50 research outputs found
The spin-statistics connection in classical field theory
The spin-statistics connection is obtained for a simple formulation of a
classical field theory containing even and odd Grassmann variables. To that
end, the construction of irreducible canonical realizations of the rotation
group corresponding to general causal fields is reviewed. The connection is
obtained by imposing local commutativity on the fields and exploiting the
parity operation to exchange spatial coordinates in the scalar product of
classical field evaluated at one spatial location with the same field evaluated
at a distinct location. The spin-statistics connection for irreducible
canonical realizations of the Poincar\'{e} group of spin is obtained in the
form: Classical fields and their conjugate momenta satisfy fundamental
field-theoretic Poisson bracket relations for 2 even, and fundamental
Poisson antibracket relations for 2 oddComment: 27 pages. Typos and sign error corrected; minor revisions to tex
Graded contractions and bicrossproduct structure of deformed inhomogeneous algebras
A family of deformed Hopf algebras corresponding to the classical maximal
isometry algebras of zero-curvature N-dimensional spaces (the inhomogeneous
algebras iso(p,q), p+q=N, as well as some of their contractions) are shown to
have a bicrossproduct structure. This is done for both the algebra and, in a
low-dimensional example, for the (dual) group aspects of the deformation.Comment: LaTeX file, 20 pages. Trivial changes. To appear in J. Phys.
Brazil, Blasphemy, and Free Speech: Why the US Must Maintain Strong Freedom of Expression Protections in Spite of International Pressure to Punish Anti-Religious Hate Speech
Line-Drawing, Embryonic Stem Cell Research, and the Dickey-Wicker Amendment
Human embryonic stem cell (hesc) research is the culmination of a multi-step process: creating an embryo through in vitro fertilization (IVF), deciding whether to donate or destroy embryos left over from that process, harvesting stem cells from embryos donated for research, and finally doing research with the stem cells themselves. Each of these points presents different ethical issues. For those for whom human embryos command relatively little moral weight, this entire process is acceptable. But for those who consider embryos the moral equivalent of persons ,and also for those for whom embryos, while not equal in importance to born humans, do carry a great deal of weight, everything depends on when in that process one comes to a moral crossroads. I argue that the line drawn by NIH in its response to the Dickey-Wicker Amendment, is not morally defensible. I also argue that for those who wish to stop or at least to decrease the destruction of embryos for stem cell research, the moral crossroads occurs much earlier: with the creation of those embryos in the fertility clinics