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| Is physical time travel possible? |
| Yes |
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| "Dude! Where's my DeLorean?" |
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ramonmercado Psycho Punk
Joined: 19 Aug 2003 Total posts: 17933 Location: Dublin Gender: Male |
 Posted: 22-07-2010 12:57 Post subject: |
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| Timble2 wrote: | | I started (back when Virgin had the range) writing a Doctor Who novel, in which turned out that the TARDIS had a quantum computer at its heart that enabled it to navigate the time lines... |
Thats MY idea. I'm going back in Time to kill your grandmother. |
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| ramonmercado Psycho Punk
Joined: 19 Aug 2003 Total posts: 17933 Location: Dublin Gender: Male |
| Posted: 06-03-2011 19:45 Post subject: |
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More on that theory after an experiment. Chart at link.
| Quote: | Time travel experiment demonstrates how to avoid the grandfather paradox (Update)
http://www.physorg.com/news/2011-03-grandfather-paradox.html
March 1st, 2011 in Physics / General Physics
This graph shows that, as the accuracy of the quantum gun increases (from 0 to 180 degrees) so that it is more likely to flip a qubit’s state, the probability of successful self-consistent teleportation (red dots) decreases. While the theoretical probability of teleportation of qubits in opposite states is zero, the experimental probability of qubits in opposite states (blue diamonds) is about 0.01. Image caption: Seth Lloyd, et al. ©2011 American Physical Society.
(PhysOrg.com) -- Among the many intriguing concepts in Einstein’s relativity theories is the idea of closed timelike curves (CTCs), which are paths in spacetime that return to their starting points. As such, CTCs offer the possibility of traveling back in time. But, as many science fiction films have addressed, time travel is full of potential paradoxes. Perhaps the most notable of these is the grandfather paradox, in which a time traveler goes back in time and kills her grandfather, preventing her own birth.
In a new study, a team of researchers has proposed a new theory of CTCs that can resolve the grandfather paradox, and they also perform an experiment showing how such a scheme works. The researchers, led by Seth Lloyd from MIT, along with scientists from the Scuola Normale Superiore in Pisa, Italy; the University of Pavia in Pavia, Italy; the Tokyo Institute of Technology; and the University of Toronto, have published their study in a recent issue of Physical Review Letters. The concepts in the study are similar to an earlier study by some of the same authors that was posted at arXiv.org last year.
“Einstein's theory of general relativity supports closed timelike curves,” Lloyd told PhysOrg.com. “For decades researchers have argued over how to treat such objects quantum mechanically. We believe that our theory is the correct theory of such objects. Moreover, our theory shows how time travel might be accomplished even in the absence of general relativistic closed timelike curves.”
In the new theory, CTCs are required to behave like ideal quantum channels of the sort involved in teleportation. In this theory, self-consistent CTCs (those that don’t result in paradoxes) are postselected, and are called “P-CTCs.” As the scientists explain, this theory differs from the widely accepted quantum theory of CTCs proposed by physicist David Deutsch, in which a time traveler maintains self-consistency by traveling back into a different past than the one she remembers. In the P-CTC formulation, time travelers must travel to the past they remember.
Although postselecting CTCs may seem complicated, it can actually be investigated experimentally in laboratory simulations. By sending a “living” qubit (i.e., a bit in the state 1) a few billionths of a second back in time to try to “kill” its former self (i.e., flip to the state 0), the scientists show that only photons that don’t kill themselves can make the journey.
“P-CTCs work by projecting out part of the quantum state,” Lloyd said. “Another way of thinking about closed timelike curves is the following. In normal physics (i.e., without closed timelike curves), one specifies the state of a system in the past, and the laws of physics then tell how that state evolves in the future. In the presence of CTCs, this prescription breaks down: the state in the past plus the laws of physics no longer suffice to specify the state in the future. In addition, one has to supply final conditions as well as initial conditions. In our case, these final conditions specify the state when it enters the closed timelike curve in the future. These final conditions are what project out part of the quantum state as described above.
“Although one would need a real general relativistic CTC actually to impose final conditions, we can still simulate how such a CTC would work by setting up the initial condition, letting the system evolve, and then making a measurement. One of the possible outcomes of the measurement corresponds to the final condition that we would like to impose. Whenever that outcome occurs, then everything that has happened in the experiment up to that point is exactly the same as if the photon had gone backward in time and tried to kill its former self. So when we ‘post-select’ that outcome, the experiment is equivalent to a real CTC.”
