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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.
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.
"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.
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.