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.
“...reality does not exist if you are not looking at it...”
Ah ha! Mrs. Clinton’s popularity explained finally!
What you said was true up until that point.
The physics of time-paradoxes [if they exist] has not yet been written. There is only speculation, and it has nothing to do with this.
It is also untrue that the "future affects the past." The correct statement is "the future reflects the past." If causality is real [and it certainly appears to be] it is not possible for the future to contain outcomes without causes. When you add to this that the total number of outcomes is very severely constrained by physical laws, it gives rise to the illusion that where things end up affects where they started. But it does not. They end up because, contrary to what the moron is saying in this article, quantum mechanics is FULLY CAUSAL. It is not deterministic, and it is probably not locally real on some scale [although there is actually still some controversy about this.] But it is a causal theory, and quantum fields and particles are quite real whether you observe them or not.
It explains her emails. You can’t look at ‘em ergo they don’t exist.
The past affects the future (obviously) and the future affects the past. Too bizarre.
...
Consider this. When you look at a star that is a 1000 light years away, there is a light wave that travels backwards in time to the star, 1000 years in the past, long before you were born, and enables the light wave that travels 1000 years into the future to hit your eye.
http://mist.npl.washington.edu/npl/int_rep/tiqm/TI_toc.html
The answer is neither and both.
Yup, I can buy that.
When you translate a rigorous mathematical result into English, you must be equally accurate and precise.
Most of the statements made in this article are actually either false or gibberish. Here are just a few:
reality does not exist if you are not looking at it
False. Not what quantum mechanics says.
quantum theory, which governs the world of the very small
Nope. Governs everything, large and small. And contrary to popular science writing, there are lots of examples of large scale quantum mechanical effects.
"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,"
Nope. It doesn't. We've suspected that massive particles were quantum particles since DeBroglie wrote his PhD thesis in 1924, and had proof of it since 1927. Nothing newer or weirder is happening here at all.
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.
If one chooses to believe that, one is choosing to believe what no physicist has believed for almost 100 years.
"The atoms did not travel from A to B.
Yes. They did.
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,"
Gibberish. The atom travels every spacetime path between A and B, and it is only when a particular experimental measuring apparatus [or, in this case, gimmick] is used that a particular behavior appears to be seen. But this is an illusion. Atoms are not "sometimes" particles and "sometimes" waves. They are neither of those things, but when certain kinds of measurements are performed on them, they seem to display a behavior consistent with one or the other model. But as good as a model is, it is sometimes necessary to remind ourselves that our models are not reality.
This kind of nonsense gives rise to all sorts of loonieness, and professional physicists shouldn't be encouraging it. Most are highly disdainful of this sort of language.
QM in a nutshell...
“This statement is false.”
Or, for more fun.... entanglement...
“The next statement is true.”
“The previous statement is false.”
Hi, Fred!... Very interesting. Thanks so much for once again steering me in the right direction on things having to do with physics. I need it and do appreciate it, and always look forward to your input.
Cordially,
Very astute of you. I see that all the time in math and in physics (at least that elementary part of physics I actually do understand)... If you understand the mathematics of something, the derivations, etc., it’s easy to understand. Otherwise, it can be very difficult and will surely be the source of much confusion.
When I read things in the popular press about quantum mechanics, say, I’m really no better off than someone who doesn’t understand a thing about it. The math is key.
If a man speaks in the forest, and there is no woman to hear him, is he still wrong?
Once again, I call B.S.
Not at you, LibWhacker, at the “science”.
Makes me think I should just stop reading the popular press and sit down with a good textbook in quantum mechanics and get to crackin’. You would think Phys.org could do better than that, given the name of their website.
I understand. You have a much better BS detector than I do; I fall for this stuff every time! :-(
Yes, and if you try to "understand" it, "You will go down the drain into a blind alley, from which no one has ever escaped."
I maintain that the language of weirdness is all predicated on an attempt to retain a classical concept of objects. The correct view is that objects are emergent constructs of multiple quantum events. I don't see why people can't just accept this, as Feynman advocated.
Lol
I had a feeling the entire physical universe is an illusion. None of it is real. It is a projection of the ego that is perceived by the ego. Notice the operative word perception not observation. I will be glad when I wake up someday.
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