What is covered, week by week, and which topics each lecture draws on.
The twelve lectures form one chain, where each week’s unresolved question becomes the next week’s opening question.
Why is the night sky dark?
The darkness between the stars looks empty. It is not. A dark night sky already tells us that the universe has a history.
Week 1 · 27 July 2026
What is the oldest light we can see?
The dark sky is not really dark. Point the right instrument upward and the whole sky glows in microwaves — with a spectrum that looks exactly like something at a temperature.
Week 2 · 3 August 2026
What is a temperature?
One molecule in an empty box has a speed and an energy. It does not have a temperature. Add an enormous number of them and temperature becomes one of the most reliable things you can measure.
Week 3 · 10 August 2026
How does a crowd have properties its members don't?
You cannot predict where one gas molecule will be a second from now. Give a physicist a litre of the gas and they will tell you its pressure to several decimal places.
Week 4 · 17 August 2026
Why does time run one way?
Run the film of a gas filling a room backwards and it looks obviously wrong, even though every collision in it still obeys ordinary mechanics. The arrow of time is not written into the laws. It has to come from somewhere else.
Week 5 · 24 August 2026
How do organised structures persist at all?
The second law says disorder tends to grow. A whirlpool, a flame, and a living body all keep their shape anyway. None of them are cheating. All of them are open.
Week 6 · 31 August 2026
Why hasn't the Sun burned out?
Chemical burning gives the Sun a few thousand years. Gravity gives it tens of millions. The rocks say billions. This is the week where arguing stops working and you have to calculate.
Week 7 · 21 September 2026
How do two nuclei that can't touch, touch?
The Sun's core is hot, but not remotely hot enough to force two protons past their mutual repulsion. Quantum mechanics does not get them there by giving them more energy. It gets them there by not requiring a sharp edge at the wall.
Week 8 · 28 September 2026
What is a particle?
Fire particles through two slits one at a time, and each one lands as a single point. Do it enough times and the points draw stripes only a wave could make. No single old picture explains both facts.
Week 9 · 6 October 2026
What happens when you look?
A measurement is not a human blinking at reality. It is a physical interaction that spreads a quantum system's alternatives across an enormous environment until they can no longer interfere. That explains a great deal. It does not explain everything.
Week 10 · 12 October 2026
Why does matter behave like matter?
A table feels solid. Push on it and it pushes back. The honest explanation for that push is not one tidy principle — it is atomic structure, electric repulsion, and quantum exclusion, all doing work at once.
Week 11 · 19 October 2026
Where does explanation break?
Push a dead star's mass past its limit and gravity wins outright — that part we understand. Push relativity and quantum mechanics into the same extreme regime and neither is enough alone. Zoom out and most of the universe's contents have never been identified. Those are three different kinds of not-knowing.
Week 12 · 26 October 2026