To demonstrate, the scientists stored two qubits in a single photon, one of which represents the forward-traveling qubit, and one of which represents the backward-traveling qubit. The backward-traveling qubit can teleport through a quantum channel (CTC) only if the CTC ends by projecting the two entangled qubits into the same state.
After the qubits are entangled, their states are measured by two probe qubits. Next, a “quantum gun” is fired at the forward-traveling qubit, which, depending on the gun’s angle, may or may not rotate the qubit’s polarization. The qubits’ states are measured again to find out if the gun has flipped the forward-traveling qubit’s polarization or not. If both qubits are in the same state (00 or 11), then the gun has not flipped the polarization and the photon “survives.” If the qubits’ states are not equal (01 or 10), then the photon has “killed” its past self. The experiment’s results showed that the qubits’ states were almost always equal, showing that a qubit cannot kill its former self.
The scientists noted that their experiment cannot test whether an actual CTC obeys their new theory, since it is currently unknown whether CTCs exist at all. In the future, they plan to perform more tests to better understand time travel paradoxes.
“We want to perform the so-called `unproved theorem paradox' experiment, in which the time traveler sees an elegant proof of a theorem in a book,” Lloyd said. “She goes back in time and shows the proof to a mathematician, who includes the proof in the book that he is writing. Of course, the book is the same book from which the time traveler took the proof in the first place. Where did the proof come from? Our theory has a specific prediction/retrodiction for this paradox, which we wish to test experimentally.”
More information: Seth Lloyd, et al. “Closed Timelike Curves via Postselection: Theory and Experimental Test of Consistency.” Physical Review Letters 106, 040403 (2011). DOI:10.1103/PhysRevLett.106.040403
Copyright 2010 PhysOrg.com. |
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Zilch5 Vogon Poet
Great Old One Joined: 08 Nov 2007 Total posts: 1527 Location: Western Sydney, Australia Gender: Male |
| Posted: 03-10-2012 01:45 Post subject: |
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| Quote: | Wash. attorney: 'I have physically traveled in time'
VANCOUVER, Wash. - The new Bruce Willis movie "Looper" opens this weekend, in which Willis' character is sent back in time to kill himself.
And while most scientists say time travel isn't possible, a Washington attorney claims he's done it dozens of times as part of a secret Cold War project.
"I have physically traveled in time," says Andrew Basiago, an attorney in Vancouver, Wash. "We have - we did over 40 years ago."
Now Basiago is on a mission - to reveal what he calls a 40-year government cover-up - of Project Pegasus - where he says he was teleported back and sideways in time, dozens of times.
"I have the whole story, I have hundreds of facts," he says. "I can tell you what personnel were at what locations where and which travel device was being used."
And his time travel wasn't recent - it's when he was a kid.
"I entered the program officially in the fall of 1969 as a third grader, age 7," says Basiago.
He says he was one of 140 kids, 60 adults - chrononauts, including his dad, who he says joined him on his first jump.
"My dad held my hand, we jumped through the field of energy, and we seem to be moving very rapidly but there was also a paradox and we seemed to be going no where at all," he says.
The TV show "Fringe" aired a similar scene two years ago. A coincidence?
Paradoxes, unscientific claims, unbelievable stories and encounters on Earth and Mars - including meeting Barack Obama when the president was a kid.
Basiago also says he time-traveled six times to the Ford Theatre on the day President Lincoln was shot - but he didn't see it happen. He also saw President Lincoln on another famous occasion, he says.
"In fact, during one probe, the one to Gettysburg, the Gettysburg Address, I was dressed as Union bugle boy," he says.
That's right - he was at the Gettysburg Address. He says a famous photo taken that day proves it. The picture shows a bugle boy who he says is him. It's the only visual evidence he provides for any of his travels - nothing else.
"I was physically at Gettysburg," says Basiago. etc etc etc |
Source: http://www.komonews.com/news/local/Wash-attorney-I-have-physically-traveled-in-time-171952681.html
PS: This all sounded vaguely familiar - and indeed we had already covered this guy here:
http://www.forteantimes.com/forum/viewtopic.php?t=43705 |
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| Kondoru Unfeathered Biped Joined: 05 Dec 2003 Total posts: 5788 Gender: Unknown |
| Posted: 03-10-2012 20:17 Post subject: |
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| I am not hiring him; at least not in this Reality. |
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| rynner2 What a Cad!
