Time Travel Possible. Possibly...
- Thread starter Relayer1
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That science is going way over my head, but "simulating" the whole thing using a second photon that they just declared to be the "older self" of the other photon, sounds strange. I mean I can simulated whatever I want, like blue smurfs, but that doesn't they actually exist, does it?
And I do wonder if the whole grandfather paradox thing is just a limit of human understanding, but not a physical limit itself.
And I do wonder if the whole grandfather paradox thing is just a limit of human understanding, but not a physical limit itself.
I don't completely understand the discovery, but the headline seems to be overly exaggerated. For sufficiently small degrees of possible, time travel has always been possible.
There is always some non-zero probability that random particles will undergo quantum tunnelling and arrange themselves, purely by chance, into a configuration of a future person. Likewise, an infinite number of monkeys can, purely by chance, write the detailed future history of Earth. While not constituting time travel, were these to happen, they would both be completely indistinguishable from legitimate time travel.
As such, I would discount any possibility that's comparable in its (non-existing) practicality. I believe we've known that there's a temporal link between entangled particles that have undergone time dilation, but since this makes it impossible to transmit information, it doesn't constitute time travel. IIRC, particles can tunnel themselves backwards in time, or at least tunnel themselves on FTL trajectories that would seem backwards from certain frames of references, and while there's an actual "travel" occurring, the randomness of such occurrences still makes transmission of information impossible. Stephen Hawking even compares some of the microscopic effects that occur to actual wormholes, with just about as little practical applicability – you still cannot travel or break causality by sending messages into the past.
As such any research that's been performed on individual particles, without any particular perspective for extending it for multiple ones, sounds just as impractical, so even if that did constitute time travel on some level, the way the article presents it, it sounds nothing like what you have in scifi. I say we need to stop ruining results that are great for science with "OMG TIME TRAVEL" headlines.
As for the simulation part – if I understand correctly, the particles that they are simulating could exist – theory says that they might or that they do, but for the same reasons they are useless for actual time travel, they cannot use the actual particles in their tests, so they are simulating them. Would that be a correct interpretation of what the article states?
There is always some non-zero probability that random particles will undergo quantum tunnelling and arrange themselves, purely by chance, into a configuration of a future person. Likewise, an infinite number of monkeys can, purely by chance, write the detailed future history of Earth. While not constituting time travel, were these to happen, they would both be completely indistinguishable from legitimate time travel.
As such, I would discount any possibility that's comparable in its (non-existing) practicality. I believe we've known that there's a temporal link between entangled particles that have undergone time dilation, but since this makes it impossible to transmit information, it doesn't constitute time travel. IIRC, particles can tunnel themselves backwards in time, or at least tunnel themselves on FTL trajectories that would seem backwards from certain frames of references, and while there's an actual "travel" occurring, the randomness of such occurrences still makes transmission of information impossible. Stephen Hawking even compares some of the microscopic effects that occur to actual wormholes, with just about as little practical applicability – you still cannot travel or break causality by sending messages into the past.
As such any research that's been performed on individual particles, without any particular perspective for extending it for multiple ones, sounds just as impractical, so even if that did constitute time travel on some level, the way the article presents it, it sounds nothing like what you have in scifi. I say we need to stop ruining results that are great for science with "OMG TIME TRAVEL" headlines.
As for the simulation part – if I understand correctly, the particles that they are simulating could exist – theory says that they might or that they do, but for the same reasons they are useless for actual time travel, they cannot use the actual particles in their tests, so they are simulating them. Would that be a correct interpretation of what the article states?
I am CERTAIN that's intentional. This appears to be yet another example of how modern physicists have evolved the practice of polishing turds into a truly spectacular art form.
This doesn't even appear to be that. A couple of guys SIMULATED a hypothetical scenario using elements they know nothing about (bonus points for using wormholes AND photons at the same time), based on an interaction (photon-to-photon interaction) that wouldn't occur in the first place except at extremely high energies.
How do you create an accurate model of something for which almost every agent IN it is an unknown? The short answer is, you don't. If the thing produces any results at all it's because those are the results you programmed it to produce, in which case it isn't a "simulation" it's really just a glorified flash animation illustrating your theory.
Bullshit science is bullshit.
Actually, it's just an issue of grammar. There's nothing really about becoming your own grandfather than a reasonably open-minded and well-adjusted family couldn't cope with, but trying to describe those actions using normal past/present/future tense verbs is troublesome and clumsy.
Anyway, the grandfather paradox is logically impossible because it assumes that non-universality of relativistic effects, which actually contradicts the basic assumption of relativity anyway. Time dilation isn't a real effect in SR, just an observed one.
