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Understanding AGN and their host galaxies
Everyone and their dog makes a Spectral Energy Distribution (SED) fitting code. It’s not hard. The data are a few numbers, you just need Gaussian statistics, and connect to a model library. The design choices vary wildly though: Computation and uncertainty quantification cigale is a community platform mostly focused on galaxies, with quite limited uncertainty…
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The state of nested sampling research in 2026: II) Fundamental algorithm research
see also part I. Nested sampling as an algorithm has a few papers presenting convergence proofs. It’s interesting from how many angles people have looked at this problem. See the relevant section in the literature review. Diagnostics (ongoing) Andrew Fowlie proposed an elegant test for diagnosing live whether nested sampling is sampling in an unbiased…
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The state of nested sampling research in 2026: I) Scaling nested sampling to high-dimensions
Since I wrote a systematic literature review (arxiv, scholar) in 2023, and written or contributed to several nested sampling packages, I’m someone who people turn to and ask, “what is next in nested sampling research”? In this first part, I will write about scaling nested sampling to high-dimensions. Contrary to conventional wisdom, nested sampling does…
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How many people does it take for society to be against you?
Let’s say society is divided into two factions. One faction is univocally for equality between men and women in all areas. Another faction thinks that due to various factors, women and men should in some areas have different societal roles. People treat others according to their values. Let’s say the ratio is 80:20 in favor…
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Simulation-based inference for X-ray astronomy
In simulation-based inference, you train a neural network with pairs of model parameters θ and correspondingly data D, (θ, D). In the case of NRE, the network is a classifier, which predicts the probability that the data came from the (θ, D) stream corresponding to the joint p(θ,D) vs. a scrambled-up (θ, D) stream, corresponding…
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Conflicts in politicial coalitions
Coalitions become very unpopular when politicians are seen fighting and haggling. Calls for re-elections appear, together with the phrase “Instead of fighting all the time, the government should work.” Elections represent the choices of the people, ideally not just in the representatives but the direction they intend to lead towards. If people were to already…
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How many people does it take for a person to have a miserable life?
Let’s say you are a victim of bullying. A fraction of your work place or school decides that they will feel better if they make you feel lower. You go there every day. What fraction of people would it need to have a bad experience? Let’s say you interact with 30 people there on average…
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Sei nicht zufrieden nichts Schlechtes zu machen, schau jeden Tag etwas Gutes zu tun. ― Nicholas Winton
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Movies are unrealistic because of communication bandwidth
Movies have scientific inaccuracies, for example: We also often see unrealistic or unfair depictions: People complain about these, but I have some sympathy with movie makers. As a movie maker, you have to communicate relatively quickly to get the story along. Using tropes and concepts that the audience is already familiar with is not only…
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Astronomer’s logarithms
A few generations ago, you might have learned how to take logarithms with the slide rule scale. Here I’ll teach you the fast algorithm astronomers use to take logarithms in their head. Algorithm: dex: the units of logarithm differences Finally, we can talk differences in logarithmic plots. A difference of 1 in a log plot…