I’ve been busy. There is a lot I’d like to say here, but I’ve been writing the actual science papers. Can’t keep up with myself, let alone everything else. I am prompted to write here now because of a small rant by Maury Goodman in the neutrino newsletter he occasionally sends out. It resonated with me. First, some context. Neutrinos are particles of the Standard Model of particle physics.

I read somewhere – I don’t think it was Kuhn himself, but someone analyzing Kuhn – that there came a point in the history of science where there was a divergence between scientists, with different scientists disagreeing about what counts as a theory, what counts as a test of a theory, what even counts as evidence. We have reached that point with the mass discrepancy problem.

Last time, I expressed despondency about the lack of progress due to attitudes that in many ways remain firmly entrenched in the 1980s. Recently a nice result has appeared, so maybe there is some hope.

I have become despondent for the progress of science. Despite enormous progress both observational and computational, we have made little progress in solving the missing mass problem. The issue is not one of technical progress. It is psychological. Words matter. We are hung up on missing mass as literal dark matter.

It often happens that data are ambiguous and open to multiple interpretations. The evidence for dark matter is an obvious example. I frequently hear permutations on the statement This is said in all earnestness by serious scientists who clearly believe what they say.

Reality check Before we can agree on the interpretation of a set of facts, we have to agree on what those facts are. Even if we agree on the facts, we can differ about their interpretation. It is OK to disagree, and anyone who practices astrophysics is going to be wrong from time to time. It is the inevitable risk we take in trying to understand a universe that is vast beyond human comprehension.

Mass is a basic quantity. How much stuff does an astronomical object contain?

A common objection to MOND is that it does not entirely reconcile the mass discrepancy in clusters of galaxies. This can be seen as an offset in the acceleration scale between individual galaxies and clusters.

This title is an example of what has come to be called Betteridge’s law. This is a relatively recent name for an old phenomenon: if a title is posed as a question, the answer is no . This is especially true in science, whether the authors are conscious of it or not.

This post simply announces that I will be giving a Golden Webinar at 3pm EST Friday 15 January 2021 courtesy of the Instituto de Astrofisica of the Pontifica Universidad Catolica de Chile. The seminar is free and open to all but you need to register in advance if you want to hear it. There are many excellent speakers in previous episodes of this series that you can hear on Youtube.

“Galaxies are made of stars.” Bob Schommer, quoted by Dave Silva in his dissertation on stellar populations This tongue-in-cheek quote is a statement of the obvious, at least for the 90+ years since Hubble established that galaxies are stellar systems comparable to and distinct from the Milky Way.