Trust in wave-particle duality I am doing an essay in school to consider how much trust is needed to accept knowledge within the natural sciences. For one of my points I decided to look into W-P duality. I know the photoelectric effect shows that light is made up of photons, diffraction patterns suggest EM wave, and the Davisson-Germer exp suggest both (with debroglie wavelength). However, my teacher says that in classical mechanics light cannot be both and for quantum mechanics we can. Does this mean we need more trust in the validity of quantum mechanics because there is a sense of ambiguity?
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However, my teacher says that in classical mechanics light cannot be both and for quantum mechanics we can. Does this mean we need more trust in the validity of quantum mechanics because there is a sense of ambiguity?

We only trust that we know more about nature than a hundred and fifty years ago, not because of ambiguity. We have gone to much smaller dimensions and much larger energies, and have discovered quantum mechanics which predicts probabilities of observing states, whereas classical physics is deterministic,
The wave particle duality of light in particular is clear in this one photon at a time experiment, where single photons compose the light , as they accumulate from left to right the classical interference patterns is seen. That is the duality, the wave is a probability of finding the photon
wave.


Single-photon camera recording of photons from a double slit illuminated by very weak laser light. Left to right: single frame, superposition of 200, 1’000, and 500’000 frames.

The same is seen  with the electrons, here

So we trust in the data measured the last hundred years, and use/trust  the theory that describes them well, knowing that any new theory in the future will have to include these observations, because they have small measurement errors.
