Well, since I do physics, I figured I mightaswell say a
little something. I'm a graduate student at Caltech , doing either
particle theory (including String Theory) or
quantum information theory
 Teasers for some new things I've done that I haven't time to write up :
 Bosonization provides insight into nonperturbative structure
(also: every 2d theory is supersymmetric (in disguise))
 Fluid dynamics is a 3d gravity theory
 There's a nonperturbative diagrammatic way to do topological QFT ;
I can get HOMFLY from ChernSimons, Conway from BF, and Vassiliev from 2d graphs.
 Feynman amplitudes can be generalized to allow nonasymmetric time flow
with only minor (mathematical) changes.
 There's a measure tighter than Holevo Information in quantum
computing which seems to be the correct bound on accessible information.
 more.. ?

Charles Bloom / cb at my domain
send me email if
you have a comment on anything here.
 The 2d Dirac Equation via lightcone lattice.
Corners are a (i) amplitude. This is new work, so far as I know. (4198)
Also, for reference, the old style The Dirac RQM equation , derived
using "matrix composition" (modified 8297),
a formalism of my own invention (ok, so its basically trivial, but few
people have actually written down the formalism, which is quite useful).
 My infotheory news articles contain more and more physics.
One of them is An Adaptive Quantum Coder.
 Some posts from sci.phys.research on susy and sugrav, and sustr
(that's supersymmetry, supergravity, and superstrings, and takes a superlong time to say).
 geometry and duality is amazing stuff.
 The Feynman Amplitude Postulate is more
powerful than you think. (more to add here)
 The KaluzaKlein and other topological
aspects of YangMills + Gravity
 Don't be afraid of more than four dimensions
 Some thoughts on statistical mechanics
 Some thoughts on quantum mechanical measurement
 Generalization of the relativity postulate
 Proof of Heisenberg's Uncertainty Principle
directly from the [p,q] commutator. Very simple and nice.
 Take a look at my news section for an
artictle on timeasymmetry, entanglement, and complexity.

Hi, maybe some people with more astronomy knowledge
could fill me in on the details of the "dark matter"
question (and what's known).
My problem with the issue is exactly the opposite
of the astronomer's : why isn't there more dark
matter?
From a fieldtheory viewpoint, physics is all about
"what consistent theory can I write down", then the
question becomes "why did nature choose NOT to use
such and such a theory?". A question I've always
pondered is : why aren't there an infinite number
of other types of matter that decouple from our own?
That is, if I can write the L for QED, I can just
as well duplicate it for "2electrons and 2photons"
then for 3,4,.. ; I could have several copies of
the standard model, or just lots of free scalars
particles, etc. They all decouple (and hence, this
question is usually blown off by field theory textbooks),
except via gravity  in which case we would see them
as something like dark matter (or perhaps a cosmological
constant). (perhaps a measurement of a negative
cosmo. constant means there is a preponderence of
"shadow world" fermions)
 There seems to be some hypocracy in the current physics consensus towards
renormalization. As Weinberg so incitefully emphasizes : we would need renormalization
regardless of whether or not there are divergences, because the "base" quantities (mass,
charge,etc.) are corrected by dynamical effects (recall the classical selfresistance
of the electron which corrects its mass) so not equal to the "real" experimental
quantities. The renormalization flow (I refuse to say "group") only emphasizes the
fact that this is important. Thus, the infinities of QFT are invisible to the predictions
of the theory. From an outside observer (an alien), the mechanics of our theories is
irrelevant, perhaps primitive or crude; only the predictions of the theory are physical,
the the divergences are nowhere in them. In this sense the divergences in our machinery
are just a coincidence caused by the modality in which human beings do mathematics.
Nothing I have said here is very new or shocking; what I find strange is that physicists
who are aware of this find the exactly finite theories (supersymmetric QFT, and susystrings)
so appealling; after renormalization (which is necessary in either case) they are
aesthetically invisible to divergences. (I do not deny that the finite theories are so
unusual as to consitute an amusing mathematical construct).
