130,074 reputation
8216356
bio website ratsauce.co.uk
location Chester, United Kingdom
age 54
visits member for 4 years, 2 months
seen 3 hours 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.


Mar
25
comment Ejected Photoelectrons
Isn't this just Compton scattering? For a 13.6keV photon and forward scattering I get about 2.6% of the photon energy transferred to the electron, which is way lower than relativistic energies.
Mar
25
comment Why doesn't the light get out?
John, I don't really get what you're asking. If you turn on your torch at the event horizon then the light doesn't go anywhere but you fall inwards away from it at the speed of light. Does that help?
Mar
25
comment Why is the Specific Heat of Helium 36 times greater than Xenon?
In an ideal gas atoms have three degrees of freedom, the $x$, $y$ and $z$ directions, and each DOF gets about $\tfrac{1}{2}kT$ of energy. So the total internal energy is $\tfrac{3}{2}kT$ times the number of atoms.
Mar
25
comment Why does the Higgs field have less energy when it's non-zero than when it's zero?
@innisfree: what I would guess the OP wants to know is why the Higgs potential is the shape it is. Whether that has an answer I'm not sure.
Mar
25
comment Why does the Higgs field have less energy when it's non-zero than when it's zero?
Yes, agreed.${}{}{}$
Mar
25
comment Why does the Higgs field have less energy when it's non-zero than when it's zero?
I don't think this answers the question because it doesn't say why the VEV is not zero. The VEVs of all the other known bosonic fields are zero, so what is it about the Higgs that mkes it different?
Mar
25
comment Why doesn't the light get out?
You might also want to have look at If you shoot a light beam behind the event horizon of a black hole, what happens to the light? and for a more technical discussion Would the inside of a black hole be like a giant mirror?.
Mar
25
comment Why doesn't the light get out?
I thinm this is a duplicate of Speed of light in a gravitational field?. I won't flag it as such because that would immediately close your question, but I thnk you should have a read through my answer to the question I've linked.
Mar
25
comment Dimensional analysis explanation and teacher issues!
Hi Mark. You're basically asking us to write an article on dimensional analysis. A quick Google should find you many such articles so there seems little point in writing yet another here. It's impossible to comment on how fair your teacher is being since we don't know the details. However dimensional anaylsis is an important skill and even we real physicists use it as a routine part of our work. Your teacher is right to insist you master it.
Mar
23
comment Validity of naively computing the de Broglie wavelength of a macroscopic object
@tom: well, a single photon will diffract therefore so should a single bullet.
Mar
22
comment Does the assumption of $c$ being perfectly defined mislead us about the fundamental nature of space and time?
Special relativity is simply the geometry of flat spacetime, and everything you need to know about it stems from the Minkowski metric: $ds^2 = -c^2dt^2 + dx^2 + dy^2 + dz^2$. Once you've grasped this it's extraordinarily simple. Massive essays like the one you've written above are a poor substitute for understanding the basic principles.
Mar
22
comment Time, time perception and time dilation
@Helwar: if you don't mind a bit of algebra you might be interested in my attempts to explain time dilation here and here
Mar
22
comment Energy Conservation in Quantum System?
@irishphysics: it isn't useful to approach QM by starting with classical intuition and trying to mangle it into a QM form. You have to drop everything you thought you knew and just do the maths. Eventually you will build a new understanding. It takes time though - I've been working on it for the better part of forty years :-)
Mar
22
comment Energy Conservation in Quantum System?
@irishphysics: see for example this thread in the Physics chat
Mar
22
comment Is dark energy & matter God?
I'm voting to close this question as off-topic because it is not about physics
Mar
22
comment Energy Conservation in Quantum System?
@irishphysics: it's doing it to me as well. It's a bug in the SE somewhere that has been cropping up occasionally for the last week or so. It will eventually fix itself.
Mar
22
comment The athlete feels a centrifugal force when whirling the hammer - is there always a centrifugal force associated with a centripetal force?
You ask there is always a centrifugal force associated with a centripetal force. Well the string isn't going anywhere, so the net force on the string must be zero. That means the centripetal force the string produces on the hammer head must be equal and opposite to the centrifugal force the string produces on the thrower. So yes, in this case there is an equal and opposite centrifugal force associated with the centripetal force.
Mar
22
comment The athlete feels a centrifugal force when whirling the hammer - is there always a centrifugal force associated with a centripetal force?
... would both start moving in a straight line at constant speed. So the centripetal force is the force the string produces on the hammer head, and the centrifugal force is the force the string produces on the thrower.
Mar
22
comment The athlete feels a centrifugal force when whirling the hammer - is there always a centrifugal force associated with a centripetal force?
It's a shame this has been closed because I think you have put your finger on an important point. The head of the hammer is not moving in a straight line at constant speed, so we know from Newton's first law that there must be a force acting on it. Likewise the hammer thrower is not moving ina straight line at constant speed, so there must be a force acting on them. These are real forces - there is nothing fictitious about them. The force is, as you say, being produced by the string. To see this imagine suddenly removing the string, at which point the head of the hammer and the thrower ...
Mar
22
comment Impulse required to stop a rotating rod at a pivot provided there is no horizontal force at the pivot
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.