NOTE: I don’t actually know anything about physics, and I didn’t do much research before writing this stuff because I enjoy the exercise of just thinking through it. Consequently, everything that follows is probably wrong.
Einstein proved that there’s no giant clock continuously ticking, determining what time it is everywhere in the universe. Rather, time is relative, and affected by speed; if you leave the earth in a spaceship and approach the speed of light and then come back, you can be younger than your children. That’s just a thought experiment, of course — but if relativity is a law, that means it applies in ALL circumstances. Even if, rather than approaching the speed of light, you’re driving down a highway at 65mph.
Say I get in my car and drive across town to see a movie. I take the highway, so I’m driving 65mph all the way there, and I’m driving 65mph all the way back. According to relativity, when I get back, I’m infinitesimally younger than my neighbor Bob, who stayed at home. So far, so good.
Now let’s assume Bob and I meet for coffee, and we both reach forward to shake hands. In that moment, our hands are traveling faster than the rest of our bodies are, which means when we’re done shaking hands, our hands are infinitesimally younger than the rest of our bodies. Our elbows are also younger than our bodies, but not as much younger as our hands, because our elbows didn’t travel as fast.
What I’m getting at is this: Everything is moving at different speeds all the time, which means that time, rather than being a straight line, is a huge, insanely twisted mess. Things on Earth constantly travel at different speeds, becoming younger than or older than other things. And because of the handshake effect, even the idea of things breaks down — in reality, time is warping on a much smaller scale, an atomic scale. Every atom, in other words, has a temporal relationship — a degree of being older-than or younger-than — with every other atom in the universe, based on the speeds they have traveled relative to one another.
So what does it mean if, at a given moment, atom A has a different idea of what time it is than atom B? This question doesn’t even make sense, because it assumes the existence of universal time, the big ticking clock that you compare everything against. A more meaningful question is, what does it mean if I am perceiving these two atoms that have different ideas of what time it is?
This is where my head explodes. So the thing that is coercing all of these atoms into sitting next to each other when they have different ideas of what time it is is ME?
Obviously that’s not the case (at least, I don’t THINK it is), because atoms with totally different ideas of what time it is can still bump into each other. But it begs the question: If there’s no universal ticking clock, and every atom has a different idea of what time it is, then what determines what “now” is?
I think I’m asking the wrong question — atoms don’t have different ideas of what time it is, they just have different ideas of how old they are. The big ticking clock actually does exist, it just doesn’t work in quite the way I thought it did. But the question makes me wonder: What would the universe look like if you perceived it in such a way that every atom was always the same age?
This one is tough. For starters, Imagine if you were able to figure out the exact age of every atom, and you could ask, “I want to know where these two atoms were when they were so many microseconds old.” It’s possible (albeit unlikely) that they could both have occupied in the exact same position in space when they were the exact same age. (It’s only our human perception that would declare that they were in that position at different points in time.)
So what would the universe look like if you saw everything through a lens that perceived all atoms as being synchronized by age? I’m having a real hard time getting my brain wrapped around this one. In a universe perceived from this perspective, not only could multiple things occupy the same spot, causality would look really strange. For example, assume a plane lifts off from a runway, flies for a few hours at high speed, and then lands on the same runway five seconds younger than the runway. Further, let’s say it crushes a beetle under its wheels. The atoms of the beetle would be five seconds older than the atoms in the plane wheel at the time of the crushing, which would mean that the beetle would not get crushed until five seconds after the plane rolled over it.
That’s a simplified example, of course; I can’t picture what things would really look like in my head. But I feel pretty sure that they would look very strange indeed.