February 15, 2013 report

# Researchers demonstrate Heisenberg uncertainty principle at macro level

(Phys.org)—Physicists working at the University of Colorado have succeeded in demonstrating one of the major tenets of quantum mechanics—namely the Heisenberg uncertainty principle—at the macro level. In their paper published in the journal *Science*, the team describes how a small but still visible drum they built in their lab, outfitted with mirrors, a laser and a detector, demonstrated that it was not possible to measure a photon's position and momentum simultaneously.

It was Heisenberg who famously noted that it was impossible to measure the momentum of an object and its position at the same time. As an example, he pointed out that using a microscope to look at a single electron, would require shining light on it. Those photons would cause the electron to move slightly, changing its momentum. Up till now, researchers testing or demonstrating this principle have worked at the micro level because attempting to do so with objects large enough to be seen with the naked eye seemed impossible due to the many variables at play. In this new research, the team in Colorado showed that this not necessarily the case.

They started by building a square drum frame out of silicon, with each side 0.5 millimeters long. They then stretched a thin film of silicon nitride over the skin to create the drum head. The drum was placed in a vacuum between two very tiny mirrors and was chilled to just 4 degrees above absolute zero to eliminate extraneous noise. The experiment was conducted by shooting a laser at the drum and measuring how much the head was distended by the photons striking it as they were bounced back and forth between the mirrors. As more photons struck the drum, greater fluctuations occurred in the measurements recorded, distorting the readings, and proving that the Heisenberg uncertainty principle can indeed be demonstrated with objects large enough to be seen with the naked eye.

The results of the experiment could also have an impact elsewhere, as researchers in Washington and Louisiana are planning a similar experiment over a much more vast scale—they will be seeking to measure gravitationally waves, which the theory of relatively says, should cause a change in distance between two objects. Their experiment will involve the use mirrors as well, but instead of a small drum, they will be trying to measure what happens when two black holes merge.

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© 2013 Phys.org

**Citation**: Researchers demonstrate Heisenberg uncertainty principle at macro level (2013, February 15) retrieved 17 August 2019 from https://phys.org/news/2013-02-heisenberg-uncertainty-principle-macro.html

## User comments

tiggerInfinumHeisenberg uncertainty principle deals with precision of the measurement process.

What you seem to be referring to is the Schrodinger's cat principle i.e. the 'to be measured' value is 100% unknown until it is measured.

Did I understand your comment correctly?

sigfpe> It seems so obvious that measuring something means interacting and interacting means change.

Can you quantify the change? You said it's obvious so surely you can provide some kind of lower bound on how much the position of something is modified if you measure its momentum.

vacuum-mechanicsThis is interesting manifesting of the uncertainty principle, but the problem is that we cannot understand how it works! Knowing it mechanism as below would be nice…

http://www.vacuum...19〈=en

ValeriaTdeepsandValeriaTjohanfprinsBravo.

This experiment only proves that your measurement can change what you measure: It DOES NOT prove that their is an inbuilt uncertainty in the position and momentum of a moving entity; and most certainly it does not prove the Voodoo concept of "wave-particle" duality.

I do not see why they went to such extraordinary lengths to prove something that is so obvious that it can be proved on a pool table. Assume that your light-wave is the white ball, and you use it to detect the black ball. When it collides with the black ball the point of collision has a "probability distribution" which is spread over a distance of two times the diameters of the two balls; and the black ball's momentum changes. This DOES NOT PROVE that there is an uncertainty in the position and momentum of any one of these balls when they are moving.

ValeriaTjohanfprinsBullshit!

Bullshit: A wave has a center-of-mass.

YOU "enforce" your Voodoo duck all the time and refuse to answer pertinent questions about this absurd model of yours.

I have asked all time for a definition of a "particle". You cannot do this, but claim that I do not understand it: LOL

ValeriaTjohanfprinsThere is not a single wave in our universe "without a beginning and an end" and which has "no shape, size and only an amplitude and frequency". Anybody who believes this lives in Voodoo cloud-cuckoo land! That you are a citizen of cloud-cuckoo land you have amply demonstrated by your numerous bullshits on this forum!

Where do you get a wave without a beginning or an end! REALLY!!!

Obviously you are not able to tell me anything more about a wave since you are too stupid to solve a differential wave equation. Ask any radio-engineer whether your concept of a wave can be a reality, and he/she will immediately phone the loony bin to come and pick you up.

