Various particle physics-related science fiction and fantasy news:
Discover has an interview with Kip Thorne, who is working with Steven Spielberg on a science fiction film tentatively entitled Interstellar for release in 2009. The plot evidently involves the novel idea of a group of explorers who travel through a worm hole and into another dimension. Thorne expects that “nothing in the film will violate fundamental physical law.” He also seems rather involved in fantasy as well as science fiction, believing that the LHC has a “good shot” at producing mini-black holes, and that “String theory is now beginning to make concrete, observational predictions which will be tested.” (via Angry Physics).
Also on the fantasy front, I hear there’s a new movie out called The Golden Compass, which supposedly has a plot based on multiple dimensions and particle physics. According to this review, the plot is not really fantasy, because:
In the past thirty years or so, a majority of scientists have come to accept string theory as a so-called “Theory of Everything,” one that helps to explain how everything in the universe works.
and string theory explains these extra dimensions.
One can follow the progress of the LHC project on the web, and unfortunately it’s looking like the current official schedule, which plans on trying to circulate a beam next May and physics starting in July, is pretty much a fantasy. This schedule already was sticking to these dates in the face of delays that made them look unrealistic, but there have now been further delays. According to the schedule, sector 45 should be completely cooled down now and nearing the end of powering tests, with four others in the middle of cool-down. The actual state of affairs is that sector 45 is just finally getting fully cooled down to 1.9K, and the only other sector being cooled down is sector 56. A rough guess would be that they’re three months or so behind the official schedule, so if nothing else goes wrong they might have a beam in late summer, physics sometime late in the fall. The CERN Council will be meeting later this week and get a status report on LHC progress, perhaps there will be an official update on the schedule at that time.
Michael Dine and collaborators have a new preprint about the Landscape, one that tells a rather different story than Dine’s recent article in Physics Today. The authors discuss the question of the stability of Landscape states, given that there may be many nearby states, considering the possibility that this favors supersymmetric states. They also mention the problem of how to calculate transition probabilities into whatever the relevant metastable states are, which suffers from the well-known problem of how to pick a measure for eternal inflation, writing
While we currently have little new to add to this discussion, we point out that the landscape is likely to be more complicated than assumed in many simple models of eternal inflation.
There’s nothing in the paper that could possibly justify the Physics Today claims of hopes that landscape studies would soon be making “definitive statements about the physics of the LHC” and able to “specify some detailed features.” Instead, there is a discussion of the possibility that landscape statistics are dominated by large volume, non-supersymmetric states, in which case:
[if] they are otherwise undistinguished, it is unclear how one might imagine developing a string phenomenology. Not only would we fail to make predictions, e.g. for LHC physics, but we would not know how to interpret LHC outcomes.
Update: For more sci-fi, tonight’s arXiv postings include Warp Drive: A New Approach by string phenomenologist Gerald Cleaver and his graduate student Richard Obousy.
A question on sci-fi, pop-sci, and culture: Does anyone have any idea when and how the idea of alternate realities became conflated with the idea of dimensions? This predates string theory by a few decades, I’d guess.
Speaking of science fiction, I’m looking forward to Michio Kaku’s new book:
I seem to recall reading somewhere that Carl Sagan consulted with Kip Thorne while writing Contact, to tidy up some of the theory behind the alien contraption used for FTL interstellar travel. It was this collaboration, if memory serves, that got Thorne really active in the wormhole-as-time-machine business. I don’t know if Thorne was also brought in for the movie.
Yes, Kip was involved in Contact. The story as I remember hearing it is that Sagan originally wanted to use a black hole, and asked Kip how reasonable that would be. Kip of course told him that it wasn’t a good idea, but that wormholes could more realistically serve the purpose Sagan really wanted. Kip later went on to write that series of wormhole papers investigating the issue in GR.
And yes, I think he might have been involved to some extent in the movie, though I don’t think he was credited. Also, Lynda Obst, one of the co-executive producers (with Kip and Spielberg) of Interstellar, was also a producer of the Contact movie.
Interesting to learn where some theorists may be getting their inspiration :).
