Henning Makholm wrote:
> Scripsit "Regnar Simonsen" <regnar.simo@image.dk>
>
>>Der er f.eks. ikke noget til hinder for at man i et givet øjeblik
>>kan finde en eletron på månen (hvis man målte [Men der måles ikke!]) - og et mikrosekund
>>efter på mars (også uden at man kan sige, at elektronen har bevæget
>>sig fra månen til mars).
>
>
> Ikke? Hvis man faktisk *har* fundet elektronen på månen (dvs målt den
> dér), er dens position i dét øjeblik jo veldefineret. Det tager
> adskillige minutter før bølgefunktionen kan nå at tvære så meget ud at
> der er positiv sandsynlighed for at finde den på Mars.
>
...
Hej Henning
Jeg tror det Regnar havde i tankerne var, at elektronen er overalt i
universet på samme tid - eller rettere den kan i princippet
registreres/måles overalt i universet i henhold til elektronskyens
sandsynlighedsfordeling:
Electron probability
http://www.badastronomy.com/mad/1996/electron.html
Citat: "...
Message:
Explain what is meant by the probability of finding an electron at a
point in space.
...
One big effect of this is with electrons as they orbit an atom nucleus.
Most people think that electrons revolve around the nucleus like planets
revolve around the Sun, but that's not really true. Really, the electron
only has a probability of being at some point near the nucleus. It can
be somewhere in a volume of space, but you can never know just where in
that volume it is. That volume is called an orbital, and it is defined
by solving the probability function for the electron.
..."
-
Er du nysgerrig er her flere kvantemekanik besynderligheder:
Her er eksempler med photoner:
Photonet er overalt i universet - det kan "registrere" begge spalter og
interferere med sig selv. Påstanden i den forrige sætning, er dog kun en
måde at fortolke det på:
The Quantum World
The Double Slit Experiment
http://www.idmon.freeserve.co.uk/quant12.htm
Citat: "...
The basic element of quantum theory is the double-slit experiment. It is
a phenomenon which is impossible, absolutely impossible to explain in
any classical way and which has in it the heart of quantum mechanics. In
reality it contains the only mystery ... the basic peculiarities of all
quantum mechanics.
Richard Feynman
...
however, even if the intensity of the light falling onto the slits is
reduced to individual photons being fired one by one onto the barrier -
say one every 5 seconds, then if we wait long enough for a huge number
of separate photons to make it through the slits and to each be recorded
by a single dot on the photographic plate, these dots will build up to
form the image shown in figure 3.
...
Crazy: photons that would have passed through the right slit and hit the
plate in one of the dark bands in Figure 3 fail to do so when the left
slit is opened! How can a tiny bundle of light that passes through one
slit be at all affected by whether or not the other slit is open?
..."
--
The Quantum World
Weird at Heart - More Uncertainty
http://www.idmon.freeserve.co.uk/quant6.htm
Citat: "...
More subtly, Aspect's test of Bell's theorem showed that any attempt to
recast quantum mechanics as a pseudo-classical theory was bound to be
inadequate. Quantum theory is and always will be truly different.
The nature of the difference is, fundamentally, a concept called
"non-locality." Classical physics embodies a strictly local law of cause
and effect. What happens at point A can have an immediate effect only at
point A, and if the effect makes its presence felt at point B, some
physical influence has to travel from A to B, taking some finite time to
do so.
Quantum theory is non-local. In an EPR experiment, a measurement at
point A has an elusive, instantaneous and -- through Bell's theorem --
quantifiable influence at point B. Whether anything physical travels
from A to B is debatable. In Bohm's theory, the pilot wave carries that
instantaneous influence. In Everett's idea, non-locality is dispersed
throughout the many universes. However you look at it, non-locality just
happens in the quantum world. There's no getting away from it.
..."
-
http://directory.google.com/Top/Science/Physics/Quantum_Mechanics/
--
http://www-theory.chem.washington.edu/~trstedl/quantum/quantum.html
Citat: "...
Quantum tunneling
...
Let's say you are throwing a rubber ball against a wall. You know you
don't have enough energy to throw it through the wall, so you always
expect it to bounce back. Quantum mechanics, however, says that there is
a small probability that the ball could go right through the wall
(without damaging the wall) and continue its flight on the other side!
With something as large as a rubber ball, though, that probability is so
small that you could throw the ball for billions of years and never see
it go through the wall. But with something as tiny as an electron,
tunneling is an everyday occurrence.
