The grand aim of science is to figure out how it all works, which includes giant questions like: Where did the Universe come from? What is it really made of? How does all that stuff work and interact with each other? And how is it that human intelligence exists and is able to experience the Universe and probe it with our minds? You know, small stuff like that. Ever since someone stood underneath a starry sky, looked up and went, ugh? people have been asking these questions. We can see forms of science as far back as the ancient Mesopotamians and Egyptians, but the theory of science has its roots in philosophy, with the Greek philosopher Aristotle being the first to think about how to actually go about doing science. This methodology has been refined over the ages and is now called the philosophy of science. This core of science is the scientific method, which contains principles like logic, rationalism, empiricism, evidence, testable hypotheses, objectivity, and reductionism.

This is the toolkit of science and helps us process the information we get about the universe to work out what is and isn’t true. Mathematics and computer science are not technically sciences because they don’t study the natural world, but they are very close to science and are incredibly useful tools for scientists to use. Mathematics is the machinery of physics, and it is kind of a mystery why mathematics describes the universe so well. Computers are used in all branches of science because to do science you need a brain, and computers are an amazing tool to augment our brains. The core of science is made of physics, chemistry, and biology, which contain a load of surrounding disciplines as well. I don’t have space to include them all, but I have done in-depth maps of all of these subjects, so check those out if you want to find out more. If you take a step back and look at all of science, it is interesting to see how the scientific

method changes as you apply it to different subjects. Physics made huge amounts of progress to understand the Universe through reductionism, breaking things apart into their smallest components and understanding them one by one. But when you move up the chain towards chemistry and biology, reductionism becomes increasingly difficult to apply because these subjects deal with much more complex systems. If you want to study a part of biology, the properties of a single thing are strongly defined by its relationships with everything else. You can no longer study individual pieces in isolation. Because removing them from their relationships actually changes the thing you want to study. So there are so many complicated relationships in things like how your genes in your DNA are expressed to make you, or how your neurons and neurochemistry chemistry all combine to create the unique experience you are having now. These systems emerge out of a massive number of very complicated relationships, and so capturing all of that complexity in one model is incredibly hard.

In fact, as we get further and further up the chain away from physics, the entire scientific method starts breaking apart. You can see this in fields like nutrition and psychology, where incredibly important historical results are looking increasingly questionable, like eating saturated fat leading to high cholesterol, or how it is hard to replicate the results of many famous psychology studies, like willpower being a limited resource. But I think that these mistakes are understandable because trying to come up with a scientific theory that explains why people do the things that people do is just a very hard thing to do because people are… complicated! And, in fact, there is an argument that the human brain is the most complex system that we know about in the Universe! And so, when you get a load of those together doing stuff, like in sociology, it just gets, it just gets crazy. Which brings us to the social sciences, which I have arranged vaguely from more sciency to less sciency.

These subjects often contain a mixture of scientific practices and practices from the humanities, like archaeology, which uses hard science techniques from physics to detect structures under the ground, or carbon date objects, but then the interpretation of what this evidence tells us about the humans that lived at that time becomes a lot more subjective. Or in fields like economics or political science, where people can apply rigorous statistical techniques to their data, but then the interpretation of those has to be done by a human brain who is by nature subjective. So the proof that the interpretations are not scientific is the fact that they can’t predict the future. So in economics, it seems we can’t predict when a recession is going to happen, or what bitcoin is going to do tomorrow, whereas in physics, if I throw a ball, I can describe the future of that ball incredibly well. But please note that I’m not saying that subjectivity is necessarily a bad thing. If you’re studying a subject matter that has these very complex systems in them, and

you have taken the scientific method to its breaking point. What else are you going to do? Subjectivity really is all you have left. But the trouble comes when it is not recognized or flagged appropriately. People think they are being objective when they are actually being subjective, and that does happen. But this is forcing people to innovate with the scientific method and come up with new techniques to deal with these systems. One example from history is randomized controlled trials in the pharmaceutical industry to really tell if a drug is working or not. And with the recent replication crisis in the social sciences, scientists are now trying to come up with new techniques and methodologies to deal with these complicated systems. And it is a very hard challenge, but that’s how you progress. But if you want to get at the truth of something in the world, the scientific method is still our best way of doing that. But now let's carry on our journey and leave the burden of scientific rigor behind us.

and move into the arts, a place of pure subjectivity. Is this good art? Well, I like it. Okay. The one thing they do share with science is exploration, pushing the limits of what has been done or thought before. They explore the human condition through books, movies, music, art, and are always trying to find new ways of reflecting on what it is to be alive, and a human with emotions and a brain with the ability to create. And I think it is just as well we can’t explain all of those things with science because they would lose all of their charm. That intangible nature is what makes them so much fun. Some of the most enduring art has tackled the biggest questions like what is it to be a human? Why are we here? And what should we do with our time here? These are very similar to where we started and brings us right back to the other side of philosophy. So I got a bit carried away this map isn’t really a map of science, it is a map of human

endeavour. And it isn’t even a map, but a giant cosmic doughnut of knowledge! Anyway, that’s it. Thanks for watching, and if you want to get hold of the donut of knowledge, check out the link in the description below to get a poster. And if you yourself want to learn some science, I’d recommend checking out the sponsor to this video, brilliant dot org. It is a website where you learn a lot of the core concepts in this map, like mathematics, computer science, physics, and many more. And you learn them by answering questions. So, in general, when you’re learning a subject, you might feel like you know it, but there is only one way to make sure, and that is by actually answering questions to test your knowledge—that is, using the scientific method on yourself. So, that is what you do on brilliant dot org; you learn by answering questions, but they are fun and engaging. They are very satisfying when you get one right, and if you get one

wrong. There is lots of help and descriptions to help you work out why. So if that sounds interesting, check out brilliant.org/dos, link is also in the description below. And as an added bonus, the first two hundred people to sign up can get a twenty percent discount of the annual premium membership, which unlocks all of their content. So check that out. And also, we’ve just released the next in the professor astro cat books, which is the space rockets book. So if you have got a youngster in your life who you’d like to get into science at a young age, they are a really good place to start, link is also in the description below. Well, that’s it for me, thanks so much for watching, and I’ll see you on the next video.

Map of Science (and everything else)

Map of Science (and everything else)