GG has an ability to ask really interesting questions and to frame them in a way that seeks logical answers. I like that. Nothing wrong with philosophy. It has a long and vibrant history of working alongside science to try and answer questions about reality.
You ask interesting questions too. You are absolutely right that you cannot observe a particle like an electron without changing it's energy and momentum which is part of why according to the Uncertainty Principle, you cannot observe position and momentum at the same time. The minute you shine photons on something, it changes it from a probabilistic state to having definition in space and imparts energy. It's pretty bizarre when you think about it.
That also brings up and interesting philosophical discussion about observer created reality on a macro scale. Can we interact with anything in our environment without changing it fundamentally? How much are we creating the world we see around us by observing it if at all?
As for your other observation, a river is going to flow from a high energy state to a lower one and yes gravity influences that by curving time/space the river exists in. So, think of a dam holding back a river basin. That is a situation with high potential energy. All that water wants to go downhill to relieve that high energy situation. And given enough time it will through earthquakes or failure of the dam or whatever. It is inevitable unless we put energy into maintaining the high order state of the dam. If we don't it WILL fail eventually just as your garden will go back to a wild low energy state if you don't maintain it.
What sort of energy could make time flow backward? We don't know yet of any kind of energy that could do that. Time is always going to move with the expansion of the Universe as long as it continues to expand if we consider time to be the order in which events occur. It has to do with thermodynamics and entropy in the Universe which always goes from greater to lesser order (low to high entropy) which is also connected to how energy moves in space/time as the Universe expands.
But, what gravity can do is curve time/space which causes an effect called time dilation. The closer we get to an object with great mass, the more slowly time is going pass because it is moving a greater distance on a more curved path than a straight one. Think of it as going from a point a. to a point b. If you go in a straight line, you are going to get to b. faster than if you are going on a curving path.
So, if you come close to a really massive or even infinitely massive object like a black hole, what is going to happen to space/time as you near?
That is a question. Brian tells it really well again:
Here are a couple more short videos that explain really well:
This one is more nerdy and hard to follow: