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The Quantum Experiment That Simulates a Time Machine
KentuckyFC writes One of the extraordinary features of quantum mechanics is that one quantum system can simulate the behaviour of another that might otherwise be difficult to create. That's exactly what a group of physicists in Australia have done in creating a quantum system that simulates a quantum time machine. Back in the early 90s, physicists showed that a quantum particle could enter a region of spacetime that loops back on itself, known as a closed timelike curve, without creating grandfather-type paradoxes in which time travellers kill their grandfathers thereby ensuring they could never have existed to travel back in time in the first place. Nobody has ever built a quantum closed time-like curve but now they don't have to. The Australian team have simulated its behaviour by allowing two entangled photons to interfere with each other in a way that recreates the behaviour of a single photon interacting with an older version of itself. The results are in perfect agreement with predictions from the 1990s--there are no grandfather-type paradoxes. Interestingly, the results are entirely compatible with relativity, suggesting that this type of experiment might be an interesting way of reconciling it with quantum mechanics.
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> The results are in perfect agreement with predictions from the 1990s--there are no grandfather-type paradoxes.
There is no time travel citizen! Go on about your lives.
Meanwhile the military starts researching chrono-troops. Because, you know, Australia has always controlled the world with its benevolent Empire...
You don't need grandfathers to have paradoxes
This isn't news. They already did the same experiment in January 2015.
They can only tell you who WON the Superbowl, because everything will happen in the past anyway.
...gis sdrawkcab (usually not responding to ACs; don't bother posting as AC)
Time travel is possible but not in the way you think about it. It exists going backwards but is tied to alternate realities, or tied to multiple universes. When the quantum particle loops back on itself, it's going back to an alternate universe which is similar but slightly different. The farther it loops back on itself the closer the alternate universe is similar to ours. This is because of the Big Bang, and we all originated from the same point in space. if you keep going farther back eventually all universes converge. On the flip side, the farther ahead in time one travels, the more random a universe. The present time is the only constant
If the particle were to kill itself, it would only kill the version in the new universe it is in, not the original from which it originated. One can never travel back in time in their own universe, and if they travel forward, it will never be their original universe but a similar one, and the farther in time they go forward, the more different the universe would be from their original one.
The universe and everything we know follow a set of laws, and it was designed in a way that we could not alter our own universe. At least past universe. However, you could change your original future universe by gathering knowledge from other universes and returning at the exact moment in time you left if you could find the correct signature of your own original universe before you traveled in time. So Leave original universe, gather info, return to exact universe using a signature you already know about gathered at the exact moment you left. If you return a few seconds later, your signature would be off as things could have happened different in those few seconds somewhere in your universe, and would not be your true original universe.
Obviously we have a long way to go to be able to accomplish such tasks, but that's the general theory, and with this article this is the beginning steps of time travel.
Yes, I have traveled back in time already and am here in an alternate universe. However I cannot return to my original universe as we didn't have the means to capture signatures in my timeline yet when I left. I came here knowing that. No I will not tell you about your future, because your future is not my future, so I don't know it yet.
The results are in perfect agreement with predictions from the 1990s--there are no grandfather-type paradoxes
Nice first step, but I'll be more impressed when the results are in agreement with predictions from the 1890s
/. posts from Colorado have gotten stranger and stranger...
"Various physicists have discovered solutions to Einstein’s field equations that contain loops that return to the same point in space and time."
What a lazy bit of reporting! Mr. Kurt Friedrich Gödel first discovered the Einstein's general relativity allowed for closed timelike curves. He presented a paper describing this solution to Einstein as a birthday present, while they were both working at the IAS. It grieves me when Gödel is not given the recognition he is certainly due.
Or not. Until we can find or set up a region with a closed timelike curve, we won't be able to test such things, and it all is, well, entirely theoretical. There are several possibilities.
PHEM - party like it's 1997-2003!
Screw your superbowl, I want to know when Overwatch comes out.
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Speak for yourself.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
You mean a big ball of wibbly-wobbly... timey-wimey... stuff? Even the light sci-fi tends to be a couple steps ahead of physics.
Let me know when someone builds a Predictor.
his same post, with slight tweaks, shows up after every story about quantum mechanics. That doesn't make it any more insightful. You can talk about flocks all you want, and there are some rough analogies to wavefunctions, but flocks of birds or subparts don't handle the issue of wavefunction collapse and projections very well, or if you came up with a convoluted method you would just be adding a layer of abstraction on top of the wavefunction already in quantum mechanics.
