Sometimes, renowned scientists say things that blow my mind.

I was reading this news article about a quantum physics experiment. It all seemed suitably exciting and mysterious to my lay eyes, and then the article hit me with this:

“Experiments are only relevant in science when they are crucial tests between at least two good explanatory theories,” [David] Deutsch says. “Here, there was only one, namely that the equations of quantum mechanics really do describe reality.”

I’m sorry, but that’s just… wrong. A lot of real-life experimental work involves testing a single idea against a null hypothesis (e.g. “this mutation causes disease A” vs. “this mutation doesn’t cause disease A”). And you don’t need two competing explanations for one explanation to turn out wrong (e.g. a particular mutation is the only cause you can think of for disease A, but then you find lots of people having the mutation but not the disease). Sure, QM has passed many, many tests – but remember, science can only ever say “this is right to the best of our knowledge”, not “this is Right”. As far as I understood the article, this experiment also looked at QM in a new way, so it’s not like it was a boring replication of something we’d seen a thousand times. Maybe Deutsch is right to question its importance, but I think he chose a really poor reason for doing so.

(Disclaimer: the quotes that appear in articles like this are not necessarily the words that came out of the interviewee’s mouth/keyboard. So like a good scientist, I’ll leave some reservations in my judgement there.)