Atlas Shrugs: Jewish Genius:
"The team stresses the main question is whether — according to the principles of curvature development in the theory of relativity — a time machine can be created. 'In other words ' can we cause spacetime to curve in such a way as to enable travel back in time? Such a journey requires a significant curvature of spacetime, in a very special form.' "
I can prove to you right here and now that either a time machine will never be invented (or if invented never used in any meaningful way - most of all by a Jew. I'll explain). If there were a time machine in the future, then we can assume that they would be able to go to the past, not just their past, but more importantly our past. If they went to the past and changed it, even if we didn't know it had been changed, it would still be our past. When we stand in the present and look at the past, what we are looking at is either events that either have not been changed or have been changed in ways that we don't know. The reason for example that I would say that more than anything a Jew can be proven to not create a time machine is the holocaust. There was a massive killing of Jews in world war II, that is historical fact. If a Jew invented a time machine why would that person not go back and change the historical facts, so those people did not die. In which case we would be living in a present where there was no killing of the Jews in World War II. You can say, well maybe they will, but the nature of the event makes it so that if they will, then they already have. Unless they used the time machine to stop some even worse crime from taking place. It is interesting to note that without the holocaust there might not be an Israeli state, so there are reasons to not change it.
At a basic level, the idea of going back to the past is silly. There are few things that can be changed in the past that wouldn't have unpredictable changes on the future, both good and bad. The inventors could even change history to kill themselves and destroy their invention. If there was no Israeli state, then there would be Israeli Universities to promote the research, probably the researchers parents would not meet and conceive them. Time may move forward and backward, but changing the past is a dangerous and futile exercise.
Which of course means that maybe it is invented but it is either never used, or it is used in strictly observational purposes, and parallel technology is invented to prevent beings in the past from experiencing beings from the future.