29,752 reputation
33994
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 43
visits member for 3 years, 5 months
seen 7 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.


Apr
12
comment Very short decay: A bare quark?
You might find the comments under a post where I relayed this tidbit useful.
Apr
12
revised Very short decay: A bare quark?
edited tags; edited tags
Apr
12
comment Very short decay: A bare quark?
Do you know what the word "hadronize" means in this context?
Apr
12
comment Experimental evidence for the relic neutrinos
What should I say that isn't in the Wikipedia article? There are three known flavors of neutrinos with some hints that there might be 1--3 sterile flavors. The cosmology is mostly consistent with 3 flavors early and prefers four at later times. (I'm out of my depth on this stuff but naively I would expect the sterile flavors not to contribute early on, and to start to come in at later times.)
Apr
12
answered Experimental evidence for the relic neutrinos
Apr
12
comment Is it possible to look into the beginning of the Universe?
The BICEP experiment has now reported a positive result using the method suggested by @FrankH here.
Apr
12
comment Experimental evidence for the relic neutrinos
There is no direct evidence at this time. We don't even know how to begin.
Apr
12
comment Which is the smallest known particle that scientists have actually *seen with their eyes*?
This question is one that seems obvious and clear to the layman, but is very subtle in the mind of an expert. You have said on one hand that Davidmh's answer is what you want, but on the other hand it fails your own "same photon" test because that is the scan of a long exposure photograph. The question could just as well be "opinion based".
Apr
12
comment Vapor pressure formula
This question appears to be off-topic because it is about what some unspecified piece of computing code is doing.
Apr
12
comment Vapor pressure formula
"The dos exe program can't be reverse engineered to get the original program" That is too strongly stated. There is no general purpose reverse compiler, but you (or rather, an expert in x86 assembly) certainly can examine the executable to determine what it is doing.
Apr
11
comment Why can lights(photons) bends in a curve through space without mass?
Expressed the other way 'round, but having the same answer: physics.stackexchange.com/q/18900. Which leads back to physics.stackexchange.com/q/10612.
Apr
11
revised Can a neutrinos mass oscillate in a similar way to its flavour?
Capitalization, apostrophes, tags; leave the British spelling alone.
Apr
11
comment Concerning a previous possible tachyon observation?
To be very clear, OPERA involved CERN, but the LHC is not CERN. LHC is at CERN, but it is only one of a great many things at CERN. OPERA's neutrino beam was produced by a different accelerator (the SPS).
Apr
11
comment Do particles keep on emitting energy?
The laws of physics as they are usually written down (like "accelerating charges radiate") only apply in inertial frames. There are mathematical prescriptions that allow you to produce the laws that apply in non-inertial frames, but they do not always have the same form and content as the ones we usually talk about (i.e. a rotating frame has centrifugal and coriolis pseudo-forces). You are trying to apply the untransformed laws to a non-inertia frame. That's an error. It's not valid to compute the electron's acceleration based on it's distance from you without subtracting your acceleration.
Apr
11
comment Do particles keep on emitting energy?
Pay attention to the postulates of special relativity here. You can only assume that the laws of physics apply to your observations if you are in an inertial frame.
Apr
10
comment If 'pure energy' is photons, and energy is conserved, how can matter and antimatter (electrons and positrons) annihilate into photons and vice-versa?
Just a hint: the phrase "pure energy" will only confuse you. It doesn't have a useful meaning. Just write and say "energy".
Apr
10
comment Does ordinary refraction exert a couple on the refracting medium?
Don't know the answer right off, but you must include the reflected beam in your consideration.
Apr
9
comment Why are cgs units the norm in astrophysics?
Time, place and people. A field gets hot and a bunch of seminal works are written, and the choice of conventions always depends when, where and who. In effect it is a historical accident, possibly modified by strong personalities at a later date.
Apr
9
comment Could a tetraquark $q \bar{q} q \bar{q}$ be colorless?
Tetraquarks fit just fine in the standard model and have been sought for a long time. They are neither baryon nor meson, but they are still hadrons. (I suppose the definition of "meson" might be extended to cover this case, but pentaquarks---if found for real---would call for a re-think.)
Apr
9
comment Does it really make sense to talk about field lines?
While I discourage people from talking about "field lines" because I see students confuse themselves that way, the construct can be made mathematically equivalent to a vector field that is divergenceless except at charges. So this becomes a questions about pedagogy.