I was talking to someone the other day who explained to me that the laws of physics as we understand them are not necessarily ‘rules’ that things on a really tiny scale obey, and the calculations we use to talk about physics on a scale that’s relevant to humans are more like estimations of what will *most probably* happen as a result. This also means there’s no such thing as a perfect circle or a perfect sphere I think? Could someone ELI5?
In: Physics
Physics itself does *not* work differently at different scales. Objects of all sizes from ants to galaxies are made of the same tiny particles like molecules, atoms, electrons and quarks. they follow the same rules, and interact through the same waves like microwaves, visible light, and X-rays.
However physics *appears* to work differently when we focus on a certain scale and try to tell a simple story. For example a basketball bouncing on the floor, or a chemical reaction, or a rocket taking off, or a star exploding into a supernova. For each of these, going back to the behavior of elementary particles to try and piece the whole story together would be way too complicated. But at each scale, we’ve often been able to come up with a few simpler rules that do the job. We don’t care about what happens to atoms in the basketball or molecules in a glass of water, so we can make the story much simpler.
It’s a bit like a historian talking about an army marched against another army, instead of talking about how a particular grain of sand ended up in the pocket of soldier #13546834. At some point we decide that the details don’t matter.
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