Question: I wouldn't call this scientifically accurate, but would like some opinion on sensibility of the idea.

As part of a story about two time travelling engineers, they discover that their own universe actually updates itself whenever a frontier in technology is crossed. So basically, the invention of time travel itself caused certain updates to support this new paradigm by offering system-wide resolutions to various time-travel induced paradoxes.

Now, I was wondering which direction to take when trying to offer an explanation - since this one does drive curiosities. I've got two ideas to branch out:

1. The universe is a living organism with a nucleus, mitochondria and RNA, and it is actually responding in a way that gene mutations occur.
2. The universe is an AI driven program, and is continuously updating a logical universe.

Which one of these would be more likely in case of a reactive universe? I'm trying to figure out a way to *know* this to be true from the character's perspective.

Answer: 
**AI and simulations**

If you're set on your 2 branches, the AI one makes most sense. The Singularity is an idea that people are uploading their conscious into a computer. In some ideas they retain their individuality. Alternatively it can be just like the Matrix. A fully simulated reality created to live out your lives. Lastly there are idea's that the universe is a simulation on the edge of a super massive black hole.

All of these have one thing in common. They are existing theories of how all of this could be a simulation. Simulations can be controlled and changed by AI.

A living organism however is very difficult to explain. It can't directly be observed in our universe, so it could be "living" throughout the multitude of dimensions. When time travelling, it would change the universe. However, this is much more hand-wavy than the actual existing theories of an AI simulating every experience.
**Observing changes things**

I'm proposing a 3rd option.

The [double slit](https://en.wikipedia.org/wiki/Double-slit_experiment) experiment shows us that observing things can change the properties. How and why lies in the quantum realm on which I've read a lot, but can't pretend to truly understand. As far as I read it, there is a form of uncertainty everywhere. When observing, this uncertainty collapses and resolves into a certainty. This whole experiment shows that this small difference of just observing has 2 wildly different outcomes. In one outcome it's like an energy wave in a sound wave kind of way. In the other one a particle, like ball thrown at something.

Possibly observing can go much further. The moment you can travel through time, different ways of observing are available. The universe doesn't change, but the act of time travel does change the outcome. Essentially "updating" the universe that happen to support your version of time travel.

As an aside, I once heard a theory that the moment we research and discover more about the universe, it gets more complex. Another way to perceive the observing changing the world around you.