Let's look at the facts.
1. If someone COULD build a time machine, they would have to be able to reverse time, which is impossible.
2. Time is NOT a mess of ticking and blobs and whatnot. (You know what I mean.)
3. God set a rhythm for time, which cannot be broken.
Bottom line- It is as impossible as arm-powered flight. (By arm-powered flight I mean flapping one's arms up and down to fly.)
I honestly do not thing there will ever be a way of physically going back in time as in bring your body back years or days in the past like in terminator. How ever viewing the past and slightly changing it like observed in Gravity COULD be possible however it is highly unlikely with our current understanding of physics. Also there have been theories suggested about how the universe repeats itself after every big bang and big crunch so it could be possible to wait it out or access an alternate dimension
But right now it's all just a mess of theories.
I honestly don't know what technology will be developed in the future (Who thought smartphones would be invented in Ancient times!) But I don't think we will be able to make all the incidents that are factors of other future incidents to happen in a small amount of time. And even if there is a way to do it (somehow) your physical body will not be preserved on your way to get to a different time period.
Because if there was a timemachine, Than would somenbody have already came to the world? If there was a timemachine again, than we would have faced the son-of the son, right now. So I am guessing that there is not going to be a timemachine, unless somebody does make one.