There's nothing really revolutionary about the notion of time travel in the quantum world, where some of our basic notions of cause and effect don't apply. The alternative to what Einstein called "spooky action at a distance" is something called "advanced action." (Also sometimes called "reverse causation.")
In a classical experiment, you set up the experiment by establishing the initial conditions, you watch the system evolve, and make observations at the end. The constraints you place on the system are the initial conditions.
In a quantum experiment, thanks to the Heisenberg principle, you don't get to watch the system evolve before you make measurements at the end. In this experiment, the initial conditions you impose and the final conditions you impose (by your act of measurement) both constrain the behavior of the system during the experiment. This is essentially a case of information traveling backward in time, from the final measurement to the earlier behavior of the system. Because you cannot observe the behavior of the system before you make your measurement, you are unable to create a paradox by imposing final conditions that are inconsistent with the earlier behavior.
In a classical experiment, you set up the experiment by establishing the initial conditions, you watch the system evolve, and make observations at the end. The constraints you place on the system are the initial conditions.
In a quantum experiment, thanks to the Heisenberg principle, you don't get to watch the system evolve before you make measurements at the end. In this experiment, the initial conditions you impose and the final conditions you impose (by your act of measurement) both constrain the behavior of the system during the experiment. This is essentially a case of information traveling backward in time, from the final measurement to the earlier behavior of the system. Because you cannot observe the behavior of the system before you make your measurement, you are unable to create a paradox by imposing final conditions that are inconsistent with the earlier behavior.
The problem with becoming your grandfather is that you carry a sixteenth of your own chromosomes that you didn't inherit from anybody. They come from nowhere. There isn't a specific reason why these chromosomes would be even human chromosomes – you don't inherit them from a human. So one might wonder why being human isn't as likely as having two heads, seven legs, fifteen eyes, pink scales, and a genetic radio transceiver. Worse yet, there isn't a specific reason why they would work at all (other than for reproductive means). You're likely to be born with a genetic disorder where nothing in your body outside of reproduction works. It's immaculate conception, and unfortunately, not an imaginary one.
If I was my own grandfather I would constantly have doubts and insecurities of whether I am human, and whether my DNA is integral. That's what I would find difficult to cope with. Pronouns are children's stuff.
I once had a nightmare where I grandfathered myself. Or actually prevented myself from being conceived. The moment I did, my reflection turned into a featureless slob of disintegrating matter having enough integrity to allow me to prevent my own conception, but otherwise incapable of anything other than causing horror to everyone I knew. Sick stuff. That's the opposite, but my dream solution to the grandfather paradox is based on the same idea – chromosomes coming out of nowhere, so the end result should be similar.
(Obviously, these concerns have answers, which are simple. Like converging timelines, a real ancestor from a virtual timeline, a parallel human evolution in a virtual timeline, and Occam razor's favourite – almost identical duplication of your other grandparent's genes.)
ETA: Well, no, sorry, I am wrong. Since 75% of the chromosomes you inherit from yourself came from your other three grandparents, only a quarter of those are unaccounted for – that is, a sixteenth, which is one or two. Since there's a very real chance for those to be zero, that wouldn't be at all incredible. Being your own father, and in the more extreme case – your own father and mother – that's the real conundrum. Or is it?
What is somebody invented a time machine, then went back and killed themself before they invented the time machine. 
What is somebody invented a time machine, then went back and killed themself before they invented the time machine.
The wedding of River Song happens.
Of course they did. They came from your grandmother (aka "sweetie") who inserted that chromosome into the loop in the first place when she gave birth to your dad. It's a causality loop: the same chromosome keeps running around in a circular timeline, always coming back around to the same spot once every generation until it eventually encounters itself, interacts with itself, and starts the loop all over again.
Meh. I'm secure enough in my humanity not to give a shit where my chromosomes come from.
It's becoming my grandfather I'd have a serious problem with. Much as I love the old man, he's kind of an asshole.
Unless you go forward into time by the acceptable means of traveling near the speed of light for a while and coming back to your launch point (putting you in the future of your own timeline), you aren't going to travel in time within your own timeline.
IMO, to go backwards into time the multiple universe thing has to be real. That way you can travel back in time to an alternate universe that was exactly as it was at your arrival date as it was for you in your time line. At that point, the alternate universe you are in is already branching off from the one you grew up in so you can do whatever you want. It isn't the same timeline.
That would make it recreational and usable, which is the reason for traveling into the past anyway I would think.
IMO, to go backwards into time the multiple universe thing has to be real. That way you can travel back in time to an alternate universe that was exactly as it was at your arrival date as it was for you in your time line. At that point, the alternate universe you are in is already branching off from the one you grew up in so you can do whatever you want. It isn't the same timeline.
