Thank you, although Tasche also makes a good point too.
The difference between our statements is that my point assumes you remain in our exact universe the whole time.
It is also possible that if you back into time to a point within our universe and cause a strange event that would alter the present that you effectively branch that universe from ours. If you killed your grandfather, that universe would be one in which you were never born, yet you still exist because you come from a parallel universe where you were born.
It would be rather tricky to return to your home universe in this scenario. It would involve space travel through 6 dimensions. The first three dimensions are easy. The fourth is time, which if we think of it as a line which we move along, then the fifth dimension is a line stemming from the first line just as the second dimension branches from the first dimension. If these multiple timelines exist in the fifth dimension, then to travel between them, one would have to master the sixth dimension.
i'm going to do this for the first time ever and not speak my mind.-- eheath on december 14th