Category: Time

Red Letter Days in the Time Traveler’s Almanac

The Main Line SF Book Discussion Group (is that the official name Denise?) which meets the third Tuesday of each Month at 7:15pm at Mainpoint Books, is doing the Vandermeer’s Time Traveler’s Almanac at our next meetup March 17th.

I’m pleased with this collection:  I’m a big fan of time travel & try to read  everything on the subject that doesn’t involve a strong yet sensitive woman going back in time to the Scotland of the clans & claymores to help a rough yet sensitive Scottish chieftain find true yet sensitive love.

The Vendermeers have done a good job of getting a wide range of good stuff.  There are some clunkers (avoid getting yourself trapped into Loob’s time loop) but overall average good & some standouts, including several I had not seen before.

The MLSFBDG decided we’d pick a few of the 80 odd stories to focus on.

Herewith my own favorites.  I used a really simple test:  I had already read thru the volume; these are the ones I particularly found myself wanting to read again.

  • Needle in a Timestack — love & time travel, spreadsheet time where you can feel the changes when you personal time line is recalculated
  • The Gernsback Continuum — the glorious futures of the lamented past, and a great addition to my collection of Imaginary Books: The Airstream Futuropolis:  The Tomorrow That Never Was
  • Triceratops Summer — cabbage stealing triceratopses & a meditation on impermanence
  • A Sound of Thunder — the classic butterfly effect story
  • Vintage Season — tourism more fun for the tourists than the tourees
  • Fire Watch — what can’t be changed can be remembered, is it enough?
  • Under Siege — George R. R. Martin shows his usual delicate concern for his character’s well-being
  • Traveler’s Rest — “No one knew what really happened to Time as one came close to the Frontier…”
  • At Dorado — her past is his future
  • Red Letter Day — curiously appropriate title for an almanac, interesting balancing act between free will & the desire to know how it will come out

And some more, likely to be good for discussion:

  • Ripples in the Dirac Sea — reminiscent of the Stevenson’s the Bottle Imp
  • Himself in Anachron — time & self-sacrifice
  • Time Travel in Theory and Practice — good review of the basics
  • The Final Days — Iron Man thinks the time travelers are watching him because he is about to do so well
  • On the Watchtower at Plataea — the time travelers are there to view the Peloponnesian War but get caught up in a war of their own
  • The Gulf of Years — love & bombs
  • Enoch Soames — time travel deal with the devil
  • Palindromic — opposite arrows of time collide
  • Delhi — time ghosts in Delhi, intriguing
  • Terminos — bottled time (see Tourmaline’s Time Checks, Momo) with an interesting narrative method
  • The Waitabits — classic Analog story-with-a-point: slowly, slowly, they get conquered that move fast
  • Music for Time Travelers — non-fiction
  • As Time Goes By — Tanith Lee channels her inner Moorcock, with a bit of Robert Service: “The nature of time, What do we really know about it? Two thousand streams, and us playing about in them like salmon.”
  • Against the Lafayette Escadrille — carpe diem — a frequent theme of this collection: Fokkers, crinolines, & Confederate spy balloons.
  • Palimpsest — Stross does the reductio ad absurdum of Heinlein’s All You Zombies (recently made into a not-bad movie), Gerrold’s The Man Who Folded Himself, Asimov’s The End of Eternity. If you like your absurdum’s reductio’d, this is the tale.

Most of the rest were worth reading as well: the only real clunkers — personal opinion obviously — were Loob & Forty, Counting Down with its companion Twenty-One Counting Up.

If you want to get on the Book Discussion’s list, email Denise who will be glad to add you to the list.  And check out Mainpoint Books, which has provided & new & hospitable home for the group (even staying open late just for us!).

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

Time and Quantum Mechanics

I’ve submitted an extended abstract for my paper “Time and Quantum Mechanics” to the Center for Philosophy of Science’s workshop on Quantum Time. I’m not sure what the odds are of my getting in, but at a minimum prepping the abstract for the center has been a big help getting the paper organized, working out what is essential to the argument, and what can be let go.

