Category: Theories of Time

Time to the Power of Tim

Three Time Travel Tales by Tim Powers

Three Time Travel Tales by Tim Powers

This year the guest of honor at Capclave was Tim Powers. (Capclave is the Washington DC Science Fiction convention.) Tim is not only the author of many fine science fiction novels, but a very nice guy.

This turned out to be a good thing, as the initial proposal was to have Tim & I appear together and do something physic-y about his novels.  I have never done a talk with a live author before (dead authors are no problem, I have that down cold), so I was a bit nervous about the whole thing.

But it worked out well:  Tim was very helpful & gracious and when the audience asked him if one of my theories about the time travel in his novel The Anubis Gates was correct he said, essentially, “Now it is.” 🙂

I focused on three of his novels, The Anubis Gates — his first big success (with romantic poets & time-traveling Jackel Gods), Three Days to Never — something like the bastard child of John Le Carre & H. P. Lovecraft, and Medusa’s Web — who can resist the Time Spyders?

One of the distinctive features of Tim Powers working method is that he starts with a place and a time, researches it looking for the curious facts, bizarre details, & strange omissions that point to an unknown but dark reality, then gradually teases out the true story of whatreallyhappened!

“I made it an ironclad rule that I could not change or disregard any of the recorded facts, nor rearrange any days of the calendar – and then I tried to figure out what momentous but unrecorded fact could explain them all.”

So Tim builds his novels from the bottom up. As a result, they tend to differ wildly from each other.  Other authors, once they have got a setting that works, tend to reuse it, Tim builds anew each time.  No ten volume trilogies here!

And he also works out the timelines of all of his critical characters.  At each moment, he knows where each of his on and off stage characters are & what they are up to.  His notes on this are a kind of secret history of the secret history!

He has 20 or more novels out, so I focused on just three, all involving time travel.  And in each the theory of time travel was radically different!  I had a lot of fun linking each up to the corresponding physics and going back & forth about all this with my stage-mate Tim. 🙂

The talk, minus alas, the actual talking, is now up on slideshare.  Download if you will & any questions/comments please let me know!  thanks!



Stargates: The Theory & Practice

Doors and Portals and Stargates, Oh My!

Call them Stargates, Jumpgates, Fargates, Hypertubes or just an invitation to every unwanted pest from the far reaches of the Galaxy to visit, they are absolutely necessary if we are to have the glorious Science Fiction action we desperately need.  But could they actually be built?  We look at what modern physics has to say:  how to glue black holes together to build a wormhole, how to avoid the dangers of spaghettification, radiation poisoning, and paradox noise, and just what it would take to build one in practice.

This was a talk I did at the last Philcon, went over well.  And I had a lot of fun doing it.  I’ve got it up as a talk on slideshare.  And I may do variations on this at the 2017 Balticon & also Capclave.

It is the kind of subject you can go anywhere with!


Invisibility, Anti-gravity, Ethics of Time Travel, & Balonium

I’ve just received my schedule for Philcon, being held in a bit over a week, November 8th thru 10th.  Curious collection of subjects, but looks like a lot of fun.  If you are in the Philly area, it would be great if you can come by!

Sat 1:00 PM in Crystal Ballroom Two (1 hour)


[Panelists: John Ashmead (mod)]

How do we hide a jet fighter, a tank, even a city from sight? For
millennia people have dreamt of invisibility rings, caps, & cloaks:
how close are we to Harry Potter territory? Progress in the last ten
years has been extraordinary, and, with some help from general
relativity, 3d printers, advanced photonics, and more than a pinch
of ingenuity, we can now bend, fold, & spindle light in ways
unimagined ten years ago
Sat 3:00 PM in Crystal Ballroom Two (1 hour)

[Panelists: John Ashmead (mod), Ed Bishop, Walter F. Cuirle, Jay

Both creating and negating gravity are very common tropes in science
fiction. It’s taken for granted in most Science Fiction that
spacecraft have normal gravity, although they do not spin. How this
is achieved is rarely discussed. Anti-gravity is nearly as common,
(and convenient for the plot).. Are either of these concepts
scientifically plausible? Could such a technology ever actually be


