I just saw a comment that linked to an article explaining how Nobel prize winners recently discovered the universe is not locally real. My brain isn’t functioning properly today, so can someone please help me understand what this means?
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So there’s two terms; local and real.
“Real” means an object exists and has definite properties when it’s not being observed. For example, if you park your car in your driveway, it’s going to stay in your driveway whether or not you are looking at it. Whatever color your car is, it will still be that color. The wheels will not change, etc.
“Local” means what it sounds like, the car is subject to things going on in its immediate vicinity. But an exploding star happening light years away is going to have no observable effect on it. Another part of being “local” is that you can’t be affected by things going faster than light.
However, when we get into the very tiny world of sub-atomic particles, locally real seems to not be a thing. In the very smallest building blocks of our universe, particles either spin up or spin down. However, they won’t “choose” whether they’re spinning up or down until someone looks at them. In other words, these particles *do not* have definite properties *unless* we’re looking at them; they’re not “real” based on the classical definition.
Now, if you have two particles that are linked or “entangled”, then one particle has to spin up and one has to spin down. Like we said previously though, they don’t “choose” one until someone looks at them. What they found was that, even if these two particles are on opposite sides of the universe, if you measure one as spinning up, the other entangled particle will instantly become “real” and spin down. This breaks Einstein’s theory of relativity, because the information between the two particles is instantaneous regardless of distance. In other words, *information* can travel faster than the speed of light. So this messes with both ideas of locality, being affected by things near you and being affected by something going faster than light.
Since these extremely tiny particles make up the entire universe, it can be said that the universe itself isn’t” locally real”, in other words, it does not have definite properties. At this macroscopic level, we live in a universe that has definite properties. Your red car will continue to be red no matter what. But the universe at the quantum level deals with probability.
One of the biggest question in physics today is how to combine these two theories, the determinate large scale universe governed by Einstein’s relativity, and the probabilistic very small scale universe ruled by quantum mechanics.
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