mohannikam19

this video explains much better way:

Well, I think it must depend upon the position (or relative motion) of device, used for time travelling... If it is not so, then there is not just the orbital motion of the earth, but also our solar system is moving around, in milky way galaxy, at much greater speed, and even our galaxy is moving at much much higher speed (as galaxies are saperating) So, it must depend upon relative motion, and not orbital motion. There would arise a paradox. If the time traveler had taken a gun with himself, and kills his past version, existence of his future version cannot be explained.

There are questions, being raised, that we currently cannot predict the behavior of universe, with great certainty (due to Heisenberg’s uncertainty principle) and quantum world is full of randomness. I completely agree with these facts, but I have not stated that this supercomputer is currently possible to create, or we are having all the laws of physics with us, at this moment, to feed in a computing device. There may be future possibilities, that we may discover some theories, which may be able to determine exact positions, instead of probability, of a particle. For example, there is string theory... In String theory, there are proposed some extra dimensions, rather than the 3, we are familiar with, currently (or may be even 4th as time). So, these extra dimensions might certainly predict our currently uncertain world. Taking an example, on how limitations on dimensions may result in uncertainty, let us suppose an ant, laying on ground (2D- space). If we throw a ball upon the floor, the ant (bounded to look only on ground) will be only be able to see the ball, when it is hitting the ground. Even when ball is following all the laws of physics, ant will not be able to make predictions of the ball, looking on the same 2d plane...And ant will consider appearance of ball, random. Hence, it is not at all necessary that what’s not possible currently, will be impossible forever… (may be, unless we have proof) But, Even if world (even quantum world) becomes predictable, we will not able to compute our future, considering every aspect of universe...

http://plato.stanford.edu/entries/qt-uncertainty/ If the velocity of the electron is at first known, and the position then exactly measured, the position of the electron for times previous to the position measurement may be calculated. For these past times, δpδq is smaller than the usual bound. (Heisenberg 1930, p. 15) Indeed, Heisenberg says: "the uncertainty relation does not hold for the past".

One of the key things, to know on how to predict the future is the mechanism, we would use to do so. Let’s consider an example of predicting something basic. Let’s say, I want to predict what is the result of (2+2) for that, we may use a calculator, or a computing device or our brain itself… but, what we’re goanna do, in order to predict this simple calculation is that we would introduce a faster computing device, which is performing that same calculation, and put the result before than slower calculator (or any other device). But, for predicting our future, we need to simulate everything that has happened after the beginning of the universe, up to the present, and continue the simulation to get to know our future. But here arises a paradox. To justify our past, and then to predict the future, we need to feed all the laws of nature into a supercomputer, and allow it to process them, to simulate, at faster speed than they had occurred. If a supercomputer does that and simulating the past, it reaches the present, there arises a problem, that now there is another same supercomputer in simulated version of the universe. So now, to proceed simulating further, the supercomputer would need to predict its own computations that is work faster than itself, which is certainly impossible. Hence, there cannot be any computing device, which can predict our future with certainty.