If I drive my car through a corner slowly I’ll be fine. If I go fast, the car will skid off the road. All the materials are the same, the execution is the same. The only difference is over what amount of time this happens? The example is not important, the same goes for pretty much anything. Filling a bottle, ripping a sheet of paper..
I understand this from a intuitive perspective, but I wonder if someone can explain why time matters in physics in a simple way. What is the fundamental difference between doing something fast vs. slow.
I’m sure this is a silly question if you know some thermal dynamics or special relativity, but remember, I’m only 5!
In: Physics
This is not a silly question. But I don’t think you’re going to find a satisfying answer in the way that you want. There are some things that physics takes as basic facts of existence. Space, time, energy, etc. The laws of physics start by accepting that these things matter, and then use these concepts to describe and explain other things. Physics is more about answering questions like “How do things change with time?” than questions like “Why does time even matter in the first place?”.
[Relevant quote](https://www.lesswrong.com/posts/W9rJv26sxs4g2B9bL/transcript-richard-feynman-on-why-questions) from Richard Feynman on magnetism: “And when you explain a why, you have to be in some framework that you allow something to be true. Otherwise, you’re perpetually asking why. … But it’s a force which is present all the time and very common and is a basic force of almost – I mean, I could go a little further back if I went more technical – but on an early level I’ve just got to tell you that’s going to be one of the things you’ll just have to take as an element of the world: the existence of magnetic repulsion, or electrical attraction, magnetic attraction.”
I would add time to this list of things that physics just accepts as true as an element of the world. There is no “why” answer for why time matters in the way that I think you’re looking for. With that said, there are interesting scientific debates about time in physics. Time often plays different roles in different theories of physics. For example, the role of time in quantum mechanics is not quite the same as the role of time in relativity. There are some good essays on this question [here](https://fqxi.org/community/essay/winners/2008.1). I also liked the book Time Reborn by Lee Smolin, in case that helps. This [page](https://en.m.wikipedia.org/wiki/Problem_of_time) might also be interesting.
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