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.

comment who determines what is "not constructive"?
It took a long time to bring the crowd around on this, but it eventually became clear to a lot of people just how poisonous those popularity contests are. Thank FSM there will be no more of them.
comment who determines what is "not constructive"?
This has been thrashed to death. These days most of the posts have gone to meta.stackexchange. Start with meta.stackexchange.com/questions/56669/…
answered Problems with Stack Overflow's Creative Commons license agreement
comment Is it possible to produce images of pair production in home-made cloud chamber?
@DanS You can buy well sealed sources CoTS (in fact, there is more paperwork to get access to raw radio-isotopes than for the sealed sources). And the quantities needed are pretty low. That $\mu\mathrm{Ci}$ that Chris mentions is about $40000\,\mathrm{Bq}$ which is plenty for what the OP desires. The OP will want to store them in a source safe or something equivalent, but they pose no danger to someone outside the garage.
revised Is it possible to produce images of pair production in home-made cloud chamber?
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answered Is it possible to produce images of pair production in home-made cloud chamber?
comment If atoms never "physically" touch each others, then how does matter-antimatter annihilation happen?
It can be (and is) simultaneously true that electrons scatter like point-particles (down to $10^{-18}\,\mathrm{m}$ experimental precision) and that their wave-function gives significant probability to distances on order of $10^{-10}\,\mathrm{m}$.
awarded Enthusiast
comment Is it really okay to treat the Earth as stationary when doing free fall experiments?
The general procedure for answering this kind of question is: compute the size of the neglected effect to first order and compare to your uncertainty in actually performing such an experiment. If the neglected effect is comparable your uncertainty, then you should probably insist on it. If it is much smaller than your uncertainty then you can safely forget it. If you improve the precision of your measurement you may have reconsider such questions.
comment How does radiation shielding using absorbing materials work?
There is a second advantage to light nuclei in stopping neutrons. The target-frame, kinetic-energy loss of the incident particle is largest when the projectile and target have the same mass. Neutrons hitting $^1\mathrm{H}$ nuclei dump energy faster than when they hit any other nucleus.
comment If two events both have a spacetime interval of zero, can they both be said to be happening "now"?
It is the ability to know about events that propagates at no more than c.
comment What happens after death?
Covered on the mother meta: meta.stackexchange.com/q/38742. The short answer is "nothing, you'll just stop contributing".
comment Why do hydraulic jumps form?
Jim, the geometry that you show is only one way to generate a hydraulic jump and my discussion is not specific to it. In your case the liquid far from the nozzle is slowed down by simple viscous drag, and it is then overtaken by a faster flow from the rear.
comment Why don't we talk about angular momentum at all in fluid mechanics?
Not even remotely an expert in fluids, but it occurs to me that scale is important in all but the simplest cases and angular momentum implies that different parts of the volume are treated at different length scales (comparable to the distance from this neighborhood to the center around which $L$ is evaluated).
comment Why is Silver-108 unstable
The short and unhelpful answer is "Given the decay modes it is simply that Palladium-108 and Cadmium-108 are both sufficiently lower energy states than the silver isotope." If I was trying to track this down, I'd note that Ag-108 is a odd-odd nucleus, so it pays a penalty in pairing energy.
comment How much could one slow down aging using existing spacecraft?
"the gamma rays emitted by matter anti-matter annihilations in its reacor" The problem with simple matter-antimatter reactions (aside from the bit about getting enough anti-matter together) is that much of the energy is released in neutrinos and pions not photons. In principle you can steer about half the pions to your advantage, but the neutrinos are isotropic and you can't steer them.
awarded electromagnetic-radiation
comment Why Light and Observers have different laws of physics
Excitations of quantum fields, like photons (and indeed every other fundamental particle), are the things we call particles. These things are what particle physics studies. Photons are particles. And photons travel at the speed of light. And this is OK and not at all a problem. Their path between two non-identical places takes zero proper time and finite time as measured by all observers and this is OK and not at all a problem.
awarded Good Answer
comment Is fibromyalgia a discrete clinical entity?
Note the use of "syndrome" in the answers and references. The word is not always used in exactly the same way, but it tends to mean something like "a cluster of symptoms which occur together" and may or may not have a understood cause. The "syndrome" appellation is often dropped once the underlying cause s sufficiently understood.
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