26 April, 2012

A-Z Blogging Challenge: Wave-Particle Duality

Example of a double slit experiment, by Timm Weitkamp,
CC-BY-3.0-de. SOURCE.
Wave-particle duality is a principle of quantum physics that says matter and light act as both waves and particles, and that the observed behavior depends on the experiment.

Since the 1600s, scientists tried to figure out whether light, a type of electromagnetic radiation, came in waves or was made up of particles. Christiaan Huygens developed a wave theory (also suggesting that there was a luminiferous ether through which waves traveled, since it was generally thought waves needed a medium) and Isaac Newton a particle (or corpuscular) theory. It wasn't until the 1800s with Thomas Young's double-slit experiment and the buildup of other evidence pointing toward the fact light acted like a wave that Newton's theory was overturned. At least until the Michelson-Morley Experiment, which tried and failed to find any ether.

There are six major types of light phenomenon: reflection, refraction, interference, diffraction, polarization, and the photoelectric effect, all of which can be explained by wave theory, except for the photoelectric effect. Then Albert Einstein published a paper that explained it (introducing photons as continuous waves in 1905), wave-particle duality was also proved to take place with matter by Louis de Broglie (who was awarded the Novel Prize in 1929), and Niels Bohr proposed that light could take on either wave or particle characteristics. Hence, with no other explanation, duality was accepted as reality.

Example of an interference pattern, by Thierry Dugnolle,
public domain image. SOURCE.
One of the more famous experiments done which helped prove wave-particle duality was Young's Double Slit Experiment. To take Richard Feynman's analogy, imagine someone shooting at a wall through two slits in a sheet of metal. You would expect the bullets to be centered close to two narrow bands on the far wall--but with light, that isn't true. Instead (to stretch the example a bit far) the pattern of bullets would show up as an interference pattern (bright and dark bands, in the case of light; see above image) as though projectiles were passing through the slits at the same time and bouncing off each other.

No notable scientist today. Quantum physics is far from stagnant, of course, but I don't know of any wave-particle dualicists. But if you'd like a simulated ripple tank to play around with that has an example of the double-slit experiment (just make sure you have Java):

http://www.falstad.com/ripple/ex-2slit.html

**********

Sources:
http://www.britannica.com/EBchecked/topic/637889/wave-particle-duality
http://www.colorado.edu/physics/2000/schroedinger/two-slit3.html
http://hyperphysics.phy-astr.gsu.edu/hbase/mod1.html
http://library.thinkquest.org/28383/nowe_teksty/htmla/2_10a.html
http://micro.magnet.fsu.edu/primer/java/interference/doubleslit/
http://physics.about.com/od/lightoptics/a/doubleslit.htm
http://physics.about.com/od/lightoptics/a/waveparticle.htm
http://science.howstuffworks.com/light6.htm
http://www.supraconductivite.fr/en/index.php?p=supra-quantique-dual
http://www.thefreedictionary.com/wave-particle+duality
http://www.upscale.utoronto.ca/PVB/Harrison/DoubleSlit/DoubleSlit.html

**********

Do you think any other strange properties such as wave-particle duality will be discovered?


-----The Golden Eagle

35 comments:

Elliot Grace said...

...I can remember hammering for a test on reflection v. refraction back in school.

Quite informative, Eagle ;)

El

Em-Musing said...

And this observer wonders why this kind of cool info gets more interesting the older one gets. Quantum aging?

Rusty Webb said...

I'm not entirely sure I know the context for your question today. I do think weirdness abounds however. One thing I was told that has always stuck with me is this: "We evolved to survive in the universe, not understand it."

The implication, of course, is that very little of how the universe works is intuitive. We just do our best.

Chris Fries said...

I think the wave-particle dualiy is just a great example of the fundamental yin-yang duality underlying everything.

Jack said...

Gosh, this is even too deep for me. I just loved reading this post because I learned something I didn't know existed. :)

Cheryl Klarich said...

Cool and Awesome!!!

Love Em-Musing's "quantum aging" theory!!

stuartnager said...

OK...that link led to a great way to see it work, and I loved playing with it. Thanks GE

Libby said...

I just started studying quantum physics and it's a doozy. But super cool.

Old Kitty said...

Love your particle graphic!!! I'm mesmerised! Take care
x

Cherie Reich said...

The particle graphic is awesome!

I'm sure we'll find more such dualities in time. Things are rarely so simple to be just one way.

Alex J. Cavanaugh said...

Think I'll skip making my own tank and take their word for it.

....Petty Witter said...

I seem to remember having heard of Young's Double Slit Experiment at school and not understanding it. Like Jack I think this goes way too deep for me also.

Ciara said...

My one blonde brain cell just exploded. I'm not sure why.
I loved reading this post, even though I had to read it twice before I understood it. :)

Matt said...

I remember watching a video about the double-slit experiment for the 1st time and being blown away. Crazy stuff.

Inger said...

Way above my brain, but interesting and informative nevertheless.

Joshua said...

A name I remember is E.H. Carlson. I know he's retired from Michigan State, but I wonder if he's still alive.

Clarissa Draper said...

I think my brain just exploded. So many fascinating things there are to learn.

Elise Fallson said...

Wonderful post. Reminds me of stuff I've tried to forget over the past 10+ years lol! As to weather or not I think any other strange properties such as wave-particle duality will be discovered, I'd say sure. As long as we keep asking the right questions. (:

David P. King said...

