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Most Beautiful Experiment in Physics 141
An anonymous reader writes "Robert P. Crease has concluded his poll
asking what the most beautiful experiment in physics is. The winner was Young's double slit experiment performed using a single electron. Attentive readers will remember that Slashdot had a discussion of Crease's question previously, which Crease mentions in his current article." If you're unfamiliar with the experiment, Google pulls up a bunch of applets and demonstrations.
Re:What? (Score:1)
Simple != Simple (Score:2, Offtopic)
Simple, brilliant and something that the more you learn about physics the more you learn about what the experiment shows.
Re:Simple != Simple (Score:1)
The slit thought experiment compares really well with Schroedinger's Cat as sublime in it's simplicity to convey an advanced Quantum Mechanics idea to someone without lots of math background.
Re:Simple != Simple (Score:2, Redundant)
This shows that matter is made up of waves too. Everyone knew that light was made up of waves...
Re:Simple != Simple (Score:1)
Re:Simple != Simple (Score:3, Informative)
Actually, it proves that light travels as either a wave or particle.
It depends on the experiment. An experiment looking for particles will show particles, and waves, waves.
Check out The Copenhagen Interpretation [washington.edu]
I love Quantum Theory so much I read the same book three times: In Search of Schrodinger's Cat [2think.org]. Might be out of date, but an easy read for us lay men.
Re:Simple != Simple (Score:2)
Nope. Common misconception. Travels as a wave, arrives as a particle.
It depends on the experiment. An experiment looking for particles will show particles, and waves, waves.
True. But some experiments look for both. For example if you put a photomultiplier after Young's slits, you can literally watch the particles arrive (this was pointed out by Feynman).
And the interesting thing is, they only arrive where the wave doesn't cancel.
Carver Mead vs. "Copenhagen Interpretation" (Score:1)
An interview with Mead about his book & ideas:
http://www.spectator.org/AmericanSpectatorArticles /carver.htm
As an enthusiast rather than someone educated in physics, I would like to hear what you guys think about the validity of his arguments.
Re:Simple != Simple (Score:1)
no WAY!!! (Score:5, Funny)
* photons gets converted to electric impulses;
* these electric impulsese are stored, usually by dielectric tunneling, into a floating gate (Flash memory)
* the information is then read back, sent through 7 (read it, it's SEVEN) layers of network stack, to a physical link
* the data is digitized into more packets of light, and sent across the atlantic from RUSSIA to the US.
* after more routing (some in light-packets, some in electrical), it climbs back up the 7-layers.
* mozilla interprets them, and through some seriously complex transistor networks, the signals cause some polymers to twist just the right amount
* and i see some pr0n.
wait a sec; that would probabbly be "the most beautiful engineering feat"... ahh fsck it.
Re:no WAY!!! (Score:1)
*boggle* You've figured out a way to unite the OSI model with the Real World at least well enough to run Mozilla over it? Color me impressed..
WOOHOO!!!! (Score:2, Interesting)
Why, I do believe that this is the first time I have ever been published. Thanks, guys!
Blockquoth PhysicsWeb:
My original article was also mentioned on Slashdot.org, an extremely active website. Although Slashdot bills itself as "news for nerds", its audience evidently includes a large number of science-history aficionados. A discussion with more than 500 comments ensued, many dissecting the merits of particular experiments. Here too the double-slit electron-interference experiment topped the list. One participant remarked that this and other experiments illustrating quantum-mechanical principles "even seem to reveal something about ourselves", noting that "philosophers and cranks are attracted to the results like moths".
Other Slashdot participants proposed many of the same experiments as Physics World readers - and often for similar reasons. However, they also came up with an imaginative variety of examples of deep play. These included fun things like putting discarded CDs into microwave ovens, firing potatoes using lengths of pipe and cans of hairspray, and synchronizing coloured lasers to the music of Pink Floyd.
One of the contributors described watching small plastic bags circulating in wind pockets, commenting that "sometimes there's so much beauty in the world, I just can't take it". Another mentioned the fact that a hunter firing at a falling monkey always hits the monkey no matter how far away it is, even though it drops just as the hunter fires. One person even cited sitting outside a hospital to hear the Doppler effect, with the comment: "Anytime an ambulance passes me, I'm amazed."
