The Future of Fundamental Physics

October 20, 2010 3:33 PM

Renowned theoretical physicist Nima Arkani-Hamed gave a series of five Messenger lectures on "The Future of Fundamental Physics" at Cornell University two weeks ago. 1 3 4 5

Formerly a professor at Harvard, Arkani-Hamed currently sits on the faculty at the prestigious Institute for Advanced Study in Princeton, New Jersey, where Einstein served from 1933 until his death in 1955.

Previous distinguished speakers in physics for the Messenger lectures include Richard Feynman, J. Robert Oppenheimer, and Robert Millikan.

These Messenger lectures are intended for a general audience with some physics background.

Lecture 1: "Setting the Stage: Space-time and Quantum Mechanics"
Lecture 2: "Our "Standard Models" of Particle Physics and Cosmology, and their Discontents" (sadly not posted, perhaps due to recording problems... maybe it will come up later)
Lecture 3: "Space-Time is Doomed: What Replaces It?"
Lecture 4: "Why Is There a Macroscopic Universe?"
Lecture 5: "A New Golden Age of Experiments: What We Might Know By 2020?"

posted by bread-eater (15 comments total)

If you are interested in yet another (but very good) explanation of what we might get to know from the LHC, watch lecture 5 in particular.
posted by bread-eater at 3:36 PM on October 20, 2010 [1 favorite]

This is great, thank you.
posted by empath at 3:59 PM on October 20, 2010

This is really good.
posted by Blazecock Pileon at 4:11 PM on October 20, 2010

Is one of the lessons that there's no such thing as the number 2?

(Just kidding, but there does seem to be a link missing above.)
posted by JHarris at 4:26 PM on October 20, 2010

Ah, I see, nevermind you explain it in the More Inside text.
posted by JHarris at 4:27 PM on October 20, 2010

I never took physics in high school and didn't make it to college but I've read all the dumbed down books and watched 100s of hours of NOVA and now the first lecture in this series and I'm left with the same frustrating BASIC question(s) - starting with: when these guys say "particle" it seems like they are not talking about a tangible thing but rather a set of behaviors. Is that right? Is there an actual thing there? Or is it really just "we looked over there and then that happened"?
posted by victors at 12:59 AM on October 21, 2010 [1 favorite]

@victors Good question! In a way, yes, it is a set of behaviors discovered by observations. Based on those observations, patterns are discovered. Then the patterns are interpreted by creating models.

If you read about Rutherford you see that shooting "alpha particles" at a sheet of gold created patterns on a sheet of ZnS. Those patterns were the beginning of the model called 'atom'. Atoms were once so small no one could 'see' them ... but now we -can- see them ('image' them is a better term).

So what we have are (now several hundred) models we call particles. Are they tangible? Not to the touch. But these pattern sets are very stable; anyone in the world can set up proton-measuring equipment and get a pattern of measurements ... mass, charge, spin ... that are the same (always with some small error) for everyone, everywhere.

They're so very, very small that they seldom affect us in 'tangible' ways. Scientists have observed cosmic ray particles moving so fast that their energy (billions of electron-volts) is the equivalent of a fly buzzing along. If one of those hits something organic, it will do detectable damage. And particles will fog up photographic film exposed to them (X-ray!).

The models, constructed from observation patterns, are considered accurate because they let us predict very well (and very usefully ... as in computer chips) how matter will behave. So while the particles ARE too small to sense directly, there's every reason to be confident that they are stable objects with consistent properties.
posted by Twang at 2:10 AM on October 21, 2010 [3 favorites]

I'm left with the same frustrating BASIC question(s) - starting with: when these guys say "particle" it seems like they are not talking about a tangible thing but rather a set of behaviors. Is that right? Is there an actual thing there? Or is it really just "we looked over there and then that happened"?

That's actually a very deep, and very good question. There's a point of view called Instrumentalism which says that the actual existence of these things is irrelevant. If you can construct a theory which gives exactly the same observations but which does not include "particles" then that theory would be just as good and theories are judged purely by their elegance.

My own position is that if a particle were to exist that has never interacted other particles, cannot now interact with them, and never will be able to, then that particle is not in our universe. This also means that if you can exhaustively describe the interactions between particle X and the rest of the universe, then you have fully described particle X.
posted by atrazine at 4:58 AM on October 21, 2010 [1 favorite]

Wow, thanks for that question, victors. It seems that one of my problems understanding this stuff is that the term "particle" inevitably makes me picture billiard balls and trying to cram the weirdness of subatomic physics onto this everyday metaphor absolutely doesn't work.
posted by storybored at 7:32 AM on October 21, 2010 [1 favorite]

Here are some of the ways in which sub-atomic particles differ from macroscopic particles such as billiard balls:
They are not solid; one particle can occupy the same space as another particle (note that a collection of superimposed particles is known as a Bose-Einstein condensate, and this has been created in the laboratory, so it is not just a theory!).
Depending upon how you are measuring them, they often do not have specific locations as much as a range of probable locations.
They might be little spheres, but they can have lots of other shapes. Electrons, for example, do not orbit atomic nuclei so much as distribute themselves in the form of an electron cloud that surrounds atomic nuclei - and even a single electron (as in a hydrogen atom) can form such a cloud, which has the shape of a hollow sphere. When there are several electrons surrounding a nucleus, they fit together in rather intricate shapes which algebraically add up to hollow spheres.
posted by grizzled at 8:13 AM on October 21, 2010

I certainly hope that we will get a chance to see/hear lecture three because it would be about the category of the standard interpretation's discontents and it is there that we might get a broader picture of what is going on in fundamental physics, and what it might actually mean beyond the walls of Plato's cave. After all, so-called particle physics is currently busy trying to prove its validity by spending billions on getting a glimpse of the so-called God particle, or more correctly, he Higgs Boson, that will tell us everything we will ever need to know. But so far, it hasn't turned up. In the meanwhile we have quantum field theory which has some rather different ideas along with ontological theories and many mind and/or many world theories and so on. And that's not mention string theory which, at last count needed 11 dimensions to for the algorithms to come together and make any sense. And what all these dimension might consist of, is another question.
posted by donfactor at 9:39 AM on October 21, 2010

I owe this group a round of IPA - I think I'm starting to get it.

I got a million of these btw - maybe I should start askMe'ing them....

meanwhile, great post.
posted by victors at 10:03 AM on October 21, 2010

The lectures (I've seen #3 so far) are very good. #1 and 2 are history. #3 explains the holographic universe in more detail than I've seen, why black holes don't lose information, delves into the history and application of string theory ... wow this is very comprehensive picture. Thanks for the post!
posted by Twang at 6:53 PM on October 21, 2010

#1 and 2 are history.

For anyone who hasn't watched and/or is deciding whether to start from the beginning, the first two are history in the sense that he goes over theory that we have already pretty much completely figured out, but it's not like he talks about names and years more than physics.

very comprehensive picture

Yup. Quite a feat, I'd say.
posted by bread-eater at 4:42 AM on October 22, 2010

Lecture 2 Our "Standard Models" of particle physics and cosmology (As the description notes, the audio is not so good in this version, so turn up the volume.)
posted by bread-eater at 8:53 AM on October 28, 2010