sci.physics.research Google Group

Re: Cocycles in definition of "momentum operator"

nowh...@canonicalscience.com (Juan R. González-Álvarez) — Sun, 21 Mrz. 2010 13:04:32 UT

Omega Cubed wrote on Sat, 20 Mar 2010 06:00:39 +0000:
Gauge theory does not change the definition of momentum operator.
Gauge theory propose replacing ordinary partial derivatives by gauge
derivatives in presence of fields.
The momentum operator continues being the same. This is not terminology

Re: Virtual particles help

fredifi...@hotmail.com (FrediFizzx) — Sun, 21 Mrz. 2010 08:35:46 UT

Tricky question but not sure it even should be applying to your research
on virtual particles. IMHO, virtual particles do not travel backward in
time any more than real particles travel backward in time.
I would add to that FAQ that "virtual" in particle physics simply means
"off-mass-shell" which is allowed by the Uncertainty Principle.

Re: R. Feynman left a puzzle.

khrapko...@hotmail.com (Khrapko) — Sun, 21 Mrz. 2010 08:35:37 UT

Sorry, I did not understand that a single photon will heat the polaroid
1/4 of the time means that the probability of absorbing is 1/4. This
English formula seems to be not very good.
R.K.

Re: Virtual particles help

n...@charlesfrancis.wanadoo.co.uk (Oh No) — Sun, 21 Mrz. 2010 07:19:05 UT

Thus spake bj88 <bolanos...@yahoo.com>
In the Stuckelberg-Feynman interpretation antiparticles are particles
travelling backwards in time. More on this at
[link]
Relativity does not allow you to travel backwards in time - faster than
light means space-like, which is different from the negative light cone.

Re: Cocycles in definition of "momentum operator"

omega_cu...@netzero.net (Omega Cubed) — Sat, 20 Mrz. 2010 06:00:39 UT

<snipped a pretty good post on the subject>
Just want to note that a mathematically cleaner way of looking at this
is to treat the wave function, instead of a complex-valued function
over physical space, as a section of the (topologically trivial) complex
line-bundle over physical space. The traditional momentum operator assumes

Re: Virtual particles help

arnold.neuma...@univie.ac.at (Arnold Neumaier) — Sat, 20 Mrz. 2010 06:00:39 UT

bj88 wrote:
Although the discussion given there is in terms of perturbation theory,
it is not emphasized enough there that virtual particles are an
artifact of perturbation theory, rather than objects that exist in
any reasonable physical sense of the word. (Individual Feynman diagrams
do not make formal sense - they come all out infinite, even after

Re: Cocycles in definition of "momentum operator"

hendrik.vanh...@physik.uni-giessen.de (Hendrik van Hees) — Sat, 20 Mrz. 2010 06:00:39 UT

First of all, as a moderator of this groups, I want to say that I'd very
much regret, if you won't write such nice articles as this one anymore
only because of some rough discussion. I hope, it was not my little
remark on the factor 1/2 which I felt necessary to make, not to confuse
other readers of the group. It's all about physics, not about personally

Re: Motion Molehill

jth...@astro.indiana-zebra.edu (Jonathan Thornburg [remove -animal to reply]) — Sat, 20 Mrz. 2010 01:27:43 UT

In an earlier message <80df93Fbm...@mid.individual.n et> in this thread,
I wrote
An addendum: Uhe University of Washington Physics Education Group,
originally founded by Prof. Arons and now led by Prof. Lillian C.
McDermott, is one of the (if not *the*) world's leading research
groups on the scientific study of physics learning/teaching. The

Virtual particles help

bolanos...@yahoo.com (bj88) — Fri, 19 Mrz. 2010 18:23:22 UT

Hello People,im doing research on virtual particles for my project and
was wondering if virtual particles travel backwards in time without
travelin violating causality as i understand relativity says if you
travel faster than light you will end up in the past.what im Asking if
you can travel backwards in time without traveling backwards in time?

Re: Time dilation and constant velocity vs. acceleration

mlf...@comcast.net (Mike_Fontenot) — Fri, 19 Mrz. 2010 16:33:09 UT

I contend that it is the ONLY result that doesn't contradict the
observer's own elementary measurements. I address this issue at length
in my previously referenced paper.

Re: Time dilation and constant velocity vs. acceleration

mlf...@comcast.net (Mike_Fontenot) — Fri, 19 Mrz. 2010 16:26:23 UT

I contend that it is the ONLY result that doesn't contradict the
observer's own elementary measurements. I address this issue at length
in my previously referenced paper.

Re: R. Feynman left a puzzle.

army1...@foo.invalid (Army1987) — Fri, 19 Mrz. 2010 08:30:11 UT

What on Earth is supposed to be "puzzling" about this?

I can't imagine any reason why one could think about a different answer.

Geodesics

dgoncz.703.475.7...@gmail.com (The Dougster) — Fri, 19 Mrz. 2010 08:04:14 UT

====== Moderator's note ============================== ===
Relativistic bicycles? I wonder, how fast you want to make them ;-))
SCNR, HvH.
============================== ============================== ==
Rit Booth, Jan Bochenek and I are trying to improve bicycles and save
lives with regenerative braking. We need to know how much energy is

Re: Questions About Nuclear Radii

ralivings...@sbcglobal.net (Rich L.) — Thu, 18 Mrz. 2010 16:22:04 UT

This months issue of Physics Today has a "Physics Update" on page 22.
It summarizes a paper (K. Tanaka et al., Phys. Rev. Lett. 104, 062701,
2010) about carbon-22 with 16 neutrons and a nuclear radius of twice
the more common C-12 isotope. FYI
Rich L.

Re: Definition of "momentum operator" in quantum theory

jyab...@nycap.rr.com (Jay R. Yablon) — Thu, 18 Mrz. 2010 09:21:11 UT

Thanks. My first reply was to your second post. This second reply is
to your first post. Such are the vagaries of the SPR moderation, as
Jonathan just pointed out.
That is just a question of ordering of presentation, but I agree that
(5) logically precedes (3).
A typo.
Good.
I guess based on my experience with Lie groups (such as 2x2 = 3+1 for