Who is grandfather time

What he wants to know is what happens when you go back into your own past - not a copy of it - and alter things, what actually happens, according to physics?

Basically, if you go back in time and kill your grandfather, you don't exist, so your grandfather can't be killed. So there are two realities happening in parallel here. While all of this is percent hypothetical, because no one's actually gone back in time to test this out, we do have evidence of two separate realities happening in parallel. As MinutePhysics explains , subatomic particles regularly do multiple different things in parallel - a process known as quantum superposition.

It's happening in the core of the Sun right now. If you apply this kind of thinking to the grandfather paradox, you get something called a closed time loop, where your grandfather is simultaneously dead and alive, and so are you as a result.

What are you asking about? But contradictions such as the grandfather paradox don't mean that time travel is impossible. The logical consistency of time travel largely depends on the concept of time, and physicists have many different ways of conceptualizing time. For example, if some laws of physics are considered probabilistic, rather than precisely determined, it opens the possibility of multiple outcomes from a trip back in time, some of which may not be contradictory.

For a logically consistent time travel story, he gives the example of a traveler going back in time to shoot themselves. They aim to kill, but miss because of a tremor in their hand. The non-lethal shot strikes a nerve in the past version of the traveler, causing a tremor in their hand for the rest of their life. The concept of time travel can also be separated from the idea of changing the past, or backward causation.

But Maudlin doesn't think backward causation is possible. People in Western cultures tend to think of time as a line. In most instances, the opposing facts or situations that are presented as being paradoxical seem to be mutually exclusive in the sense that if one fact or situation is true, the other cannot possibly be true.

Nonetheless, while the premise of the Grandfather Paradox is not particularly obtuse or difficult to understand, its potential to disrupt the relationship between cause and effect makes it both particularly interesting, and extremely resistant to a resolution from scientific, if not philosophical perspectives, which begs this question can it be resolved?

Is there a consistent solution to the grandfather paradox? There is no single or clear answer to this question that satisfies both physicists and philosophers , or more precisely, philosophers and physicists that are interested in finding a resolution. The problem is this; the paradox consists of two disparate, and seeming irreconcilable propositions , the first being that backward time travel might be possible , and the other being that it might be possible to side step the causality problem.

It is argued that a time traveler would therefore be unable to change the past , and could only act in a way that is consistent with what has already happened. Compossibility theory basically states that since history happened in a certain way, it cannot happen in any other way. Named after Igor Dmitrievich Novikov, who formulated it, this principle states that history is immutable , and therefore cannot be changed by the action of a time traveler from the future.

Put another way, since persons or objects exist in the present, they must necessarily have been part of the history that created them. Obviously because the grandson will never exist in the first place.

This proposition is the potential basis for Predestination or ontological paradoxes such as the Bootstrap Paradox. This seems to be self-evident. Adding to the discussion, theoretical physicist Stephen Hawking explains:. This would seem to give rise to all sorts of logical problems, if you were able to change history. For example, what would happen if you killed your parents before you were born. It might be that one could avoid such paradoxes by some modification of the concept of free will.

But this will not be necessary if what I call the chronology protection conjecture is correct: The laws of physics prevent closed timelike curves from appearing. When exploring the grandfather paradox from a relativistic point of view, one of the main questions that has to be considered is whether time travel is actually possible. Many physicists have been at great pains to point out that the Theory of General Relativity does not exclude the possibility of time travel.

In fact, Relativity actually predicts the possibility that time might flow at different rates for different observers in different frames of reference.