So the thing you know as a photon, is actually a flock of something smaller that is sufficient in density to promote an electron
And this keeps going back to some AC that insists photons are made out of parts, and part of their evidence is that the only way to measure photons is to excite an electron in an atom. Except that is wrong, there are other detection methods for photons based on scattering that are not a quantized process and allow for a continuum of responses.
refuse to accept the divisibility of photons despite the evidence slapping you in the face
And assuming this is the same person posting these AC posts for years, how long will you ignore evidence and behavior of photons that we've known about for nearly 100 years that flies in the face of your strawman about how photons can be detected?
We need a "Wow, that sounds impressive although I didn't understand a single word" mod option.
First they ignore you. Then they laugh at you. Then they fight you. Then you win. -Gandhi
but kept up back at the beginning
If I go back in time and kill the old version of myself - is that suicide or murder?
Well if the science here is correct you can only see who won the superbowl in THAT alternate reality... You don't know for sure who won in OUR reality until, of course, it happens.
I don't fully understand what they did. But, here's my take. It would seem to me that they may have demonstrated that there is not a single timeline, which kinda goes along with some other assumptions in Quantum mechanics. Relativity assumes that Time is a constant so-to-speak. Quantum Mechanics does not. How this experiment might lead to unifying Relativity with Quantum I don't know, and don't believe, because I think both theories (and they are both THEORIES) are flawed.
The correct answer is 42.
Screw your superbowl, I want to know when Overwatch comes out.
Overwatch is already out: Overwatch
Oh, you mean the game formerly known as Overwatch, by Blizzard? Blizzard's Opps
So what exactly is your solution to the paradox? There are a few possibilities: alternate universes, total lack of free will preventing you from killing your grandfather, some sort of physical conspiracy of the universe always making something happen that thwarts your efforts (gun not firing), etc.) but none of them are as straightforward and obvious as you make it seem.
Just because quantum mechanics doesn't make intuitive sense to you, doesn't mean you can come up with any old analogy and dismiss the work of people far more qualified in the field than you. Well, you can, obviously, but it doesn't make you right.
It's amazing, that if you know the starlings are flying east to west, and you can only detect a starling as a complete *flock* of starlings, and not see the individual birds, then the flock can jump back east, i.e. back in time, interacting with the previous version of itself.
How is "jumping back" analogous to "interacting with the previous version of itself"?
Gosh!
How about, instead of being condescending, you perform some experiments - or even just provide more than a half-baked analogy - to disprove the last 100 years of quantum mechanics? Obviously all the devices we've been able to create based on this hard-won understanding must be figments of our imagination...
So the thing you know as a photon, is actually a flock of something smaller that is sufficient in density to promote an electron.
Isn't that completely incompatible with the photoelectric effect? You know, the very phenomenon which lead to the concept of the photon in the first place?
systemd is Roko's Basilisk.
http://www.neogaf.com/forum/sh...
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Lighten up, John Titor.
Is that you, John Titor? I thought you went back to 2036 from 2003? Why are you back in 2015?
This immediately made me think, well what if time travel isn't possible, but a simulation of it, of the past, is, using this.
And of course that immediately made me think of the possible scifi stories that could explore this concept or use this as a literary device.
And then I realized this has sort of been done already, in the episode of ST:NG, The Inner Light (a personal favorite).
The guy who said the election was rigged won the presidency with the second-most votes.
How about, like QM, it simply doesn't work on the macro level? That while the photon may have been looped back in time (although another explanation might be forthcoming), massive objects cannot.
It must have been something you assimilated. . . .
what you don't realize is that the AC in the GP only started posting these comments next week!
but because he is a non-divisible person and not a flock of starlings, or something like that, the posts are going back in time and being attached to random articles about quantum mechanics.
I prefer the oscillating version. You travel back to kill your grandfather, this causes you to not exist which in turn makes you not travel back to kill your grandfather.
Like an oscillation in an electric circuit the oscillation is either stable, reaches an endpoint or is dampened out.
Typically I would imagine that the time will continue to change until it reaches a stable point.
As long as time machines exists, and are used, they will together with the butterfly effect probably cause time oscillations that causes the time traveler to not go back in time.
Because of this reality is always changed to a point where paradox causing time travel doesn't happen.
The only likely outcomes are either that time machines doesn't get invented because every time it is used it changes the past in a way that makes it not get invented, or that it gets invented, possibly used, then locked away in a museum to not cause further time oscillations.
