Jun 04 2026
Planets Around Black Holes
My mental map of the universe has evolved over my life, partly due to new scientific discoveries and partly due to my own education. As if often the case, as you learn more, things get more complicated. The simplistic picture I had as a child was that the universe consisted of many galaxies in which there are many stars and around which there are planets, likely something similar to our own solar system. I have had to modify this model dozens of times, and perhaps I need to make another little tweak. This has to do with where planets exist.
First, galaxies are not randomly distributed throughout the universe. They are bound together in local groups, those groups are gravitationally bound into galaxy clusters, which in turn are part of superclusters which are finally organized into giant filaments, the largest gravitationally bound structures in the universe. So our universal address is – the Sol system within the Milky Galaxy, part of the Local Group within the Virgo Cluster which is part of the Laniakea Supercluster.
At some point I also learned that not all stars (and therefore, not all planets) exist within galaxies. Estimates of the number of stars within and between galaxies just overlap, so they may be equal, but the average estimates indicate that likely 1-10% of all stars are not in galaxies. They are wandering between galaxies, mostly within galaxy clusters. The first intergalactic star was discovered in 1997. It is likely that most such stars were formed within galaxies (you need clouds of gas and gravitational disturbances for stars to form) but then were flung out because of gravitational interactions with other objects, such as a black hole. Two galaxies colliding can also spray their stars throughout the cluster. It is also very likely that such stars would retain their planets.

In Isaac Asimov’s
Understanding, at a deep level, the differences between legitimate science and pseudoscience is increasingly critical in our modern world. Science, in my opinion, is perhaps the most powerful tool humans have collectively developed for understanding the universe in which we find ourselves. (I would clarify that it is complementary with philosophy which is important to ensure that we are thinking clearly, rigorously, and consistently.) Pseudoscience pretends to be scientific but is essentially doing it wrong. There are many underlying reasons for the existence of pseudoscience – it is sometimes just poor quality science due to poor training or sloppy technique, it may result from a motivation to achieve a desired result rather than letting the empirical chips fall where they may, researchers may not appreciate their own biases, or it may be part of a dedicated campaign motivated by profit, politics, ideology, religion, culture, or just wishful thinking.
Dozens of people have e-mailed me about a
If I were a UFO enthusiast, someone who believes that some UFOs (now UAPs) are aliens visiting the Earth and that the US government knows this and is covering it up, I would be really disappointed. I might engage in some serious motivated reasoning to convince myself that the
I came across a few news items that I could possibly write about today and couldn’t decide which to cover, so I will write about all of them, since they all relate to renewable energy.
I thought everyone needed one more thing to worry about, so here you go: evolving AI. When I hear this phrase I think of two things. The first are AI systems designed to simulate organic evolution. The second are artificially intelligent systems that are capable of evolving themselves. That latter one is the type you need to worry about.
It is long past time the US eliminated gerrymandering, the drawing of district lines specifically for the purpose of favoring one political party, across the board. This requires either a 50 state agreement, or action at the federal level. This has been a problem since near the beginning of our democracy, and seems to be getting worse. We are now in the middle of a mid-decade tit-for-tat rash of gerrymandering that is extremely anti-democratic, so it’s a good time to raise this as an issue voters should definitely understand and prioritize.




