen 49 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.


Apr
4
reviewed Approve suggested edit on Aharonov-Bohm Effect and Integer Quantum Hall Effect
Apr
4
reviewed Approve suggested edit on Lagrangians not of the form $T-U$
Apr
4
reviewed Close The context of definition of work
Apr
4
comment Which big bang theory has more assumptions?
...to which it has been subjected. To call it unproven is certainly true, in the sense that experiment could still find a flaw in it, however it is widely accepted as a good description of the universe at least until we get down to quantum scales.
Apr
4
comment Which big bang theory has more assumptions?
@rowanman28: The link between conservation of energy and time shift symmetry is provided by Noether's theorems, but this is hard maths. There is a gentler introduction written by John Baez, but even this is probably out of reach for non-physicists. I can see that it will seem unsatisfactory to you to be told you just have to accept it, but then isn't that true of most of modern physics? GR has so far passed every experimental test ...
Apr
4
reviewed Approve suggested edit on Energy, time and force
Apr
4
comment Heat transfer and temperature difference of 2 liquids
@nemu: see the Wikipedia article for details, though all they do is use a constant called the heat transfer coefficient that needs to be determined experimentally. For a rigorous treatment you'd need to solve the heat equation.
Apr
4
comment How can water evaporate at room temperature?
This is basically the answer I would give. Christoph, would you consider fleshing this out a bit? At the moment it's so brief only people who already know the answer will be able to see what you're getting at.
Apr
4
answered Measuring cross-section area of a flexible tube (5mm dia approx)
Apr
4
revised Qualtitative explanation for the link between low magnitude of high z supernova and accelerated expansion
Typos
Apr
4
reviewed Approve suggested edit on Is there a limit to acceleration?
Apr
4
reviewed Close Loss of kinetic energy in inelastic collision
Apr
4
comment Recoil from a shotgun
@Luke: once the shot has left the gun it has no further effect on you, so facing a wall would make no difference (unless the shot ricochets off the wall and hits you!).
Apr
4
comment Why is superdeterminism generally regarded as a joke?
Luboš Motl is someone I have enormous respect for (just look at his answers on this forum!) but he has a rather sharp tongue and I suspect many physicists would take a more moderate tone. Experimental tests of Bell's inequalities have convinced most of us that hidden variable theories are unlikely, however that hasn't stopped people looking for loopholes. And good luck to them. It's a relatively small part of the science budget to pay some theorists to have a go at it and I don't begrudge them the opportunity.
Apr
4
answered How to measure the wavelengths of ultraviolet lines in the hydrogen spectrum?
Apr
4
comment Recoil from a shotgun
@User58220: true, though I have no way of knowing what fraction of the momentum is carried by the gases. In any case, I think this is one of those approximate calculations in which understanding the method is more important than the final result.
Apr
4
comment Pendulum (highschool)
@kecer: I would measure $g$ using a range of different values for $\alpha$, i.e. use different initial displacements. You should see the calculated value of $g$ increase with angle, with the zero angle limit matching the simple formula.
Apr
4
comment Speed of light originating from a star with gravitational pull close to black-hole strength?
@user6972: in GR the speed of light is only locally constant.
Apr
4
comment The other side of the lever
@supercat: that's covered by Draksis' answer. He got in first so I had to come up with something a bit more extreme. Note that my method is purely static. You just measure a static torque. Draksis/your method is dynamic i.e. you have to measure an acceleration.
Apr
3
comment If you shoot a light beam behind the event horizon of a black hole, what happens to the light?
@SachinShekhar: in GR the speed of light is locally constant. If you measure it at your location you'll always get the value $c$. However anywhere else it can differ from $c$.