Note the abstract is more extended than abstract, about two pages:


Talks now on Slideshare

I’ve uploaded a number of my more recent talks to Slideshare.  Physics, with occasionally a wee bit of speculation admixed:

  1. Thought experiments – talk done 1st April 2012 for the Ben Franklin Thinking Society.  Role of thought experiments in history, use by Galileo & by noted violinist, how they can turn into real experiments.
  2. Not Your Grandfather’s Gravity – done last year (2011) on the latest developments in the suddenly hot area of gravity.  The stuff on faster-than-light neutrinos is, alas, already out of date:  boring won:  looks as if the FTL neutrinos were due to experimental error.   But Verlinde’s entropic gravity is still one of the most promising lines of attack.
  3. Temporal Paradoxes – physics talk given at NASA’s Goddard Space Center 2011.  A slightly NASA-fied version of a talk I’d given at several SF conventions in 2010.
  4. Quantum time – physics talk given at Feynman Festival in Olomouc in 2009.  I did popular versions of that talk as well.
  5. How to build a (real) time machine – talk given at several SF conventions in 2009.
  6. Life, the Universe, & the Second Law of Thermodynamics.  Or, the Infinite Probability drive.  About the role of entropy in the universe, complete with Babelfish.  2008.
  7. Faster Than Light – talk on faster than light travel:  theory, practice, applications. Given at several SF conventions in 2007.
  8. Confused at a Higher Level – arguably one of the funniest talks ever given about problems in quantum mechanics. OK, competition not that fierce.  Given at several SF conventions in 2004.
  9. The Physics of Time Travel.  Review of time, with respect to the bending, stretching, folding, & tormenting thereof.  Given at Philcon & Balticon (in various versions) in 2003.
  10. The Future of Time Travel – mostly about the science fiction thereof.  Probably 2002.

These are not all of my talks — I’ve probably done 20 or 30 SF talks over the last 20 years, at least one per year — these are just the ones done using Keynote or Powerpoint.  The 2005 & 2006 talks have gone walkabout.  If they reappear, I will upload.  I generally talk at Balticon, Philcon, & more recently Capclave.  I’ve spoken twice at Farpoint, but that is really more of a media convention, not as good a fit.

Talks before 2002 were done with Word & overheads. Overheads are easier to make than slides, but have a tendency to get bent, flipped, out of order, or in one especially memorable talk:  burnt.  That talk I was doing at the Franklin Inn Club: the projector failed at the last minute & I had to rent another from a nearby camera shop.  The rented projector ran hot. If I stayed on a specific slide for more than 60 seconds, the slide began to smoke.  Literally.  Colored smoke of course, wafting in strange tendrils towards the ceiling. Taught me a lot about pacing, mostly to make it faster.
By the way the word you are looking for, in re me & time travel, is not obsessed, it is focused.  Let’s just be clear about that.

Other talk(s), marginally less speculative:

  1. Overview of Backbone – talk on the jQuery library Backbone, given at PhillyCoders. April 2012.
  2. How to Destroy a Database – talk on database security.  October 2007.  Wile E. Coyote & other experts on correctness & security are enlisted to help make key points.
  3. Getting started with MySQL – talk given at PACS and my Macintosh programming group in 2006. Manages to work in the Sumerians, the Three Stooges, a rocket-powered daschhund, some unicorns, and – of course – dolphins (the totem animal of MySQL).

Not Your Grandfather’s Gravity – 3rd time is the charm

I did this talk — basically interesting developments in gravity & related subjects — for the third time at Philcon this last Saturday.  The talk was scheduled for 1pm, so I spent a few hours in the morning refreshing it.

The big news was that the OPERA project had done a second version of the experiment that saw superluminal neutrinos, dealing with some of the objections (objectinos?) to their first results.  They sacrificed quantity of neutrinos to quality:  going from 16,000 to 20, but getting much tighter time resolution.   This made the New York Times Saturday morning, so I clipped the headline for use in a slide.  Good stuff, but of course everyone wants to see Fermilab & others reproduce the experimental results.

However the combination of refreshing the talk, roadwork on Interstate 76, & a parade or some such on the Benjamin Franklin Parkway meant I got in with no time to check the AV setup before the talk.  While the impromptu AV crew wrastled the difficulties into submission (thanks Margaret Trebling, Jay Wile, Ron Bushyager, & Ferne Welch!) I invited the audience to “open the theater of your mind” & painted word pictures thereon till the AV was working.  Didn’t take the crew long:  we hadn’t even gotten past the Black Death slide before we had light!  Actually I think the difficulties may have helped the talk go over; shared troubles create bonding between speaker & audience.  Lots of good questions; SRO crowd.

As I promised then, I have posted the talk as Keynote, PDF, PowerPoint, & HTML.  Comments, questions, and suggestions very welcome!

Had a lot of fun on the six panels I was on; will post on them over the next few days.

11/23/2011 I’ve just updated the references page to include the references from the talk.

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:

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