35,931 reputation
350122
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 43
visits member for 4 years, 1 month
seen 1 hour 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.


Dec
3
answered What is the general definition of signal acceptance?
Dec
3
comment What is this simple mechanism called?
My (personal, not moderator-power) opinion is that this is not a physics questions. This mechanism is a perfectly ordinary piece of mechanical equipment. Asking about specialized lab equipment would be one thing, but what is there about this thing that makes Physics the right site for it?
Dec
3
comment Looking for the actual reason of refraction explained precisely without analogies
@TomášZato It's the magnetic susceptibility.
Dec
3
comment Looking for the actual reason of refraction explained precisely without analogies
@TomášZato They have a momentum distribution of non-trivial width and therefore a non-zero current distribution. Certainly the situation is better defined by a quantum state, but for the purposes of this basically classical description it will do.
Dec
3
comment What property of medium is directly related to light propagation speed in that medium?
Is this earlier answer of mine the kind of thing you are looking for?
Dec
2
comment A test for virtual particles by measuring gravity fluctuations possible?
You have to work pretty hard to measure the gravity of a hundred kilogram test mass. How big do you think the fluxuation you are looking for are?
Dec
1
comment Does the mass of an electron change with its “energy state”?
Only correct if you use a text from the Eisenhower administration (to quote a Physics SE regular). The invariant mass remains invariant. Nor is this answer helpful for a bound electron which does not have a well defined momentum.
Dec
1
comment A student of mine wants to build a Gyroscopic Inertial Thruster
From the first paragraph of the Wikipedia article that you link to "To date, no reactionless drive has ever been validated under properly controlled conditions.". In other words the whole idea is bunkum. Sorry.
Dec
1
comment Which assumption is less plausible, “action at a distance”, or that “virtual particles” can exist for a short time?
It is worth recalling that "virtual particles" are a way of talking about the terms in a series that arises when using second quantization of fields to compute interactions. That is "virtual particles" are fields. And there are a lot of reasons to like fields.
Nov
30
comment How does the Lorentz force work?
Not in the least responsive to the question.
Nov
30
comment What is the refractive index of a gas-like system solely consisting of protons?
Spoil sport. I'm not criticizing either the question or your answer. Rather I initially envisioned it wrong and was playing games with that.
Nov
30
comment Possible solutions to the crown problem of Archimedes
No, cross-section divided by length.
Nov
30
comment Can the relative position of two masses connected by a spring become negative?
I could probably rig an example system in which this was possible just to be a pedantic-jerk, but for the system that most people envision when they read "two masses on a spring" that would require to object moving through each other.
Nov
30
comment Possible solutions to the crown problem of Archimedes
The thermal conductivity (measured in W/(m K)) is is a function of the material, put the thermal power (measured in W) is a function of both the temperature difference (which you presumably control) and the cross-section over the length (A/L). The time it takes the wax to melt depends on the shape of the piece connecting the two sides.
Nov
30
comment Possible solutions to the crown problem of Archimedes
Ah. I withdraw that objection, but have another. The thermal conductivity of the crown depends on the cross-section which (in the original story) is highly variable because the object is ornate and spiky---that was the thing that was giving Archimedes trouble in the first place. The physical insight here is fine and I wouldn't down vote on this kind of basis but the answer so far have ignored the context of the legend.
Nov
30
comment Is $F = G\dfrac{{m_1}{m_2}}{r^2}$ really true?
On the matter of subconscious cherry-picking or otherwise diddling the data, it is always safer to blind the data if you can.
Nov
30
comment What is the refractive index of a gas-like system solely consisting of protons?
Hmmm ... in free space the density is, obviously, rapidly dropping. Can I just wait a while and say "approximately 1.0"?
Nov
30
answered Must Matter Particles Have A Hard Edge?
Nov
30
comment Possible solutions to the crown problem of Archimedes
At the time no one anywhere in the world knew how to manufacture clear glass and even the less cloudy variants were not available in large batches. Indeed any quantity of glass was a luxury item.
Nov
30
comment Is $F = G\dfrac{{m_1}{m_2}}{r^2}$ really true?
'86 would have been one of the very short-lived and unreproduced "fifth-force" claims. I won't blame the author for putting it in the book, but I think it is fair to suggest that more conservative language would have been better.