One Slashdot participant described a method of producing a fractal using a coin, marker and tape measure, claiming to have nearly cried the first time they saw it. Another described an impromptu game that he and classmates had invented at the end of a lab class, in which a liquid-nitrogen-filled styrofoam cup with holes in the bottom can be made to glide pleasingly around the floor when kicked about as the gas leaks out.
Re:WOOHOO!!!! (Score:1)
Quoting you, quoting him:
One of the contributors described watching small plastic bags circulating in wind pockets, commenting that "sometimes there's so much beauty in the world, I just can't take it".
It certainly doesn't read as though he got the joke [slashdot.org].
Re:WOOHOO!!!! (Score:2, Funny)
Proving the physics crowd needs to get out to the movies more often [imdb.com].
Re: (Score:1)
Re:WOOHOO!!!! (Score:5, Funny)
I love how this sentence is written as if it's some sort of contradiction.
falling monkeys (Score:2)
Re:falling monkeys (Score:1)
Re:falling monkeys (Score:2)
Re:WOOHOO!!!! (Score:2)
That's an easy one..... (Score:2, Funny)
Kudos to one of my physics professors, Dr. Richard Mancuso, for his toy collection. Any student that brought him a toy that clearly demonstrated a principle of physics for that wasn't already in his collection got extra credit for the semester. I clearly remember the collection filling a few display cabinets, and there was at least one toy for every lecture. I learned 10 times more in his course than I did the previous semester with another instructor because he made it interesting.
My favorite Physics Experiment (Score:3, Interesting)
For our experiment, we used a mirror set up to rotate at 6000 RPM. A laser is aimed at the rotating mirror, bounces about 20 meters across the room and back. The theory is that the rotating mirror will slightly rotate by the time the beam of light returns to the rotating mirror. Even at 6000 RPM, the mirror only rotates a very small amount, but enough for the laser's endpoint to change a few fractions of a mm.
By knowing the displacement between the endpoints of the laser at 6000 RPM and 3000 RPM, we could easily calculate the angle that the mirror rotated from the initial path to the return path across the room. Using this info, we solved for the time required for it to rotate that angle. That is the time required for the Laser to travel across the room and back. The distance:time ratio is the speed of light. Mad props to the dude/chick who designed that experiment.
Re:My favorite Physics Experiment (Score:2, Interesting)
He also demonstrated in Paris in 1851 that the earth did indeed revolve upon it's axis, by using a large pendulum. (Of course, people in 1851 had generally accepted that the earth did revolve around an axis, but this was the first physical demonstration of the effect of such rotation)
Re:My favorite Physics Experiment (Score:1)
Re:My favorite Physics Experiment (Score:1)
physics makes me gaga (Score:1, Offtopic)
HUZZAH FOR QUANTUM WEIRDNESS!! (Score:2)
"Like, huh? It's interfering with ITSELF? Like, is it a particle, or a wave, or what, teach?"
I think some of the crazy new laser "faster than light" experiments could probably give it a run for the money, but they are a lot harder to understand. There is nothing quite like the quantum world jumping up through your apparatus and presenting itself in all it's non-Newtonian glory.
Re:HUZZAH FOR QUANTUM WEIRDNESS!! (Score:2)
This gets especially freaky on the astronomical scale, when you have to large gravity sources widely separated that bend light back, like slits, from an even further distant light source. If you look for the particles from the distant star, it will come to you in a straight line. If you look for the wave pattern, it goes wide and around both(!?!!) gravity slits and shows up as an interference pattern... Thus, by observing, you made the photon that left the start billions of light years away either be a particle or a wave for all of its existance, though it wouldn't know which one to be unless you looked at it.
Freaky.
Re:HUZZAH FOR QUANTUM WEIRDNESS!! (Score:1)
This is what really peeves me about particle physicists. This makes absolutely no sense, and WILL NEVER MAKE SENSE if people continue to think about it in such an asinine way.
What the hell is the variable here? Is it me? Because if I damn well don't "observe" the particle then we have no fucking way of knowing whether it fits into our pre-conceived notions of how a "particle" or a "wave" should act.
If we agree that the "observer" plays no part in the experiment, and, furthermore, if he does, it's not a properly constructed experiment, then we shouldn't immediately assume (without any evidence, mind you) that the metaphysical act of "observing" plays any part in the "existence" of the photon, especially when the "observation" occurs AFTER the photon was created.