No way! You toughed the tip of the ice berg to the theory that makes my sci fi series plausible. Only there's some updated information here that will help with the update. Thanks again for science! :)

Pat Hatt said...

I think much will be found, the moment we think we know all the answers is when we find out we don't know a thing.

Laura Marcella said...

Hello! This is fascinating. I love learning cool things like this! Thanks for sharing. Have a lovely week and happy A to Z!!

Susan Gourley/Kelley said...

You have made me very aware that there must be many more things to be discovered.

Andrew Leon said...

I agree with Rusty: "weirdness abounds."

Texas Yellow Rose said...

Thanks for visiting my blog and for your kind comments! Welcome as a new follower, too. I'll be following along here with you, not just in returning the favor, but I find yours interesting, aesthetically appealing and - this is refreshing - well written! Cheers!

Monti said...

Goodness, what an impressive blog. I had trouble with physics as a teenager, but I enjoyed reading your blog. Thanks for sharing.

Monti
Mary Montague Sikes

Kayla Beck said...

Hold on while I go find my brain. I think she went to hide under the couch. Heh, all kidding aside, that was a FANTASTIC post. I can kinda understand physics if I concentrate really hard, but I'm lazy. I always enjoyed the college-level sciences that I took to keep me sharp, so I think I need to follow your blog now. :-D

Sherri Lackey said...

I read about this before but I can't remember where. It is fascinating. I'm sure there is a whole lot we haven't discovered about the universe we live in. :)

Duncan D. Horne - the Kuantan blogger said...

Keep it up with this great series! You're almost finished!
Duncan In Kuantan

Michael Offutt, Tebow Cult Initiate said...

Excellent post on wave particle duality. Quantum mechanics is a mysterious thing to study and understand.

J.C. Martin said...

Err ... you lost me a bit on today's post. Physics was always my weakest science! I got as far as reflection, refraction, and diffraction... :)

J.C. Martin
A to Z Blogger

The Golden Eagle said...

Elliot: Thank you!

Em-Musing: Maybe. :)

Rusty: Oops . . . on further thought, perhaps I should have phrased that differently. I meant what Cherie Reich managed to phrase below--if we'd ever find any other properties that are attributable to the same, seemingly indivisible thing.

Good point about understanding the universe, though; evolution doesn't necessarily allow for an organism to understand what's happening to it.

Chris: That's an interesting thought!

Jack: Glad you learned something from my post. :)

Cheryl: Thanks! Quantum physics/wave-particle duality is one of my favorite subjects.

Stuart: You're welcome. I had hoped someone would find the link useful!

Libby: Agreed!

I want to learn more about quantum physics sometime. All I know is what I've read from internet sources and a few books--would be nice to take some kind of course.

Old Kitty: Glad you like it! I enjoy watching it, too. :)

Cherie: That's definitely true of life at least!

Alex: I don't think I'm ever going to build a ripple tank; they seem like they need really fine control, and electronic simulations are just as cool to watch. :P

Petty Witter: Quantum physics sometimes stumps me, too. Complicated stuff, it is!

Ciara: Understanding's the main goal, though! And it's not like blog posts disappear after you read them once. ;)

Matt: It's pretty strange how light shows up on that back wall, isn't it?

Inger: Thanks!

Joshua: Never heard the name before. I just found a document by him addressing wave-particle duality, though:

http://physnet2.pa.msu.edu/home/modules/pdf_modules/m246.pdf

Clarissa: There definitely are! :)

Elise: Thank you!

More reason to admire the scientists in physics . . . they're asking all kinds of questions these days.

The Golden Eagle said...

David: You're very welcome! :)

Pat: That reminds me of a quote . . . but darn it, I cannot remember how it went. But someone said something along the lines of taking a journey, gaining knowledge, and then taking the journey all over again with the knowledge and therefore new experiences.

Laura: You're welcome!

You too. :)

Susan: I hope there are. And there are still a lot of open questions in physics.

Andrew: No shortage of weirdness in this universe, that's for sure. :P

Texas Yellow Rose: You're welcome! I really enjoyed visiting your blog. :)

Thank you so much!

Monti: I'm glad you liked the read. :)

Kayla: Thank you!

There are plenty more science posts in my April archives, in case you're looking for more. And there are still two more days left of the A-Z Challenge in which science will be explored. ;)

Sherri: That's why I love science; it's always pressing the boundaries of what we know.

Duncan: Thanks!

I can't believe the A-Z Challenge is drawing down; it feels like April started just a few days ago, in some ways. :P

Michael: Thank you!

It definitely is.

J.C.: Wave-particle duality is partly just an extension of that. Only . . . not quite. :P

Paul Tobin said...

Great stuff, my knowledge of science increases daily.

The Golden Eagle said...

Paul: It was one of my goals when I started this series to inform people about science, and to see what they thought of recent developments.

Helmut Hansen said...

If I should reformulate your question in a way that fits to my own work I would ask: Is there any other property belonging to wave-particle duality that is still undiscovered?

I would say: YES; there is another property. Today we know light itself is of dual nature. There are particle-like and wave-like aspects of light. But strangely, the speed of light as defined by special relativity is not of dual nature. The second principle of it (i.e. the Principle of the Constancy of Light) is exclusively defined in wave-like version. There is indeed no particle-like version. But if the speed of light is actually a quantum mechanical property there should be such a particle-like version as well. Just this assumption I am calling "The Principle of Dual Constancy of Light". I have no doubt, this principle is a notion that revolutionizes our understanding of the fundamental constant of c.