With respect to the dual slit experiment and the conclusion of probability waves, I was watching a documentary that said without "accepting chance" we couldn't have functioning technology in today's world.

I am sure the precision of probability waves and the way quantum mechanics makes use of it has lead to much of today's technology. But is it necessary that electrons behave according to probabilistic laws for such technologies to work?

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    $\begingroup$ This seems to be coming at it from the wrong angle. Quantum mechanics isn't a bunch of weird effects overlaid on a fundamentally classical world. The world just is quantum, through and through. If you remove quantum mechanics, the sun won't shine, solids won't hold together, atoms won't be stable... basically nothing works. $\endgroup$ – knzhou Nov 2 '16 at 20:42
  • $\begingroup$ @knzhou I do not agree with that. I think it is a legitimate and interesting question to ask to what amount are purely quantum mechanical properties necessary for certain technologies to work. For example, to ask why is the "probabilistic nature" of quantum mechanics necessary for quantum cryptography to work is a valid question, with a relatively trivial answer if you are familiar with the subject but nonetheless worthy of answer $\endgroup$ – glS Nov 2 '16 at 20:47
  • $\begingroup$ It is necessary for us to rely on the laws actually in place to make our technologies work, they just happen to be probabilistic, hence "accepting chance". I am not sure what "necessary that electrons behave according to probabilistic laws" means. If they behaved according to different laws we'd have different technologies based on those. $\endgroup$ – Conifold Nov 2 '16 at 20:47
  • $\begingroup$ So, lasers could not function without the laws of quantum mechanics? $\endgroup$ – JG Questions Nov 3 '16 at 16:08

Absolutely yes.

The "probabilistic nature" of quantum mechanics that you mention is a consequence, very roughly speaking, of the quantum mechanical properties of fundamental particles to exist in superposition of many different states. Because of this, there are quantum mechanical states for which it is intrinsically not possible to deterministically predict certain measurement outcomes.

This property of quantum mechanics is an essential ingredient of many quantum technologies. A couple of relevant examples are quantum cryptography and quantum computing. In both cases you can have computational or security advantages with respect to what is possible with classical physics thanks to these "weird probabilistic properties" of quantum mechanics.


All the technological advances rely on our understanding of how matter interactions at the atomic and molecular level work, and the nuclear technology advances on how the interactions of nuclei work.

It is not enough to see that electrons' double slit interference can be described as the result of a probability wave, to get at the point we are. A consistent and valid mathematical model, a physical theory, was needed. This theory is the theory of quantum mechanics and the fact that all calculations give probability distributions is within the axioms( physical postulates) of the theory.

Quantum mechanics is continually validated not only by the technology, but by all new experiments at the frontier of physics searches. The question

does it REQUIRE that electrons behave as % probability

has the answer: all matter has to obey quantum mechanical equations, which come up with probability distributions for experimental numbers.

One cannot pick a theory a la cart, it is either obeyed whole, or invalidated, and this has not happened to quantum mechanics.

  • $\begingroup$ Anna v, If quantum mechanics on paper were to cease to function in relation to technology, would this technology cease to function? $\endgroup$ – JG Questions Nov 2 '16 at 17:12
  • $\begingroup$ The mathematical model does not mold reality, it describes existing data and predicts new possibilities. If all equations were burned and mathematial knowledge was lost, the present day technology would work but nothing new would be discovered, technology would become static. $\endgroup$ – anna v Nov 2 '16 at 17:27
  • $\begingroup$ It is interesting that something is used to create another thing has no requirement of existence to function. $\endgroup$ – JG Questions Nov 2 '16 at 17:38
  • $\begingroup$ most of primitive technology was like that, wheels, once discovered exist up to now. The brain model that invented the first wheel was never written down. Mathematics and theories based on it are brain models recorded on paper for posterity , so posterity could extend on paper and test new technologies . $\endgroup$ – anna v Nov 3 '16 at 6:55

Two technologies that are quite wide spread and are based on quantum mechanics, are lasers and microelectronics.

Let's first look at lasers. The operation of a laser is based on a microscopic process called stimulated emission. Through this mechanism, light is amplified when it passes through a material where most of the atom are in appropriate excited states. This process follows a probabilistic law. An excited electron will fall down to a lower energy level and release a photon with a certain probability that depends on the number of other photons with the same energy that are present. This is not a deterministic law, because then it would have had to depend on something else and the process would not have worked as it does. Hence, we would not have had lasers.

Microelectronics is based on semiconductors. In semiconductors, one has energy levels separating so-called valence bands from conduction bands. The devices, such as transistors on which microelectronic technology is based, consist of different layers of semiconductors with different properties (I'm trying not to go into too much detail here), such that voltage differences across these structures can cause the electrons from the valence band to enter the conduction band to produce a current. This process is again a probabilistic process. Each electron has a certain probability to cross the energy gap. This leads to tiny fluctuations in the current even when the voltage is kept constant. These tiny fluctuations can be measured as noise called shot noise. Again if this were not governed by a probabilistic law, then one would have had to have some deterministic effect, which means it would have had to work differently. As a result transistors would not have work as they do in our microelectronic based devises.

  • $\begingroup$ you should add that even talking to each other on these boards relies on transistor and derivative technology $\endgroup$ – anna v Nov 3 '16 at 6:52
  • $\begingroup$ @annav: Yes, I could probably have added many other examples. Superconductors, such as those used in LHC; radioactive decay such as used in radiation treatment for cancer, etc. I chose two examples. $\endgroup$ – flippiefanus Nov 4 '16 at 5:10

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