One remembers, first, that all matter used in anything is constructed of atoms, where atoms are made of particles, where quantum mechanics (QM) physically works.
Any physics, chemistry, engineering, computer science, even mathematics -- where the electrons, light, wave, and number behaviors are determining these fields by Nature -- will obey quantum rules, such as NO "law of the excluded middle" and NO "axiom of choice", and where QM principles play main roles.
One reads, for example, at Stanford U. that: the concepts and techniques of quantum mechanics are essential in many areas of engineering and science such as materials science, nanotechnology, electronic devices, and photonics.
Nominations by participants here (in order of appearance) include:
Superfluidity, superconductivity, HVDC with QM rectification by a thyristor (semiconductor), incandescence, laser, quantum decoherence, entanglement, P-type or N-type semiconductors, transistor radio, and the entire known universe for 13.8 billion years so far.
What is your reasoned opinion? What is your best example of QM having visible effects on microscopic and macroscopic scales?
All: I note these macro applications of QM, partially as a Thomas Edison vs Nikola Tesla story.
Edison was committed to direct current (DC), but Tesla liked alternating current (AC). In the background, quantum mechanics (QM) (by means of semiconductors such as a thyristor, where a thyristor is a four-layer device with alternating P-type and N-type semiconductors P-N-P-N), allowed AC to change to DC in high-voltage direct current electricity (HVDC) -- maybe even economically at just 50 km distance.
One major commercial importance is that when HVDC pays for itself with lines 50 km long, connecting more people and renewables on dispersed islands can become more economical.
There are facilities worldwide that transmit in HVDC. The typical examples are the transmission lines of large hydraulic power stations: the Itaipu power station in South America, the Three Gorges power station in China, and others. The HVDC generation uses high-voltage AC rectification, followed by high-voltage switching, all using solid-state QM gates (i.e., a thyristor), showing that there is a macro QM effect on solids -- to deliver electricity to a city.
Superconductivity can also be added in favor of HVDC, as another well-known application of QM, and also demonstrate QM effects on a macroscopic scale.
In electric engineering, then, the transmission loss of quantum-generated superconducting DC power transmission is ten times less than that of superconducting AC power transmission, and thirty times less than the transmission loss of ordinary AC power transmission.
Since superconducting DC power and QM starkly reduce electric transmission loss, it could significantly reduce the amount of electricity that needs to be generated, if used to replace normal AC power and transformers à la Nikola Tesla.
And, before adding superconductivity as a macro quantum effect affecting the electrical transmission of electricity to a city, one can also talk about the influence of another macro QM effect, the incandescence loss on delivering electricity to a city. It is a well known fact that as an object's temperature is increased (i.e., on the transmission wire carrying current to the city), it begins to produce photons -- a loss.
This effect, known as incandescence, was accurately explained through QM by Max Planck in 1901 -- and can be contrary to classical physics calculations.
Planck's quantum equation relates the spectral power density of photons emitted from a perfect radiator, to the object's temperature. This relation can be used to describe the spectral distribution of a wire transmitting an electrical load, by specifying the temperature of the radiating object. The loss is QM in origin, and can be so reduced.
Dear Ed, firstly, thank you for the interesting question, it was a pleasant surprise to find this in my suggestions on RG.
You 'r gonna have to forgive my english this time, since I feel there are gonna be many ideas to write and not as much time to check all my grammars.
The first thing I want to tell is about Quantum Decoherence.
As you well made the point, if atoms and electrons are governed by the rules of QM... and we and all the matter (leaving aside Dark Matter and Neutrinos) in the Universe is made from atoms and electrons, by extention, oirselves, planets, rocks, the moon, etc, etc, should obey the rules of QM too. And this is true, I agree.
Every macroscopic object like us, humans, or this computer where I'm typing into, are made of atoms, so they should obey the rules of QM; they should obey Heisenber's Uncertainity Principle and be described by the Schrödinger Eq. And this is so, however there is a subtetly which is Entanglement and Quantum Decoherence.
Even though that we or rocks should obey the rules of QM, we will never see or experience the direct implications of the basis of Quantum Physics. this is to say that, even all the atoms in our body should behave like (and be entangled) Quantum Mechanical System evolving according to the Schrödinger Equation, we will never see the core predictions of QM for the systems of particles that compose us ... i.e. Superposition, electrons spreading trought all the space, particles with a non-defined velocity and momentum , etc...
This is due to the quantum phenomenon called Quantum Decoherence. When we think of a Quantum system, like an atom, and then we think on other atoms bounding to make a molecule, the whole system becomes Entangled (its quantum states are now entangled, meaning they are strongly correlated. The values of the quantum state of each of the particle composing the system), and if the system doesn't become entangled with the enviroment, this system will continue evolving according to the Scrödinger Eq. and the rules of QM will apply.
but when Quantum systems start to grow in scale, more interactions start to be involved, interactions with other particles, and with the environment, and Quantum Decoherence happens, (in easy words; Schrödinger's Cat). So we evolve from a Quantum Mechanical system, since we are a huge bunch of quantum mechanical particles and interactions, the evolution of the Schrödinger Eq. happens (if you follow the Many-Worlds interpretation of QM). This is why small quantum systems, like a Bose-Einstein condensate should be maintained near absolute zero temperature; to avoid the system to become entangled with the environment and Quantum Decoheres...
