Tag Archives: analysis

Can hell break out of a .2% difference in Planck’s constant?

This is an untold story, part of my personal history in academia, when all things were still coming up roses on me. Somehow, the news regarding the update of four of the fundamental constants we use in Physics and science triggered a memory.

It is 2001, last few months of data analysis towards my PhD thesis. A shared data set between my folder and a senior German collaborator’s one is analyzed in parallel with two different methods. Final results show up eventually from both sides and we immediately see that there is a constant 0.2% difference in the extracted values, despite that they should be exaclty the same in principle. Intense discussion breaks out among all collaborators why this is happening. As a student I was the easy target: “you, Theo, have made a mistake”. New round of independent analysis breaks out by a post-doc. He comes back with the same results I produced and still a persistent 0.2% difference with the German guy’s values.

A month later, we are still stuck. The 0.2% does not go away whatever the effort. Then, I decide to dig better. I revisit the fundamental constants, Planck’s h and speed of light, c I found in the CODATA evaluated tables. Cross-checking with the German collaborator shows he had used values found in an appendix of a nuclear structure book published in the ’60s. The values merely differed by exactly 0.2%. A couple of hours after our discovery, I get chinese for lunch and a fortune cookie offers me a metaphysical touch with the quote: “The truth is in the numbers”.

I remembered this story earlier in the morning, when I read about the update of the fundamental constants. The new values can be found in this paper. Just use them cautiously; they might give you hell. Especially if you are a PhD student.