A New Theorem Maps Out the Limits of Quantum Physics
I just listened to an old podcast on this topic - the tension between quantum physics and the Einstein Theory of General Relativity. The guest said the last great scientific revolution was about 400 years ago when science abandon religious and philosophical inquiry for what we call hard science- measurements and reproducible experimentation.
Today, or rather starting at the turn of the 20th century to today, we have gotten to the point where science has measured our observable universe as completely as we will (meaning the laws of physics that operate). But quantum mechanics, first theorized in the early 20th century, cannot be measured and cannot be tested with reproducible experimentation. There was a lot more to it, but the bottom line is quantum physics brings use back to prior to 400 years ago where science is again considering things it cannot measure or test.
The guy who was on the podcast made this documentary although it really only touches on the above.
Anyway, the article:
Read the rest at the link.The result highlights a fundamental tension: Either the rules of quantum mechanics don’t always apply, or at least one basic assumption about reality must be wrong.
The founders of quantum mechanics understood it to be deeply, profoundly weird. Albert Einstein, for one, went to his grave convinced that the theory had to be just a steppingstone to a more complete description of nature, one that would do away with the disturbing quirks of the quantum.
Then in 1964, John Stewart Bell proved a theorem that would test whether quantum theory was obscuring a full description of reality, as Einstein claimed. Experimenters have since used Bell’s theorem to rule out the possibility that beneath all the apparent quantum craziness — the randomness and the spooky action at a distance — is a hidden deterministic reality that obeys the laws of relativity.
Now a new theorem has taken Bell’s work a step further. The theorem makes some reasonable-sounding assumptions about physical reality. It then shows that if a certain experiment were carried out — one that is, to be fair, extravagantly complicated — the expected results according to the rules of quantum theory would force us to reject one of those assumptions.
According to Matthew Leifer, a quantum physicist at Chapman University who did not participate in the research, the new work focuses attention on a class of interpretations of quantum mechanics that until now have managed to escape serious scrutiny from similar “no-go” theorems.
Broadly speaking, these interpretations argue that quantum states reflect our own knowledge of physical reality, rather than being faithful representations of something that exists out in the world. The exemplar of this group of ideas is the Copenhagen interpretation, the textbook version of quantum theory, which is most popularly understood to suggest that particles don’t have definite properties until those properties are measured. Other Copenhagen-like quantum interpretations go even further, characterizing quantum states as subjective to each observer.
“If you’d have said to me a few years ago that you can make a no-go theorem against certain kinds of Copenhagen-ish interpretations that some people really believe in,” said Leifer, “I’d have said, ‘That’s nonsense.’” The latest theorem is, according to Leifer, “assailing the unassailable.”
Bell’s Toll