On the flip side of tunneling, when a particle encounters a drop in
energy there is a small probability that it will be reflected. In other
words, if you were rolling a marble off a flat level table, there is a
small chance that when the marble reached the edge it would bounce back
instead of dropping to the floor! Again, for something as large as a
marble you'll probably never see something like that happen, but for
photons (the massless particles of light) it is a very real occurrence.
..."
--
En kvantemekanik skeptiker:
The Tangled Methods of Quantum Entanglement Experiments:
http://users.aber.ac.uk/cat/Tangled/tangled.html
Citat: "...This paper concerns quantum theory, but you do not need to be
familiar with the subject to appreciate the problems I discuss. These
are matters more of our limitations as human beings - the conflict
between our natural ways of doing things and the rigours of science,
especially science that is beyond our everyday experience. ...I became
involved in the story of quantum entanglement in 1993, when I stumbled
upon a statement in a book review that scientists had shown
"instantaneous action at a distance", which was, to my way of thinking,
impossible. I simply could not imagine how the claim could be taken
seriously. A magician might make such a claim, but not a scientist! How
could twiddling a knob here instantaneously - not just fast but in zero
time - produce an effect over there? There had to be something wrong
with the experiment. There had to be some built-in bias or artifact that
they had not understood....Acceptance of the idea that this kind of
mysterious quantum effect really happens has wide implications. If you
add to it Einstein's ideas on relativity, with his doubts on the concept
of absolute time, you open the door to the paranormal, time-travel,
whatever you wish, for you can no longer distinguish the rational from
the irrational. The universe might not be rational!..."
--
Web archive mirror: New Scientist, 28 June 1997: "Light's spooky
connections [=entanglement] set distance record":
http://web.archive.org/web/20010530160702/http://bse.newscientist.com/ns/970628/nlight_nf.html
Citat: "...it's getting even spookier out there. Particles can be
strangely connected over at least ten kilometres, according to results
from physicists in Geneva...."
--
December 10, 1997 Science fact: Scientists achieve 'Star Trek'-like feat:
http://europe.cnn.com/TECH/9712/10/beam.me.up.ap/
Citat: "...Scientists have pulled off a startling trick that looks like
the "Beam-me-up, Scotty" technology of science fiction. ... If the
notion of entanglement leaves your head spinning, don't feel bad.
Zeilinger said he doesn't understand how it works either. "And you can
quote me on that," he said. . [ Prof. Anton Zeilinger
http://www.quantum.univie.ac.at/zeilinger/ ] ..."
Og kreativiteten har "fremtryllet" følgende:
UniSci, 26-Nov-2001 Holograms Based On 'Spooky Action At A Distance'
[=entanglement]:
http://unisci.com/stories/20014/1126013.htm
Citat: "...It's the interference of the possible paths that encodes the
holographic image of the hidden object, which is very spooky indeed. ..."
I princippet burde entanglement hologrammet betyde, at man kan "se"
indholdet af et sort hul, hvis ikke de entanglede måle fotoner er for
lang tid om at nå "objekter" indenfor det sorte hul.
--
IBM research: Quantum Teleportation:
http://www.research.ibm.com/quantuminfo/teleportation/
27. september 2001 Dansk gennembrud i kvanteforskning:
http://www.comon.dk/index.php?page=news:show,id=9499
Citat: "... Kvantekommunikation og teleportation er rykket et skridt
nærmere... Ph.d.-studerende Brian Julsgaard, forskningsadjunkt Alexander
Kozhekin og professor Eugene Polzik har demonstreret det såkaldte
"entanglement" af to objekter, som hver især består af omkring en
trillion atomer. ... Dermed kan et objekts tilstand transporteres fra et
sted til et andet - teleportation er en realitet, men endnu kun i lille
målestok ..."
--
Vores reduktionistiske tankegang er et godt redskab og der er masser af
udfordringer endnu:
Physics World, December 1999, Volume 12 Issue 12 Article 2: Quantum
gravity presents the ultimate challenge to theorists:
http://physicsweb.org/article/world/12/12/2
Citat: "...Physics in the 20th century is founded on the twin pillars of
quantum mechanics and the theory of relativity. However, in spite of the
enormous successes of each theory individually, the two appear to be
incompatible. This embarrassing contradiction at the very heart of
theoretical physics remains one of the great outstanding challenges in
science..."
mvh/Glenn