New theory. Hear me out.

[Tommy_Carcetti]

A little over 2 years ago, some genius invented a time machine.

Naturally, he or she wanted to go back in time to see the dinosaurs in person, because that's what one does when one invents a time machine. They see dinosaurs.

That person gets in a time machine, goes back to the Jurassic era, walks out, sees a Stegosaur nibbling on some plants, thinks to him/herself, "Cool", and walks back to the time machine to go home.

As he/she is walking back to the time machine, he/she breaks a twig on a nearby tree.

He/she returns to the present and---BOOM!---Donald Trump is now the president!

Don't tell me that wasn't how this all happened.

[Fla Dem]

1. Well sure....that certainly could be one theory.

[unblock]

2. Definitely the most plausible theory.

Definitely.

[N_E_1 for Tennis]

3. Actually they took a...

Dump behind a rock that was too close to the primordial pond a little of the drumph ran into the pond and grew into the person now regarded as Wallnutto the Russian stooge.

[mac56]

4. It's the only theory science will support.

[DetlefK]

5. On a serious note: Here's why any time-traveller would alter the timeline, whether he wants or not.

How is a human made? A sperm meets an egg.

A woman has only one egg at a time, but a man has millions of sperm at the same time, and each sperm has a slightly different genetic code.
* Sperm don't stay around. They have a lifetime of only a few days, after which they die, decay and get reabsorbed by the body.
* Pure chance dictates which sperm meets the egg.



So... Imagine being a time-traveller. You bump into a random male bystander.

What if that male bystander has a different body-temperature because of you?
Or his hormone-output changes?
What if you caused a situation that changes how much energy and nutrients his body needs?
What if he eats sooner or later or something different?
What if he makes love to a woman just a few days or a few hours or a few minutes or a few seconds too late or too early?

Anything like this would alter which sperm fertilizes the egg.

And this would create an entirely new human that didn't exist in the previous timeline. A new human with different ideas and different talents who simply is not supposed to exist.



And now try to imagine how that would resonate through time.

Imagine becoming a contemporary of Elvis Presley and writing a romantic song. Two generations later, the world would be radically different.

[zipplewrath]

7. Total mass

I've often wondered about the mass of the universe. If I go forward or back in time, the mass that is me will already be there in some form. So when I enter that time period, the total mass of the universe will increase. But mass can neither be created or destroyed so now what happens? Gravity waves? Singularities?

[DetlefK]

9. Mass can be annihilated. Energy can't. Okay... Time to go crazy:

Energy is a physical attribute of a system that determines how much that system can change over a given period of time. The more energy, the more it can change.

Energy is conserved as long as the physical system is invariant under time-translations (= as long as it doesn't matter which point in time you define as zero).



If we transfer energy into the past, then the past world has a wider range of final states it can change to.

Wouldn't that mean that the mere act of travelling into the past causes a certain probability for altering the present?

What happens if a tunnel continuously pumps energy into the past and offers the past world more and more new possible future worlds to evolve into? Would the result be a sequence of closed-loop timelines where each iteration of the cycle creates a new timeline between past and present, and each new timeline happening between past and present deviates more and more from the original timeline that was between past and present?
And wouldn't this avalanche of new timelines happen "instantly"? Because we wouldn't know how many cycles there were.

[zipplewrath]

12. Mass/Energy

Mass and energy are the same thing, kinda like space/time. And yes, the mere act of adding mass to the past (or future) would alter that universe. The only caveat I can see is if the act of taking mass back in time causes energy to be transported forward in time to balance.

[DetlefK]

13. Mass is a form of energy. Mass is not identical to energy.

[Codeine]

14. "Starplex" by Robert J. Sawyer

is a very good SF novel that deals with that issue. Nominated for a Hugo and a Nebula.

[C_U_L8R]

6. It's more believable than anything Trump ever says

[Thyla]

8. It was Barron

They wrote a book or two about it.
Creepy as.
https://en.wikipedia.org/wiki/Baron_Trump_novels

[Tommy_Carcetti]

11. Travels and adventures of Little Baron Trump and his wonderful dog Bulger

Poor kid has to travel into the past because his father is too much of a prick to get him a pet. That's sad.

There's also this:

" (H)e discovers weird underground civilizations, offends the natives, flees from his entanglements with local women, and repeats this pattern until arriving back home at Castle Trump."

Come on, Barron. We know you are better than your dad. Don't let your last name define who you are, man. Break free!

[Chichiri]

10. A Sound of Thunder. Great story.