"Be open-minded, but not so open-minded that your brains fall out." Suggested topic for discussion: Logical imperative the subtle simplicity sought by science. It often goes widely unrecognized. .
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"Be open-minded, but not so open-minded that your brains fall out." Suggested topic for discussion: Logical imperative the subtle simplicity sought by science. It often goes widely unrecognized. .
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...furthermore,
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Six sinister oversimplifications that bring suffering to too many people:
. bumper to bumper POLITICS DRIVES GOVERNMENT WHAT CAN WE DO? |
following meeting of October 7, 2003
| Bose-Einstein Condensates
(strictly
science)
WHY do atoms move in lockstep in a B.E. condensate? And what kind of lockstep....all at once (entanglement) or who goes first? Sounds to me like space could be different at 500-3000 (or so) picokelvins. jerrible I didn't hear much of this discussion. And I haven't followed
much of the recent work on BEC. The basic stuff is this. Bosons
are particles that don't obey the Pauli Exclusion Principle; that is, when
they are close enough to each other to interact, they can "occupy the same
quantum states." Which means the values of their significant parameters,
like spin, energy, momentum..., can have the same value (their quantum
"numbers" are the same--the values are usually numbered, rather than given
values in physical units). Bosons have values of spin that are integers
(0, 1, 2, 3,... -- photons, for example) whereas fermions--the "opposite"
of bosons--have values that are odd-integral halves (1/2, 3/2, 5/2,...electrons,
for example). The names "boson" and "fermion" come from the names
of the people who worked out the statistics of how energy gets distributed
in a system of the particles. There are a couple of equations that
give us, as a function of temperature, the relative numbers of particles
within any given range of energies. (Energy histograms for a given
T.) Bose and Einstein gave us the "Bose-Einstein" equation
for the particles which don't obey the exclusion principle.
Fermi and Dirac gave us the "Fermi-Dirac" equation for those which do.
(The only difference between the two equations is the sign between two
of the terms in the denominator.)
When fermions condense (come together) near absolute zero they clump into atoms and molecules, and energy added goes mostly into promoting electrons into higher quantum states ("orbitals"): new energy gets associated with individual atoms. At higher temperatures inter-atom bouncing around ("phonons") becomes more and more significant. When bosons condense, the B-E condensate is a possibility. The BEC is a single quantum state--not something that's much like the marble-and-billiard-ball way we think about (in terms of everyday perceptions). The wave nature of matter swamps out the mables and billiard balls. Such matter is all fuzzy-fuzzy, buzzy-buzzy stuff. New energy doesn't get localized in electron orbitals, but rather goes all throughout the system. The lockstep is quantum mechanical--not at all like military or political lockstep, or even pulses of motion travelling down a suspended slinky. Fermion condensates are more intuitive that BEC. I'm not familiar with much of the interesting things that have been happening recently in the research. And a bunch of O4R'ers went to Monmouth last year to show some of our illusions and puzzles to a gathering of outstanding high school science students: the keynote speaker was the Nobel Laureate from Oregon who got a Nobel Prize for his work on BEC. I still don't remember much (senior momenta). Phil Paul, what can you add and/or correct. Hi Phil, I think this is a very good description of the phenomena. The only thing
I would add is that fermions do not really condense, but pair to form bosons
which then condense. This is how superconductivity ( Cooper pairs
of electrons) and He3 (triplet pairing) superfluidity arise and these
are common examples of Boson condensed systems. The real interesting
part of Bose Einstein condensates is the macroscopic quantum nature of
these systems and the surprising behavior of these systems, such as lossless
electrical conduction, persistent currents in a magnetic field, quantized
vortices in superfluids, Meissner effect.. etc. One of the more interesting
applications of the new atomic condensates is to slow and or stop light.
This is done by creating a "hologram" in the condensed atomic system which
records the amplitude and phase of the photon (photon cloning). A
very recent article in Nature, claims to have stopped light with several
miles of photons in a fiber backed up into a condensate. (Harvard
group) Here is a link
I will work on making my universal medical proposal a little more clear. |
| Paul commented on how medical care and technology
might get consumed, especially as a function of the wealth of the consumer.
In particular, very expensive procedures, such as heart, lung (plus) transplants
cannot be available to anyone who wants it, or even everyone who might
benefit from it. "Rationing" must occur, and the wealthy are
going to get some medical care that the poor won't.
Paul,
could you word this better to fit your concept?
I would like to add that many expensive medical treatments,
such as questionable, possibly crackpot, things, also cosmetic procedures,
such as liposuction and face lifts, should definitely be available only
to those who can afford them. That is, when (if) society helps the
needy with medical care some things don't belong in the system.
The basic question is, what if any essential medical care should be a matter of public interest with the costs shared by all. Should simply being a human being be sufficient to assure access to necessary medical care? Where does preventing epidemics fit in? I believe that "tollgate
costs" can be a reducible waste. But how do we analyze such costs?
PhilThe question of "worth" of individuals needs to incorporate multicomponented concepts of value. "Tollgate costs" is from the discussion of Devlin's levels of abstraction as seen by primitive man. |
Frank Theiss (retired from physics-UCSD, now
in Hood River) told me----at least I think he said that -----the answer
to my lockstep question is that the mish-mash at higher temperatures is
caused by electromagnetic fields interacting and that these are suppressed
at super-cool temps. Perhaps this means that the gravitational field
rules (and makes the rule)
My take on health availability begins with the premise that the body politic has the same type of stake in providing SOME health care as it has in providing SOME education . Were it not so obvious I would point out that every other 1st world country does this. This said there is the more difficult ? of rationing what's available. In education we provide free K-12 and almost free 13-14. It is assumed that this is adequate to provide almost everyone the opportunity needed to maneuver in our society. Programs for the handicapped, at least in the past, usually continued as long as is required. As I understand it, the Oregon health plan was set up in a manner (essentially) consistent with the education principles. It makes sense to me. No amount of inveighing against (inherited) inequality is ever going to keep the rich from getting the best. None of this, of course, answers the dilemma about the $5,000/dose massive- hemorrhage stopper which consumes 10% of the OHSU pharmacy budget but does save lives. But then, I live in Washington Since the plan is to retire someplace for discussion after dinner perhaps
people might want to pre-select a topic for discussion
jer
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See a page made for a paper given at the Fall meeting of
the Oregon Chapter of American Association of Physics Teachers:
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