Sat 6:00 PM in Plaza II (Two) (1 hour)

[Panelists: John Ashmead (mod), Evelyn Leeper, Andrew C. Ely]

Everyone talks about killing Hitler in his crib, or stopping Booth
from shooting Lincoln. But if you could change the past, would you
Sat 7:00 PM in Plaza III (Three) (1 hour)

[Panelists: John Ashmead (mod), Darrell Schweitzer, John Monahan,
Sharon Lee]

From cavorite to kryptonite, science fiction fiction writers love to
add new elements to the periodic table. How do you create
convincing imaginary substances and what do you do with them

10 Big Idea Books

In a recent conversation Brad Denenberg of was lamenting that the pressures of being in a startup had kept him from reading anything non-work related for months.  We got to talking about what a list of big idea books might be.  Herewith a list of ten of my favorites, chosen because they are

  1. Readable
  2. Are about a big idea (or several)
  3. Changed the way I think about something
  4. Keep coming up in conversation

The 10,000 Year ExplosionGregory Cochran and Henry Harpending. Human evolution hasn’t been frozen by culture: in fact it seems to happening at great speed, with some significant changes in the last 10,000 years. Cases in point:

  1. Malaria resistance
  2. Lactose tolerance
  3. Higher intelligence in the Ashkenazi

The Selfish GeneRichard Dawkins — How genes use us to propagate themselves. Dawkins invented the term “meme”, one of those pesky terms that refer to themselves.

Incomplete Nature: How Mind Emerged from MatterTerence Deacon. Online talk. Extra capacity, coalesced into language, then became fixed. Analogies to entrepreneurship.

Reading in the Brain: the New Science of How We ReadStanislas Dehaene — Dehaene hooked people up to NMI machines while they were reading & watched how the brain processes text. For instance, there seems to be more need for context to understand Chinese than English, so brain activation patterns are different when reading Chinese than English.

Consciousness ExplainedDaniel C. Dennett — what do we mean by consciousness, by free will? Most striking, Dennett discusses this without reference to the underlying physics:  he defines free will in operational terms, in terms of our ability to make choices.

The Beginning of InfinityDavid Deutsch.  Argues with great force for the superiority of open-ended, evolving societies over static.

Guns, Germs, & Steel: the Fates of Human SocietiesJared Diamond — how geographic factors led to the success of the west. Diamond argues geography explains why European diseases decimated American Indian populations (rather than vice versa) & why European technology out performed Indian, Chinese, & American Indian technology.

The Checklist ManifestoAtul Gawande. Simple checklists can produce significant improvement in medical results.  For instance, a five step checklist for inserting a catheter reduced mortality rates enormously.  In a hospital environment, one of constant interruption, it was just very easy to lose track of what had been done/was till to be done, with often fatal results.

Thinking Fast & SlowDaniel Kahneman — how our instinctive responses to problems can lead to error & failure. We can’t function without relying on our instincts; at the same time they often lead us astray — and in fairly predicable ways.

Freakonomics: a Rogue Economist Explores the Hidden Side of EverythingSteven D. Levitt & Stephen J. Dubner — economics in everyday life; why drug dealers live with their moms.

Time’s Arrow and Archimedes Point: New Directions for the Physics of Time – Huw Price.  Price argues that our normal view of time as asymmetric & one way has a stronger foundation in psychology than physics.  The only thing that gives time a direction is that the Big Bang was a point of low entropy.  It has all been downhill since then.

The Black Swan: The Impact of the Highly ImprobableNassim Nicholas Taleb — how real world success is dominated by rare “black swan” events; the failure of Long Term Capital Management a case in point.

Temporal Paradoxes Talk Done: World Safe for Grandfathers

Had a very good time at NASA’s Goddard Space Center doing my talk Temporal Paradoxes.  Nice crowd; lots of good questions.  NASA’s audio-visual support was first rate, as you would expect, and the talk should be up on their site in a bit.  I’ll post a link here when that happens.