I have to wonder if Thorne was misquoted somehow. I also seem to recall reading that this whole practice of serious academics doing reasearch into time machines was motivated by the very legitimate desire to push GR to its logical limits, so-to-speak. The upshot, if I understand correctly, is that if you can (with a dollop of exotic matter or some comparable unobtainium) actually construct a time machine without violating GR, thus producing something that could, in principle, violate causality, you’ve got yet another good indicator that maybe there’s something seriously lacking in GR. Ergo, the fact you’re not violating “fundamental physical law” means you surely need some better fundamental physical law. Then again, he appears to be saying ST fits that bill, so maybe the time-machine industry has evolved into something I’m not aware of.
I was recently a student in Kip Thorne’s group, and while I can’t speak for him, and he certainly doesn’t need me defending him, I will say that he always seemed to me to be basically noncommittal on the “string theory wars.” The only time I heard him discuss quantum gravity in a public lecture, he did make a point of mentioning both string theory and loop quantum gravity.
I’ll also say that (as far as I’ve heard) he still hasn’t conceded on his half of the bet with Hawking against Preskill on whether black hole evaporation is unitary. So he’s certainly not a conventional string theory partisan.
As for his “good shot” statement, I think he just really likes taking the side of underdogs, and in the public press these days, string theory seems to be the underdog.
Thanks for the update! Maybe we are witnessing the dawning of a new era in theoretical physics? If computer animations can do it in virtual, who cares about actual reality? Can we just compute another part of the multiverse and sell the fundamental laws to Dreamworks? Chances are we are just living in a computer simulation anyhow. Either way, seems like you missed out on Denzel Washington in Deja Vu, where a group of crime investigators together with some scientists watches the past through a wormhole. Memorable quote: “I asked you to explain it to me, not to talk science.”
(the movie is entertaining, but not really recommendable)
Low Math Meekly Interacting:
Well, this causality thing has a lot of ins and outs. The existence of closed timelike curves doesn’t necessarily point to a problem in GR, or even necessarily a problem at all. I haven’t really looked at this stuff, but I remember that Novikov was involved in some work showing that “consistent histories” (to borrow a phrase) can still arise even in the presence of closed timelike curves. He probably talks about this in his essay for the book “The Future of Spacetime.”
I’m afraid I was being snarky about the originality of the wormhole as plot device, having seen a rather large number of movies or TV shows where wormholes appear (including Deja Vu..). Presumably the Thorne/Spielberg wormhole will be a less cheesy and more authentic one than the usual, run-of-the-mill wormhole that normally puts in an appearance.
Thanks for the addition to my library list!
yeah, I read your remark as sarcasm, was just looking for an occasion to place that quote. I wish people would stop asking me about wormholes, time travel or the free will in quantum mechanics when they hear I’m a physicist.
From what I’ve heard, the central motivation of the project, both for Kip and for Spielberg, is to make a “scientifically realistic” science fiction movie. Obviously they’ll stretch the limits of practicality, but they at least intend that everything should be basically in line with published (though sometimes speculative) science. Hopefully it will remain that way after being filtered through screenwriters and special effects houses.
For example, one very early idea that I heard (and I’ll presage this with the disclaimer that I’m not at all privy to the developments) was that the wormhole would be discovered by LISA. Some would say that LISA taking measurements is no more realistic than finding a wormhole, but we relativists still like to think those people are wrong.
“consistent histories” (to borrow a phrase) can still arise even in the presence of closed timelike curves
Yes, it’s possible to write down theories that have CTC’s but no inconsistencies. One way is just to stipulate that, if S is the quantum operation acting around a CTC, then as the “input” to the CTC nature has to postselect a state &rho such that S(ρ)=ρ. (Such a ρ always exists by linear algebra.) This idea goes back to a 1991 paper of Deutsch.
However, these theories have an extremely interesting further problem. This is that, in order to find a consistent evolution around the CTC, nature has to solve an extremely hard computational problem! (In particular, it has to solve a PSPACE-complete problem, which is even worse than NP-complete.)
