# Physics

This recent Nature article makes people jump up and down in classical, non-quantum jumps as we speak: “Experimental non-classicality of an indivisible quantum system”.

There are plenty of misleading news articles already, including here on Science2.0, about that this experiment is disproving classicality without even needing “spooky action at a distance” or entanglement. The message one often takes away is therefore that this new experiment may be the best proof yet, the most convenient disprove of hidden variables.

*spukhafte Fernwirkung*- “spooky action at a distance” and sought to note the flaws in Heisenberg's uncertainty principle and the Copenhagen interpretation. The result was the Einstein–Podolsky–Rosen paradox.

Discounting the Bohmian song and dance, we are led to conclude that each electron does in some sense pass through both slits. But in what sense? Saying that an electron went through both slits cannot be equivalent to saying that the electron went through L

*and*that it went through R, for to ascertain the truth of a conjunction we must individually ascertain the truths of its components, and we never find that an electron launched at G and detected at D has taken the left slit

*and*that it has taken the right slit.

There is nothing strange or particular about the fact that any hard production process at a hadron collider can produce, in addition with a massive state such as a top pair, additional energetic photons. That is because any charged particle involved in the process will have a small but finite chance of radiating electromagnetic energy, with a strength governed by our good-old fine-structure constant.

What is exciting to me is that I am asking questions and developing answers. I want to emphasize the plural. This is not a one trick pony (quaternions can do 3D rotations and nothing else of interest). Many different topics are being raised and looked at from odd angles. I didn’t have a plan to write these puzzles, but am glad they emerged from the blog writing process. Now back to the questions and their answers.

The Quantum Randi Challenge (QRC), first introduced here, exists in order to stop the spread of pseudo-science by simply teaching quantum mechanics. Here is the official version of the challenge (also published here and partially in Annals of Physics 339: 81-88). *[ We are still looking for people who can help to turn it into a multiplayer internet app.*]*

**What is a “Randi-type” challenge?**

The mathematical formalism of quantum mechanics can be built up on the basis of the following rules. Suppose that you want to calculate the probability of a particular outcome of a measurement M

_{2}, given the outcome of am earlier measurement M

_{1}. Here is what you have to do:

Quantum physics has proven that the world cannot be described by local realism. Therefore, Many-Worlds Interpretations (MWI) are now in vogue.

*This is already wrong: Everett's is a relative state description, not necessarily a multiple worlds interpretation.*