40,229 reputation
355127
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 44
visits member for 4 years, 6 months
seen 53 mins ago

Experimental nuclear and particle physicist. These days I'm teaching, but I've spent a lot of time on nucleon structure in fixed target electron scattering and neutrino oscillations using reactors and beam sources.

Been reading Zemansky & Dittman's book on thermodynamics recently. Quote: ``The concept of temperature is rich in interpretations and levels of abstraction.'' Nice.


May
10
comment Coefficient of friction on a loop-the-loop!
Hard problem to do in closed form. Possible harder than you know. If you are worried about the time variation of the friction, then you may need to worry about the atmospheric drag as well. Good candidate for simulation.
May
9
answered Ambiguity with reaction equations
May
9
comment Why is Einstein solution to the twin paradox different from the one on the internet?
My subconscious has been niggling away at the phrase "moment of acceleration" in this context and I had a light-bulb moment tonight. Despite the olde timey feel of it, there is an elegant economy of phrase there which packs a lot of punch into a few words. Think of it in terms of a space-time diagram: acceleration is a change in the angle of the line of simultaneity, and the size of the proper-time difference implied by a fixed acceleration is proportional to the separation of the two actors. Sweet.
May
9
comment Looking for name of mapping procedure
Also this might be better on Computational Science. Would you like me to move it there for you?
May
9
comment Looking for name of mapping procedure
Unfortunately "making small tweaks to the values iteratively until no changes occur" covers a host of algorithms that rely on the convergence of <something> starting with Newton's minimization and moving up from there. Do you recall anything more substantial?
May
8
comment How to prove or disprove that elementary particle has no spatial extention?
While this answer is not wrong, it is a bit of a hodgepodge of ideas from modern physics without a unifying treatment.
May
8
comment Since the gravitational force is only attractive, why does matter not just concentrate into a small sphere?
Somewhat related: physics.stackexchange.com/q/182679
May
8
comment What does “interact via strong force” mean?
Item (4) is completely unrelated to the others, and should be removed. It is answered in part by physics.stackexchange.com/q/142303 .
May
8
answered What does “interact via strong force” mean?
May
8
comment Using Ampere's circuital law for an infinitely long wire & wire of given length
I suppose that for many cases you could assume that the wire ends on a small but finite-sized spherical capacitor, thus avoiding the need for a singularity. Then choose your surface to not intersect the capacitor.
May
8
comment What happens when an anti-proton and an electron collide with each other?
Sorry, that comment was about "sensitive to violations of isospin symmetry". I was trying to think of a use for the reaction you are asking about and comparing the weak amplitudes of $e^+/p$ or $e^-/n$ to get access to isospin violations was all I could come up with. If that is gibberish to you, then just ignore it: the first two sentences contain the answer.
May
7
comment speed of light and conservation of linear momentum
See physics.stackexchange.com/questions/2229/…
May
7
comment speed of light and conservation of linear momentum
"and thus the law of conservation of momentum doesn't apply to them" This is not correct. Even classically light carries momentum and that momentum must be accounted for to maintain the conservation rule.
May
7
revised Why is the strong nuclear force > electrostatic repulsion?
added 294 characters in body
May
7
answered Why is the strong nuclear force > electrostatic repulsion?
May
7
comment Wave properties and temperature
@danimal It should be useful, but as actually taught it is usually counterproductive. Student come away thinking that these ideas represent a mystery to be solved rather than two useful limits of a deeper theory.
May
7
comment Why is the strong nuclear force > electrostatic repulsion?
"then we would need $g+x=e$ (because the attractive and repulsive forces must balance)" You are thinking of nucleons like little billiard balls and that model isn't really appropriate in this intrinsically quantum realm. That equality does not hold.
May
7
comment Does (mass $\rightarrow$ pure energy) conversion need both matter $and$ antimatter?
To amplify @ACuriousMind's comment, mass isn't a thing distinct from energy, it is a kind of energy just as kinetic and potential energy. But that is a finally drawn distinction that introductory books often ignore or handle badly. For the purposes of class you need to know what the expected answer is.
May
7
comment Both Special and General Relativity carry long term unresolved paradoxes. Should not they now be “inconsistencies”?
"Both Special and General Relativity carry long term unresolved paradoxes." [citation needed]
May
7
answered Conserved quantities in an angular system