38,962 reputation
354126
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 44
visits member for 4 years, 5 months
seen 5 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.


Jun
2
comment How do you build a nuclear reactor in your garage?
For that matter, even fission piles are not intrinsically complicated things to build. They are fiendishly complicated things to run safely while still producing net power output, but that is a much different problem then just generating a sustained chain-reaction. After all, a team working with Fermi built one by hand in the squash court in the University of Chicago...
Jun
2
comment How do you build a nuclear reactor in your garage?
Your assumption that "Nuclear reactors are immensely complex devices" is simply incorrect when applied to accelerator based fusion reactors. Mind you, these things are far, far below unity of power generating ability: they require net power input to run. But if you want to fuse nuclei to say you've done it it just takes some vacuum kit, a way to accelerate ions to a few 10s of MeV, and some careful focusing of the beams.
Jun
2
reviewed Approve Relative to the speed of light
Jun
2
reviewed Reject What is the difference between a measurement and any other interaction in quantum mechanics?
Jun
2
comment Is Brownian motion a deterministic system?
This is the traditional answer of the 19th century, but it doesn't really account for the combination of quantum mechanical uncertainty and the fact that sufficiently complicated systems can diverge exponentially starting from arbitrarily small perturbations. The unpredictability is built in at the ground level; there is not--even in principle--a way to treat the universe as a deterministic system.
Jun
2
comment Is Brownian motion a deterministic system?
No proof or reference, but I suspect that you are looking at "sensitive dependence on initial conditions" (i.e. chaos), which when combined with the Heisenberg Uncertainty principles leads to necessary unpredictability.
Jun
2
comment Pion production in proton-proton collision
To a significant extant the answer is "Because it can be." There is sufficient energy and the quantum number of the final state agree with those of the initial state.
Jun
1
reviewed Approve Why, in EXAFS spectrum, does the absorption coefficient monotonically decrease with increasing photon energy?
Jun
1
comment Spread and direction of the cosmic background radiation
Related: physics.stackexchange.com/questions/16074/… (and it's linked sidebar) physics.stackexchange.com/questions/18792/… physics.stackexchange.com/questions/52435/… physics.stackexchange.com/questions/20056/…
May
31
comment Dose the gravitational force produces precession in the spinning top?
Static friction at the tip is responsible for the tip not circling as much as the free end, but ... static friction can only ever counter an otherwise unbalanced force along the surface. Where have you got that in the system? Besides, your idea doesn't explain how it works when you hang the gyroscope from a rope.
May
31
comment Clear up confusion about the meaning of entropy
"hot gas seems super disordered, but put cold gas in thermal contact with it, let them come to thermal equilibrium, and now they are more ordered!?" Well, the deal hear is that you have to compare the disorder of the combined system before and after. While the hot system had a lot of entropy the cold system had little, so now you ask how does the loss in the hot system compare to the gain in the cold one...
May
31
reviewed Approve If hydrogen and helium are lighter than air, why won't liquid hydrogen and liquid helium defy gravity?
May
31
reviewed Approve When a gas expands against an external pressure of 0, must the stopper on the cylinder be massless?
May
31
comment Heat transfer in a pipe
For a non-trivial need that is something that you would compute, but you don't expect it to be linear in the distance traveled unless little heat is lost by the working fluid because all those heat transfer mechanism depend on the temperature difference and the temperature difference depends on how much heat was lost earlier in the system. The full problem is hard. If you want a computational solution you should ask on SciComp. Also, get ready to learn about a lot of dimensionless numbers named after otherwise obscure people.
May
31
comment Feedback on the paper, 'CCC-predicted low-variance circles in CMB sky and LCDM' by V. G. Gurzadyan and R. Penrose
It is worth noting that the authors have a later pre-print with the same title that was published (which the earlier one was not). Presumably you should look at the differences. In any case, I think the question remains "overly broad": you seem to ask does anyone have anything to say about this paper.
May
31
answered Discovery of $E=hf$?
May
31
revised photons wiki excerpt
Emphasize that photon == particle and that this is an alternative to understanding light as electromagnetic waves
May
31
revised Discovery of $E=hf$?
edited tags
May
31
comment Discovery of $E=hf$?
Einstein got the prize in part for using it to explain the photoelectric effect. It was proposed by Planck to as a way to fix the ultraviolet catastrophe. What do they teach children in school these days?
May
31
reviewed Reject Photon Statistics of a Coherent Gaussian Beam