34,574 reputation
347119
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 43
visits member for 3 years, 11 months
seen 2 mins 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.


Feb
20
comment Electric field caused by magnetic field
May be related to my answer to physics.stackexchange.com/q/5573/520 (or rather a comment under it). Short answer is "yes", but if you didn't believe me the first time there doesn't seem to be much point in repeating myself.
Feb
20
revised $\alpha$ decay to more than one nuclear state
edited body
Feb
20
comment $\alpha$ decay to more than one nuclear state
BTW, the daughter nucleus has got to be plutonium and not promethium.
Feb
20
revised $\alpha$ decay to more than one nuclear state
added 27 characters in body
Feb
20
comment $\alpha$ decay to more than one nuclear state
Hmmm. Curium-241 has spin-parity of $\frac{1}{2}^{+}$; the ground state of Pu-237 has $\frac{7}{2}^-$, and the alpha is $0^+$. To make the angular momentum work the alpha would need to be emitted with a orbital angular momentum of 3 which is parity negative and would seem to be allowed. Can't say.
Feb
20
answered $\alpha$ decay to more than one nuclear state
Feb
20
comment Stone thrown in empty space
Bookkeeping aside: you can get this registered account merged with your previous unregistered account if you want.
Feb
20
comment Is cosmic background radiation dark-matter and/or dark-energy?
@AlanSE I think you misunderstood what I was using the MACHO data for. I wanted to show that we understand photons in GR. My evidence is the success in predicting the light curves that would appear in MACHO events. If we understand photons in GR then we don't have a misunderstanding of the sign of the pressure.
Feb
20
comment Is cosmic background radiation dark-matter and/or dark-energy?
@AlanSE Well, we know enough about photons in GR to have corrected computed the family of light curves associated with MACHO microlensing events in advance. I find it difficult to believe that e could do that and misunderstand the sign of the pressure related to photons.
Feb
20
comment Can the speed of an electromagnetic wave be measured in the absence of neutrinos?
Nor is the wikipedia a good reference in the event of a controversy. However, one presumes that the footnote the OP keeps cutting a pasting points to something reliable. Hmmm...seems to be an outdated edition of the PDB.
Feb
20
comment Is cosmic background radiation dark-matter and/or dark-energy?
@AlanSE EM radiation has positive pressure the same as normal matter, therefore it contributes to a decelerating universal expansion. That is clearly different from the observed acceleration. To my knowledge the only observation contributing to the belief in dark energy is the observed time dependence of the Hubble (non-)constant which is incompatible with the known and understood categories of stuff. See Lubos' notes in the comments to the question.
Feb
20
comment Can the speed of an electromagnetic wave be measured in the absence of neutrinos?
The vacuum contains virtual particles of all species. Note that there are several question one could reasonable ask in this realm. Things like "Would the speed of light be different in the absence of field-theoretical fluctuations?" or "Can QFTs explain the permitivity and permeability of free space from first principles?"
Feb
20
answered Is cosmic background radiation dark-matter and/or dark-energy?
Feb
20
comment How do I publish a physical constant
Look the fine structure constant, $\alpha(k \to 0)$, is a number. That's not a problem. On the other hand, there are more cranks and crackpots out there than under-appreciated geniuses. You might want to check that you're in the latter category at some point.
Feb
20
comment How do I publish a physical constant
No. Short articles are accepted by very nearly every journal. Some, such as Physical Review Letters specialize in short articles (thought PRL likes them to be in rapidly advancing fields).
Feb
20
revised How do I publish a physical constant
added 3 characters in body
Feb
20
answered How do I publish a physical constant
Feb
19
revised Can we make images of single atoms?
added 97 characters in body
Feb
19
reviewed Approve suggested edit on Can we make images of single atoms?
Feb
19
comment Why is the majorana particle a fermion?
"one has to say that these Majorana fermions have not been observed in nature except [...]" Well, we've observed neutrinos and don't yet know if they are Dirac or Majorana, so let's say "have not been demonstrably observed" or some such weasel word.