40,826 reputation
356130
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 44
visits member for 4 years, 7 months
seen 37 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.


Jun
28
comment How much wind power is needed to lift someone up?
The above considerations should also explain something about the design of the human-powered rotor-wings that @CuriousOne mentioned.
Jun
28
comment How much wind power is needed to lift someone up?
One of the several problems with the framing of this question is that you are asking for power of an operation that intrinsically doesn't require any at all. What is required is force. Now, because you are hoping to generate that force as a reaction from pushing air around, there is an actual power cost, but how much depends on your thrust geometry: moving a lot of air slowly requires less power for the same thrust than moving a little air fast. But that brings us squarely into an engineering problem, not a physics one.
Jun
27
comment Is it possible for two events happen at the exact same time?
My point was that "basketballs hitting the ground" is not in any detailed and reasonable understanding something that happens at a single point in time. It can only be treated that way in the highly simplified approach used in the first few weeks of introductory classes. By the time you have the concept of impulse it should be clear that the event can't be confined to a single mathematical point in time.
Jun
27
comment Is it possible for two events happen at the exact same time?
Non-trivial, physically-realizable events generally require a finite period of time in which to happen, as well, so overlapping those periods doesn't even require arbitrary precision.
Jun
27
comment Could a spaceship design incorporate several kinds of force or effect?
This is more or less explicitly an engineering question.
Jun
27
comment Is there any basic physics textbooks that do not have reference to sport?
Note that there has apparently been an informal effort to remove the formerly numerous war-related references from textbook examples and exercises in recent year and many seem to have gotten replaced with sport related equivalents. You could try an older text. I also see books now that use the exercise formerly known as "shoot-the-monkey" without that name and often with out the simian.
Jun
27
comment Can one verify the Earth tide in his yard?
As @Curious says, a fixed, integrating GPS station can achieve better than 20 cm resolution, so you ought to be able to pick the approximately diurnal variation out of the observations. The signal will be buried in a fairly noisy background, but it should be there.
Jun
27
awarded  photons
Jun
26
comment Relativity… Twin paradox
In particular if you follow the procedure in physics.stackexchange.com/questions/2554/… you can can answer your question for yourself.
Jun
26
comment Relativity… Twin paradox
I fear that I'm going to come across as being a jerk, but I want to say this anyway. The "paradox" is fully resolved and the resolution applies to all the variants that newcomers to the subject think up. All of them. Every one. The resolution can be stated clearly in a couple of different ways, and you would be better served finding one of the many other twin paradox questions on the site and working on the resolutions until you understand them. Just asking another version of one of the standard variant (as here) isn't going to get you a new explanation.
Jun
26
comment Carroll's derivation of the geodesic equations
I've fixed the first two equations here. Note the use of blocktset equations (use $$, not $), the use of \tag{} to get numbering, and the use \mathrm{} to force the typesetting of differentials in the conventional upright text, and finally the use of \, if you want to forcibly insert a thin space.
Jun
26
revised Carroll's derivation of the geodesic equations
added 4 characters in body
Jun
26
answered What happens to theoretical physics if a photon has non-zero mass?
Jun
26
comment Confusion in understanding the proof of Uniqueness Theorem
Depending on what is troubling you about that statement it might help to recall that the choice of sphere is arbitrary, and that means it is no help assuming a conspiracy to works in a particular geometry: I can pick a smaller sphere...
Jun
26
comment Inertia of a disk - axis of rotation through the x-axis
You should look closely at the meaning assigned to $r$ in the first expression you exhibit. You'll find that it means "the distance of this mass element from the axis", and not "the distance of this mass element from the origin" as you seem to be assuming. After that you still have to reconsider the way you are performing the volume integral.
Jun
26
revised Hooke's Law Problem
partially latexify
Jun
26
comment Layman summary about the properties of the sixth state of matter, the fermionic superfluid?
Just as a random comment: there are many states of matter known and nobody except the popular press tries to give them numbers.
Jun
26
comment Detectable interactions in Cherenkov detectors
Also, deep underground detectors get a significant number of spallation neutrons from the over-burden. Of course super-k is so big that they rarely penetrate deeply into the detector and I believe there is a fiducial volume cut to help remove these events. KamLAND is under the same mountain but is much smaller and found it necessary to model and measure nearly a score spallation triggered isotope production processes. I could provide a paper reference if you cared.
Jun
26
comment Detectable interactions in Cherenkov detectors
Just as a terminology issue the way you are using "quasi-elastic" is the way I learned it in a nuclear context, but neutrino physicists also use the term to apply to the plain charged current reaction $\nu + n \to e^- + p$ when the energies are high enough to neglect both lepton masses and the proton-neutron mass difference. So a charged-current nucleon knock-out reaction could be quasi-elastic both ways.
Jun
26
answered Detectable interactions in Cherenkov detectors