I went on a bit of a twitter bender yesterday about the early claims about high mass galaxies at high redshift, which went on long enough I thought I should share it here. For those watching the astro community freak out about bright, high redshift galaxies being detected by JWST, some historical context in an amusing anecdote… The 1998 October conference was titled “After the dark ages, when galaxies were young (the universe at 2 < z <

In order to agree on an interpretation, we first have to agree on the facts. Even when we agree on the facts, the available set of facts may admit multiple interpretations.

Big galaxies at high redshift! That’s my prediction, anyway. A little context first. New Year, New Telescope First, JWST finally launched. This has been a long-delayed NASA mission; the launch had been put off so many times it felt like a living example of Zeno’s paradox: ever closer but never quite there.

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.

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.

The following is a guest post by Indranil Banik, Moritz Haslbauer, and Pavel Kroupa (bios at end) based on their new paper Modifying gravity to save cosmology Cosmology is currently in a major crisis because of many severe tensions, the most serious and well-known being that local observations of how quickly the Universe is expanding (the so-called ‘Hubble constant’) exceed the prediction of the standard cosmological

I have been busy teaching cosmology this semester. When I started on the faculty of the University of Maryland in 1998, there was no advanced course on the subject. This seemed like an obvious hole to fill, so I developed one.

At the dawn of the 21st century, we were pretty sure we had solved cosmology. The Lambda Cold Dark Matter (LCDM) model made strong predictions for the power spectrum of the Cosmic Microwave Background (CMB). One was that the flat Robertson-Walker geometry that we were assuming for LCDM predicted the location of the first peak should be at ℓ = 220.

In the previous post, I wrote about a candidate parent relativistic theory for MOND that could fit the acoustic power spectrum of the cosmic microwave background (CMB). That has been a long time coming, and probably is not the end of the road. There is a long and largely neglected history behind this, so let’s rewind a bit. I became concerned about the viability of the dark matter paradigm in the mid-1990s.