Aperently, theoretically, with the use of wormholes and negative energy, and all that shtufff, it could be possible one day to create trips back in time.
Here is an explaination of why i dont understand how this works:
I would beleive that once traveled back in time, you would obviously do something that would change the path of the future. Now, in this new future, you might not creating a time machine, so you wouldn't have been able to change the past, so you would have actually created the time machine, and .... yeah.
Looking past this problem, I would beleive that changing the past could create either a time machine earlier, or later. Now, if we loop back to the past in either of those scenarios, we alter the past, and the time in which civilization creates the time machine would continually change. Eventually, the only possibility is that the loop continues until we have a universe in which the time machine is never discovered.
Looking past this looping problem, each time we would make a loop to the past, we are allowing some radiation to enter in with us. After thousands or maybe even millions of these loops (we aren't limited timewise if time keeps being "reset") there would be waay to much radiation and life would die out.
These problems seem pretty prominent in my eyes, but im sure that some of you out there may provide a better angle or new knowlegde on this topic to help me better understand it. A solution that i believe i have heard before, is that when traveling back in time, you actually enter a whole different parallel universe, seperate from the original one, but similar in many ways. This i believe would solve the problem, buuut how exactly would that work.... I think i have somewhat of a grasp on these concepts, but want someone to clarify.