Great Old One Joined: 13 Dec 2008 Total posts: 21365 Location: Under the moon Gender: Male |
| Posted: 09-11-2012 18:11 Post subject: |
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I've found a new book called INTERVENTION - How Humanity from the Future has Changed its own Past. Published this year, it's written by Alan Butler, who has written several other books on Fortean fringe topics.
| Quote: | Publisher's description:
Everyone who thought time travel was pure fantasy or theory will now have to think again, as this amazing book demonstrates that humankind's origins, evolution and historical turning-points have been planned in the future - follow Alan Butler as he persuades us that without the reality of time travel we would not be as we are today.
http://books.telegraph.co.uk/BerteShopWeb/viewProduct.do?ISBN=9781780283883 |
| Quote: | Many key events in the history of humankind show evidence of having been intended by human beings from the future, who took specific actions that would steer the world in a particular direction. This 'intervention' theory is based on sound mathematical and scientific arguments, consistent with Einstein's demonstration of the possibility of time travel.
Time travellers - some of them anonymous, some celebrated in history - have made alterations to our planetary and global environment (the creation of the Moon, the extinction of the dinosaurs) that were necessary to allow us to exist and to develop as an intelligent species. They have also left us markers that show what steps we need to take to progress further.
All these interventions were placed retroactively within the 'timeline' for future generations, not for those immediately affected. Key interventions include: The creation of the Moon If the Moon did not exist, nor would we. The author demonstrates that the Moon was built to make it possible for the Earth to become an incubator of life.
The metal revolution The development of humanity's mastery over metal is a mystery, since the required temperatures for smelting metal exceeded anything that Neolithic man would have needed for any purpose. So how and why did smelting start? Add to that the fact that the first usable metal, bronze, is an alloy of copper and the much rarer tin and we begin to see the scale of the puzzle. Intervention supplies a convincing answer.
The megalithic yard Neolithic peoples created a sophisticated, fully integrated system of measurements based on the actual size and mass of the Earth - a 'marker' for future scientific developments, surfacing again, apparently out of the blue, in 18th-century Washington, DC.
But the most spectacular revelation lies in our future. By looking at the mathematics underlying many of the inventions, we discover, with unexpected precision, when our first contact with our future selves will happen. This will occur within the lifetime of most readers of this extraordinary book. 
http://www.thebookpeople.co.uk/webapp/wcs/stores/servlet/qs_product_tbp?storeId=10001&catalogId=10051&langId=100&productId=310420 |
I've only just started the book - I'll let you know how I get on!  |
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| rynner2 What a Cad!
Great Old One Joined: 13 Dec 2008 Total posts: 21365 Location: Under the moon Gender: Male |
| Posted: 09-11-2012 20:59 Post subject: |
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And by a spooky coincidence, I find this on iPlayer:
Frequently Asked Questions About Time Travel
Comedy about three ordinary blokes who hold the fate of the world in their hands when they discover a rift in the space-time continuum in the gents' of their local pub.
http://www.bbc.co.uk/iplayer/episode/b00tc29d/Frequently_Asked_Questions_About_Time_Travel/
Duration
79 minutes
First broadcast
BBC Two, 10:30PM Sun, 1 Aug 2010
Available until
1:24AM Sun, 11 Nov 2012 |
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| rynner2 What a Cad!
Great Old One Joined: 13 Dec 2008 Total posts: 21365 Location: Under the moon Gender: Male |
| Posted: 09-11-2012 22:30 Post subject: |
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That was brilliant! Very amusing and thought-provoking, with a good cast of likeable characters.
And don't switch off when the credits start to roll - watch till the film finally stops! |
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| Hachiminh Liberal Militant
Yeti Joined: 03 Feb 2012 Total posts: 55 Gender: Unknown |
| Posted: 14-11-2012 18:14 Post subject: |
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You go from point a to point b in the space of 1 second. Then you go back to point a but speed up enough to travel from a to b instantaneously. What happens if you go even faster? The only possibility then would be to arrive at b at an earlier time, assuming of course faster than light travel is even possible.
