ChatterBank3 mins ago
The dividing line
Is there a definitive boundary where science crosses over from the universe of the very big to the universe of the very small.Just where does the quantum world begin?
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No it's not a matter of knowledge - it's to do with the nature of the boundary.
Quantum mechanics is based on statistica outcomes. You simply can't set up an experiment and repeat it and get the same outcome - even if the set up is *exactly* the same.
What you get is a probability that one outcome will occur and when you repeat it a lot that is what you will see.
When the scales get larger those probabilities start to get large - Very large!
So for example there is a probability that I can throw a ball at a wall and it will quantum mechanically tunnel straight through - but that probability is so large that if you wrote it on a piece of paper it probably wouldn't fit in the known Universe!
As you get to smaller scalesthe probabilities get to values where you can realistically expect to see effects.
it gets interesting at the molecular level - I've heard talk of doing the Youngs slits experiment with Benzene rings although I'm not sure if it's been done you might expect the effects to be weak here.
The above experiment though is by far the largest scale attempt I've seen.
Although you can simply see Quantum mechanics with 3 pairs of polarising sunglasses.
take two of them and hold at right angles - you'll see no light through - you'd expect this wouldn't you?
Now introduce the third between them ad 45 degrees you should now see light getting through!
Quantum mechanics is based on statistica outcomes. You simply can't set up an experiment and repeat it and get the same outcome - even if the set up is *exactly* the same.
What you get is a probability that one outcome will occur and when you repeat it a lot that is what you will see.
When the scales get larger those probabilities start to get large - Very large!
So for example there is a probability that I can throw a ball at a wall and it will quantum mechanically tunnel straight through - but that probability is so large that if you wrote it on a piece of paper it probably wouldn't fit in the known Universe!
As you get to smaller scalesthe probabilities get to values where you can realistically expect to see effects.
it gets interesting at the molecular level - I've heard talk of doing the Youngs slits experiment with Benzene rings although I'm not sure if it's been done you might expect the effects to be weak here.
The above experiment though is by far the largest scale attempt I've seen.
Although you can simply see Quantum mechanics with 3 pairs of polarising sunglasses.
take two of them and hold at right angles - you'll see no light through - you'd expect this wouldn't you?
Now introduce the third between them ad 45 degrees you should now see light getting through!
You build intuition through every day experience - when something comes up like this that runs against your experience your head "get's done" because common sense doesn't work.
The mental model of how this works is demonstrated to be wrong and you get that Duh! feeling
Remember it's about probabilities.
when the two polarisors are at 90 degress there's zero probability of a photon getting through.
But when there lens is at 45 degrees there's (as I recall) 1/root 2 probability
the third lens is now at 45 degrees to the middle lens and so again has the same probability of getting through.
The model of a wave in a particular orientation that goes through slits and emerges without being affected is incorrect
The mental model of how this works is demonstrated to be wrong and you get that Duh! feeling
Remember it's about probabilities.
when the two polarisors are at 90 degress there's zero probability of a photon getting through.
But when there lens is at 45 degrees there's (as I recall) 1/root 2 probability
the third lens is now at 45 degrees to the middle lens and so again has the same probability of getting through.
The model of a wave in a particular orientation that goes through slits and emerges without being affected is incorrect
Jake, I reckon it has to be a matter of knowledge, Most scientists are very uneasy about that word "probabilities". Any experiment that only gives probabilities as an outcome is not proven therefore it is only theory,and until more knowledge is gained it will remain so. But in the world of quantum mechanics there are probably questions that will remain unanswerable.
The boundary of Quantum is Relativity (including Gravity). Otherwise Quantum explains every known interaction in the Universe.
As Jake says it is about probabilities. When a single Quantum object is observed its probabilistic behaviour is obvious. The bulk behaviour of large scale objects are produced by the interactions between the myriad quantum mechanical probabilistic behaviours of the individual elements.
These interactions result in the Classical macroscopic behaviours we normally see but underneath that Quantum is still what is governing the whole situation.
As Jake says it is about probabilities. When a single Quantum object is observed its probabilistic behaviour is obvious. The bulk behaviour of large scale objects are produced by the interactions between the myriad quantum mechanical probabilistic behaviours of the individual elements.
These interactions result in the Classical macroscopic behaviours we normally see but underneath that Quantum is still what is governing the whole situation.
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