32,211 reputation
343106
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 43
visits member for 3 years, 8 months
seen 9 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.


2h
awarded  Nice Answer
11h
revised Transmission/Equilibrium Question
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11h
comment Variation in measurements of $g$ on the Earth's surface due to the Moon's gravity
My understanding is that "Earth tides" usually means the distortion of the solid planet due to the tidal driving force (which is a small but non-trivial fraction of the ocean tide), not the basic differential gravitational effect due to the finite distance to the moon. No idea which way Feynman meant it. The answers to the follow-up question seem to explain the four-bumped structure of the daily variation.
11h
revised Transmission/Equilibrium Question
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12h
revised Transmission/Equilibrium Question
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12h
answered Transmission/Equilibrium Question
16h
comment In a neutron star - what force keeps the neutrons from getting closer and closer?
@Michael Hmmm...it's been a while since I wrote that. I have to admit that I have waffled over time on how to answer that question. There is no force carrier, but the effect can be unambiguously and correctly written in terms of a pressure. Alternately the combination of gravity and the residual strong forces (carriers graviton and light mesons) have pushed the Fermi energy too high for further compression to be energetically favored.
16h
answered How can individual photons have different amounts of energy?
17h
comment How can individual photons have different amounts of energy?
This is not a duplicate of physics.stackexchange.com/q/3541, but the answer is the same.
19h
comment Interaction between neutrino and an anti-neutrino?
@jazzwhiz Well, yes, but they have to be off-shell in the first place for that.
21h
revised How do we know that the nucleus isn't a quark-gluon plasma?
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21h
answered Why is binding energy $\Delta mc^2$?
1d
comment F-mu-nu notation
Is the questions about the general meaning of tensor indicies or about the distinction between raised and lowered indicies?
1d
comment Active-sterile mixing for KeVins
"I think they call them KeVins (horrible name btw)." Egads, that is bad.
1d
comment In scattering, how does a particle 'know' which direction it is being illuminated from?
@WaqarAhmad The point is that it is not fundamentally any different. Both systems have to conserve momentum and that is what sets and communicates the axis of the interaction.
1d
awarded  Good Answer
2d
revised What is it that makes an electron maintain a distance from the positively charged nucleus?
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2d
comment What is it that makes an electron maintain a distance from the positively charged nucleus?
Another good duplciate: Why do electrons occupy the space around nuclei, and not collide with them? and related Why doesn't orbital electron fall into the nucleus of Rb85, but falls into the nucleus of Rb83?.
2d
answered In scattering, how does a particle 'know' which direction it is being illuminated from?
2d
comment Is this kids experiment a legitimate way to show that air has mass?
@ACuriousMind "If your experiment does not match the theory, it's the theory that's wrong, not the experiment." Or that you have a problem in your analysis. Or in your execution.