That's entirely possible, but that's not what the ObiWanKenblowme was talking about. He said there was no problem and compared it with Zeno's paradox.
Ah, but this machine only goes forward in time, so you won't be able to change history or do something disgusting like sleep with your own grandmother. -Farnsworth
The zeno's paradox is resolved by the discovery of the planc distance.
The runner will have a nonzero probability of instantly tunnelling to the finish line after reaching the planc distance. This means zeno's paradox is false.
Take THAT zeno! :P
It took me a few re-reads as well but I think he is saying that you are looking at a different starling/photon in the flock and not the same going back in time.
But oscillations imply some kind of meta-time so that history itself can change. There would need to be some other, perpendicular time-dimension in which these changes to spacetime would take place. History "used to be" a certain way but "now" (measured in meta-time) history is different.
And then we can start arguing about whether or not it's possible to go back in meta-time, etc...
Not this again.
Wavefunction collapse and complex amplitude means QM is not simulatable using a flock of starlings. They may produce quantum-like behaviour, if you squint hard enough, but they don't reproduce QM.
When the photon flock divides around a tunnel, say, with one half going through the tunnel and one half going above the tunnel, and you detect the flock in the tunnel, ALL the flock suddenly appears in the tunnel. You can't detect half a flock at all and detecting a whole flock in the tunnel means that's where the whole flock is now. Starlings don't behave this way. That's why flocks of starlings are divisible and photons are not divisible.
This isn't even a good model of QM for yourself, so please drop it, and learn QM properly, and stop peddling this nonsense to others. It does not work as a replacement interpretation for QM. It does not reproduce QM. End of.
This straightforward solution is that time travel does not exist.
The results are in perfect agreement with predictions from the 1990s--there are no grandfather-type paradoxes.
That is the beauty of time travel experiments. You just go back in time and adjust the predictions. Simple, eh?
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Bah. The BBC has been simulating a time machine for decades.
Time travel is possible but not in the way you think about it. It exists going backwards but is tied to alternate realities...
I see someone read Anathem.
-1, Too Many Layers Of Abstraction
No, just further and further away from your original universe.
But what's wrong with branching time? You go back, kill your grandfather and end up on a timeline on which you will never be born.On the original timeline you have disappeared.
Sounds no less plausible.
Some stoner got hold of a time machine and went back in time and somehow legalized pot in Colorado... Who knows what those time ripples will do to the continuum...
Best part of the Novikov self-consitency princple is that if it's true, it means that Bill & Ted's Excellent Adventure is the most scientifically accurate time travel movie ever.
The Copenhagen interpretation is so much more religion than science, I can't stand it. What you are speaking of has nothing to do with experimentation.
Ever wondered why they are called "interpretations" instead of theories? Just about every sizable write up I've seen addressing interpretations in quantum mechanics makes it clear that they don't change predictions, and are not something that can be tested for. They're half philosophy (yes, scientists study, think and write about philosophy from time to time) and half about intuition/pedagogical. While the math has a final say, having intuition in these fields can help find mathematical short cuts.
Excellent!
Mit der Dummheit kämpfen Götter selbst vergebens
Andrew Cleland and Aaron O'Connell have demonstrated macroscopic quantum behavior: http://web.physics.ucsb.edu/~m...
Yves Couder et al. have demonstrated Single-Particle Diffraction and Interference at a Macroscopic Scale.
Even if the interpretation isn't true, we can program it.
We can program multiple virtual universes, or a universe where I can go back in time and there's a fork.
If we think it, it is true. We can make it true if it isn't already.
When you're measuring properties of pool balls by bouncing other pool balls off them, why can't people just accept the limitations of what we're working with without turning to this strange philosophy that the particles wont "let" us look at them.
Because it's the "philosophy" which best explains what is observed. If you've got a better one, present it to the world (with evidence) and claim your Nobel prize.
systemd is Roko's Basilisk.
So if you considered both string theory(?) of multiple universes formed from choices (all simultaneous outcomes exist until one choice is made then the rest collapse) and the paradox problem, it seems that a paradox is not actually a problem, as the logical outcome of that choice ( to kill your grandfather) would collapse itself leaving all the other choices/universes.
So basically, paradoxes cannot exist. what can exist does.
There are no paradoxes; somebody invents time travel, and somebody goes back and changes things, and changes ripple forwards, and somebody else (or the same) goes back and changes things, and changes ripple forwards, and so on and so on, until somebody changes things into a future where time travel is never invented, and that is a stable trap, and everything marches forwards from there.
Star Trek transporters are just 3d printers.