Verified answer

There are basically three schools of thought on this.

1) can't happen - time travel is impossible. There is a fair bit of physics to support this idea, but you never want to say never - so who knows?

2) you can time travel, but can never alter the past. No matter what you try do to change history, or kill your former self, etc - you are predestined to fail. Basically, the universe will conspire against you, like Murphy's Law on steroids. Your gun won't go off, you'll get hit by lightning, a bee will fly up your nose and put you into a coma. Whatever. It won't happen, because it can't happen.

3) you change history, but now you are on a different timeline, not the one that you came from. This ties in with the Many Worlds theory of quantum mechanics which says that there's a nearly infinite number of universes in which all possibilities get played out. All you're doing is making another one. No big deal.

If you time traveled to the past and killed yourself you and everything you have ever done in your life would never have happened. You would cease to exist.

If you went into the past and did something like stop the Titanic from sinking, the world would be very different in boating. It could be possible that ships would not have more than enough lifeboats as they do today, because they were not motivated by a tragic sinking to do so.

Honestly, mankind will evolve and perform time travel, it is possible, and we've all seen it in movies, just like cloning, so don't think in the next 200 years time machines will be 1$, It will be about 60Billion.

You would get into the Time Travel PAradox, which is proof that time travel -- at elast into the apst -- is not possible.

Time Travel Paradox:

If you travel to the past and kill yourself, then you would never be able to reach the present time. But since you couldn't reach the present time, you wouldn't be able to kill yourself, so then you WOULD be able to reach the present time and go back and kill yourself, which means that you would not reach the present time and could not kill yourself (and so on and so on and so on. . . . . . .)

It is the shear stupidty of this result that prove that time travel into the past is not possible.

The answer is whatever fantasy you want to write. Folding into multiple dimensions. Destroying the universe. The Doctor comes and shoves a sonic screwdriver up your nose. Something else. Pretty much the same answer for any variation of of "If I did something that can't be done, what would happen as a result?"

What if you sprout wings and fly to the Moon?

Just as likely.

Time travel is impossible. Any question that starts with illogical assumptions has not logical answer.

It would be impossible to do because how could the present version of you kill your past self when your present self doesn't exist yet in that time? Same applies to the other question. This creates paradoxes.

There are two possibilities here:

(1) after you kill yourself, you will disappear from the future and never be able to go back in time to kill yourself, therefore make yourself alive again -- paradox.

(2) after you go back and kill yourself, your killer self will continue to exist because the past version of you that you killed is actually a different copy of yourself, and it exists in a different universe than the one you came from.