One of the exciting things about science is discovery. The fact that many important things about astronomy were never predicted by a theory or anticipated by astronomers before they made the observations, we never predicted the existence of dark energy or dark matter or black holes. But we've observed these things, and we've observed extraordinary things in the universe that were based on surprises to people looking at the world in new ways. As a metaphor and an analogy for discovering nature, let's look at sequences of cards. Regular playing cards with the face cards taken out, so just the number cards. It's a toy model, but it meaningfully captures some of the essence of how science works. You're gonna see four different sequences of cards, and the goal in this little game is to decide what is the rule that governs how these cards were laid down. what is the pattern in nature? In this case, the pattern in a numbered series of cards of four different suits that describes what's going on. The first example is obvious. I don't need any explanation for me, it's just a numbered sequence of the same suit. The rule is obvious. The second patter, is a little more interesting, it's an alternating red and black sequence. But notice here that some information is important, the alternating red and black sequence, and some information is irrelevant. The actual numbers of the cards or the difference between the two red and the two black suits. This is a lesson that in nature and in science, it's not obvious what the most important information is when we seek a pattern and don't need understand it. But now look at the third and fourth patterns, and see if you can decide before I give away the answer what is the rule that governs how these cards were laid down. You can see it's a little subtle. There do appear to be sequences or patterns embedded in that layering of cards. But it's not obvious. By trying to imagine the rule, you are doing what a scientist does. You're developing a hypothesis and testing it against nature, in this case, a sequence of cards, and you're using a small sequence of the data to see if your prediction matches what comes later. Immediately you're testing a feature of science where we have to understand how much data is needed to test the hypothesis. We're also seeing another aspect of science where possibly, more than one hypothesis can explain the same set of data. Looking at those last two sequences of cards, C and D, it's quite possible that more than one simply stated rule governs the sequences. This is partly why astronomers argue about theories. Sometimes it's not obvious what the best theory is, or there's not a unique theory at all. The rule or rather I should say one rule that governs sequence C is, when you play successive cards you're either matching the color or the number of the card. That's a very simple rule stated in only a few words. But notice how subtle a pattern of cards it makes. A rule that describes the fourth card sequence, is that a red card is placed on top of an even numbered card and a black card is placed on an odd numbered card. Again, it's a very simple rule stated in only a few words and it produces a surprisingly subtle pattern of cards in sequence. When you stare at the sequences cold without any idea of what's going on, you can see how difficult it is to elicit the rule or the underlying law of nature if you like, that describes C sequences. So this is just a cartoon example, but it does illustrate many of the features of the scientific method. The periodic table is an excellent example of patterns in nature and how science works. The first notion of a periodic table came from the Greek philosopher, Empedocles, almost 250 years ago. Empedocles came up with the idea that everything in nature, all the material substances of the earth and the atmosphere and even if human beings, were made of four essential elements; earth, air, fire, and water. The combinations of those four fundamental elements produced the diversity of the material world, that's an extraordinary idea but it's the basis of modern chemistry. Flash forward almost 2,000 years, and we have made a lab, doing simple experiments and drawing the skeleton of the modern periodic table. Where the associations and the properties of similar elements eventually gives us the idea that those elements have physical underpinnings. It's not until the modern atomic theory that we truly understand the periodic table. But the patterns in nature, the similarities between reactive elements, metals, and noble gases, is the basis of understanding how the atom works. The idea of discovery leads to a debate that's gone on for many centuries. The distinction between what is invented in science and what is discovered. Is science a product of the human mind and imagination? Or is it purely the discovery of things that exist in nature that we and maybe other creatures elsewhere in the universe can understand? This is an interesting debate, and artists and scientists have often found themselves intriguingly on opposite sides of the debate. We might imagine that like Newton, we are dissecting the rainbow. The science is pure analysis, turning white light into its component colors, and Newton was the one who put it all together in a theory of light. So the standard view of science is that it is reductionist, that it takes complex observed phenomena and then reduces them to their simplest elements. But science also involves synthesis, and that synthesis is an important part about how we understand nature and build scientific theories. As an example from the artistic side, consider Michelangelo, who wrote poetry and sonnets and we know as a scientist and an engineer. We might imagine that an artist is imposing their will on a canvas or a lump of marble or clay, imposing a vision of what they might imagine that to be and creating it from scratch. But that's not how Michelangelo saw it. He talked about roaming around the northern Italian towns where the marble was quarried, Carrara, and he would scramble over the hillside looking for a piece on the hillside where he saw something hidden in the rock that he could liberate through his talent. That's an unusual view of art, that there's something in nature in the lump of marble that he is liberating or seeing for the first time. It's more of a scientific idea. I think a true and nuanced view of both science and art, shows that the truth is more complicated, that there is synthesis and analysis and dissection and recompiling into a hole that occurs in both fields of human endeavor. Discovery is an important and exciting part of science. Many of the things we understand about the universe, were not predicted by any theory. There were completely unanticipated. So scientists must always be alert to patterns in nature, to something new and surprising that might lead them to a deeper understanding of the universe. This is true in art as in science. The whole idea of whether things are discovered or invented and are products of the human mind, is an interesting philosophical debate that's never been resolved.