Posted on 05/28/2015 6:02:31 PM PDT by LibWhacker
The bizarre nature of reality as laid out by quantum theory has survived another test, with scientists performing a famous experiment and proving that reality does not exist until it is measured.
Physicists at The Australian National University (ANU) have conducted John Wheeler's delayed-choice thought experiment, which involves a moving object that is given the choice to act like a particle or a wave. Wheeler's experiment then asks - at which point does the object decide?
Common sense says the object is either wave-like or particle-like, independent of how we measure it. But quantum physics predicts that whether you observe wave like behavior (interference) or particle behavior (no interference) depends only on how it is actually measured at the end of its journey. This is exactly what the ANU team found.
"It proves that measurement is everything. At the quantum level, reality does not exist if you are not looking at it," said Associate Professor Andrew Truscott from the ANU Research School of Physics and Engineering.
Despite the apparent weirdness, the results confirm the validity of quantum theory, which governs the world of the very small, and has enabled the development of many technologies such as LEDs, lasers and computer chips.
The ANU team not only succeeded in building the experiment, which seemed nearly impossible when it was proposed in 1978, but reversed Wheeler's original concept of light beams being bounced by mirrors, and instead used atoms scattered by laser light.
"Quantum physics' predictions about interference seem odd enough when applied to light, which seems more like a wave, but to have done the experiment with atoms, which are complicated things that have mass and interact with electric fields and so on, adds to the weirdness," said Roman Khakimov, PhD student at the Research School of Physics and Engineering.
Professor Truscott's team first trapped a collection of helium atoms in a suspended state known as a Bose-Einstein condensate, and then ejected them until there was only a single atom left.
The single atom was then dropped through a pair of counter-propagating laser beams, which formed a grating pattern that acted as crossroads in the same way a solid grating would scatter light.
A second light grating to recombine the paths was randomly added, which led to constructive or destructive interference as if the atom had travelled both paths. When the second light grating was not added, no interference was observed as if the atom chose only one path.
However, the random number determining whether the grating was added was only generated after the atom had passed through the crossroads.
If one chooses to believe that the atom really did take a particular path or paths then one has to accept that a future measurement is affecting the atom's past, said Truscott.
"The atoms did not travel from A to B. It was only when they were measured at the end of the journey that their wave-like or particle-like behavior was brought into existence," he said.
The past affects the future (obviously) and the future affects the past. Too bizarre.
Time is an illusion. - Albert Einstein:
Shades of Bishop Berkeley.
“Reality for a liberal begins every day when they wake up” - Norm Lenhart
I was ahead of my time too ;)
What is "proving", then? Can it be measured?
And what is "measuring" if reality does not exist?
A darn convincing one.
Sounds like dangerous place.
“I got bronchitis! Ain’t nobody got time fo’ dat.” — Sweet Brown.
https://www.youtube.com/watch?v=bFEoMO0pc7k
The effect of a bill before Congress cannot be known until it is passed. Nancy Pelosi, Democratic Party quantum genius
“Knew Something Was Wrong When A Little Pretty White Girl Ran into a Black Man’s Arms.”
I’m sure that I’m not the first to point out that there is nothing weird about quantum level physics as long as you understand quantum behavior. Of course, as Dr. Feynman pointed out, nobody actually does.
That’s pretty awesome.
I wouldn't get too excited about it, because as a statement of what quantum mechanics actually says, it is not, in fact, true.
The correct interpretation is: "The reality of an outcome is contingent on what you choose to observe."
That is not a terribly earth-shattering ontological principle.
ah - a thought experiment....
The statement is false; it is not even close to what the axioms of quantum mechanics say. Scientists should not comment about ontology if they haven’t studied it seriously — and most HAVE NOT.
I was watching the Science Channel last week and it was explained thusly: The past must be consistent with the future. Therefore the future affects the past in that sense. The Universe will necessarily end in a particular way (the Big Crunch, the Big Rip, etc.), and whatever happens in the past must be consistent that ending. Similarly, you cannot go back in time and kill your own father when he was a little boy. You know he exists in the future and the past must be consistent with that. Therefore, you could not kill him in the past. The future affects the past.
This stuff doesn’t map well to the English language. Basically something for which we have only a mathematical description behaves in a manner for which we have only a mathematical description. The result is now to be expressed in non-mathematical terms. Best of luck with that.
No, and also, No.
The experimenter is engaged in an exaggeration that ultimately invalidates what he's said. There is nothing new in what has been done, and, as pointed out already, the result was completely predicted by the great American physicist, John Archibald Wheeler.
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