This is the most half-baked theory in all of physics, and people go around repeating it as though it were bible-fucking-truth. Just admit it: Einstein was right, God doesn't play dice.
Re:HUZZAH FOR QUANTUM WEIRDNESS!! (Score:1)
Yeah, he's more of a Blackjack guy.
Re:HUZZAH FOR QUANTUM WEIRDNESS!! (Score:1)
God does indeed play dice, and they are loaded...
Re:HUZZAH FOR QUANTUM WEIRDNESS!! (Score:1)
This is one of the really cool ones... (Score:1)
This experiment shows off wave/partical duality (it even has cool terminology). The cool bit about physics (yeah, it has cool bits) is the things it takes your head a while to get around.
OK, background: waves spread round corners. Think of a wave at a harbour mouth. The closer the gap is to the wavelength of the wave, the better it spreads (look up diffraction [wolfram.com]) (troll me, I know this is a gross over-simplification) - ever think about how you can hear but not see round corners? Light == really short wavelengths (nanometres), not like door width lengths (m) (doesn't bend well round the corner), sound == long wavelengths, kinda door-width like (m/cm ish) (bends very well round the corner).
So you get two bits of card with a light behind them, and a screen to shine light through them onto. The first card has one slit, so it shines a little line of light onto the second.
The second has two parallel slits in it, within range of the spread of light, and the light that gets through the first card onto a slit in the second card makes it to the screen.
Now the cool bit.
You get a ripple of light on the screen. Not a black screen. Not two lines showing up the second card shape. Ripples [phys.ethz.ch].
Now, modern physics can explain this. It's the wavefront from the first slit (think ripple hitting a harbour mouth) that spreads out in a circle and hits the next two slots, starting another ripple on the other side of both.
At the far wall, you get points where the peak of a wave from one slit hits the peak of a wave from the other, and you get a really tall peak. Or a trough and a trough, and get a really low trough.
Re:This is one of the really cool ones... (Score:2)
Re:This is one of the really cool ones... (Score:1)
Same physics. Still is a gross generalisation, tho.
Okay (Score:2)
The cool part of the experiment is when you start sending that light 1 photon at a time, so we can demonstrate that individual particles are being sent. The diffraction pattern STILL appears... so we end up with a particle interfering with itself.
Now, as people view light as some kind of weird beast.. the experiment is even more exotic when done with an electron beam. Done with single electrons, which we REALLY think of as particles, we still get the diffraction pattern. That's where things get really weird.
Re:American Beauty (Score:1)
well done! (Score:1)
eddington (Score:1, Offtopic)
just a simple physics student's comment.
Re:eddington (Score:1)
Re:eddington (Score:1)
I like the Pound-Rebka Experiment (Score:2, Interesting)
Pound is an interesting guy. He experimented with using microwaves to heat people instead of wasting energy heating entire buildings. He tested it out by rigging his microwave oven to operate with the door open. He told me that he had to bypass three interlocks, but that he got it working: there was a nice warm glow, like standing in front of a campfire.
Needless to say, don't try this at home unless you're a damn competent physicist.
Ugh, Double Slit? (Score:1)
The prettiest experiment has to be Milliken's Oil Drop.
My favorite beauty (Score:2)
Nothing lighter than C60 (Score:2)
Quantum Polaroid Demonstration (Score:2)
http://www.themechanicaluniverse.com/
Highly recommended. The best demonstration I ever saw on that show involved three light polarizers. The setup was three polarizers on optical stands with a lamp shining through all three. That is, all three in the same orientation so the light shines through. The third is turned through 90 degrees and of course blocks the light of the lamp from the screen. Dr. Goodstein then turns the second middle filter through 45 degrees and almost half the light makes it through the screen. The result is completely counterintuitive and is an excellent and easy macro scale demonstration of quantum principles.
Re:Quantum Polaroid Demonstration (Score:4, Funny)
You have a field with cows. To make sure that now cows get out, you put up two fences. They stay in their field. But you're really paranoid, so you put a third fence in between the two. Now, all of a sudden, one fourth of your cows are wandering in your neighbor's field.
My Choice... (Score:1)
Jaysyn
And what about thought experiments? (Score:1)
challenging our sense of reality (Score:2, Interesting)
Likewise, Michelson-Morley refuted the traditional hypothesis of the Ether(or aether). This concept was a kludge used to validate various assumptions. At that time, it was assumed that light needed a medium, and Ether was as good an explanation as any. By creating a beautiful experiment to refute the ether, Michelson-Morley forced scientist to study the problem instead of just making assumption. Progress is made when our fundamental assumption is proven false.
