To start the new year, I provide a link to a discussion I had with Simon White on Phil Halper’s YouTube channel: In this post I’ll say little that we don’t talk about, but will add some background and mildly amusing anecdotes. I’ll also try addressing the one point of factual disagreement. For the most part, Simon & I entirely agree about the relevant facts; what we’re discussing is the interpretation of those facts.

Screw the Earth and its smoking habit. The end of 2023 approaches, so let’s talk about the whole universe, which is its own special kind of mess. As I’ve related before, our current cosmology, LCDM, was established over the course of the 1990s through a steady drip, drip, drip of results in observational cosmology – what Peebles calls the classic cosmological tests. There were many contributory results;

Last time, I expressed extreme disappointment that fossil fuel executives had any role in leading the climate meeting COP28. This is a classic example of putting the the fox in charge of the hen house. The issue is easily summed up: Setting aside economic self-interest and other human foibles, it is clear from the comments that the science is not as clear to everyone as it is to me. That’s fair;

In 1986, I was a grad student at Princeton, working in the atomic physics lab of Will Happer. It was at a department colloquium that I first heard a science talk that raised serious concerns about our use of fossil fuels potentially impacting the climate. This was not received well. People asked all sorts of questions, with much of the discussion revolving around feedback effects.

I have tried very hard to remain objective and even handed, but I find that I weary of the wide binary debate. I don’t know what the right answer will turn out to be. But I do have opinions. For starters, it is a big Galaxy. There is just too much to know. When I wrote about the Milky Way earlier this year, the idea was to set up an expectation value for wide binaries in the solar neighborhood.

People have been asking me about comments in a recent video by Sabine Hossenfelder. I have not watched it, but the quote I’m asked about is “the higher the uncertainty of the data, the better MOND seems to work” with the implication that this might mean that MOND is a systematic artifact of data interpretation.

One of the most interesting and contentious results concerning MOND this year has been the dynamics of wide binaries. When last I wrote on this topic, way back at the end of August, Chae (2023) and Hernandez (2023) both had new papers finding evidence for MONDian behavior in wide binaries. Since that time, they each have written additional papers on the subject.

People often ask me of how “perfect” MOND has to be. The short answer is that it agrees with galaxy data as “perfectly” as we can perceive – i.e., the scatter in the credible data is accounted for entirely by known errors and the expected scatter in stellar mass-to-light ratios. Sometimes it nevertheless looks to go badly wrong. That’s often because we need to know both the mass distribution and the kinematics perfectly.

In the series of recent posts I’ve made about the Milky Way, I missed an important reply made in the comments by Francois Hammer, one of the eminent scientists doing the work. I was on to writing the next post when he wrote it, and simply didn’t see it until yesterday. Dr. Hammer has some important things to say that are both illustrative of the specific topic and also of how science should work.

Taking a break from galaxies and cosmology, I’d like to post a little praise of NASA for safely returning a piece of an asteroid to Earth. One of the amazing things to me about astronomy & astrophysics is that we have learned how to decipher the composition of distant stars and gas clouds by observing their spectra. I worked on this early in my career and retain an interest in the cosmic abundance of the elements.