Physics

Experiment suggests that reality doesn't exist until it is measured

Experiment suggests that reali...
A recent experiment by researchers at ANU into the quantum behavior of particles seems to suggest that reality appears not to exist until it is actually measured
A recent experiment by researchers at ANU into the quantum behavior of particles seems to suggest that reality appears not to exist until it is actually measured
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A recent experiment by researchers at ANU into the quantum behavior of particles seems to suggest that reality appears not to exist until it is actually measured
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A recent experiment by researchers at ANU into the quantum behavior of particles seems to suggest that reality appears not to exist until it is actually measured

Researchersworking at the Australian National University (ANU) have conducted anexperiment that helps bolster the ever-growing evidence surrounding the weird causal properties inherent in quantumtheory. In short, they have shown that reality does not actually exist until it is measured – at atomic scales, at least.

Associate Professor Andrew Truscott and his PhD student, RomanKhakimov, of ANU's Research School of Physics and Engineering conducted a version of John Archibald Wheeler's delayed-choicethought experiment – a variation of the classic double-slit experiment, where light is shown to display characteristics of both waves andparticles – where anobject moving through open space is provided the opportunity (some would say "achoice") to behave like a particle or a wave.

In thisinstance, however, the ANU team replicated Wheeler's experiment using multipleatoms, which was much more difficult to do than a test using photons. This extra difficulty is due to the fact that, as they have mass, atoms tendto interfere with each other, which can theoretically influencethe results.

"Anatom is a much more classical particle," Associate Professor Truscottsaid. "For the theory to hold with a single atom is significant because itproves that it works for particles with mass."

To carryout the experiment, the ANU team initially trapped a collection of helium atomsin a Bose-Einstein condensate (a medium in which a dilute gas is cooled to temperatures very close to absolute zero),and then forcibly ejected them from their containment until there was only asingle atom left behind.

This remainingatom was then released to pass through a pair of counter-propagating laserbeams (that is, beams moving in opposite directions), which created a pattern toact as a crossroads for the atom in the same way that a solid diffusion gratingwould act to scatter light.

Afterthis, another laser-generated grating was randomly added and used to recombinethe routes offered to the atom. This second grating then indiscriminately producedeither constructive or destructive interference as if the atom had journeyed onboth paths. Conversely, when the second light grating was not randomly added,no interference would be introduced, and the atom would behave as if it had followed only one path.

However, andthis is the really weird part, the arbitrary number generated to determine if thegrating was added or not was only generated after the atom had passed throughthe crossroads. But, when the atom was measured at the end of its path – beforethe random number was generated – it already displayed the wave or particle characteristics applied by the grating after it had completed its journey.

Accordingto Truscott, this means that if one chooses to believe that the atom really didtake a particular path or paths, then one also has to accept that a futuremeasurement is affecting the atom's past.

"Theatoms did not travel from A to B. It was only when they were measured at theend of the journey that their wave-like or particle-like behavior was broughtinto existence," said Truscott. "It proves that measurement iseverything. At the quantum level, reality does not exist if you are not lookingat it.”

Eventhough the findings of the experiment add to the perceived weirdness of quantumtheory, the results also validate it. But, even without regard to the weirdaspects, quantum physics almost certainly governs the world at the atomic level,and this existence has enabled the development of quantum technologies ranging fromcryptography to solar cells.

From aneveryday point of view, our minds perceive that an object should behave like awave or a particle, quite independently of how it is measured. However, as thisexperiment supports, quantum physics predicts that it doesn’t seem to matter ifa particle or object should show wave-like behavior or particle-like behavior;it all depends on how it is actually measured at the end of its journey.

"Quantumphysics' predictions about interference seem odd enough when applied to light,which seems more like a wave, but to have done the experiment with atoms, whichare complicated things that have mass and interact with electric fields and soon, adds to the weirdness," said Roman Khakimov.

The firsttime ever that Wheeler's delayed-choice experiment has been conducted using asingle atom, the quantum weirdness represented by this experimentmuch more closely approaches the macro world in which humans perceive reality,which adds to the significance of the findings.

