So a Physics master’s student friend of mine tried to explain it to me but I just got more confused. Apparently it has to do with whether time is an actual thing or a 4th dimension on the space-time blanket?
He said that because you can look at the cat and see if it’s alive or deaf that meant Quantum mechanics implied a discrete existence of time, there was a time where the cat was uncertainty both alive and dead, and a time after the observation, but relativity… wouldn’t have an event take place in actual time?
Help me out hivemind this has gone over my head but I feel so bad he looked so crestfallen when I didn’t get it. I studied English in school and managed to avoid even touching Calculus. I want to at least understand the thing he said.
In: Physics
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Schrödinger’s cat is a though experiment about quantum mechanics that’s not relevant here.
The reason is really hard to eli5 because you really need the math to understand why, but I’ll give it a shot.
The ELI5 answer is that that quantum mechanics is discrete and general relativity is continuous. Think of stairs vs a ramp. Quantum mechanics is like stairs. Stairs have individual, separate steps. You can have 1 step or 2 steps, but you can’t have 1.5 steps. They exist as discrete things. General relativity on the other hand, is like the ramp. It’s smooth and continuous. You can measure any arbitrary section of the ramp – it doesn’t have discrete parts.
When you do the math and you try to treat quantum mechanics as if it’s continuous or general relativity as if it’s discrete, you get nonsense. It’s like putting 2 + 2 into a calculator and the calculator tells you the answer is potato. It’s just doesn’t make any sense.
So in short, when we try to combine quantum physics and general relativity, the math doesn’t make any sense, which tells us that they cannot be combined in any way that we’re doing now.
Do you mean the cat is either alive or *dead*? Schrodinger’s cat is an amusing little thought experiment but it’s not meant to be taken literally.
> Quantum Mechanics and Relativity, they don’t work together apparently?
Important caveat: quantum mechanics and special relativity work together perfectly OK. General relativity is a more general theory (hence the name) that incorporates gravity. Gravity only has measurable effects at large-ish scales, and the effects specific to general relativity only show up at really large scales when you have large masses (like planets) with strong gravitational fields.
Quantum mechanics, on the other hand, describes how things work on small scales. It works in a very fundamentally different way from general relativity, so it’s hard to work out how to combine the two. But the big problem is that it’s very hard to come up with real scenarios in which both are relevant. You can’t detect quantum effects on the scale of planets, and you can’t detect gravity on the scale of subatomic particles. It’s thought that they probably are both relevant in situations where you have extreme gravity, e.g. close to black holes and the very early universe, but it’s hard to study those. You might question why anyone wants to combine them if there are so few situations in which the combined theory would be of any use, but (a) the origins of the universe, and to a lesser extent black holes, are something that people are really interested in, and (b) people like the idea of having a fundamental “theory of everything” that explains the universe at the deepest level, though we have no way of knowing if such a thing really exists.
> Apparently it has to do with whether time is an actual thing or a 4th dimension on the space-time blanket?
> He said that because you can look at the cat and see if it’s alive or deaf that meant Quantum mechanics implied a discrete existence of time, there was a time where the cat was uncertainty both alive and dead, and a time after the observation, but relativity… wouldn’t have an event take place in actual time?
This is all nonsense.
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