Gave the Physics of Paradox talk at the Library of Congress Thursday (10/21/2010) & then again at Capclave Saturday (10/23/2010). Good audiences both times, lots of good questions. At Capclave talk was standing room only & Brent Warner, from the Goddard Space Center has asked if I would be interested in doing it there this spring.
I made some changes to the talk over the weekend, in response to audience feedback & further reflection. The latest version is now up as Keynote (for Mac users), PowerPoint (for PC users), PDF in slides-only and also annotated forms.
I’d like to thank Dick Ladson, Walt Mankowski, Bruce Bloom, Shelley Handen, Ed & Marguerite Rutkowski, & of course Ferne Welch for their feedback at the dry run, which improved it immensely. And I would like to thank Nathan Evans of the Library of Congress & Colleen Cahill of Capclave (& as it happens the Library of Congress) for having me. Lots of fun!
Announcement, History of Time, Paradox, Popular, Quantum Gravity, Quantum Mechanics, Science Fiction, Theories of Time, Time, Time Machines | John Ashmead | 
October 26, 2010 10:45 am | 
Comments Off on The Physics of Paradox — Followup
This talk — scheduled for the Library of Congress & for Capclave next week — is now up.
It was a lot of fun to put together: I discuss time in relativity & quantum mechanics, kinds of time, some possible time machines, the three kinds of paradox (grandfather, bootstrap, & freewill), the Hawking & Novikov consistency conditions for avoiding paradox, some ways to implement those conditions, paradox noise, what the world might look like if paradox avoiding time travel were possible, and of course why this is likely.
I’ve got the talk on line as Keynote (for Mac users), PowerPoint (for PC users), PDF in slides-only and also annotated forms.
I’m doing a practice run on the talk in two days at the Radnor Memorial Library in the Winsor room from 6pm to 8pm (when we have to be out). I start the actual talk about 6:30pm. This is a dry run (well more of a wet run really) for the talks next week.
If you are not too far from Wayne, PA & have an interest in time & paradox (but then if not why are you reading these words?) please feel free to come!
This was my Balticon Time & Quantum Mechanics talk, adjusted for a general (rather than a science fictional) audience. I covered over a hundred years of physics in less than an hour — a lot — but the audience survived & even seemed to prosper, asking some good questions!
I’ve uploaded the
power point and
keynote versions of the talk so you can see the animations of the double slit experiment, if you have power point and/or keynote. You may have to tell your browser how to handle .ppt and/or .key files, for all parts to work with maximum smoothness. I’ve also uploaded the
pdf and
html versions.
The references — several asked after them — are on
slide 36. Enjoy!
I’d like to thank Oz Fontecchio for organizing this, Ferne Welch for moral & practical support, Bob Rossberg (sp?) for critical help on the AV, & the Chestnut Hill Book Festival for providing the venue!
Did the talk Saturday evening as planned. Very sophisticated audience: almost everyone there had heard of the double slit experiment!
The talk went over well: audience enthusiastic; lots of good questions. Post talk I was asked if I would do similar presentations for Capclave & for the Library of Congress. Leaning in favor.
I think that to really get across quantum mechanics, especially in a short time, nothing beats animations; the animations of the single & double slit were probably the most effective bits. In future talks I shall be more animated.
The animations were courtesy of Bernd Thaller’s Advanced Visual Quantum Mechanics. He provides a useful kit of Mathematica functions for building such; looks a good starting point.
I’ve uploaded the power point & keynote versions of the talk so you can see the animations of the double slit experiment, if you have power point and/or keynote. You may have to tell your browser how to handle .ppt and/or .key files, for all parts to work with maximum smoothness.
The pdf & html versions are still present, of course. These are the talk as delivered, slightly different from the version previously posted (I added several more slides on the quantum eraser).
… there are known knowns: there are things we know we know. We also know there are known unknowns: that is to say we know there are some things we do not know. But there are also unknown unknowns — the ones we don’t know we don’t know.” — Donald Rumsfeld.
I’m doing a popular talk on “The Nature of Time & Quantum Mechanics” tomorrow at Balticon. I’m deliberately not including anything from my paper “Quantum Time“.
Instead I look at a couple of areas at the intersection of time & quantum mechanics. There are too many such areas for one talk. In accordance with my father’s rule of three (you can only get three points across in any one talk) I selected three of them, one from each of Donald Rumsfeld’s categories.
- The delayed choice quantum eraser. I find this amazing: if you try to see which slit the particle went thru in the double slit experiment, it becomes a single slit experiment. But if you do something that should tell you which slit it went thru — and then deliberately erase your knowledge — the single slit experiment turns back to a double slit experiment & we recover the interference pattern. And this is the case even if we do the probe/erase after the particle has gone thru the two slits! Weird but well understood & tested.
- The time symmetric formalism of Aharonov, Bergmann, & Lebowitz. They formulated quantum mechanics in a time symmetric way, demonstrating that it is not essentially asymmetric in time. It’s just usually drawn that way, as Jessica Qubit might put it. There has been some speculation that their formalism could imply retro causation. I doubt it myself but this would be a known unknown.
- The competition between the inflationary universe model & the ekpyrotic (cyclic) model of the universe. The inflationary model now has a bit of competition in the ekpyrotic model of Steinhardt & Turok (see their book Endless Universe for a popular treatment). Colliding branes, bouncing universes, & decaying dark energy oh my! We have no idea what about the start, expansion, & finish of the universe we don’t know. We don’t even know if the terms start & finish make sense, universe-wise.
I’ve put the slides for the talk up as a pdf & as html.
I’ve finished re-checking the dissertation: 629 equations, 188 references, 110 pages, 83 input files, 48 lists, 36 footnotes, 28 quotes, 17 figures, 6 chapters (counting the appendix), 5 requirements, 1 idea. It should be up on the physics archive in a day or two.
Catherine Asaro, Jay Wile, & I had a good crowd for our quantum gravity panel at Philcon: I was impressed that that many people (perhaps 40 or 50) wanted to hear about a relatively esoteric subject. Esoteric but hot: there are (right now) 663 papers on the physics archive with quantum gravity in the title, in just the last five years!
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