MOVIE CLIPS: "Doc."
"Don't say a word."
"Stand back. In less than three minutes, I shall
have escaped this age of madness."
STEPHEN HAWKING: Nevertheless, it is an
important question.
Bonjour Sébastien,
David Deutsch, qui est-il ?
http://www.edge.org/3rd_culture/bios/deutsch.html
Quelques liens intéressants:
"It's much bigger than it looks", A talk with David Deutsch
http://www.edge.org/3rd_culture/deutsch/deutsch_index.html
http://www.edge.org/3rd_culture/deutsch/deutsch_p1.html
et pages suivantes.
Page web de David Deutsch (Oxford University)
http://www.qubit.org/people/david/David.html
UN document PDF
The Structure of the Multiverse,Quantum Physics, abstract quant-ph/0104033
From: David Deutsch <david.deutsch@qubit.org>
http://xxx.lanl.gov/abs/quant-ph/0104033
Centre for Quantum Computation at the Clarendon Laboratory, Oxford University.
http://www.qubit.org/Intros_Tuts.html
Vous n'avez probablement pas vu l'émission (suis-je dans l'erreur ?) et vous avez du vous contenter d'en lire la retranscription, ce qui n'est pas l'idéal.
Je suis en mesure d'éclaircir certaines ambiguités.
Il n'est suggéré à aucun moment dans l'émission qu'il existe un lien quelconque entre l'effet Casimir et l'expérience de Young.
L'effet Casimir, c'est pour la production d'énergie négative.
NARRATOR: To travel through a wormhole, a
human being would have to find a way to hold
it open.
KIP THORNE: So we then asked ourselves,
what is it that you need to thread through the
wormhole to hold it open long enough for
somebody to travel through it? And Einstein's
equations told us the answer. We just had to do
a page or two of calculations. What you needed
was something very exotic, some material that
has negative energy.
Lire également Lamoreaux et Visser.
L'espérience de Young (1909) figure plus loin dans le texte de la retranscription. Aucune association possible avec l'effet Casimir ni dans le texte ni dans les images.
David Deutsch écarte l'interprétation traditionnelle de l'expérience de Young et il en propose une autre.
http://www.2think.org/hii/tfor.shtml
Passons maintenant à Carl Sagan.
Carl Sagan avait écrit une nouvelle et il fit appel à Kip Thorne (Caltech) pour corriger son texte.
http://www.biols.susx.ac.uk/home/John_Gribbin/Time_Travel.html
"...It happened like this. Carl Sagan, a well known astronomer, had written a NOVEL in which he used the device of travel through a black hole to allow his characters to travel from a point near the Earth to a point near the star Vega. Although he was aware that he was bending the
accepted rules of physics, this was, after all, a novel. Nevertheless, as a scientist himself Sagan wanted the science in his story to be as accurate as possible, so he asked Kip Thorne, an established expert in gravitational theory, to check it out and advise on how it might be tweaked up. After looking closely at the non-commonsensical equations,
Thorne realised that such a wormhole through spacetime actually could exist as a stable entity within the framework of Einstein's theory.
Sagan gratefully accepted Thorne's modification to his fictional "star gate", and the wormhole duly featured in the novel, Contact, published in 1985. But this was still only presented as a shortcut through space. Neither Sagan nor Thorne realised at first that what they had described would also work as a shortcut through time. Thorne seems
never to have given any thought to the time travel possibilities opened up by wormholes until, in December 1986, he went with his student, Mike Morris, to a symposium in Chicago, where one of the other participants casually pointed out to Morris that a wormhole could also be used to travel backwards in time. Thorne tells the story of what happened then in his own book Black Holes and Time Warps (Picador). The key point is that space and time are treated on an essentially equal footing by Einstein's equations -- just as Wells anticipated. So a wormhole that
takes a shortcut through spacetime can just as well link two different times as two different places. Indeed, any naturally occurring wormhole would most probably link two different times. As word spread, other physicists who were interested in the exotic implications of pushing Einstein's equations to extremes were encouraged to go public with their own ideas once Thorne was seen to endorse the investigation of time travel, and the work led to the growth of a cottage industry of time travel investigations at the end of the 1980s and in to the 1990s. The bottom line of all this work is that while it is hard to see how any civilization could build a wormhole time machine from scratch, it is much easier to envisage that a naturally occurring wormhole might be adapted to suit the time travelling needs of a sufficiently advanced civilization. "Sufficiently advanced", that is, to be able to travel through space by conventional means, locate black holes, and manipulate them with as much ease as we manipulate the fabric of the Earth itself in projects like the Channel Tunnel..."
Et plus loin:
"...Was there any way to dress up the mumbo-jumbo of Sf hyperspace in a cloak of respectable sounding science? Sagan didn't know. He isn't an expert on black holes and general relativity -- his background specialty is planetary studies. But he knew just the person to turn to for some advice on how to make the obviously impossible idea of hyperspace connections through spacetime sound a bit more scientifically plausible in his book Contact.
The man Sagan turned to for advice, in the summer of 1985, was Kip Thorne, at CalTech. Thorne was sufficiently intrigued to set two of his PhD students, Michael Morris and Ulvi Yurtsever, the task of working out some details of the physical behaviour of what the relativists know as "wormholes". At that time, in the mid-1980s, relativists had long been aware that the equations of the general theory provided for the possibility of such hyperspace connections. Indeed, Einstein himself, working at Princeton with Nathan Rosen in the 1930s, had discovered that
the equations of relativity -- Karl Schwarzschild's solution to Einstein's equations -- actually represent a black hole as a bridge between two regions of flat spacetime -- an "Einstein-Rosen bridge". A black hole always has two "ends", a property ignored by everyone except a few mathematicians until the mid-1980s. Before Sagan set the ball
rolling again, it had seemed that such hyperspace connections had no physical significance and could never, even in principle, be used as shortcuts to travel from one part of the Universe to another. Morris and Yurtsever found that this widely held belief was wrong. By starting out from the mathematical end of the problem, they constructed a spacetime geometry that matched Sagan's requirement of a wormhole that could be physically traversed by human beings. Then they investigated the physics, to see if there was any way in which the known laws of physics could conspire to produce the required geometry. To their own surprise, and the delight of Sagan, they found that there is..."
|