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100th Anniversary of Quantum Physics
EricR writes "On December 14, 1900, Max Planck presented experimental results in front of the German Physical Society and announced that they could best be explained if energy exists in discrete packets, which he called "quanta." Today is the 100th birthday of Quantum Physics."
Gotta love quantum physics...
Check out the University of Chicago's Physics Department for all the information you could want to know about modern research in quantum physics.
Oh, and December 2, 2002 was the 60th Anniversy of the first self-sustaining controlled release of nuclear energy
Since I goofed on the last post, I'll add the obligatory links to:
CERN
The Enrico Fermi Institute
Fermi National Accelerator Laboratories
Agronne National Laboratories
Los Alamos National Laboratories
Yep, all the information you could want on modern Quantum Physics.
He also said "look at me, everything I do is brilliant, you must listen to me, BTW I designed the H-bomb whilst hacking into someone's safe isn't that cool?".
My favourite quote from a quantum mechanic was Einstein's "Two things are infinite: the Universe, and human stupidity. Oh and I'm not so sure about the first one." If you're worried about the phrase quantum mechanic being applied to Einstein, I suggest you read about the photoelectric effect.
this page talks about some other interesting scientific events that have their anniversary today:
1986 - First non-stop, non-refuelled flight around the world
1967 - Announcement of first synthesis of biologically active DNA
1962 - Mariner transmits information from first-ever rendezvous with Venus
It all goes downhill from first post
Max-Planck-Gesellschaft - [ Translate this page ] ...
n
Max-Planck-Institute betreiben Grundlagenforschung in den Natur-, Bio-
und Geisteswissenschaften im Dienste der Allgemeinheit. Insbesondere
Description: Übersicht aller Institute in Deutschland.
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MPIfM ... Max Planck Society for the Advancement of Science Max ...
MAX PLANCK INSTITUTE OF MATHEMATICS MAX-PLANCK-INSTITUT FÜR MATHEMATIK
Vivatsgasse
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Max-Planck-Institut für Informatik: Home Page
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g en
and fellowships for graduates of all nationalities European Union Marie
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Max-Planck-Institut fuer Astrophysik, Garching - [ Translate this page ]
Description: Prominent research institution in astrophysics.
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Planck
... Max Planck came from an academic family, his father being professor of law at ...
Kiel and both his grandfather and great-grandfather had been professors of
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Max Planck Institute for Psycholinguistics, Nijmegen - Home
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for advanced research in the social sciences. It builds a bridge
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Max-Planck-Institut für Plasmaphysik - [ Translate this page ] ...
Das Max-Planck-Institut für Plasmaphysik untersucht die physikalischen Grundlagen
für ein Fusionskraftwerk, das - ähnlich wie die Sonne - Energie aus der
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[english]. Aktuell, Das Institut. Forschung, Mitarbeiter.
Öffentlichkeit, Intranet. webmaster@mpifr-bonn.mpg.de.
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The wavelength distribution of blackbody radiation had been determined some (many?) years earlier. However, no one could figure out how to to explain how it could come about.
Somehow, Planck worked out an equation which yielded that wavelength distribution quite precisely. I believe that it is correct that his model was a "what if" conjecture about energy exisiting in discrete packets.
As discussed, the rest is history.
53 years of passing time has dimmed my memory, but I'm pretty sure that is the story.
Basically, formalism in quantum mechanics is expressing quantum mechanical ideas in the language of QM, namely linear algebra. Operators and observables (physical quantities like position, velocity, etc.) are represented either by matrices or " notation". This allows one to delve further into quantum mechanics, and allows one to use mathematics to predict phenomenon. In a sense, this complication of the mathematics for simple problems (like the hydrogen atom) allows one to do more complex problems (like the hydrogen atom in a magnetic field, where the energy levels of the orbitals will split).
So today, quantum is taught by trying to relate basic concepts in QM to those in classical mechanics (such as postition, energy, momentum, etc.) in the first few chapters in a book. Then to faciliate communicating QM ideas, formalism is introduced. It's like no one wants to write three plus two equals five, when 3+2=5 will suffice. This allows more difficult problems to be tackled more easily.
Wow... I don't even know where to start...
"it doesn't even matter how far apart they are in the universe; they'll always do the same things at the same times no matter where they are in the universe"
Wrong wrong wrong wrong wrong. Quantum entanglement says that the two particles *started off the same (or opposite or some such relationship of the initial states). It follows, then that if you do not *observe* either particle for quite some time, and take the two of them far distant from one another, then the instant that you *observe* the state of one particle, you immediately *know* the state of the other particle (wherever it is).
