Natural Science Forum / Physics / Research / December 2005

I am trying to track the first occurrences of the expression
"philosophia experimentalis" ( "experimental philosophy", just in case
) famously used by Newton in the Principia . The earliest record I
could find is Nicola Zucchi's "Optica Philosophia Experimentalis et

Suppose just for fun that space is a simplicial complex. (By space I
mean some spacelike hypersurface.) Its Euler characteristic is zero, but
if we take some connected piece of space (a set of tetrahedrons, say,
where there's a path from any one to any other through adjoining

I was wondering, given the behavior of quantized rigid rotors, what
would happen if a long and perfectly straight carbon nanotube were to be
slowly spun around its midpoint like a propeller. Would the quantized
rotation angle at the center be magnified at the ends of the tube to ...

Hello to all:
As I mentioned previously, DRL earlier pointed out some problems endemic to
general relativity with respect to volume integrations of energy / momentum
in spacetime, and Igor had some comments regarding connections I was

Take a look at this NewScientist.com Article
http://www.newscientist.com/channel/fundamentals/mg18825305.800.html
-J.

Although gravitational waves have never been experimentally discovered,
is there any definite prediction from the theoretical models as to how
much energy and momentum they carry? For example, how is a
gravitational wave of a certain frequency thought to compare with an EM

There is a CMB and also a neutrino background. Does QCD imply that there
is also a cosmological gluon background? If not, why not? If so, how
much energy would it contain and why isn't it mentioned in the text
books?

I know that the electromagnetic, strong, and weak forces have been
unified.  Is it true that all "forces" except gravity fall under this
theory?

I've been thinking about what it means that the connection coefficients
don't transform like a tensor.  Given that we start off with the idea
that thing that have a co-ordinate independent reality are tensors i.e.
transform like tensors does the fact that the connection isn't a ...

Also available as http://math.ucr.edu/home/baez/week223.html
November 14, 2005
This Week's Finds in Mathematical Physics - Week 223
John Baez

In perturbative QCD the beta function goes to infinity at an energy
given roughly by Lamda QCD.
There is therefore an entire energy range between 0 and Lamda QCD which
cannot be explored

Brief Summary (In reverse order)
http://www.planetary.org/programs/projects/pioneer_anomaly/update_200511.html

A while ago, a biographical series on Einstein was presented on PBS
which reiterated a widely-held Physics folk-myth regarding the relation
of Einstein and Maxwell's equations.
Whatever route of inquiry Einstein took to get to his ideas, the one

I intend to go beyong Zee's great book on QFT, and was wondering
whether anyone had comments about Nair's recent "QFT: A Modern
Perspective", published by Springer.
Thanks,

When Shroedinger discovered his wave equation everyone eventually got
used to the appearance of 'i' and accepted that quantum mechanics has an
innate imaginary element. But what would have happened if
quantum mechanics had come along before the advent of complex numbers