So Quantum Decoherence is the reason that even though we are made of a bunch of a lot quantum mechanical particles, we don't observe the the direct Quantum effects observed at the atomic, or microscale.
Speaking of the Macroscopic effects from QM. there exist, "secondary" effects, which are manifestations of physics of the Wave Equation of QM: like Superconductivity, Superfluidity, the Quantum Hall Effect, etc... but these have to be observed in systems of small number of particles, and when the conditions of the experiments are set up so that the interaction with the enviroment is almost null, and there are no observers which can interact with the system. This is the reason these experiments are too costly in resources, and very difficult to conduct.
But the more practical concern of your question is very interesting...
People who are in Material Science always tell us that almost all the fields in Nanotechnology or Solid State Physics, its technical applications, are due to direct consecuences of QMs; Electronics, Phononics, Photonics, Solar Cells, , etc, etc,.. but they never get to explain to us how is the direct link between the maths/laws/or Eqs. of QM and the practical outcome of all these XX's century applications. The one thing the most resounding almost in every occasion is the Transistor, or modern electronics they say ... computer chips, solid state flash memories , etc.
Of the following part of my answer I'm not sure, so maybe I don't have the answer to this part of your question, but, I want to think the LASER (solid State LASER) could be one of the practical examples where QMs can explain very well how does it work, and that we use in almost every day basis...
In overall terms, a Solid State LASER is composed of a crystal (a Silicon crystal e.g.), a source of energy, which can give sufficient energy to electrons in the valance band to bring these electrons to the conduction band, and left a hole in the valence band (e.g. a battery), a Light-resonant cavity, and one or two mirrors (or other reflective materials)... so for example the rate of ...
Changing AC to DC is known as rectification, nothing to do with QM, do not know where you get these strange ideas from.
Quantum decoherence is relevant to the limitations of QM, not QM itself.
That the quantum may have infinite range is more of a fairy tail. In practice there is always a finite length.
Power transmission using superconductors is only practical
for short distances, because you have to refrigerate so much.
You have to be at least below liquid nitrogen temperature.
A more practical apalication is superconducting magnets, superconductors also allow levitation effects for fast trains.
To have a current moving through a superconductor is already to limit the superconductivity, so there is a max threshold of possible current.
All: The modern understanding of the properties of a semiconductor relies on QM to explain the movement of charge carriers in a crystal lattice. A small radio, with transistors, also shows QM in use -- and macroscopic results of QM.
In general, any P-type or N-type semiconductors can be used to create a macro quantum effect.
A thyristor is a four-layer device with alternating P-type and N-type semiconductors (P-N-P-N).
A thyristor is also a QM device showing a macroscopic use. Its discovery allowed the use of high-voltage AC and then to change it to DC in high-voltage direct current electricity (HVDC).
One major commercial importance is that when HVDC pays for itself with lines just 50 km long, connecting more people and renewables on dispersed islands can become more economical. There are facilities worldwide that transmit in HVDC, being more and more economical today for distances larger than 50 km. Read more in my previous answer above.
ALL: Even the rudiments of quantum mechanics seem to be challenging to most. It seems like most are stuck in the classical wave formalism, that was helpful in the past but today hides new horizons.
Let us hope for a level jump on that. QM is always relevant, even when the building blocks (e.g., atoms) are not explicitly considered -- like in a macroscopic string, or new methods to transmit electricity from power plants.
Yes, quantum waves exist on a string or water, even if one does not think that they are made of atoms, in the quantum realm microscopically. Certainly, they are quantum also in the macroscopic realm as well as in the microscopic realm.
Consider the case of a string of length a, with mass per unit length σ and under tension T, while fixed at each end. Mathematically, y can be expressed, since the sine function possesses both completeness and orthogonality, in the sine series Fourier expansion (defining m to be a number large enough for the series to include all significant frequencies, avoiding any use of explicit infinities).
The string can then be understood to be equivalent to a finite set of decoupled harmonic oscillators (i.e, quantum) with frequencies ωn = (T/σ)1/2(n. π /a)2, up to the maximum assumed frequency, as represented by m.
In quantum field theory (*) the E-L equation can likewise use the Fourier series to represent a finite set of decoupled harmonic oscillators (i.e, quantum), leading back to a general solution in the time coordinate.
Reference:
* in QM, the time-independent Schroedinger equation in one dimension is clearly in a Sturm-Liouville form, where y'' ~ Q(x)y. The Sturm-Liouville differential equation can then also be seen in terms of the Euler-Lagrange (E-L) equation, and the E-L equation specifies the solution to variational δI = 0 for the functional. Note that this can be seen as the potential and kinetic energy terms (Hamiltonian).