And what is the opposite effect, how do you travel forward in time? What is the opposite of speed? I wonder if absolute motionlessness somehow slows time, we all experience the feeling of time dragging whilst waiting for an appointment, or time 'flying' whilst we are rushing around. But I wonder if complete motionlessness actually results in a sort of time travel. The numeorus cases of frogs and even a pterodactyl trapped inside rock might support this theory, maybe somehow they have been slowed down, much like meditation allows practitioners to slow their heartbeat (if we accept the general premise that certain species have a certain number of heartbeats in their life, this theoretically extending their life). |
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| rynner2 What a Cad!
Great Old One Joined: 13 Dec 2008 Total posts: 21365 Location: Under the moon Gender: Male |
| Posted: 14-11-2012 21:15 Post subject: |
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| rynner2 wrote: | | I've found a new book called INTERVENTION - How Humanity from the Future has Changed its own Past. Published this year, it's written by Alan Butler, who has written several other books on Fortean fringe topics. |
I've now finished the book. The writer's style is rather diffident, but he introduces some interesting ideas, particularly regarding the megalithic yard and other measurements, including those involving the size and movement of the moon. (In fact he summarises these in an appendix, and there are certainly some thought-provoking coincidences there.)
However, I cannot see that it supports his theory about time-travelling descendents from the future. He claims they've somehow caused great events, such as artificially creating the moon, billions of years ago, yet he often weakens his argument by saying they can't actually change anything recorded in history. (Luckily the Moon has long been recorded in history... ) Nor does he spell out exactly why they have to carry out interventions.
But he does give one interesting prediction, that those of you much younger than me might like to note in your diaries: somehow, in 2022, on the 27th of March, the time-travellers will reveal themselves in the middle of the President's Park in Washington DC. (This park used to be known as Ellipse Park.)
The book covers a lot of history, and several of the usual Fortean suspects, so some of you might like it for your Fortean bookshelf. But for me, the author attemps to cover too wide a canvas without really nailing down his premises. |
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| eburacum Papo-Furado
Great Old One Joined: 26 Aug 2005 Total posts: 1587 Gender: Unknown |
| Posted: 15-11-2012 01:23 Post subject: |
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| Hachiminh wrote: | | You go from point a to point b in the space of 1 second. Then you go back to point a but speed up enough to travel from a to b instantaneously. What happens if you go even faster? The only possibility then would be to arrive at b at an earlier time, assuming of course faster than light travel is even possible. |
You are quite right that faster-than-light travel would cause time travel to occur- but it is not a simple matter of going back in time if you go faster-than-light.
Relativity says that if you travel faster than light then in certain frames of reference you will see things occur in a different order to someone who does not travel faster than light. But you will still be moving forwards in time from the point of view of most of the rest of the universe.
This page examines the question in exhaustive detail.
http://www.physicsguy.com/ftl/html/FTL_part4.html#chap:unsolvableparadoxes |
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| Hachiminh Liberal Militant
Yeti Joined: 03 Feb 2012 Total posts: 55 Gender: Unknown |
| Posted: 15-11-2012 01:54 Post subject: |
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| eburacum wrote: | | Hachiminh wrote: | | You go from point a to point b in the space of 1 second. Then you go back to point a but speed up enough to travel from a to b instantaneously. What happens if you go even faster? The only possibility then would be to arrive at b at an earlier time, assuming of course faster than light travel is even possible. |
You are quite right that faster-than-light travel would cause time travel to occur- but it is not a simple matter of going back in time if you go faster-than-light.
Relativity says that if you travel faster than light then in certain frames of reference you will see things occur in a different order to someone who does not travel faster than light. But you will still be moving forwards in time from the point of view of most of the rest of the universe.
This page examines the question in exhaustive detail.
http://www.physicsguy.com/ftl/html/FTL_part4.html#chap:unsolvableparadoxes |
Thanks for the link, it looks well beyond me at the best of times, but I'll have a look tomorrow when hopefully I am less tired! I don't think time travel would ever work like the almost instantaneous teleportation type occurence portrayed in films, they seem to forget that if it did work that way, chances are they would end up in space many miles from earth, or if they were extremely unlucky right in the middle of an asteroid! |
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| OneWingedBird Great Old One Joined: 19 Nov 2012 Total posts: 542 Location: Attice of blinkey lights Age: 44 Gender: Female |
| Posted: 05-01-2013 20:09 Post subject: |
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| Quote: | | I am not hiring him; at least not in this Reality. |
It's the way he describes it, that's like.. "Ooooh look there's a paradox over there" the way you might point out a cow in a field while on a train journey.  |
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| rynner2 What a Cad!
