Category: Theories of Time

Time Dispersion in Quantum Mechanics

If a quantum wave function goes through a single slit in time is it diffracted or clipped?

I will be speaking at the  2018 meeting of  the IARD — The International Association for Relativistic Dynamics  this afternoon.  Had a nice chat with the organizers & some early arrivals last night over coffee:  my talk clearly a good fit to the conference.

The decisive test is what happens if you send a quantum wave function through a single slit in time, say a very fast camera shutter.  If quantum mechanics does not apply (current generally accepted view), the wave function will be clipped — and the dispersion at a detector arbitrarily small.  If quantum mechanics does apply (proposal here), the wave function will be diffracted — and the dispersion at a detector arbitrarily great.

I’ve uploaded the talk itself  in several formats Time Dispersion in Quantum Mechanics – KeynoteTime Dispersion in Quantum Mechanics – Powerpoint, and Time Dispersion in Quantum Mechanics – PDF.

And I’ve uploaded the latest — and now complete! — version of the underlying paper Time Dispersion in Quantum Mechanics.  I hope it will be a useful contribution to the literature on time and quantum mechanics.  I will be uploading to the physics archive, once I’ve incorporated feedback from the conference.

Your comments very welcome!

Time and Quantum Mechanics accepted at IARD conference

The physics paper I’ve been working on for several years, Time & Quantum Mechanics, has been accepted for presentation at a plenary session of the 2018 meeting of  the IARD — The International Association for Relativistic Dynamics. I’m very much looking forward to this:  the paper should be a good fit to the IARD’s program.

Abstract:

In quantum mechanics the time dimension is treated as a parameter, while the three space dimensions are treated as observables.  This assumption is both untested and inconsistent with relativity.

From dimensional analysis, we  expect quantum effects along the time axis to be of order an attosecond.  Such effects are not ruled out by current experiments.  But they are large enough to be detected with current technology, if sufficiently specific predictions can be made.

To supply such we use path integrals.  The only change required is to generalize the usual three dimensional paths to four.  We treat the single particle case first, then extend to quantum electrodynamics.

We predict a large variety of testable effects.  The principal effects are additional dispersion in time and full equivalence of the time/energy uncertainty principle to the space/momentum one.  Additional effects include interference, diffraction, resonance in time, and so on.

Further the usual problems with ultraviolet divergences in QED disappear.  We can recover them by letting the dispersion in time go to zero.  As it does, the uncertainty in energy becomes infinite — and this in turn makes the loop integrals diverge.  It appears it is precisely the assumption that quantum mechanics does not apply along the time dimension that creates the ultraviolet divergences.

The approach here has no free parameters; it is therefore falsifiable.  As it treats time and space with complete symmetry and does not suffer from the ultraviolet divergences, it may provide a useful starting point for attacks on quantum gravity.

StarGates Jump to FossCon — The Free & Open StarS Convention!

9/3/2017: I have just posted the slides from Fosscon on slideshare.  Comments, questions, problems, & buildable blueprints, all very welcome!


This coming Saturday I’ll be doing the latest revision of my StarGates talk at FossCon, the Free & Open StarS Convention!

(Pay no attention to those who assert this is the Free & Open Source Convention, that is a mere cover story.)

The convention is at International House in Philadelphia, starting at 9am, and is free.  As to my talk:

“Call them Stargates, Jumpgates, Fargates, Hypergates or just an invitation to every pest from the far reaches of the Galaxy to visit, they would be invaluable in helping mankind break free of this solar system.

Are StarGates only a convenient plot device — or could they actually be built? Accordingly to Einstein’s Theory of General Relavity, they are possible — at least in principle.

We will discuss 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 would it take to build one in practice.”

My talk’s at 1pm.  Hope to see you there!


And there I have you seen!  There was a nice turnout (in the South America room at International House) with a lot of questions.  We finished with a few minutes for additional questions, including my favorites:

What happens if you drag a wormhole through a wormhole?

I congratulated the questioner on the question & he just pointed at his young son sitting next, a lad clearly with a bright future as a scientist!

I had to admit I wasn’t sure, but I suspect it would be bad news for all concerned:  both wormholes, and any spaceships, space stations, or space-persons nearby!

How do you think this might actually be done?

I focused on wormholes because that is far & away the most popular of the approaches.  But if some sort of stargate were ever actually to come to fruition, I suspect a combination of the Einstein-Rosen-Podolsky (EPR) effect and the ideas behind the Krasnikov tube would be at work.  The EPR effect is the spooky-action-at-a-distance Einstein objected to; the Krasnikov tube is an idea of — curiously enough — Krasnikov for laying out a tube of warped spacetime behind your slower-than-light spacecraft.  You’d have to go slower-than-light while laying out the tube, but could use it for faster-than-light thereafter. And as I said in the talk, negative energy & vortices are pretty sure to be involved.

 

 

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)

THE INVISIBILITY CLOAK (1553)

[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)
A WEIGHTY MATTER: ANTI-GRAVITY AND ARTIFICIAL GRAVITY (1404)

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

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
achieved

 

Sat 6:00 PM in Plaza II (Two) (1 hour)
THE ETHICS OF TIME TRAVEL (1501)

[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)
BALONIUM, UNOBTAINIUM AND UPSIDASIUM (1530)

[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 seedphilly.com 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!

Thanks!

— John Ashmead

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