May 24th 2026

Things from Today:

• Sterile Neutrinos - We discussed a hypothetical variety of subatomic particle, called a sterile neutrino. Unlike regular neutrinos (which we know do exist), sterile neutrinos have never been detected. These particles are hypothesised as they fill in a rather conspicuous asymmetry in our understanding of particle physics. What makes them distinct from regular neutrinos is a little technical, but can roughly be described as their 'handedness' - regular neutrinos are all left handed, and sterile neutrinos would be right handed (which I realise, is a fairly bizzare thing to talk about for a subatomic particle - you can think of this as the direction they spin in, clockwise or anticlockwise). This handedness is what makes them very challenging to detect, as (again.. rather technically...) it prevents them from interacting with other kinds of matter, except through gravity or, perhaps, 'mixing' with the regular neutrinos. Sterile neutrinos are one (of many..) possible explanations of Dark Matter, and so they are still an active area of research. 

• Cygnus X-1 and Sagittarius A* - Peter shared an image taken from his garden in Southend, which contains (at least) two known black holes. See figure and text below.

• Black Hole Tidal Forces (Spaghettification) - We discussed 'Spaghettification', the real scientific term (no, really...) that describes what happens to matter when it falls into a black hole. Near to the horizon of a black hole, gravity is not only extremely strong, but also extremely variable. If you fell towards a black hole head first, the strength of gravity pulling on your head would be much greater than the strength of gravity on your feet - this results in a stretching force that would pull you apart (stretching you out like spaghetti!). Somewhat counter-intuitively small black holes are much more dangerous than large black holes, as far as spaghettification is concerned.

• "Will Scientists Ever Know Everything?" - This was a brilliant question, from a young future scientist. In short, my answer is "No!". At its centre, modern theoretical physics has the lofty goal of finding 'the theory of everything'. Now, you would be excused for thinking that this question might be akin to finding 'the meaning of life' - but what it really means is much more precise: we want to understand how gravity and quantum physics fit together in a single equation. This is a really tricky problem, which has consumed the mental bandwidth of several generations of the smartest and most determined scientists on the planet... BUT... it is not the be-all and end-all of scientific inquiry! Even if we did have this 'final theory' of physics - we would still need to understand all the nuances of how this theory applies to the real world, we would need to extract and observe all of the innumerable wonders that it describes in our actual Universe. One thing that has always been true in science - is that every question we answer, leads to ten new questions we need to figure out. So fear not, young scientists, the questions are only going to get bigger, deeper, and more important!

Extra Reading:

• [Article] Rubin Tracks Skyscraper-Size Asteroids, Failed Supernovas, and Interstellar Visitors - J O'Callaghan (Quanta Magazine)

• [Article] AI cracks 80-year-old mathematics challenge - D Castelvecchi (Nature)

Extra Watching / Listening:

• [Podcast] What Can Jellyfish Teach Us About Fluid Dynamics? - S Strogatz & J Dabiri (The Joy of Why Podcast)

• [Video] Sunsets from Different Alien Worlds Across the Universe - Universe Dimensions

Homework

This 'homework' is recurring, and one I like to set my own students (and try to stick to myself!):

1. Learn something new everyday.

2. Share what you know with someone else.

3. Look at the world and "think like a Martian".

If you learn something interesting, I would love to hear about it! Tell me about it next time or drop me an email!

spacetime-sundays@science-on-sea.com