This gives at first pass the illusion that you have gotten information at faster than the speed of light... I mean, you did just *instantaneously* learn the state of a particle far, far away, right? That's gotta mean that you communcated with that thing way over there, right? No. Not at all.
Now, what makes this interesting is the fact that quantum mechanics tells us that if you don't *observe* either particle's state, then neither particle has actually "picked" a state yet. So, it's as though the one particle *told* the other one that "hey I was observed at state A, so you must now occupy state B". So, now it appears that information has traveled faster than the speed of light... and I won't argue that point, because last I knew better scientists than me were still duking that one out.
However, one thing that anyone with a basic understanding of this can agree upon is the fact that there is no way to *use* the possible information transfer involved in the collapse of a wave function to TRANSMIT INFORMATION. Why? Well, there is no way to observe a wave function directly. You can only measure some operator on a wave function (like energy, position, spin), and by doing so, you collapse the wave function into an eigenfunction of that operator. However there is no way to tell whether the eigenfunction you observe is the result of *your* observation or someone elses. In other words, you can't tell if you collapsed the wave function or if someone else did, and quantum entanglement doesn't *do* anything other than pre-collapse the wave-fcuntion for you.
:Wq
Not an editor command: Wq
I think his main problem was the idea of Universal instantaneous collapse of the wavefunction (which leads to "spooky action at a distance"[2] and God playing "dice with the Universe"). These concepts came from the Copenhagen Interpretation, and was the best way the Quantum theoreticians could think to explain the seemingly counterintuitive results of QM - it's pure philosophy and has nothing to do with the Physics.
Of course not everyone necessarily subscribes Copenhagen now. My personal favourite explanation is the proposition popular in the 80s and in Sliders - that multiple Universes are created at each instant multiple outcomes are possible, each reflecting the different outcomes.
Quantum mechanics as we currently know it includes Bose-Einstein statistics describing the behaviour of systems of integer-spin particles (which leads to the concept of a Bose-Einstein condensate - a highly active area of research today); Light Amplification by Stimulated Emission of Radiation (described at the atomic scale by the Einstein coefficients); quantisation of electromagnetic radiation (proposed by Einstein); Einstein's explanation of the photoelectric effect (for which he received the Nobel prize). Stretching the boundaries a little, there are equations for the equilibrium number of charge carriers in Solid State physics which rely on the quantisation of charge in the material. These are known as the Einstein equations.
Even the greatest can be mistaken.Such as when he removed lambda from his equation on the state of the Universe (his "biggest blunder", indeed :-)).
[1]Point of order: even Schroedinger didn't believe in Schroedinger's Cat. He set it up as a thought experiment to show how absurd QM is (I mean, who could really believe in a dead/alive cat? Not him). The experiment has of course, since been done, sans cat.
[2]He believed that the "instantaneous" collapse of the wavefunction would lead to information being propagated instantaneously throughout the Universe. Of course, the wavefunction is not a measurable quantity so this does not occur.
Here goes...
One of the odd phenomena observed in quantum mechanics is the creation of tandem photons from certain kinds of light sources that have the odd characteristic that their dynamic properties are very strongly correlated. That is, if two observers measure the polarization of one photon each, they will observe the same value for the polarization. Quantum mechanically speaking however, if, say, the two photons are polarized at some angle perpendicular to its line of travel, and you set up your measurement apparatus to measure the polarization at a different angle, then QM does not tell you what polarization value you will observe, but gives you a probability. The observed polarization for one photon is essentially random, but the distribution of values for many photons will follow the probability predicted.
Now several physicists, notably Einstein, took this bizarre feat of the correlated photons to mean that the polarization values for the two photons had to be dependent on some hidden variables that QM just didn't know about, but that became apparent in the experiment, which became known as the Einstein-Podalsky-Rosen (EPR) paradox.
Now, in the '60s, along came Bell, who was working on the EPR paradox hoping to prove Einstein et al correct. Bell's inequality reasons what the maximum possible correlation between the two photons should be, assuming that once the two are created, the one cannot affect the other. The problem is, the EPR paradox, when carried out in real experiments, has been shown to violate this inequality: the two photons are much more strongly correlated than they have any right to be according to a hidden-variables-locality-preserved interpretation of QM.
In the mathematical description of QM, this behavior has to do with the fact that in QM the two photons are not treated separately, but must be modelled by one function in hilbert space. The two photons are "phase entagled". Einstein particularly disliked this property of QM because it seems to throw out the principle of locality (no action-at-a-distance), although currently I believe the accepted idea is that no "information" can be sent non-locally using entaglement. I'll leave those questions to a real physicist.
See EPR Paradox
"When I was in school, I cheated on my metaphysics exam: I looked into the soul of the boy sitting next to me"