34,540 reputation
347119
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 43
visits member for 3 years, 11 months
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.


3h
comment What is matter made of in the light of Quantum Mechanics?
Can you explain what matter is made out of not in light of quantum mechanics? The word effective means "the stuff stuff is made out of". It's the answer not the question.
1d
comment Why does not electron cloud collapse over Nucleus?
This probably isn't the most frequently asked question on the site (that distinction has to belong to either relativistic mass or the speed of light limit), but there are at least a dozen versions already.
1d
reviewed Leave Closed how human is affected because of particle accelerator?
1d
comment Why don't objects following a geodesic maintain their rotational state?
Another comment: for a spherically symmetric object like a ball the first order residual interactions cancel out. If you do it with a boomerang tidal effects can (in principle) come into play.
1d
comment Why don't objects following a geodesic maintain their rotational state?
Well, let's be careful here: the observer would see all the faces of the object which would always have it's features in the same orientation relative to the fixed stars. Contrast this with the moon: we see only one face, but it clearly turns (just at one rotation per revolution).
1d
comment Is $E^2=(mc^2)^2+(pc)^2$ correct, or is $E=mc^2$ the correct one?
See physics.stackexchange.com/q/1686 and physics.stackexchange.com/q/34008 and many other posts around the site about the professional take on "relativistic mass".
1d
comment Can Half Lives (hypothetically) be Measured by Wave-functions?
Half-lives can be computed in certain models by considering the wavefunction, but wavefunctions are not themselves observable: you don't (can't) measure them.
Oct
28
comment Does an externally driven Foucault pendulum really demonstrate the rotation of the Earth?
And indeed the drive circuits typically take advantage of the broken symmetry of the situation to insure this. Example: google.com/patents/US3424960
Oct
28
comment How is a photon measured?
You haven't said what would make something real, but electromagnetic interaction can transfer both energy and momentum which is real enough for me no matter how you model them (waves or photons).
Oct
28
revised What causes the dimensions of a star increase when its hydrogen fuel is exhausted?
minor blue pencil stuff
Oct
28
comment Nuclear fusion and the Sun
I write a little bit about the p-p cylce in an answer to another question. The star makes the Helium-3 as it goes along and then uses it up again to make Helium-4.
Oct
27
comment I don't get the concept of “God plays with dice” - In what scenario is it proven that he does?
Please take this to chat. At this point it has nothing to do with the question.
Oct
27
comment Why can thermal shocks damage/break materials?
Related: physics.stackexchange.com/questions/57482/…
Oct
27
comment Derivation of wave-velocity from a wave-equation
In general you can read the velocity off of the solutions. Think about how you we convinced of the velocity of very basic plane-waves in earlier treatments.
Oct
27
comment When a body accelerates, it gains (relativistic) mass; after stopping, is the (relativistic) mass different from before it started accelerating?
See physics.stackexchange.com/q/1686 and physics.stackexchange.com/q/34008 and many other posts around the site about the professional take on "relativistic mass".
Oct
27
comment How much effort would be required to fix the Earth's rotation?
@user2813274 No that only gets me 2 hours of accumulated time. I want two more hours in every single day. I believe I have to wait roughly 75 million years for that... (Figure assumes that Vernor Vinge used reasonable values in Across Realtime, because I'm not going to check it.)
Oct
27
comment How much effort would be required to fix the Earth's rotation?
@DavidHammen That just repays the sleep debt I've been hauling around since March. And without interest at that. No, I think the day should be made about 90 minutes longer to better fit my circadian rhythm. Maybe two hours, actually. Yeah.
Oct
27
comment How much effort would be required to fix the Earth's rotation?
@user2813274 Conservation of angular momentum is a fundamental principle. If you want a permanent change we'll build 800 mass drivers with relativistic muzzle velocities around the equator and shoot 1000 of the trains eastward from each one, one car at a time. Coping with the environmental effects of is another exercise for the reader.
Oct
27
comment Why doesn't a Brownian ratchet provide free energy?
From the same section of the article you reference "A simple but rigorous proof that no net motion occurs no matter what shape the teeth are was given by Magnasco.[3]" where [3] is Magnasco, Marcelo O. (1993). "Forced Thermal Ratchets". Physical Review Letters 71 (10): 1477–1481. Bibcode:1993PhRvL..71.1477M. doi:10.1103/PhysRevLett.71.1477. PMID 10054418. Likewise they give a citation for Feynmann's argument.
Oct
26
comment Deriving Newton's Second Law
I've removed some inappropriate comments. Keep it nice, folks.