Double Slit Experiment

[matrix0978]

Very interesting experiment, got me thinking.

http://video.google.com/videoplay?docid=-4...84618&q=quantum

[Maleko]

he sounds like someone off HL2??

[Zxian]

Yeah, I just had a midterm on that stuff last week. Quantum is pretty interesting stuff.

If you didn't quite understand that last bit about "collapsing the wave function", in QM (Quantum Mechanics), you are always talking about the wave function, which describes the probability of finding a particle at a particular location and time (systems change over time). Notice, that this is a probability - not a guarantee as to what will happen. The probability is determined by what the system started out with (a measurement at some point in time) and the time that has passed.

(Think of the fact that if you roll a die 6 times you "should" expect to see one of the numbers once each - but that doesn't always happen)

When you go and take a measurement, you collapse the wave function, since you know that the particle was "here" and "now", with a probability of 100%. This changes the way that the particle will behave from that point on.

The fact that the parrticle seems to go through both slits is due to a concept called the particle-wave duality, where we can actually describe everything as both a wave and a particle at the same time. This is what people refer to when they talk about photons - particles of light. These photons actually have momentum, which we can theoretically "collect" and use to move spacecraft with large solar "sails", much like conventional sails "collect" the momentum of the wind.

Just a bit of "basic" quantum for you to chew on. B)

[matrix0978]

jesus Zxian, lol thats slightly high leveled and complex.

[Zxian]

It's actually not all that high level. I'm in the first quantum course, and my girlfriend's been doing the second course... now that's complicated stuff.

There's a famous quote from Richard Feynman, a famous Physicist who did a lot of his studying in QM: "I think I can safely say that nobody understands Quantum Mechanics."

[RJM]

Heisenberg may have been there!

[<SparTacuS>]

If you think that's bad - the last course I had to sit was on "Relativistic Quantum Mechanics" and there were no set texts because (to quote the Prof) "No-ones written one yet, I'm just doing it now!".

[Lazy8]

I couldn't get the video to play, but I'm sure it's also available at http://www.whatthebleep.com.

The full-length movie showcases all sorts of 'spooky action at a distance' through acting and animated sequences--definitely worth watching.

[matrix0978]

Ya, i just bought it, im probably gunna sit down sometime and watch it very soon!.

[DonDamm]

That's a good explanation for first timers about the paradox. If you're interested checkout the work of Alain Aspect of Paris as he's one of the foremost researchers in the area.

One of the more curious quantum puzzles to come out of it all is the seemingly instant (read no delay) communication between two photons which are paired (released at the same time going in opposite directions. A chaqnge in the polarity of one photon appears to register in the other even though they are apart and do not seem to be bound in any other measurable or observable way.

This is strange stuff indeed! :^) Have fun in your course. It was my favorite area of physics when I was in university and great advances have been made since then. Make sure you check out the work of Aspect and you'll see what I mean. You might also enjoy Bose-Einstein condensates.... :^)

[sven]

oh boy, a look at my future physic course. im having enough problems understanding circular motion

[Zxian]

Hehe... some other physicists here on the forums!

Just out of curiosity, what are you (or did you) study when you were at university? Does that relate to your jobs now?