B What is the largest object that exhibits Quantum properties

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Summary
Small things go many paths, go as things or waves. What is the largest thing that has been observed or if not yet observed, is considered possible to observe.
Back when the world was experimenting with radio it took significant advances in technology to gain the benefits. As we are just getting into the Quantum world I wonder if we can ever see something with our own eyes. I wonder where the line must be drawn and how technology can move that line. We do not see which slit the wave travels, but it does. What happens in the larger world that we also do not see, but they happen.
 

PeroK

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Summary: Small things go many paths, go as things or waves. What is the largest thing that has been observed or if not yet observed, is considered possible to observe.

Back when the world was experimenting with radio it took significant advances in technology to gain the benefits. As we are just getting into the Quantum world I wonder if we can ever see something with our own eyes. I wonder where the line must be drawn and how technology can move that line. We do not see which slit the wave travels, but it does. What happens in the larger world that we also do not see, but they happen.
You could start here:

 
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I see the article talks about things we do not see with our eyes, more with electrons moving through a superconductor (I do not see them) or a superfluid that is a collection of atoms doing something. I was looking for something that a person could see in a grade school science class (I remember those magnets and iron filings) so I would like that to be addressed. I suspect there is nothing yet but I wanted to ask.
 
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@Suppaman:

I was looking for something that a person could see in a grade school science class (I remember those magnets and iron filings) so I would like that to be addressed. I suspect there is nothing yet but I wanted to ask.
I think the best introduction at this level is the doubleslit experiment with a laser. It's easy to do and show, and the result of the experiment can be talked about and reasoned about. Furthermore it gets extra interesting when it is also mentioned that the same behavior can be demonstrated when electrons are used (although the experiment setup is a bit different).

Regardless of this, I want to mention three particular demonstrations of quantum behavior:

1) One of the largest (or perhaps the largest) structures that has been put through a double slit and has displayed wave/quantum behavior is C-60 (see e.g. http://www.univie.ac.at/qfp/research/matterwave/c60/ ).

2) Here is a clip showing the very interesting behavior of helium at very cold temperatures, when the helium turns into a superfluid:

Ben Miller experiments with superfluid helium - Horizon: What is One Degree? - BBC Two


3) And here is an article and paper about superposition:
Article: Quantum effect spotted in a visible object (PhysicsWorld)
Paper: A. D. O’Connell et al, Quantum ground state and single-phonon control of a mechanical resonator (Nature volume 464, pages 697–703 (01 April 2010))
 
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You can hear collapses of quantum states in a Geiger counter.
Rainbow colors of soap bubbles are due to light interference, which is actually a quantum-mechanical effect.

Eugene.
 
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I thought the colors were a function of the thickness of the bubble. And we can see the results of the double-slit experiment but we do not see with our eyes what is causing these results. perhaps there is a law that says if something is larger then x it can not experience QED?
 

PeroK

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I thought the colors were a function of the thickness of the bubble. And we can see the results of the double-slit experiment but we do not see with our eyes what is causing these results. perhaps there is a law that says if something is larger then x it can not experience QED?
Do you think it is possible for a blind person to be a physicist?

Also, you take for granted that you can "see with your own eyes" the cause of classical physics. Can you see what is causing the Moon to orbit the Earth? Can you see why a gyroscope precesses? Can you see why a current causes a magnetic field?
 

vanhees71

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Colors are in fact not a physical but a physiological phenomenon, and it's much more complicated than the physics, if you ask me.

Also all the everyday matter around us is a manifestation of the quantum behavior of nature. Given the fact that atoms consist of a positively charged nucleus surrounded by electrons an are stable, there's no way to understand, why there is stable matter at all without taking quantum effects into account.
 
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No, but I understand the laws that govern these phenomena. If our knowledge of QED was as well established I would probably not have this question. At some point in the past, we could show the children an electromagnet, they could see it pick up that nail but could not see the magnetic field (this was me in 1955.) This may have inspired them to go into science, to explore the "what is this thing I am seeing?" What do we have today to make the kids in a science class ponder some QED demonstration?
 

vanhees71

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Hm, for the kids I'd still use the old stuff we have around. As a kid I got interested in science first by looking through a microscope of an elder friend, seeing some single-cell organisms like an amoeba eating up something. So at the next birthday I got my own microscope. Somewhat later I got interested in to electronics and tinkered with simple circuits including transistors and built radios (my favorite were some that didn't need a battery ;-)). I don't think that you can get hooked to science starting with quantum mechanics or QFT easily. Maybe the most fascinating thing to play around with would be a laser and refraction, but I'm not sure whether that's possible given all the safety regulations even teachers at highschool have to follow nowadays. Recently I read about a chemistry professor complaining that almost all chemistry freshmen have never done a chemistry experiment in highschool, because with all the regulations the teachers are afraid to let them do some. In physics I guess nowadays lasers or even some radioactive probes are out of the question too :-(, but maybe playing around with some electronics including microcomputers like an Arduino or Rasperry should be doable.
 
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It might not be quite what you're looking for, but I think the 3-polarizer experiment demonstrates quantum behavior at the macroscopic level.
 
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I grew up on science fiction, poor family, dropped out of school 16 to get a job, my last job before retiring was writing and executing testing software (13 years) for a time of flight mass spectrometer. I think we need to find people who always question the science they see. Programming can be fun but it is so focused you may miss the important stuff. I am not sure that schools today are teaching the students how to think. But thinking about QED could be very motivating to those with a capable mind.
 
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It might not be quite what you're looking for, but I think the 3-polarizer experiment demonstrates quantum behavior at the macroscopic level.

I enjoy watching the youtube videos where they demonstrate this stuff. Too often they do not attempt to explain why we see what we see. Where do you get the speculation on the "why" QED behaves as it does? This would give me more to think about.
 
...I wonder if we can ever see something with our own eyes.
According to this professor and others, birds use a quantum effect to navigate:

 
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I had seen one on this subject. It does open the possibility that consciousness is some part related to QED but it would be as hard to test as the bird navigation. Think of how we might expand our lives if we could manage such insight into our own minds.
 

A. Neumaier

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Summary: Small things go many paths, go as things or waves. What is the largest thing that has been observed or if not yet observed, is considered possible to observe.
The universe.
What happens in the larger world that we also do not see, but they happen.
The core of the earth or of the sun move in ways we infer from the laws of nature, but cannot see or observe, except very indirectly.
 
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The fact that you don't fall right through the floor is a quantum mechanical phenomenon, or that the floor is there at all.
 
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The web: "Trying to push all the table-atoms and finger-atoms together demands an awful lot of energy – more than your muscles can supply. You feel that, as resistance to your finger, which is why and how the table feels solid to your touch. " What is QM abut this?
 

A. Neumaier

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The web: "Trying to push all the table-atoms and finger-atoms together demands an awful lot of energy – more than your muscles can supply. You feel that, as resistance to your finger, which is why and how the table feels solid to your touch. " What is QM about this?
The resistance is due to forces of quantum mechanical origin.
 

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