41,439 reputation
356134
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 44
visits member for 4 years, 8 months
seen 4 hours 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.


Aug
6
comment On the theoretical aspects of the development of the first nuclear bombs
Building the first bombs required rather a lot out of nuclear experimenters in terms of getting the right cross-sections, branching ratios and so on; of nuclear theorists in terms of understanding the mechanics of a run away chain reaction and know which cross-sections and branching ratios to ask about; of computationalists in terms of Monte Carlo (mostly without the aid of electronic computers, mind you); and of the engineers at every stage of the material refinement, device design, manufacture and assembly. Huge project.
Aug
6
comment Running of gauge couplings in the Standard Model
This question appears to be off-topic because it is about using a software tool.
Aug
6
comment Are there solid materials with controllable porosity?
I can imagine systems to solve the problem (porous plug under controlled pressure; dialing the temperature of a filter with nice linear expansion) and so on, but I don't know of anything as simple as the piezo response. Are there other constraints to make those kinds of idea infeasible?
Aug
6
comment Can electromagnetic radiation (i.e. photons) produce gravity?
Questions should not be edited to completely change their character.
Aug
6
revised Can electromagnetic radiation (i.e. photons) produce gravity?
rolled back to a previous revision
Aug
6
comment What type of magnetic fields does a Hall effect semi-conductor pick up on?
@user27930 Fundamentally to understand "the math" you must understand the physics of how the device works, however with most packaged instruments the manufacturer has done the heavy lifting for you: you just have to read the products documentation (often called a data-sheet).
Aug
5
comment Why stars twinkle but planets don't?
Thought the text of Why do stars flicker? does not mention planets, the answer covers this exactly.
Aug
5
comment Imaginary time?
Because I've no interest in gaining rep on it.
Aug
5
answered Imaginary time?
Aug
5
comment Imaginary time?
After enough comment edits I'll even get the units right. ::sigh:: That's why particle physicists work in $c = 1$ units: because we're too dumb to handle SI units.
Aug
5
comment Imaginary time?
This $E = \frac{1}{2}mv^2$ is only correct in the limit of $v \ll c$ (the Newtonian or non-relativistic limit). The generally correct expression is $E = \sqrt{(mc^2)^2 + (pc)^2}$. It follows that rest of your work is also incorrect except in that limit. Never mix relativistically correct and Newtonian math. Unless you really know what you are doing, of course.
Aug
5
comment Nuclear Fission and Fusion
I'm pretty sure you've been pointed at one of physics.stackexchange.com/q/961 physics.stackexchange.com/q/68145 physics.stackexchange.com/q/26059 before, but if not (and indeed, if so) do read them. Oh, and physics.stackexchange.com/q/10186.
Aug
5
revised Size of universe after inflation?
Strip questionable link
Aug
4
comment Regarding space launch hazard and near earth debris
Have you asked how many objects are not being tracked yet?
Aug
4
comment Pair annihilation - how to generaly solve these types of problems?
@leongz The photons only have the same energy in the CoM frame. The problem can also be solved in the lab frame using the same basic method: you simply conserve four momentum.
Aug
4
comment Should normalisation factor in a QM always be positive?
The thing to be normalized is positive definite, right? And it is to be made equal to 1 not -1, right? So ...
Aug
4
comment Photon mass and life time
The current text of this questions is deeply misleading. The article assumes the correctness of relativity which investigating a theory in which the photon has mass.
Aug
4
revised Photon mass and life time
point link at the *abstract* page
Aug
4
comment Should we necessarily express the dimensions of a physical quantity within square brackets?
It is never worthwhile to dispute a question like this with your instructor. For the purposes of the class the correct answer is the one the instructor told you.
Aug
4
comment Should we necessarily express the dimensions of a physical quantity within square brackets?
He might stick to his notation, but the exam will be graded on the basis of the notation the instructor told him to use... Moreover, there are some fairly common notation conventions out there and the use of square brackets to denote the kind of dimension (rather than a particular unit) is quite common to the point that one could be tempted to use the word "standard".