So, to return to Peter’s sci-fi theme: while physical theories with CTC’s aren’t necessarily inconsistent, they do necessarily lead to effects like in Star Trek IV: The Voyage Home. There the crew of the Enterprise goes back in time to the “present” (i.e. to 1986) and, needing a type of plexiglass that hasn’t been invented yet, reveals the formula for the plexiglass to the company that’s going to invent it, thereby causing it to be invented, etc. This is not a logical inconsistency but is nevertheless exceedingly strange.
As an undergraduate at Caltech in ‘75-’76, I took a course on GR from Thorne, and I pointed out to him that you could build a time machine out of wormholes. I had in mind two separate wormholes moving in different reference frames – you don’t need to invoke time dilation at only one end of one wormhole then: the Minkowski geometry is pretty obvious.
My point is not that I am the source of Kip’s later work: it was a casual comment on my part, and I’d guess that he forgot it rather promptly. The point rather is that the idea of wormholes as time machines was pretty obvious to anyone, even an undergrad: wormholes obviously violate locality, and any particle theorist knows what that means. (Personally, I’m with Hawking on this: a wormhole time machine probably blows itself up for reasons Hawking has explained.)
And, Peter, the real news on “The Golden Compass” is that fundamentalist Christians are up in arms over it: I’ve heard this from personal contacts as well as seen it on the Web (NPR even ran a piece). Pullman is a self-announced atheist, and the theory is that the movie is really meant to seduce vulnerable Christian youth.
In fact, the movie is supposed to be pretty bland, and my own kids were actually given the trilogy by a Christian friend who had read through it all herself.
Of course, you can find fundamentalists on the Web who also denounce the “Chronicles of Narnia” on the grounds that Lewis, a famous Christian apologist, was really a secret pagan. (You see, he admired classical culture and enjoyed classical mythology…)
I am tempted to believe that critics of Christianity should just relax and allow the Christians to self-destruct.
Re The Golden Compass; in the books, at least, string theory is not mentioned at all, but the plot relies heavily on a fantasy take on many-worlds quantum mechanics and dark matter. Everett is mentioned by name, and a technology to communicate between parallel universes is said to rely on quantum entanglement. As for dark matter, well… (SPOILERS follow)…
…would you believe that dark matter is conscious particles that try to communicate with humans, that angels (including God, the oldest one of them) are complex structures made of these particles, and that human attachment to these particles, which signals sexual awakening, is what the Church calls original sin?
No, I am not making this up. Anyway, the books are awesome. Haven’t seen the movie yet, but I expect to be disappointed.
I think I read the first volume of the trilogy because it showed up on my amazon recommendation list. I didn’t bother to buy the other two. Maybe I’ve read too much Fantasy when I was a kid, but much like Harry Potter it didn’t strike me neither as well written nor original. I didn’t see the movies though. I like the part with the sexual awakening, maybe I should give it another try. To come back to the topic of Science Fantasies, since you mention dark matter it’s kind of interesting in this regard what Rudy Rucker wrote in the book ‘Dangerous Ideas’ (among essays about multiverses, understanding GR and QM, or how capitalism will make the world a better place):
“On the one hand, it could be that the mind is some substance that accumulates near ordinary matter — dark matter or dark energy are good candidates. On the other hand, mind might simply be matter viewed in a special fashion: matter experienced from the inside. […]”
Today’s news: unparticle physics provides a mechanism for black hole formation.
Hi Bee. I didn’t think too much of the first volume when I read it either -but in my case I think it was because I read it translated to Spanish; when I reread it in English I liked it much more. The other two are much more ambitious, both in a literary and a philosophical way; the whole trilogy is IMO a much “larger” thing than Harry Potter, which is a fairly conventional kind of story. Pullman’s avowed goal is to provide a subversive retelling of Milton, celebrating rebellion against God and authority, and the loss of innocence related to maturity, self-consciousness, and yes, sexual awakening.
There are some problems in the third volume -the scope becomes so large that the plot becomes confusing, there are a couple of dei ex machina, and the anti-religious message is so explicit that it is grating at points- but overall I would recommend you to read the other two books to have an opinion; the central themes of the trilogy cannot be seen from the first volume alone.
