Quantum mechanics is one of the greatest creations of the human mind. You cannot explain even the simplest molecule, the hydrogen molecule, without it, nor the covalent bond, which is the basis of organic chemistry and of biology. Molecular biology would not exist without quantum mechanics. Read Erwin Schroedinger's book, "What is life ?", 1948.
It is based on two pillar equations, the Schroedinge equation for non relativistic particles, and the Dirac equation, for relativistic particles. This equation brought to the concept of the idea of antimatter, then demonstrated experimentally by C.V.Anderson, P.M.S Blackett and G.Occhialini, with the discovery of the positron, now used in medical diagnostics.
All physicists, chemists and molecular biologists us QM as their tool of trade. What is being discussed is the "Copenhagen interpretation" of QM, made by Niels Bohr and others at Copenhagen. There are alternative interpretations, such as that of "pilot waves" by Louis de Broglie and David Bohm.
Finally, even Einstein, who opposed QM for theological reasons (God does not play dice, he said) gave a new outlook to QM with his paradox of 1935, the Einstein-Podolsky-Rosen paradox, which brought out the idea of entanglement, now used in quantum cryptography by Anton Zeilinger at Vienna, and also by the China Academy of Science which plans to use entanglement in an Earth-satellite-Earth link.
So research in QM is alive and kicking even today.
Tullio

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The Schroedinger cat was not a theory but a paradox. He wanted to demonstrate that the Copenhagen interpretation, which he opposed, brought to paradoxes. He rather followed the pilot waves idea. But evidently people do not undertand this point.
Tullio
Read "The development of the interpretation of the quantum theory", by Werner Heisenberg, in "Niels Bohr and the development of physics", Pergamon Press 1955.

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Unluckily, modern science is often Big Science, which costs a lot of money. This often is detrimental to new ideas which would need some investments. The Higgs boson was detected after 60 years, the gravitational waves after a hundred years because they needed big machines and new technologies such as lasers and superconducting magnets. Billions of euros are spent on doubtful enterprises such as the ITER nuclear fusion project because, like American banks, they are too big to fail.
But big science has also same useful fallout, as computerized tomography, nuclear magnetic resonance scans, positron emission tomography which we, sooner or later, have to try on our bodies on the doctor's advice. My daughter Elisa was doing her thesis research on a project of a hadron accelerator for cancer therapy which was to be built in Milano and then shifted to Pavia for political reasons so she is now working in a software house in Milano on process control of big firms.
I am cooperating with CERN in elementary particle research, which was my field of study, and also with the Albert Einstein Institut in Hannover searching for gravitational waves. I am doing this on three PCs, paying my electric bill and the ADSL line because it is my hobby and also because I can interact with people even if living alone in a small town outside Milano. I have a son and a daughter and they are away but they send me photos of their children which I print on my two printers. So not all technology is bad. Cheers.
Tullio

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I think that paradoxes were pointed out by scientists who desagreed a given theory, just to show its weaknesses.
At this point of view, paradoxes MUST be exagerated and then are nonsense in the real life.
Are paradoxes that useful ? I don't know for sure, but the "fool of the king" was.
Scientific knowledge grows with contestations and contestations force theories to improve.
I beleive that, as human beings, the scientists do have their personal convictions (a kind of "religious" concept) which drive their brains, even if they claim the opposite.

"God doesn't play with dies" what quite a striking sentence. Said by the man in the street, it would not have any impact.
But, because it was from Einstein, it has had a lot of weight and maybe discouraged some scientists to get involved in quantum mechanics.
The lesson, if there is one, is that the more you are powerful, the more you must be cautious in what you say.
Not only in science...

Cheers
JF

Richard Feynman introduces his lecture on Quantum Electrodynamics
"If I'm going to explain this theory, the question is, are you going to understand"
https://www.youtube.com/watch?v=_sAfUpGmnm4
He also once met Niels Bohr and presented his new diagrams that explain the QM mechanismes in an "easy" way.

Niels said "Are you mad? You cannot explain QM like that!"

The wave function of Schrödinger's cat
(|dead> + |alive>)/(sqrt 2)

The physicist Eugene Wigner extended Schrödinger's cat experiment and puts his friend in with the cat. The external observer believes the system is in the state (|dead> + |alive>)/(sqrt 2). His friend, however, is convinced that the cat is alive, i.e. for him, the cat is in the state |alive>. How can Wigner and his friend see different wave functions?
The Copenhagen Interpretation: The answer depends on the positioning of Heisenberg cut, which can be placed arbitrarily. If Wigner's friend is positioned on the same side of the cut as the external observer, his measurements collapse the wave function for both observers. If he is positioned on the cat's side, his interaction with the cat is not considered a measurement.

