Practice Run Thru on Temporal Paradox Talk

I’m doing a practice run thru on my Temporal Paradoxes talk at NASA.

The run thru will be at the Winsor room at the Radnor Memorial Library on March 12 at 2pm.  This is a few hundred feet from the main intersection in Wayne, PA.

The talk is basically the Physics Of Paradox talk, but more focused on the physics than the science fiction (tho in this area it can be hard to tell them apart) & with animations.

Since this is a complete redo of the talk, I’m hoping to get feedback on timing & clarity & focus & such like!

Please come!  And criticize!

Thanks!

— John Ashmead

Temporal Paradoxes Talk at NASA

I’ve been asked to do a talk, Temporal Paradoxes, at NASA.  This will be on the 21st of this month, at 3:30pm.  This is a NASA-fied version of my previous Physics of Paradox talk, meaning more animations & less science fiction, and perhaps a few equations in a grayish font.  Abstract:

ABSTRACT — Einstein’s general relativity is the leading theory of gravity. Simple and elegant, it has passed all available experimental tests including: deflection of light by gravity, precession of orbital apsides, gravitational time dilation (used in GPS), and frame-dragging.

However, general relativity makes a number of counter-intuitive predictions. In particular, trajectories looping around massive, rapidly rotating stars or passing through a wormhole can close on themselves in time, creating closed timelike curves (CTCs).

This creates the possibility of “grandfather” and “bootstrap” paradoxes. Recent work by Greenberger & Svozil, and others, however, questions this conclusion. That work suggests that when quantum mechanical effects are included, the paradoxes become self-canceling, eliminated by destructive interference within the wave function. If the paradoxes are self-canceling, then closed time-like curves are possible. If they are possible, can we create or detect them?

Several authors have suggested that we look for evanescent wormholes with the Large Hadron Collider. If we find them, we may be at the edge of temporal paradox. While the only safe prediction in this area is that there are no safe predictions, we look at the implications of this for general relativity, quantum mechanics, & causality.

Reality versus free will, escaping the Holodeck, are the laws of physics “more guidelines than rules”?, and more!

I’m doing five panels and my Physics of Paradox talk at the Philadelphia Science Fiction Convention, starting in a few hours.

Quite a lot of fun subjects for my panels:  Augmented Reality (for those who can’t get enough reality), Time Travel & Free Will, Are the Laws of Physics Laws (or really more just Guidelines?), Is the Universe a Hologram (& can I leave the Holodeck?), my Physics of Paradox talk in its final & perfected version, & What Came Before the Big Bang (& are we in trouble with whatever it is?)

[I’ve augmented the reality of the Physics of Paradox slides by adding the spoken text to them:  see the Keynote (for Mac users), PowerPoint (for PC users), and  annotated pdf version.]

My complete schedule is:

The Physics of Paradox — Followup

Physics of Paradox

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!

Paradox Noise

“YOUR ONLY CHANCE LIES IN PREVENTING THE ASSASSINATION OF PRESIDENT ABRAHAM LINCOLN . . .” “What?” A burst of audio and visual static reduced reception to unintelligible noise. Then the paradox-generated interference was gone again, as suddenly as it had come. ” . . . Fourteenth of April at Ford’s Theater –” blast, crackle. “. . . you must be within two meters of the President . . . just before the bullet smashes into Lincoln’s brain. Your total window of opportunity will be three seconds.” – Fred Saberhagen’s After the Fact

If the block universe view is correct, if time is “nothing but” a space dimension, then we should be able to travel in it. Leaving aside the fact that we don’t quite yet know how to do this (but see some of the books under references) shouldn’t time travel be forbidden by the paradoxes it would otherwise make inevitable?  There are three kinds of paradox to consider:

Three kinds of paradox

Grandfather paradox

Why pick on grandfather? It seems that the only way to prove that time travel is impossible is to cite a case of killing one’s own grandfather. This incessant murdering of harmless ancestors must stop. Let’s see some wide-awake fan make up some other method of disproving the theory.

– 1933 letter to Astounding Stories, as quoted in Nahin’s Time Machines: Time Travel in Physics, Metaphysics, and Science Fiction

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The Large Hadron Collider — Followup

Paul Halpern‘s talk on The Large Hadron Collider at Philcon on 11/21/2009 came off well.  I’ve since had a chance to read his Collider: The Search for the World’s Smallest Particles since.  The talk was basically the book light or, if you prefer, the book is the talk heavy.   Good jobs either way.

Paul had  a lot of fun with the idea that someone (from the future) is maliciously trying to keep us pitiful humans from building a high energy collider; first the money difficulties the Superconducting Super-Collider had in Texas and then the explosion at the Large Hadron Collider.  But now that the LHC is in fact colliding (if not yet at full strength), perhaps the little blue men have given all this up as a bad job.
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References on Time & Time Travel

Updated 12/2/2009

Recommended popular books on time. All of the authors know their physics; none are mortal enemies of the English language.  Enjoy:
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Five Popular Talks

Over the last ten or fifteen years I’ve done a number of slide talks at Balticon, Philcon, & Farpoint, three local science fiction conventions. A number of these have been relatively heavy on the physics – within the context of a science fiction convention of course – and I thought it might be fun to post them. As Rod Sterling might have put it, presented for your consideration:
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How to Build a Time Machine — Talk this evening

This evening, Friday, November 21st at 7:00 pm,  David Goldberg & Jeff Blomquist, are doing a talk:

How to Build a Time Machine

This is at the Philadelphia Science Fiction Convention, in Cherry Hill, PA. Directions and so forth at www.philcon.org.
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