Time

Somebody asked me today if time was linear? I answered it as yes, time is based on events and that events may happen at the same instant in another part of the universe slower or faster than here but still at the same instant. Cause and effect.

But If I had to think about it I'd say that if we have the freedom of choice then that means that events can change and if events can change then we do not have predestiny. That being said if time is an energy, then like any energy there is a plus and minus. Or it has to equal zero. And since there is only positive time or one direction then it might end up back where it started meaning time is circular. Which means space would also be circular. As in time that is, if you wanted to conceptualize it. In a sense time and space have no end and curve back in on themselves in a never ending repetition. But they are still a finite deviation from zero. The opposite concept to nothingness being infinite. Space/time is supposed to be curved so that would also mean it would eventually curve back in on itself. So really the way to travel back in time would be to travel forward in time, and since you'd be the only one traveling you'd be the only one changing events. consider the time traveling an event of it's own, inside of an event loop, that would not line up at the same instant as any other time travelers time traveling event. which is what einstein said "we have time so that everything doesn't happen at once". So apparent to you and every other time traveler the events would always occur the same way from your perspective as if predestiny, and you wouldn't notice if any other time traveler had just changed something unless you knew him personally and ran into him and said "Hey Fred whatcha doin?", so you'd only notice a change of events after you personally changed them using free will and a time traveling machine. So yo are not changing events that have already occurred you are actually changing future events.

So becoming your own grandma would be possible.

Then that leads to time wars and competing time travelers spoiling each others plans. And since time repeats infinitely each person would find their own loop and there would be no reason to fight. Or they would never even know each other existed in the first place.

What if you were to travel at the speed of light in a circle. Your energy and therefor mass would increase causing gravity to increase and time to decrease. Time would stop at the speed of light in that loop. I guess you could call it a bubble of time? It would basically be a black hole which would turn matter into energy. Emitting high gravity and slowing down time around it. The original matter would then eat itself and disappear into nothingness along with the black hole. If it was a spinning long object it would emit gravity waves.