VendicarE"we cannot understand how it works!" - Vacuum

What we do not understand is the nature of the wave function. Specifically the "collapse", or more appropriately the transition from a distributed statistical description to a well defined localized change.

johanfprinsThere IS NO distributed statistical description which can be directly attributed to the intensity of the wave-function. Give me an experiment that proves compellingly that this is so: You cannot!

What do you mean by "well-defined" localized change? When is a wave that morphed from an extended state to a more localized entity, when a change in its boundary conditions require this, a "well-defined" localized state? If you cannot define "well defined localized state" then PLEASE refrain from posting on issues you are incapable of understanding.

ValeriaTValeriaTOberTo the rest of you, I'd appreciate if everyone can uphold the above, so we can clean up this site and improve the level of discussion to reflect SCIENCE in a better light.

deepsandIncorrect. The uncertainty owes to the necessary forceful interaction between the observed and the instrument of observation, which exists even in the absence of such duality.

deepsandAddendum: And, that all matter/energy is QUANTIZED.

VendicarEOnce the wave function is accepted, HUP is comes about directly from the nature of waves.

"The biggest lie of ALL lies EVER!" - Johanfprins

VendicarE"There IS NO distributed statistical description which can be directly attributed to the intensity of the wave-function. Give me an experiment that proves compellingly that this is so: You cannot!" - johanfprins

The classic double slit experiment does what you claim has not been done.

The probability of a photon being detected at some position on the screen behind the slits is given by the square of the amplitude of the wave function at the screen once the integral of the square over the entire possible area of detection has been normalized to 1.

This observation is the basis for QM and has been confirmed to be correct to the limit of observation, 6,7,8 decimal places.

VendicarE"What do you mean by "well-defined" localized change?" - Johanfprins

That depends on the experiment. But in in the case of a photon interacting with a photographic plate or a phosphor screen, it means absorption by a specific atom or molecule that has a well defined position such that the position can be accurately measured.

VendicarE"When is a wave that morphed from an extended state to a more localized entity, when a change in its boundary conditions require this, a "well-defined" localized state?" = johanfprins

Strictly speaking that construct is yours. The wave function may just be a mathematical entity that facilitates the computation of the properties of the particle and has no real physical value of it's own, just as a water wave is composed of individual particles and is thus a statistical entity rather than a physical object.

VendicarE"When it collides with the black ball the point of collision has a "probability distribution" which is spread over a distance of two times the diameters of the two balls" - Johanfprins

johanfprinsA single wave is a continuous field while the traditional concept of a "particle"(whatever is meant by this term) is that it is NOT a continuous field.

Are you saying that a laser beam can only be a harmonic wave when it is is infinitely long? If this is the case, the laser beam must start off being non-harmonic, and as its length grows it becomes overall more an more harmonic? Can you not see what nonsense your are talking? In the direction of motion the wave-fronts of a laser-beam are PERFECTLY parallel to one another, and therefore, no matter how long the laser beam is, it is a purely harmonic continuous SINGLE field along the direction in which it moves.

johanfprinsThank you: I will try but make no promises when another bozo comes along patronizing me!

johanfprinsThere is ZERO probability for detection at any position on the screen when there is no atomic detector at such a position; no matter how high the square of the amplitude of the incoming wave is. If there is a detector at that position, there is obviously a probability that the incoming wave will resonate with this detector and collapse to be observed. It is also obvious that the higher the intensity of the wave is at this detector the higher the probability will be that resonance will occur. But this does NOT mean that the intensity of the wave is the probability of where one will find a "particle".

Steven_AndersonjohanfprinsIt shows that light has momentum which it can transfer to a material when the material absorbs the light. It does not prove any uncertainty in momentum and position. In fact, it proves just the opposite. But it is a nice experiment though!

jimsecorjohanfprinsHeisenberg pulled the wool over everybody's eyes; even Einstein's. The fact that one cannot measure with 100% accuracy, and that when you measure you change what you measure, has nothing to do with an "inbuilt" uncertainty in the position and momentum of the center-of-mass of an entity.

There is no such inbuilt uncertainty into the laws of nature whatsoever. The most important law in nature is Galileo's inertia as reformulated in Newton's first law. All the laws of nature will be wrong if the law of inertia, which demands that position and momentum must manifest simultaneously with 100% accuracy, is wrong: Including Schroedinger's equation.

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