That does not mean that measuring physical constants is not beautiful experimentation. Certainly Foucault and Eratosthenes and Cavendish and even Milikan are great experiments which are instructive even now. But were they earth shattering pieces of experimentation. I do not know.
wierd science hands down! (Score:2)
chips, dips, chains, whips, sex, drugs, rock and roll... your average party.
Most Beautiful Thought Experiment. (Score:2, Interesting)
Hacker types usually deride gedanken (thought) experiments as exemplified by Eric Raymond's idiotic Jargon file entry for 'gedanken'. So be warned: do not read ahead if you cannot appreciate the importance of theoretical work in physics or elsewhere.
Everyone knows the Schrodinger's cat and the Einstein's elevator experiment. By the way, if you put the Schrodinger's cat inside Einstein's elevator, would that lead to a theory of Quantum Gravity? Jokes apart, these thought experiments have also been influential:
1. The Einstein-Podolosky-Rosen or EPR Paradox: http://roxanne.roxanne.org/epr/einstein1.html
2. Maxwell's Demon
3. Object nearing a black hole
4. Feynman's QED thought experiment: what would happen when you shine light at an object passing through an interferometer, a device that can split the object into a pair of wavelets which are later recombined to produce an interference pattern. This incidentally was converted to a real experiment by an MIT team: http://www.aip.org/enews/physnews/1996/split/pnu2
Re:Most Beautiful Thought Experiment. (Score:1)
http://www.scispirit.com/Resource/aspect_experi
BTW this experiment proves EPR wrong, and is definitely on my list of most beautiful ones.
HAHA (Score:1)
I wonder if he knows the reference which this is from and is just joking or what. If not thats damn hilarious.
most beautiful physics website (Score:1)
Re:umm, how fast does it take slashdot to forget? (Score:2)
Re:Beautiful experiments? (Score:1)
Beauty is in the eye of the beholder after all.
Re:Beautiful experiments? (Score:1, Insightful)
You call yourself "PhysicsGenius" but you can't find beauty in any experiment? Perhaps you should look for a new field of study.
Maybe you style yourself a theorist. You should remember that in physics, it all comes down to experimentation. Theories unsupported by experimental evidence are nothing more than mathematics (don't get me wrong, I love math).
I conceed the point that there are no experiments in art museums. You should note however, that art museums do not hold an exclusive patent on beauty.
Re:Beautiful experiments? (Score:1)
It is possible to know when you are right way ahead of checking all the consequences. You can recognize truth by its beauty and simplicity.
- Richard Feynman
The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful. If nature were not beautiful, it would not be worth knowing, and if nature were not worth knowing, life would not be worth living.
- Jules Henri Poincaré
Re:Beautiful experiments? (Score:2)
Experiments can be beautiful (although "elegant" is the description I prefer.) An elegant experiment has a certain simplicity to it, and a certain definitiveness to it which convinces everyone. Foucault's famous pendulum, for example--there are other ways to demonstrate the rotation of the earth, but Foucault was able to do so, graphically and undeniably, with a weight and a length of wire. Beautiful.
Or take the experiment which demonstrated that nucleic acids and not proteins carried genetic information. Hershey's and Chase's method was simplicity itself: proteins contains sulfur, and nucleic acids do not; proteins contain no phosphorus (or little of it), nucleic acids abound in it. So infect cells with a virus whose protein coat is labelled with radioactive sulfur, or whose nucleic acid payload is labelled with radioactive phosphorus, and see where the radioactivity ends up when cells are infected with the labelled viruses. The phosphorus gets transferred; the sulfur does not; hence it's the nucleic acid which carries the virus's genetic information. Again, beautiful.
If your view of science is really so crudely utilitarian, I suggest either that you get out of the profession, or (far more likely) you're not really a scientist at all but you've read about it in _Skeptical Inquirer_. Get back to your Linux installation, will you?
hyacinthus.
Re:Beautiful experiments? (Score:1)
I take offense to that statement. Computer science and computer engineering are not suitable places for such a person, either.
Egg Troll Loves You! (Score:1)
Re:fp? (Score:1, Offtopic)
Re:fp? (Score:1)
Re:fp? (Score:1)