Tunneling effekt.
Øistein Wind
Jeg er i forbindelse med kvantemekanikken og fusion/fission ofte stødt på
begrebet tunneling, men det har aldrig været præcise beskrivelser jeg har
mødt. Nogle der har lyst til at byde? De fleste steder står dette omtalt
meget difust, så jeg håber der er nogen der har lyst til at udpensle det
lidt for mig... :o)
Øistein
Martin Larsen
"Øistein Wind" <*oistein.wind*@*gmx.net*> skrev i en meddelelse news:3e779607$0$20504$edfa...@dread11.news.tele.dk...
kan man ikke komme over en energibarriere hvis man ikke har medbragt
tilstrækkelig energi. I kvantemekanikken kan man låne energi blot det
bliver leveret tilbage hurtigt. Der gælder at dE*dT=h . (Energi * tid er
Planck's konstant (6.626*10^-34 Js).
Mvh
Martin
Glenn Møller-Holst
Hej Øistein
Det er simpelthen fordi ingen har en fornuftig fysisk forklaring på
tunneling. Døm selv:
Hvem kan vurdere om denne adresses Quantum Tunneling forsøg er rigtig?:
DIY (Do It Yourself): Quantum Tunneling on Your Kitchen Table
http://www.altair.org/Qtunnel.htm
-
July 22, 1997, The New York Times Company: Signal Travels Farther and
Faster Than Light:
http://dustbunny.physics.indiana.edu/~dzierba/HonorsF97/Week1/NYTJuly22.html
Citat: "...
Another deep quantum mystery for which physicists have no answer has
to do with "tunneling" -- the bizarre ability of particles to sometimes
penetrate impenetrable barriers. This effect is not only well
demonstrated; it is the basis of tunnel diodes and similar devices vital
to modern electronic systems.
...
Tunneling is based on the fact that quantum theory is statistical in
nature and deals with probabilities rather than specific predictions;
there is no way to know in advance when a single radioactive atom will
decay, for example.
The probabilistic nature of quantum events means that if a stream of
particles encounters an obstacle, most of the particles will be stopped
in their tracks but a few, conveyed by probability alone, will magically
appear on the other side of the barrier. The process is called
"tunneling," although the word in itself explains nothing.
Chiao's group at Berkeley
http://www.physics.berkeley.edu/research/chiao/
[
Tunneling speed
http://lal.cs.byu.edu/ketav/issue_3.2/Lumin/lumin.html#fig-4-2
/
Superluminal motion paper
http://lal.cs.byu.edu/ketav/issue_3.2/Lumin/lumin.html
]
,
Dr. Aephraim M. Steinberg at the University of Toronto
http://helios.physics.utoronto.ca/people/faculty/aephraim.html
and others are investigating the strange properties of tunneling, which
was one of the subjects explored last month by scientists attending the
Nobel Symposium on quantum physics in Sweden
http://www.nobel.se/nil/symposia/physics.html
.
"We find," Chiao said, "that a barrier placed in the path of a tunneling
particle does not slow it down. In fact, we detect particles on the
other side of the barrier that have made the trip in less time than it
would take the particle to traverse an equal distance without a barrier
-- in other words, the tunneling speed apparently greatly exceeds the
speed of light. Moreover, if you increase the thickness of the barrier
the tunneling speed increases, as high as you please.
"This is another great mystery of quantum mechanics."
..."
mvh/Glenn
Glenn Møller-Holst
Tunneling speed
http://lal.cs.byu.edu/ketav/issue_3.2/Lumin/lumin.html#fig-4-2
/
Superluminal motion paper
http://lal.cs.byu.edu/ketav/issue_3.2/Lumin/lumin.html
virker ikke mere, men den ene kan findes her:
Tunneling speed
http://web.archive.org/web/20020607200405/http://lal.cs.byu.edu/ketav/issue_3.2/Lumin/lumin.html
-
Her er en kvantemekanik vejviser:
http://directory.google.com/Top/Science/Physics/Quantum_Mechanics/
Lidt flere adresser om kvante tunnellering:
http://www.google.com/search?q=%22Quantum+tunneling%22
f.eks.
Quantum Tunneling
http://phys.educ.ksu.edu/vqm/html/qtunneling.html
Quantum Tunneling
http://zebu.uoregon.edu/~js/glossary/quantum_tunneling.html
4. The speed of quantum tunneling
http://www.comcity.com/distance-time/The%20Speed%20of%20Quantum%20tunneling.html
Citat: "...According to Einstein, speeds faster-than-light were
impossible because causality paradoxes could occur relative to some
observers. Nevertheless, no causality paradoxes occur because of
faster-than-light travel via a here-now. This last point is unique to
distance-time theory. In the subsections 4.4 and 5.9 of my paper, I will
explain the solutions to causality paradoxes caused by faster-than-light
travel via a here-now...."
What are the odds of me experiencing Quantum Tunneling?
http://www.physlink.com/Education/AskExperts/ae460.cfm
Sep 13, 1999, Macroscopic Quantum Tunneling in Magnets
Dr. Eugene Chudnovsky, ITP & CUNY
http://online.itp.ucsb.edu/online/bblunch/chudnovsky/
-
http://www.google.com/search?q=%22Macroscopic+Quantum+Tunneling%22
Macroscopic Quantum Tunneling and Coherence
http://www.lassp.cornell.edu/ardlouis/dissipative/mqt.html
http://physics.hallym.ac.kr/education/cornell/ardlouis/dissipative/mqt.html
3) Macroscopic Quantum Tunneling
http://boojum.hut.fi/~pjh/mqt.htm
mvh/Glenn
Martin Axelsen
<SNIP>
> I klassisk mekanik
> kan man ikke komme over en energibarriere hvis man ikke har medbragt
> tilstrækkelig energi. I kvantemekanikken kan man låne energi blot det
> bliver leveret tilbage hurtigt. Der gælder at dE*dT=h . (Energi * tid er
> Planck's konstant (6.626*10^-34 Js).
>
Mvh.
Martin Axelsen
Jeppe Stig Nielsen
>
> > I klassisk mekanik
> > kan man ikke komme over en energibarriere hvis man ikke har medbragt
> > tilstrækkelig energi. I kvantemekanikken kan man låne energi blot det
> > bliver leveret tilbage hurtigt. Der gælder at dE*dT=h . (Energi * tid er
> > Planck's konstant (6.626*10^-34 Js).
> >
> Så EM svingninger er i virkeligheden kvantebølger der så låner fra hinanden?
Det kan man næppe sige. Energien i en elektromagnetisk bølge er jo
reel og blivende nok. Her er *ikke* tale om noget kortvarigt kvante-
mekanisk brud på energibevarelsen efter ubestemthedsrelationen.
--
Jeppe Stig Nielsen <URL:http://jeppesn.dk/>. «
"Je n'ai pas eu besoin de cette hypothèse (I had no need of that
hypothesis)" --- Laplace (1749-1827)
Carsten Svaneborg
> Så EM svingninger er i virkeligheden kvantebølger der så låner fra
> hinanden?
Elektromagnetiske svingninger er bølger i det elektromagnetiske felt.
F.eks. radio, mikrobølger, infrarød, lys, røntgen, gamma stråling.
Men disse kan skabes ved kvantemekaniske fænomener, f.eks.
atomer der henfalder fra en eksiteret tilstand og udsender lys.
En foton kan også spontant opstå fordi den "låner" energi fra
Heisenberg relationen, men så henfalder den også hurtigt igen.
--
Mvh. Carsten Svaneborg
http://www.softwarepatenter.dk