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There's a mysterious threshold that's predicted to exist beyond the limits of what we can see. It's called the quantum-classical transition.
If scientists were to find it, they'd be able to solve one of the most baffling questions in physics: why is it that a soccer ball or a ballet dancer both obey the Newtonian laws while the subatomic particles they're made of behave according to quantum rules? Finding the bridge between the two could usher in a new era in physics.
We don't yet know how the transition from the quantum world to the classical one occurs, but a new experiment, detailed in Physical Review Letters , might give us the opportunity to learn more.
The experiment involves cooling a cloud of rubidium atoms to the point that they become virtually motionless. Theoretically, if a cloud of atoms becomes cold enough, the wave-like (quantum) nature of the individual atoms will start to expand and overlap with one another. It's sort of like circular ripples in a pond that, as they get bigger, merge to form one large ring. This phenomenon is more commonly known as a Bose-Einstein condensate, a state of matter in which subatomic particles are chilled to near absolute zero (0 Kelvin or −273.15° C) and coalesce into a single quantum object. That quantum object is so big (compared to the individual atoms) that it's almost macroscopic—in other words, it's encroaching on the classical world.
[Also Covered By]: http://arstechnica.com/science/2015/05/atomic-telescope-brings-atoms-to-standstill/
Original Submission
(Score: 5, Informative) by hendrikboom on Saturday May 30 2015, @10:38PM
In principle, we could calculate the behaviour of a soccer ball or a ballet dancer directly from quantum mechanics. I practice, we simply don't have enough computing power in the world to do so, and are unlikely ever to. So we take approximations, and get so-called classical physics. Bose-Einstein condensates and the like are simply situations where the usual approximations aren't accurate.
The transition is an illusion. It is an artifact of our limited computation abilities.
(Score: 2) by darkfeline on Sunday May 31 2015, @12:10AM
In that case, there should still be a statistical "transition", at which point Newtonian physics can predict behavior accurately enough to the Nth degree, for some N. Emergent phenomena, etc. etc.
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(Score: 3, Informative) by hendrikboom on Sunday May 31 2015, @02:18AM
Statistical estimates could work if the deviations of quantum mechanics from Newtonian were truly random. But they're not. Well, often they are to a usable approximation, but often they are not, and nonrandom situations can sort of gang up on each other to achieve interesting phenomona.
(Score: 3, Interesting) by MichaelDavidCrawford on Sunday May 31 2015, @12:10AM
it is trivial to demonstrate that in going from me to you, that my identity stops at the surface of my skin, and your identity starts at the surface of yours, is not actually true.
While he wasn't hip to QM, Emmanual Kant discussed this. "Phenomenal Reality" is what we experience. "Noumenal Reality" is what actually takes place. Noumenal Reality is a bunch of elementary particles discussing the standard model with each other.
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(Score: 5, Insightful) by maxwell demon on Sunday May 31 2015, @05:55AM
Yes, that is what most people believe, and it is consistent with what we know. However there's a big difference between "we assume it because we don't have a reason to think otherwise" and "we have made an experiment to test it".
Before quantum mechanics, it seemed obvious that electrons have definite paths. Before relativity, it seemed obvious that space is Euclidean and independent of time.
Just because our current theory doesn't tell you there's a limit to its applicability doesn't mean there is no limit to its applicability. It just means we don't know if there is a limit for applicability, and therefore it is rational to assume there is no limit, but yet do experiments to check for such limits.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 3, Interesting) by hendrikboom on Sunday May 31 2015, @03:15PM
Yes, certainly there's a strong case for testing theory by experiment. But calling it physics' biggest contradiction is wrong. Physics does have a real contradiction -- the conflict between general relativity and quantum mechanics. But I don't see this experiment as having any relevance to this.