That would make it recreational and usable, which is the reason for traveling into the past anyway I would think.
I don't really have any concerns about causality paradoxes that hang most people up, because the laws of physics really don't care who your grandmother allegedly slept with. That's just a human hangup based on our expectations about the world.
The laws of physics do care about conservation of macroscopic hunks of mass and energy, and that presents a real problem.
Suppose you traveled back in time to 11:30 PM Christmas day in 1968. Then there's 70 kg of mass that didn't exist in this universe at 11:29 PM that night, and that mass is equivalent to 6.3e18 Joules of energy, which is roughly the same energy as 1,500 megatons of TNT. To have that large of a yield, a modern thermonuclear warhead would have to weigh over 500,000 pounds.
That's a pretty big bookkeeping error for the universe to ignore.
The laws of physics do care about conservation of macroscopic hunks of mass and energy, and that presents a real problem.
Suppose you traveled back in time to 11:30 PM Christmas day in 1968. Then there's 70 kg of mass that didn't exist in this universe at 11:29 PM that night, and that mass is equivalent to 6.3e18 Joules of energy, which is roughly the same energy as 1,500 megatons of TNT. To have that large of a yield, a modern thermonuclear warhead would have to weigh over 500,000 pounds.
That's a pretty big bookkeeping error for the universe to ignore.
But would the mass and energy really be "missing"?
In order to time travel, the past and the future must exist in some "direction" beyond the present—otherwise one couldn't travel there. To an imaginary Higher Dimensional Being (a la the Sphere in Edwin Abbott's FLATLAND), the span of time would have some sort of "shape" and the "missing" mass/energy merely displaced. To Lower Dimensional Beings like us, time is experienced as duration, and thus any "bookkeeping error" is only the limit of our perception.
Or perhaps only the present moment exists, with no past or future in any direction to travel to. ("Time dilation" is the slowing of sub-atomic processes, not the slowing of time itself.)
Maybe it's just exchanged. 70kg of whatever you jump into is going to end up in 2014.
The other thing is... it's absolutely true, the universe doesn't care about humans. Your body renews itself with new atoms constantly. Which means that if your atoms traveled through time to replace their respective counterparts in the past, you end up in various places, dead.
In concept, that used to be called "translocation." It's a teleportation process where you literally switch places with a volume of equal mass at your destination.
I haven't thought about that in a long time, but I used to think that's how Terminator time travel worked: The T-800 materializes on a hole in the ground created by his time bubble, but of course all the material swallowed by the bubble ends up in 2029 right where he was standing. The mass exchange isn't really important, it's just two little chunks of space time have been pinched off and swapped between timelines.
IIRC, the original Mechwarrior/Battletech jumpships used to work this way, to the point that you could actually jump a disabled ship to safety by precisely targeting it with the jump engines of a functional ship. Don't remember when that changed; probably five minutes after some smartass used it to rip the guts out of an enemy dreadnaught.
Interesting. That would involve some sort of targeting apparatus so you would hit the right location and time. The only way right now to visit the past is through photons produced in stars. We can see the star as it was in the past, but if go to the star traveling in a conventional manner it would appear to age in relation to your speed until when we arrived at which point we'd see it in it's present form.
I supposed you could twist science some to find a way to go instantly to the star, but if you did that, you wouldn't be there in the past. But if you looked back at our star then, you could see it in the past and depending on your photon collection abilities, see the Earth in the past.
And if you're really good at photon collection you would create a virtual simulation with your data and create an Earth of the past and visit that. But that's not actual time travel though.
Just rambling. LOL
You would always need that. Travel back 100 years in time, Earth is at a completely different location. The universe expands, the galaxy moves, the galaxy spins, Earth orbits the sun, Earth spins.
That completely different location can be calculated precisely with no effort. Just put your time machine travelling with the necessary constant velocity away from that point, and from the frame of reference of the time machine the Earth wouldn't have moved at all. Problem solved. No need for a targeting apparatus.
If you can hit the right time.
If you can hit the right time.
Are we talking about quantum entanglement and quantum teleportation?
http://en.wikipedia.org/wiki/Quantum_teleportation
I think they talk of using a frequency bandwith 6.2-12 MHz around the laser beam used.
http://www.nature.com/nature/journal/v500/n7462/full/nature12366.html
http://en.wikipedia.org/wiki/Quantum_teleportation
I think they talk of using a frequency bandwith 6.2-12 MHz around the laser beam used.
http://www.nature.com/nature/journal/v500/n7462/full/nature12366.html
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