In other words, the time-independent Schroedinger equation for bound-states can be recast as an isoperimetric problem using Sturm-Liouville, whereby the E-L equation is equivalent to the original equation (e.g., see Courant).
The quantum may only be a small part in the discussion of
n or p doped material, that is picking an element from an adjacent column to silicon so as to supply extra electrons or holes on the appropriate side of a junction. This can be understood from simple chemistry without mention of the quantum.
One might argue that chemistry has a background in the quantum, ie. journal of quantum chemistry, but most can understand technology without going to such depth. Quantum may be true but not always practical.
The rest of the story is just diffusion of the carriers and the formation of a charge barrier.
Im afraid you have to go into detail for the topics on the stanford list, it just is not so simple.
If you need serious discussion, go for the details and we will see.
You say that in the AB effect, the particle is affected by the fields and then admit there is no electric of magnetic field in its path. This is contradictory, you cannot have it both ways.
I could give the real answer.
People are not stuck, they simply have comon sense.
JW: It strains me to see a connection between some comments still above, and this thread -- it's all off-topic here. This thread is not about vacuously doubting that QM is relevant both macroscopically and microscopically -- this is about the main stream for some 100 years, and how progress is being made today in literally 1,000s of areas, including lasers. Classical physics was useful at its time but now no one wants it, to advance.
These "points" are also not allowed under free speech rules -- a theater is not free speech, NO audience member can yell "FIRE". It is a crime (US). As another counter-example, ad hominem attacks are not allowed in research, nor here. We also should NOT consider at all that there is presently a king in France.
It thus strains me to see a connection with these "comments" in this thread -- it's off-topic. These are also not allowed under free speech rules. Please delete any message that is off-topic here.
Well, you already know the answer, yes, superconductors and superfluids,
and we know you are prone to interprate everything in terms of QM, so no need to bug us.
JW
All: See the paper as " Mode coupling by circular apertures " in pages 2800-3, APPLIED OPTICS / Vol. 15, No. 11 / November 1976, by O. O. Andrade.
There, as another example of macrosystems exhibiting quantum behavior, instead of the case of the string analyzed above, consider the equivalent case of optical interferometers.
The transverse field distribution of freely propagating beams, such as the output from single mode lasers or interferometers with cylindrical symmetry, is very closely described by Gaussian Laguerre functions. The obstruction of these beams by apertures, for example, the input aperture of an interferometer, will experimentally result in a diffraction pattern.
As the Gaussian Laguerre functions form a complete orthogonal set, they can be used (mutatis mutandis the physical string case above) as the base for the expansion of the apertured beam field. So if an interferometer were coupled to a beam mode obstructed by an aperture, even if the interferometer were perfectly matched to the incoming mode parameters, the output will no longer consist of this particular mode but of a set of them, showing a quantum effect as a finite set of decoupled harmonic oscillators.
By expanding the normalized apertured beam in a set of normalized Gaussian Laguerre functions, Osvaldo O. Andrade has obtained the power coupled to each interferometer mode as the modulus squared of the expansion coefficients.
All: I want to flip the model common today ... It is not that the macroscopic follows the microscopic... they all follow the macroworld, Nature. It does not matter on the existence of particles or atoms!
Take the Standard Model (SM), for example. The SM has not been anymore about particles for a long time now, a so-called "particle" is viewed today as an excitation in a field, fields that fill the entire Universe, in Quantum Field Theory (QFT) -- which I tried above to make more understandable, in simple cases such as waves in a string, light, or even water.
Quantum waves do not depend on the atomic structure of matter. There are no neutrons, protons or electrons, nor any other "particle" -- as well-known in physics, the CERN (LHC), the Fermilab, and even on youtube: https://www.youtube.com/watch?v=ATcrrzJFtBY
In Nature, nothing is a particle -- as we go in, we do not reach a particle or "classical waves", we reach quantum waves. Every elementary "particle" is a vibration in its own field, and these vibrations and fields interact with each other, transferring energy, momentum, charge, etc. between such vibrations and fields. The same that we observe in the ... macroworld!
BUT ... QFT predicts no-mass for all the vibrations (aka, "particles"). Mass is just bound or confined energy? The SM then became a model where there are forces, such as the weak force and EM, and they exchange "particles"for each of the forces ... BUT the gravity force is left out, the weak hyper-charge force (i.e, that allows left-spin electrons to feel the weak nuclear force, aka, called parity violation) is also left out...
The force-"particle" theory -- the SM -- has failed. It is just a parameter-fitting model, not an explanation of facts, and leaves out many things!
One thing that comes to mind in regards to your primary question is hydrodynamic quantum analogs. These experiments were done at MIT in July of 2013 published in Physical Review Letters E. Dr. Daniel M. Harris displayed that "a coherent wavelike statistical behavior emerges from the complex underlying dynamics and that the probability distribution is prescribed by the Faraday wave mode of the corral." I hope this helps!
https://dspace.mit.edu/bitstream/handle/1721.1/80700/Bush_Wavelike%20statistics.pdf;jsessionid=FCEFAD9A319FB57DCF85010DE1A36BEB?sequence=2
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