Natural Science Forum / Physics / Research / April 2006

I recently read that deep inelastic lepton-hadron scattering
experiments are performed against isoscalar nuclei. Can anyone explain
the advantages of using an isoscalar target?
Regards,

Many of the widely-studied solutions to Einstein's field equations are taken
in vacuo, that is, at events where the energy momentum tensor T^uv=0.  This
includes Schwarzchild and Kerr geometries, for example.
Have there been many exact solutions found where T^uv not= 0?  I am ...

Apologies for the cross posting but this seems to be the place to put it...
I have a question on gauge fixing and path integral evaluation. I hope
it can be answered here. Starting with say, the Maxwell action, we can
write the generating functional as

Commercial superconductors quench by 25 K and run at 4 K.  MgB2 is
highest temp BCS supercon, Tc = 39 K.  High temp ceramic supercons
have Tc between 92 K (YBCO) and about 140 K
([Hg_0.8Tl_0.2Ba]_2Ca_2Cu_3O_8.33).  There is no theory describing

I'm currently wondering about these three Theories Of Everything.
http://www.superstringtheory.com/ (Quantity G is added in an ad hoc
way.) (Mainstream, Untestable.)
http://www.qgravity.org/ (Quantity c is added in an ad hoc way.)

A question for the great and good among you,
can anybody show how to derive eq. 4.133 of Sakurai's Advanced QM ?
Thanks, Zak

I tried this on the other physics groups but I got very little
feedback, perhaps because I didn't claim to refute relativity or use
the word "conspiracy". Some replies are 'no' but no explanation.
Let there be a group of particles P moving from right to left. They

Newton refers to "philosophia experimentalis" (experimental philosophy)
in the "Principia". Looking for the origins of  that expression I have
been led to Roger Bacon's "scientia experimentalis", which in a
previous post ([1]) I naively translated  as "experimental knowledge".

I have just started working through Robert Wald's 'General Relativity'
text and I'm wondering if there are any published solutions to the
problems in this text. Some of the problems are quite difficult and I'm
not sure how to find out if I'm on the right track.

The following question cropped up recently, and I must admit I don't
know the answer (obviously asleep/absent during appropriate
lesson/lecture).
Consider a stream of photons relative to an observer travelling at a

Dear friends at SPR,
I have just posted a DRAFT paper to:
http://home.nycap.rr.com/jry/Papers/Draft%20Lorentz%20Force%20Paper.pdf
This paper is titled: "Is the Lorentz Force Law Based Upon a Relation

I would like to know what makes Einstein's curved space-time theory of
gravitation more acceptable than Birkhoff's flat space-time theory of
gravitation?
Birkhoff's theory can be found here:

This press release was very impressive to me.
http://www.fnal.gov/pub/presspass/press_releases/minos_3-30-06.html
My questions:
(1) Are the experiments -still- compatible with an exactly zero

At least at first sight it would seem that most (nearly all?) of the
testable predictions that QED makes about the electron and its
properties:
  o  Require nothing more than the appropriate choice of wave function

How much can GR and QFT be modified so that their 'axioms' work
together? Does it make the most sense to start 'from scratch', to
modify one theory while keeping the other pretty much the same, or to
find a middle ground?