I’d like to thank Brent Warner & his colleagues for their warm welcome & all the feedback during the talk.  Brent tells me he particularly liked the quote from an Astounding Science Fiction reader (1933):

“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”*

As I say in the talk, if the current literature is on target, the grandfather & other paradoxes are cancelled out by interference by the time machine’s wave function with itself.

Brent & his NASA colleagues were kind enough to provide lunch & a fascinating tool of the facilities:  they manage the Hubble & are working on the James Webb.  Huge rooms with vast devices for subjecting equipment to high G’s, vacuum, heat, noise, vibration, & every other insult that it will need to be able to withstand during launch or in space:  gives one a real sense of just how hard it is to get this stuff to work!

*as quoted by Paul Nahin in his Time Machines: time travel in physics, metaphysics, and science fiction

Temporal Paradoxes Talk Online

I had a lot of fun putting my NASA talk Temporal Paradoxes together.  The feedback I got from the assembled multitude at the Radnor Library last week was extremely helpful, leading to a near complete rework of the talk, in the interests of making it clearer.   Thanks!

The pdf & keynote versions are now online.

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!


— 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:

Fri 10:00 PM in Crystal Ballroom Two (1 hour)
[Panelists: John Ashmead (mod), Earl Bennett, Rock Robertson, Bud Sparhawk]
We’ve all heard about virtual reality and the potential it holds for gaming, learning, medicine etc., but augmented reality, while less well-known, is more likely to have a major effect on everyday life. Imagine wearing a pair of glasses while driving that produce flashing arrows to indicate your turns, or looking at a city street through your cell phone screen and seeing each building labeled by name and type of business. Learn what’s happening now and what we can expect in the future.
Sat 11:00 AM in Plaza VII (Seven) (1 hour)
[Panelists: John Ashmead (mod), Michael F. Flynn, John Grant, Helen Collins, Lawrence Kramer]
Suppose that  three weeks in the future I come back and sit on this panel,does this not imply that nothing can happen in the future toprevent me from getting in a time machine and coming back? Does this mean that time travel implies that the future is pre-determined?
Sat 12:00 PM in Crystal Ballroom Two (1 hour)
[Panelists: Paul Halpern (mod), John Ashmead, Jay Wile, Tony Rothman]
Are the laws of nature really the same across all space and time? No principal is more fundamental to physics than the idea that the laws of nature remain the same at all times and in all places. Much we believe to be true about the universe depends upon this concept. However, new observations have revealed anomalies that suggest that such physical laws as the fine structure constant and the speed of light may actually have changed over time. Will we soon have to rethink our ideas about physics and cosmology
Sat 2:00 PM in Crystal Ballroom Two (1 hour)
[Panelists: Paul Halpern (mod), John Ashmead, Jay Wile, Tony Rothman]
Is the universe a hologram? One of the strangest ideas to come out of modern physics is the holographic principal, which speculates that the universe may be a multi-dimensional projection of information encoded (in Planck length-sized  squares, each containing one bit of information) on a two-dimensional boundary called the cosmological horizon. A new experiment searching for gravity waves may have accidentally found evidence for this theory that was predicted by supporters.
Sat 3:00 PM in Crystal Ballroom Two (1 hour)
[Panelists: John Ashmead (mod)]
There is nothing in modern physics to rule out time travel, save paradox.  And — thanks to quantum mechanics — it seems any potential paradoxes would be self-canceling.  Therefore the only thing standing between us and time travel is not knowing how to go about it, exactly.  But several recent papers have proposed ways to use the Large Hadron Collider at CERN to create particle loops that
go backwards in time.  Now what?
Sat 5:00 PM in Crystal Ballroom Two (1 hour)
[Panelists: John Ashmead (mod), Paul Halpern, Eric Kotani, Tony Rothman]
Was there a time before the beginning? As incredible as it seems, new discoveries have given scientists clues about what may have existed prior to the beginning of our universe. Scientists at the University of Pennsylvania have developed a mathematical model that traces through the Big Bang to a shrinking universe that exhibits physics similar to ours. Measurements of the Cosmic Microwave
Background radiation reveal an imprint from the earliest stages of the universe may also shed light on what came before. The following links are offered as jumping off points to potential panelists who would like to investigate this topic:

The Physics of Paradox — Followup

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!

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