This is the first post from this new website.
The topic will be Reality, and what it really is.
So Young’s double slit experiment with monochromatic light, results in the characteristic bright and dark bands of light on the screen, which form as a consequence of the interference of the diffracted light from each slit.
This is as expected if light is treated as a wave, and resembles the same pattern that one sees if water is observed passing through two slits, or small gaps.
Repeating this same experiment with low intensity light, such that the energy represents a single photon passing through the slits at any one time, and waiting until a large number of these photons have sequentially passed through the slits, amazingly produces the same pattern of light and dark bands; the individual photons produce random points on the screen, which when added together produce this interference pattern. The same has been done with single electrons passing through two slits, and again the light and dark bands are produced by the sum of these single electrons. Closing one of the slits, and a standard diffraction pattern results. So these single particles passing through the slits one at a time, produce a pattern dependent on whether a single or double slit is present.
In quantum mechanics, these single particles are not point like particles, but instead are represented as spread out waves of probability: the particle is associated with a wave of probability, that represents the likelihood of being found with a specific momenta at a specific location, in accordance with Heisenberg’s uncertainty principle; one cannot represent these particles as familiar particles that exist in a particular location with a particular momenta, but instead the particle is a superposition of all these states, and these superposition of states can interfere.
So, what is real? What is happening in this double slit experiment with photons and electrons? The impact on the screen is definitely observable to us, as is the interference pattern or diffraction pattern. The probability wave is not real to us, we are unable to observe this, but we can calculate it, and we are able to measure the associated probabilities.
The question of this quantum measurement problem (i.e. how to go from probability wave to a definitive point on the screen), as well as what reality means for a quantum particle will be explored through these blogs. We are all made of atoms, which comprise these same quantum particles, so this question of what is real, really matters!
Great first blog!