Oh, and re the Rucker quote, it is rather similar to the premise of Pullman’s fiction -but Rucker seems to be taking it seriously… :S
I have read only one book by Rucker, in my teens: The Fourth Dimension, basically a layman’s explanation of 4-D concepts and their use in physics. He did get into some weird panpsychistic speculations by the final chapter, but it was all rather playful and he didn’t seem to really believe it.
Yeah, sounds interesting indeed, I might give it a try. I yet have to make it through the last Harry Potter though, since I read the first six I think I will have to read the seventh as well. I know the 4D Rucker, though I didn’t find it too illuminating, I had a couple of better books on higher dimensions that I liked better. I recall much better Rucker’s book Master over Space and Time which I read probably being too young. I got seriously confused about what quarks are and so on. Maybe I would find it amusing now, but I think books like that better come with a manual or a warning. Best,
Scott says:”if S is the quantum operation acting around a CTC, then as the “input” to the CTC nature has to postselect a state &rho such that S(ρ)=ρ”.
I am confused by that, I would say this is exactly what is *meant* by having CTC to start with. If you don’t impose periodicity conditions the curve is not closed in any meaningful sense, am I missing something?
I know Peter doesn’t actually like talk about science fiction and fantasy here, despite the title of this blog entry… but can’t resist telling Alejandro: I’ve read Pullman’s Dark Materials trilogy and liked it a lot – and I found the movie adaptation of the first part to be excellent!.
Like the book, the movie doesn’t mention string theory at all.
(It’s fantasy, not science fiction: people should only watch it if they can deal with witches, daemons and talking polar bears.)
Moshe: I agree with you — once you think about it clearly (which many people don’t!), the requirement of causal consistency is pretty much inherent in the definition of CTC’s. The slightly non-tautological observation in Deutsch’s paper was that, while a consistent evolution doesn’t always exist in deterministic theories (which is just a fancy way of stating the grandfather paradox), such an evolution does always exist in probabilistic or quantum theories. This is because every Markov chain has a stationary distribution, and likewise every superoperator has a stationary mixed state.
Thanks Scott, I like your re-phrasing of the grandfather paradox, previously I thought about it as one of those linguistic pseudo-problems, but now I see at least one way of making a non-trivial statement.
I think a lot of today’s elder generation of physicist-speculators spent too much time as kids watching The Time Tunnel. The wormhole is easily the most hackneyed notion in filmed Sci-Fi, so it stands to reason that Hollywood will want to resurrect it for yet another outing.
Glad you liked the movie, John -it gives me raised hopes.
And by the way, I remember now that string theory is mentioned in the books! (albeit obliquely). In the third volume, when Mrs Coulter is approaching Asriel’s fortress, she finds it similar to a model she saw once illustrating a “diabolical heresy” (quoting by memory, don’t have the book here) according to which space had many extra dimensions curled up a tangled and tiny way .
In other words: the place from which Lord Asriel intends to overthrow God and build the Republic of Heaven resembles a Calabi-Yau manifold!
At the above link is an equation from the paper by Deutsch that Scott mentions above: Quantum Mechanics near Closed Time-like Lines which appeared in Physical Review D44, 3197–3217 (1991).
According to Deutsch, it is the equation for the state of a quantum computer that is, by whatever means, provided with a method of sending its output back in time to interact with its input (I suppose he’d consider this “merely” an question of engineering.
He believes that the universality of quantum computation ensures that the results also apply to any time-travelling physical system, not just a computer.
I can’t reproduce the equation (really don’t know how to with my limited computer skills), but he claims that the self-consistency of this equation proves the self-consistency of time travel in quantum physics.
He says that analysis of the equation shows that if we had a time machine and tried to use it to enact ‘paradoxes’ (like going back in time to prevent our building the time machine), we would simply go back to a universe in which those events really happened.
Not being very well grounded in the math associated with this type of analysis, I settle for science fiction. It’s fun and thought provoking — tautological or not.
I’d love to see a serious discussion between Deutsch, Scott and others who obvious know much more about this than me.
The above discussion of CTCs and causal consistency ties in rather closely with an interesting and lucid new review paper on the arXiv, Causal Set Topology (0712.1648).
(Thanks to Daniel Doro Ferrante for highlighting it.)