Two addenda : an assymptotically free theory, or a nonrenormalized theory, might be "final" 
that is, small scale/high energy effects are not dominant, so we can imagine that string theory,
gravity, or whatever, cannot be large corrections. Next, I find supersymmetry particularly
annoying, because the lack of a Beta function actually makes it harder to get nonperturbative
information. Similarly, when you have divergences, it's a good thing, because then all finite
terms are small in comparison, making computations very simple.
 I have most recently done (productive :^> ) research on the
hydraulic jump in fluid
mechanics. While working on the computational simulation
of the jump, I wrote plot (25k,zip) an
interactive plotter for Win95 (zoom,scroll,etc. on 2d data or
2d vector field data).
 Here's something cool I noticed the other day : The
Cigarette Boundary Layer. Take a burning cigarette, carefully
rub it across a vertical wall; you must apply pressure, pushing
the "cherry" against the wall, but not putting out the cigarette;
now pull it away. The result : a trail of smoke is left "stuck"
to the wall in the path of the cigarette. Now, of course this
is true, but most of the cigarette smoke blows away after it leaves
the cigarette; the smoke which you have "spread" on the wall
sticks there! This is a demonstration of the fact that air is
a fluid, and that fluids have boundary layers on rigid surfaces,
where the flow is very slow. You introduce the smoke (a flow marker)
into the boundary layer, and it sticks there for a time scale
much longer than it sticks in open air.
I'm told by my cohort Ed Burns that this is even more dramatic if
you use a straw to blow the smoke onto a flat surface, like a table.
I encourage you to try this home experiment, especially if you are
under 18.
 why selfresistance of induced fields is proportional
to gravitational attraction (in nonphysics lingo, why is mass
heavy, given that we know why it's slow?) Perhaps this is one
of the things addressed by string theory. Hmm, if there were a
selfresistance to gravity, that would make things complicated :
does gravity work on the "rest" mass or the "resisting" mass?
(actually masses would be selfattracting, not selfresisting).
The answer is simple. All objects in a relativistic
theory naturally move at the speed of light. If they move at
less than the speed of light, they are "slow". A "slow" (aka
massive) object must be slow because some force is acting on
it (ie the selfresistance above). A force means that space
is full of gaugons mediating that force. Gaugons carry energy.
Gravitons couple to gaugons (energy). Hence : gravitons
couple to the "slowness", aka mass. This is why mass is heavy,
given that it's slow.
 why the eigenvalue of the particleexchange operator is
equal to the eigenvalue of the rotate360onparticlecenter
operator ( aha! this one is simple topology. apparently a few other
people wondered about this one too (such as Feynman)  why didn't
anyone tell me!) There are several web sites on this, and the
1986 Dirac Memorial by Feynman has an even better discussion. See:
 Candle Dances & Atoms
 John Baez' outline of the SpinStatistics proof
 JB's harmonic oscillator, spin, and groups
 Read Joshua W. Burton's summary of Feynman's Candle Dance argument
I'll put up my notes on this some day. Feynman also shows that T^2 (time
reversal squared) is the same as rotation by 360. This makes sense because
T^2 is just like E^2 (exchange) or P^2 (parity). However, the T result is
amusing because we can derive it a few different ways (Feynman's intuitive
spinstates method, and Heine's grouptheoretical method) and it has various
effects, like on antiparticles, and quickly leads to bose/fermi statistics.
 Transform theory. This is a very general and powerful tool in
Physics, and it is useful to think of it in terms of the imagecompression
paradigm : to work with a complex,large data set most easily, you must
first transform the data into it's "natural" basis; i.e. the basis in
which data items are uncorrelated, where only their absolute magnitude
has "information". For example, I think of Statistical Mechanics as
a functional transform from all the coordinates & momenta of particles
to the partition function. There is then a further transform which
takes the partition function to the functions T,V,E, etc. You can think
of the many body problem in the same way; transform all the coordinates
& momenta into a base state with excitations.
 Black Hole Information theory. The big deal nowadays is :
do black holes consume information? However, it seems to me that
something important is forgotten here : conservation of information
is not a law of physics! Claude Shannon came up with it in 1948
because it was a useful tool in writing the theory of coding. In
fact, the formal form of "Information" was simply derived so as to
be "reasonable" (i.e. you demand certain properties and look for
the right mathematical form. See my copy of
Shannon's Entropy. I do agree that Boltzmann Entropy and
Shannon Entropy are related, but the Boltzmann StatMech "laws" are
not something we should cling to firmly. (see my notes on statmech)
 Monopoles : here's the resolution to my previous qualms.
