Quantum Technology Research

This world line is a fixed object in four dimensional
spacetime – it doesn’t change with time. All that changes
is the ball’s position on the world line . This is why we
say that time doesn’t flow. Time is just one of the four
dimensions that the world line occupies.

In physics, the twin paradox is a thought experiment in
special relativity involving identical twins, one of whom
makes a journey into space in a high-speed rocket and
returns home to find that the twin who remained on Earth
has aged more. This result appears puzzling because each
twin sees the other twin as moving, and so, as a
consequence of an incorrect and naive
application of time dilation and the principle of relativity ,
each should paradoxically find the other to have aged less.
However, this scenario can be resolved within the standard
framework of special relativity: the travelling twin’s
trajectory involves two different inertial frames, one for the
outbound journey and one for the inbound journey.
Another way of looking at it is to realize the travelling twin
is undergoing acceleration , which makes him a non-inertial
observer. In both views there is no symmetry between the
spacetime paths of the twins. Therefore, the twin paradox
is not actually a paradox in the sense of a logical
contradiction.

If everything is happening simultaneously, your past,
present, future laid out in space — then it would be
impossible to create “grandfather paradoxes.” You
wouldn’t be making any catastrophic changes. Instead,
you will only travel through time and experience it as it is
and as it always would be.