Wandering around the net the other day and came across this 2003 thread that hauntingly reminds me of elements within this thread -- for some reason.
http://www.physicsforums.com/showthread.php?t=10443
That thread does not have the same idea about time travel that we have in 2020-2032 (time travel's practical existence; very neat date to remember though, 2020 as the first rudimentary time machine, that is, which transported light). There are no parallel universes. The Grandfather paradox is not solved by going to an alternate universe because you might end up on your own. You might say that there is a 1/infinity chance of that happening, which in mathematical terms strictly speaking is 0 (you can easily prove this by saying 1/9=0.111... then times 9, 9/9=0.9999.. which makes 1 equal exactly 0.999... making 0.00...1 = 0), but so is that same chance for going to any other specific universe, whether it's one where you had a dog named Roger, or Trigger. In any case, in the 19th century, Cantor's work on infinity discarded that objection (prematurely), while solving Zeno's paradox.
When you time travel to the past you rewrite "history". But not your history, because your history is a metaphysical remnant that your memory recorded. It's like taking a photograph of a building which is destroyed by a bomb. The building in the photograph does not also collapse. And so, when you time travel in the past and kill your grandfather the "second" you is simply never born.
This is because time is not a metaphysical "remnant" of past-being. Time was discovered by Einstein himself to be dependent upon velocity, mathematically. This can easily be shown by taking a picture of a moving car. In the picture the car is moving 0/0 meters per second. But the car itself was obviously moving, so if you were to ask the position of the car in the picture 1 second later (movement m/s), your answer would be undefined because it could have been 1 m/s or 2 m/s or 15 (if it was not a Volvo
). And so when you time travel back, you have effectively rearranged the structure of the universe (time) which you are free to arrange as you see fit (or not :d ).
The Conservation Principle elucidated by Hawking in 1992 and confirmed later on, showed not that time travel was impossible, but that opening a wormhole back through time (permitted by relativity) would not be stable enough and would vaporize a time machine going through it immediately. The question was whether this was a law of the universe (kind of like, hydrogen and other Alkali metals' violent reactions due to 1 electron in their valence shells) or simply coincidences that could or could not be overcome for whatever reasons.
In 2014, a mathematician/physicist named Amirian (in his 50's, working near Los Angeles apparently), discovered that this was not a law of nature (as intuitively it seemed), but that this was due to the unstable forces of gravity surrounding the passenger and his machine inside the wormhole, ultimately due to the black hole. The same unstable force similar to trying to keep a pencil upright on its tip. You can theoretically do it, but it is an unstable equilibrium if you do.. without any external help that is.
That's where the idea came for "external help". What was needed was to find a way to keep the gravitational forces in check, so to say, without them crushing and biforcating the theoretical time machine. It was realized that this would not happen until the problem of quantum gravity was solved, that is, I don't know how far you guys are into the problem of superstring theory, but it was needed to reconcile as you know, quantum mechanics with General Relativity, since as you must know, quantum mechanics and GR are in practicality on the same level inside a black hole (a lot of gravity, microscopic effects), and that's where everything falls apart. The solution was, coincidentally, achieved by 2018, by pretty much the same scientists, as well as a few new ones, who have been working right now on the problem since time immemorial. Then it was discovered what kind of singularities and black holes did not biforcate a specific object. I.e. some biforcated spheres due to their shape and rotation, others did not. In essence, there was a specific shape the time machine had to be. Then black holes were created. And after they were easily made, they were tested with light, and then with the research on shape on animals inside specific objects, and finally people. We quickly figured out that the appearing dogs were from the future, and it did not matter whether we sent them or not. They appeared nonetheless.
))