Maxwell says d_i B_i = 0 , ok, that's fine and true (it must be),
**except** where B is singular, at which point all bets are off. Thus
monopoles can arise because of a singular string (Dirac string) in
the vector potential. They also arise (more pleasingly) as topological
"twists" of the field due to the way the "sheet" of field is "tied down"
at infinity.
Actually, this illustration begs the question : how can the physics of singular
bundles of field be predictive? It seems whatever field equations we write
down can be violated by singular points in the field. Is this true? Fortunately,
it appears nature does not often take advantage of her ability to create
singularities. (one might say singularities cannot be created from finite fields
by any process, but of course the singularties could be left over from the big
bang, or could be produced by black holes which are singularities themselves
(maybe)).
The resolution is that there need not be a singular string (though it is
a nice picture, especially for duality). We can instead do it by asuming that
the connection A cannot cover the sphere surrounding the monopole  we must
use multiple coordinate patches. Even though A is trivial on each patch,
(D*B=0) the transition function between patches contains a "kink" (winding)
so that A has global structure. Integrated over the sphere, this kink
provides a net flux equal to that of the monopole. Dirac's string put all
the flux on a single point on the sphere  here it is on a loop (an equator)
of the sphere. Dirac's theory had a special underlying invariance of the
motion of the string (which was actually gauge invariance, but this was
not manifest). In the connectionpatch theory, gauge invariance is that we
can choose the "weld equator" to be anywhere on the sphere, so that the relation
of this invariance and gauge invariance is manifest. The kink in coordinate
patches is a "large" gauge  it can be continuously reached by infinitesimal
gauges starting at zero, so it cannot be transformed away.
There is a very real sense in which a "large" (not connected to the identity)
gauge transform is a particle (usually called a pseudoparticle, but the
word pseudo is only quasimetameaningful). For example, instantons are
also arived at in this way  as a kink in the fiber over a 4manifold instead
of over a 2manifold as was the case with the monopole. Though I understand
this as well as anyone I've ever met, this is still a bit mysterious to me.
It's quite clear how things like the "theta angle" come about in the action,
but the "dynamics" of these largegaugekinks is a little odd. In the original
Dirac string picture, duality is quite obvious:
F <> *F and e <> 1/e
E&M charges + Monopole Strings <> Monopole charges + E&M Strings
But it's not so obvious with the gaugeconfigurations.
 Group Theory. All this business with representations and
lemmas and whatnot is not group theory, it's silly formalism. You
can write group theory in terms of QM Operators, where each operator
in the group is a DiracKetBra (a = Sum(i,j) a(ij)i}{j ) and now
all the eigenket theorems fall out easily; representations just
become your choice of basis for the kets. I'll put up a short course
on this style of group theory some day.
 how to derive operators for raising and lowering, given the
operator you wish to raise/lower (I think this may be a provably
unsolvable problem) (hmm. the inverse problem is quite easy > I
should be able to show that some matrix in the linear algorithm is
not invertable..) The inverse problem is properties
of the ladder operators.
 Perturbation. There are interesting things to say about
perturbation : a general form for Nth order perturbation , and
the idea that a perturbation expansion is somehow fundamental.
I'll add these notes at some time.

For my senior Solid State Physics class (PHY 375S at the University of Texas, taught
by Robert Martinez), I wrote a thesis on the SuperFluid state of the boson Helium 4.
I took a somewhat unique viewpoint, studying the lowenergy states of He II as a
form of condensed matter, with many of the properties of crystals. For example, the
atoms act as though they were oscillating in a space confined by the lattice spacing
distance (this is due to the invariance under permutations). Similarly, the scattering
form factor has peaks at the reciprocal lattice lengths. Since He II is a liquid,
the peaks are spread out, and the lattice oscillations are much larger than those in
solids. Of course, phonons are found to be the basic excitation in He II, just as they
are in crystal lattices.
The paper is available for download here in MS Word 7.0 format
helium.zip (50k)
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