I have always like the portrait of young Feynman given by Freeman J.Dyson in his book "Disturbing the universe". They traveled by car from Annapolis to New Mexico and Dyson gives a vivid picture of him. In the return trip, made by Dyson alone by Greyhound bus, he succeeded in uniting Feynman's vision of quantum electrodynamics with those of Julian Schwinger and Sin Itiro Tomonaga. The three got their Nobel prize also through the work of Dyson, but a Nobel prize can only be given to three people at a time.
Tullio

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He was also a vivid bongo drum player:)
I have seen a clip where he sit on the floor in his room in Grand Hotel Stockholm playing those when he got the Nobel Prize.
https://www.youtube.com/watch?v=qWabhnt91Uc

"The fool on the hill sees the world spinning round"
Beatles were right in some way : look at the things as they are and accept reality as it is.

The issue is that when we look at the things, we are supposed to change them.
Not only external observers, we act in the movie.
Difficult to figure for me...

JF

Difficult to figure for me...
JF

Welcome to the club.
Instead of explaining theories most scientists choose to say "Shut up and calculate"
Why? Because they don't know either in many cases.
QM is the field that most of us get lost.

It's the Colossal Cave on the Adventure game I played on an Onyx UNIX computer in the Eighties. No graphics, no sound. Only VT terminals. Then I read about the game while translating Tracy Kidder's book "The soul of a new machine".Later I learned that Tom West, the chief person of the story had died in a car crash and I felt sorry.
Tullio

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It's the Colossal Cave on the Adventure game I played on an Onyx UNIX computer in the Eighties. No graphics, no sound. Only VT terminals.

I remember those games:)
GO EAST
GO NORTH
But it was not only VT terminals in the 80's.
Already in the late 70's there was those games on mainframes.

And then there was the editor VI that replaced row editors:)

I have used the troff and nroff text formatting programs. Berkeley had its macros (-me) instead of the standard -mm of Bell Laboratories. Then you had the tbl and eqn preprocessors. Printers had the daisy ring printheads. Happy days!
Tullio

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In the good old days of mainframes, IBM had their "Nancy-1" line printers with print chains. We had a program on our Mainframe that made the line printers sound like the 1812 Overture--when the cannons went off the covers on the printers would swing up. It was the IBM-370 168 that I managed and on which the famous 4-color problem was proven--some say not validly since they essentially used exhaustive enumeration to show that, topologically, no more than 4 colors were needed to delineate a map of countries.

Then came TeX. I compiled TeX from sources on a Bull/MIPS minicomputer, a RISC machine running UNIX System V.
Tullio

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Physicists create first photonic Maxwell's demon

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Music
Pictures

Photonic Demons !!!!

oh no somehow they came to life from Star Trek . Where's the Doc he's Photonic he can fight them .

Sounds cool thou

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It will take a better explanation and documentation of results to make me believe that the 2nd law of thermo dynamics can be violated. if they detect positive work results then the energy is coming in from a source associated with their apparatus or their environment.

If it takes energy to clear the memory of the 'photonic demon', which may be necessary for its continued operation, there might be no net gain in work, no useful energy from nowhere.
If this sort of 'Carnot's demon' does not require energy consuming erasure, or if this uses less energy than it produces, they may have discovered an exception to the 2nd law of thermodynamics.
A scientific law is only a generalization about observations. Given disconfirming observations, it may at least be said to have exceptions.
It was believed for a thousand years or so that heavier objects fell faster than lighter ones, due to Aristiotle. Better observations finally put this idea to rest.

That work can be extracted like that seem very strange.
But working with photons you are into the quantum world.
In that world the theory of physical information becomes more significant.
https://en.wikipedia.org/wiki/Physical_information#Physical_information_and_entropy
Perhaps a unification of that theory and thermodynamics is needed to understand this.
From the article.

The researchers hope that the new model will lead to a better understanding of the link between information and thermodynamics, which is necessary for understanding thermodynamics at the microscale and below. As the scientists explain, recent developments of technologies consisting of just a single or few particles require a better understanding of microscale thermodynamics, similar to how the steam engine drove scientists to better understand macroscopic thermodynamics in the 19th century.

If I remember well what I read in an article, if you cancel a bit you increase entropy.
Tullio

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