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  The stuff on faster-than-light neutrinos is, alas, already out of date:  boring won:  looks as if the FTL neutrinos were due to experimental error.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.

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).

New Hope for Space War

I’m on the Space War panel at Balticon, how & why.  Fun topic though in all candor, a bit implausible.

The main problem is that travel in space is likely to be slow, expensive, & a bit dangerous.  Given this, it is likely that space travel itself will be reserved for moving stuff that is light weight & of very high value:  information, pharmaceuticals, experts, embryos, the “unobtainium” that features in Avatar, and so on.  Bullets satisfy neither test & even nukes have a hard time.

And if it takes a century to get over to the enemy’s star, why bother having the war?  And what are you fighting about anyway?  To have a war you have to be close enough to do some damage in a reasonable time frame & similar enough to have common — if opposed — objectives.

I owe the initial observation about the high costs of space travel to Paul Krugman, the Nobel-prize winning economist.  In the spirit of not pointing out problems without also pointing out a solution, he has found an economically viable use for space war:  as a way to generating a badly-needed stimulus, a kind of weaponized Keynesianism.

Given that there is now new hope for space war, and to get me in the right frame of mind for the panel, I list ten of my favorite space war novels:

1. The War of the Worlds by H. G. Wells.  The number one space war novel.  The evil octopi are defeated by our germs. Great idea; two problems:  1) germs have to co-evolve to be effective against a host; ours probably would have no effect on the Martians and 2) real octopi are fun:  they play pranks on their experimenters & are great communicators as well.  With their ability to change skin color at will, octopi are practically eight-tentacled color television sets.
2. The Lensman series by E. E. “Doc” Smith.  Six deathless volumes, each with at least two space-shaking interstellar battles. Chlorine breathers beware!  The oxygen breathers of the galaxy have found your secret base & are going to reduce it to a glowing pile of molten rock.
3. Which is pretty much what happens to the lunar military base in Arthur Clarke‘s Earthlight.  Three Federation cruisers duel it out to a jointly fatal draw with a lunar fortress.  The war is about mineral rights & induced by attacks of mutually assured dementia, making the physics (this is Arthur C. Clarke!), the war, & the politics pretty realistic.
4. Starship Troopers by Robert Heinlein.  Heinlein wrote about space suits in his pre-WWII SF, then used ideas from his stories when helping to design pressure suits for our fighter pilots in WWII, then used ideas from those pressure suits for his Have Spacesuit, Will Travel juvenile and for Starship Troopers: a beautiful example of the inter-relationship of reality & SF.  The space combats are a bit less stupid than most; Heinlein understands something of the difficulty of taking a space war to an underground enemy.
5. The Forever War by Joe Haldeman.  This is partly a reaction to the Vietnam War & partly a reaction against Starship Troopers.  The forever war starts by accident, proceeds by error, and lasts for over a thousand years:  both humans & aliens are restricted to sub-light travel, so the war plays out in slow motion.  One of the few successful space war stories that works with existing physics.
6. Keith Laumer’s Bolo Series.  Laumer wrote a long series of stories about Bolos, giant sentient tanks that are every adolescent male’s dream weapon.  In practice, they would likely be an economic & military disaster:  witness some of the late stage Nazi vehicles:  mechanically problematic, too heavy for bridges, & absorbing a disproportionate share of the military budget.  See Arthur Clarke’s delightful story Superiority.
7. Dan Simmon‘s Hyperion series, especially the 2nd volume, The Fall of Hyperion, which concludes with a beautifully realized space battle between two fleets for control of a planetary system.  The inevitable confusion & long delays of such a battle are foregrounded.
8. Catherine Asaro‘s Skolian Empire series.  Asaro has a physics background, gets existing physics right, & invents as much as she needs to keep the action fast-moving & interstellar.  The space combats are realistic:  long periods of nothing, brief high velocity exchanges of fire & then more long pauses while the surviving opponents regroup & turn around.  They remind me of the lance combats in White’s The Once & Future King.
9. David Weber’s Honorverse series, starting with Manticore Station.  Weber is another author who tries to “get it right”.  The politics are modeled on the dueling ship combats of the Napoleonic wars, with wormholes to get realtime star to star travel without invoking faster-than-light mechanics (which would imply time-travel & a lot of confusion:  it is very rough on a space navy to first have triumphantly triumphed & then never to have been in the first place!).  He sets up the physics & weapons so that the ships even have broadsides, includes relativistic time dilation, and so on.  Weber’s Honor Harrington owes her “H’s” and general command style to C. S. Forester‘s Horatio Hornblower.  In a video game version of the Honorverse, it turned out that realistic implementing the physics/combat implied a near-planet maneuver (wish I could remember what it was) that invalided much of the combat in the novels.  With the infinite authority of the auteur, Weber passed a treaty that banned the disastrous trick.
10. And I’ll finish with John G. Henry‘s Lost Fleet series.  The first six volumes reset Xenophon’s Anabasis in a medium-future space-faring context, again with wormholes connecting selected star systems.  A nearly destroyed fleet has to work its way back home in the face of enemy attack, mutiny, and sheer running out of resources.  Henry’s focuses on the many conflicting pressures on his commander, Jack Geary, as Geary balances military requirements, the demands of honor, & the imperatives of law, democracy, and a forbidden love.  The space combat — Henry used to be a ship driver in the US Navy – takes place in four dimensions and with admirable clarity about the command difficulties created by the finite speed of light:  if the enemy is on the far side of a solar system, he will see your maneuver only hours after you make it — and you will see his response hours after that.  You have to factor his response — and the responses of your detached units — into every move you make.  It is like blindfolded chess where you don’t find out the enemy’s move until after you have made three more moves of your own.  And your pieces are moving on their own.

And a couple of titles to avoid:

• Anything by C. J. Cherryh, as least as far as space combat goes.  I remember reading one of her novels where the defenders had an advantage because they were at rest. In space, both sides are at rest with respect to themselves; the comment & resulting tactics were just nonsense.  Nonsense on stilts.
• Gordon Dickson’s Dorsai series.  Omni-competent genetically enhanced uber soldiers trash lots of stooges.  The “ho” meets the “hum”.

So, my minimal requirement for space war in science fiction(not counting the golden classics of one’s youth of course) is that the humans, the physics, & the space war should make at least a bit of sense.

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!

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

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

Read more »