Theresults of this research were recently published in the journal Nature Physics

Source:ANU

48 comments
ClauS
This is more like self-fulfilling prophecy. They wanted to shown that reality does not actually exist until it is measured, they did it, by choosing the words carefully. It's called measured only because somebody checked the result. If I hang an weight from a spring I might measure it if I would check the spring deflection, otherwise it's just an physical interaction. But in both cases the "reality" is the same. Therefore: ...this means that if one chooses to believe that the atom really did take a particular path or paths, then one also has to accept that a future interaction is affecting the atom's past. "The atoms did not travel from A to B. It was only when they interacted at the end of the journey that their wave-like or particle-like behavior was brought into existence," ... "It proves that interaction is everything. At the quantum level, reality does not exist if you are not interacting with it.”
Shawn Corey
First of all, quanta are not particles; they are waveforms of probability. Thinking of them as particles leads to foolish speculation, like them travelling backward in time. Second, we already know that entangled superposition is part of the dual-slit experiment. All this study does is confirm it. None the less, confirmation through different methodology is always a bonus.
SeanNelson
So if a tree falls in the forest and noone is there to hear(measure) it it doesn't make a sound!
John Sweet
they still have to prove that the particles moved and did not exist in both places
OzricThorncroft
This sounds like they think that their experiment is forcing the atoms to choose between behaving like a particle or a wave. However, that is impossible. At the quantum level, all particles will always behave as both particles AND waves all the time. You aren't changing the behavior of the object just because you use a measurement technique that measures a wave-like characteristic or a particle-like characteristic. The object is still both a wave AND a particle, you are only choosing to measure part of its behavior. If things don't exist until they are measured, then there would never be any pre-existing things to do the measuring. If the model you are using to try to understand a system has weird paradoxes, that should probably be a clue that the model you are using is flawed.
EdwardN.Haas
This sounds like a version of what’s commonly called “Metaphysical Solipsism”. It says there are no mind independent realities. Don’t confuse it, though, with “Methodological (a/k/a Epistemological) Solipsism”. It says one cannot observe what’s disjoined from one’s mind in anywhere near the same sense in which one observes what's joined and interior to one’s mind; therefore, all one’s knowledge of mind independent realities is INFERENTIAL knowledge, which is to say what conclusions our mind’s experiences imply. Even Einstein adhered to that principle. See pg. 290 of “Ideas And Opinions” where he states that “Physics treats directly only of sense experiences” and, speaking of “even the concept of the “real external world”, adds it “rests exclusively on sense impressions.” It never ceases to amaze me how greatly some depreciate inference and insist only observation has any significant value. EDWARD N. HAAS (79) – HAASWOOD, LA Originator of Esoptrics: The Algebraic Logic Of The Mirror a/k/a Dynamic Mirror Theory = the only theory describing in detail where time, space, matter, energy, and locomotion --- in non-spatial “indivisible chunks” (Prof. Brian Greene “Fabric Of The Cosmos” pg. 491) --- come from at an ultra-microscopic level far below Planck time (c. 10^-43 sec.) and space (c. 10^-33 cm.); thus, for time, c. 10^-95 sec., and, for space etc., c. 10^-47 cm..
jack123123
the one thing they are missing about the so-called “wave-particle duality” is that the wave part has never actually been observed it is only inferred from the behavior of the back wall during a dual slit experiment not only has the wave never been observed (again, only inferred), it could never be observed the moment you try to observe it, you find a particle and what’s more, it seemingly always was a particle, having created a back history in our universe of its existence when it could not have existed at that point it is a paradox it makes no sense i would liken it to the pixel that generates a computer game the pixels have nothing to do with the physics in the game (motion, gravity, etc.) but they are the foundation in which the game exists
Jerry Peavy
Quantum entanglement acting over time?
LennonPierre
I wonder whether this all has to do with our limited understanding of the nature of time. The experiment and theory both refer to "before" and "after". It simply can't be just observation because if then nothing could happen without some kind of observation, which makes no sense.
KrzysztofCiuba
It proves again scientists do not..reason as said Plato about mathematicians.The title is a junk: by "reality" is meant always: na object (to measure), a measuring device and the perfomer of an experiment. Idiots mix an "object" with "reality"; plus they do not know (majority) what is this object, an microbject(an alectron, photon,..) or the set/bunch of them. Riciculous and shaming for today's science!