if you had a time machine and you went back in time 10,000 years ago and say you did not even go back in time yourself and you just moved things out of place in the past with the time machine from the future. And you moved a grain of sand out of place by a centimeter do you think that would that change the whole history of the earth from that point and you the time machine all the people in the world the buildings the cars all history and everything would dissapear and soon as you moved the grain of sand out of place in the past from the future. Is this why time travel into the past is impossible because of changes that would happen in the future from changing somthings in the past. Thank you
If you go back in time and move a grain of sand out of place by a cm on a beach is that enough to change time?
A scientist answering a time travel question isn't allowed the luxury of a paradox, so even if you went back in time to shot your own mother before you were born you would find it:
a. impossible
b. possible but irrelevant since you're in a different universe now.
c. possible but irrelevant because you didn't understand the beginning conditions correctly. (example: she wasn't your real mother)
As far as moving a grain of sand, I don't think it would change the outcome of history. HOWEVER the quantum fluctuations on earth causing random events wouldn't necessarily come out the same way twice. Lets pretend there was a speck of radon in your parents home before you were born. Lets say that in your history, it didn't decay and didn't cause your mother cancer so you were born.
However if you run the movie forward a second time, perhaps the speck of radon DID decay and DID cause your mother cancer thus preventing your birth in that time line. It's a random event that doesn't need to occur one way or another. (it has no cause, it's totally random) Thus moving the grain of sand might be irrelevant BUT playing history over again can certainly result in a different future.
If you go back in time and move a grain of sand out of place by a cm on a beach is that enough to change time?
TIME TRAVEL
Time Travel into the future is possible. If Free Will exists, then time travel into the past is not possible.
Two Time Machines for travel into the future:
Type 1
Build a space ship capable of near light speed. Put it into a long orbit like a comet that returns to earth every 100 years. Get in the ship and blast off. When you return you will have aged a few years and be 100 years into the earth's future.
Type 2
Build a space station in near orbit to a Black Hole. As long as you are in the space station you age very slowly. When you leave you could be 100s of years in the future.
Special and General Relativity makes either of these possible. The science is solid, the engineering will take some work.
Time Travel into the past:
The possibility of travel to the past hinges on: Does Free Will exist? If we have Free Will then we can change the past and thus the present. The Law of Causality does not allow this. All time travel paradoxes arise from the fact that causality does not allow us to change the present. But, IF everything is fixed and we can’t change it, then some of us, at least, could be time travelers caught in a loop stretching enough years to cover a life time or more maybe 1000s of years. Time Travel need only involve “quantum leaps” that prevent us from meeting ourselves and we live the same lives over and over with no memory of the last time we did it. Something like Joe Haldeman’s “The Accidental Time Machine” would work.
Modern Theoretical Physics offers another way out of the Time Travel to the Past Paradox trap. If there are an infinite number of parallel universes, we can travel back, violate causality and snap to a different universe that results from us changing the past. I.e.: Go ahead and kill your father. You snap to a universe where your father ain’t your father, but your father, he don’t know. Or, maybe he does and he does not care. Or, your mother was raped. Or, .........
See: “Closed Timelike Curves in Asymmetrically Warped Brane Universes,” Pas, Pakvasa, %26amp; Weiler
http://science-junkie.group.stumbleupon.…
IF we do not have Free Will, everything is fixed and we can’t change it, then some of us, at least, could be time travelers caught in a loop stretching enough years to cover a life time or more maybe 1000s of years. Time Travel need only involve “quantum leaps” that prevent us from meeting ourselves and we live the same lives over and over.
You snapped to a universe where that grain of sand is where you put it. What else happens in that universe is anybody's guess