Great Old One Joined: 13 Dec 2008 Total posts: 21365 Location: Under the moon Gender: Male |
| Posted: 05-01-2013 20:59 Post subject: |
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| Hachiminh wrote: | | Eboracorum wrote: | You are quite right that faster-than-light travel would cause time travel to occur- but it is not a simple matter of going back in time if you go faster-than-light.
Relativity says that if you travel faster than light then in certain frames of reference you will see things occur in a different order to someone who does not travel faster than light. But you will still be moving forwards in time from the point of view of most of the rest of the universe.
This page examines the question in exhaustive detail.
http://www.physicsguy.com/ftl/html/FTL_part4.html#chap:unsolvableparadoxes |
Thanks for the link, it looks well beyond me at the best of times, but I'll have a look tomorrow when hopefully I am less tired! |
I wouldn't bother! Physicsguy just says "If FTL travel is possible, then we'd get paradoxes left, right and centre".
But all that is just pissing in the wind, as relativity does not allow for FTL travel in the first place! There are mathematical rules in relativity for the addition of velocities, and the sum is never FTL.
If I consider myself to be at rest in my Frame of Reference I might see a space ship travelling away from me at 0.9 times light speed, c. An observer on that ship might see another ship, also travelling away from him at 0.9 times c. So what is the speed of this second ship relative to me? More than 0.9 times light speed, but still less than c!
We could extend this chain of speeding ships as far as we like, but the fastest of them all will still be travelling at a 'gnat's crotchet' less than c relative to me.
This all sounds odd, because we are used to living in a world where speeds are well less than c, and the mathematical rules of relativity simplify to a simple addition of velocities.
The other way relativity 'bans' FTL travel is by considerations of energy. It takes energy to accelerate an object, but this acceleration also increases the mass of that object, so even more energy is required for further acceleration. As the object approaches c, the energy required for further acceleration increases beyond any practical limit, and we never achieve c.
Again, all this is logically and mathematically consistent. The maths of Special Relativity is actually quite simple. General Relativity is much more complicated, and develops into a theory of Gravity. Even so, AFAIK, GR does not allow of FTL travel either. |
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| Kondoru Unfeathered Biped Joined: 05 Dec 2003 Total posts: 5788 Gender: Unknown |
| Posted: 05-01-2013 23:17 Post subject: |
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What about world lines?
Dont they prevent paradoxes? |
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| Moooksta Muppet
Joined: 26 May 2006 Total posts: 1776 Location: Muppet Labs Gender: Unknown |
| Posted: 25-02-2013 20:59 Post subject: |
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Well this is interesting...apologies if someone has already posted it.
Man who claims he's invented a time machine...just disappears.
| Quote: |
Time Machine inventor disappears
A man who called the Victorian Emergency Services “000? number 68 times on New Years Eve has allegedly disappeared.
Andrew Carlssin, a self professed scientist became known to emergency services after he called them repeatedly claiming to have invented a working time machine.
Jack Prescott of Emergency Services Australia said, “We had pretty much written off Mr Carlssin as a nuisance. We have all kinds of crazy people ringing up the ‘000’ emergency number. After so many calls we decided to send over a police patrol car to give him a stern talking to. We did not expect what happened next.”
Constable Toby McNeill revealed in an interview this morning, “We arrived at the person of interests house at approximately 12:02am and saw three large flashes of light that resembled lightning, coming from the garage area.”
“Upon entering the house there was a distinct smell of ozone and some light smoke at the scene. The garage contained scientific equipment and a large burnt area on the floor.”
“A search of the house revealed no sign of any residents. However, a note has been recovered and is under investigation at headquarters. City forensics and arson squad detectives are also currently at the scene.”
Emergency Services receive hundreds of calls each year reporting UFO sightings, missing dogs, minor chest pains or even asking for directions to the nearest service station.
Neighbours described Mr Carlssin as a quiet man who usually kept to himself.
Speculation is rife on social networking sites as to whether Mr Carlssin had actually invented a time machine and pulled off a New Years Eve travel into the future.
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