This is Knowing the Universe. The History and Philosophy of Astronomy. I'm Chris Impey, distinguished professor of astronomy at the University of Arizona. In this module, we'll talk about mapping. Mapping the solar system and mapping the galaxy, moving our history forward to the 19th century. We're talking about the enlightenment, that's the larger set of ideas that flowed through several centuries in Western Europe, that form the backdrop to the scientific revolution and the innovations that we'll be talking about soon. The Enlightenment was a period of intellectual freedom through reason, where reason was presumed to be the primary source for knowledge. The enlightenment depended on the scientific method. Descartes, in particular, was a very influential figure in this time. But it was broader than just science, there was a broad skepticism and questioning of religious and political orthodoxy. There was a systematic undermining of church and state authority by independent-minded thinkers. There was the belief and ideals such as liberty, toleration, fraternity, constitutional government, and the separation of church and state. These are ideas familiar to us now, but this is where they originated. This movement paved the way for the revolutions of the 17th, and 18th century. In England, the Jacobite rising, in America and France, the revolutions, also in the Caribbean and Ireland, revolutionary movements. From Newton's Principia in 1687 to the beginning of the 19th century, the enlightenment influenced culture in daily life, very far beyond the realm of science. We see the creation of state-sponsored scientific societies, the Royal Society in London, for example, the first. Soon after that, equivalent organization founded in Paris. Then a while after that, in Berlin. By the end of the 18th century, these societies existed throughout Europe. We also had the rise of scientific journals, again, starting in England with the Philosophical Transactions of the Royal Society, and the Analogous Journals in France, and then in America. Another important transition was the transition from Latin to the vernacular, to colloquial English, or French, or German. These journals were translated among the European languages, so everyone could benefit from what was written there. There was also the growth of the young country, the United States, as an intellectual power. See the formation of Harvard, Columbia, Penn universities, William and Mary. They also began granting PhDs, advanced degrees in this timeframe, hugely influential thinkers and scientists like Benjamin Franklin, Thomas Jefferson, David Rittenhouse, and William Smith. This is a dynamic and exciting time to be alive. Science advanced on all fronts. In geology, we have James Hutton and the idea of deep time. The idea that the earth must have been in existence for hundreds of millions or billions of years for everything we see around us to have been created and laid down. In chemistry, we have, Joseph Black and Joseph Priestley, who gave us the basic ideas of chemical interactions. Lavoisier in France, who gave us the nomenclature for chemistry that we still use, and developed quantitative methods to chemistry. From Galvani and Volta, we have the beginning of electrochemistry and the invention of the battery. Meanwhile, in biology, there's advanced progress going beyond what Darwin did. We have Carl Linnaeus, who gave us the taxonomy of living creatures that we still use today, and Leclerc preceding Darwin with early evolutionary theory, and Harvey with this circulation system of the body, Hooke, and Leeuwenhoek used the microscope to look at the world of cells for the first time. At the level of populations, we have Malthus developing some of the ideas that will eventually turn into the field of ecology, and with Humboldt, the beginnings of the ideas of climate science. All of this happened in parallel. Meanwhile, science was not just for a few smart minds and a few specific places, there was a coffeehouse culture developed, again, starting in London, where lectures and courses were offered in a public setting where people could come and go and ask questions and engage in debate with the intellectuals of the time. There were popular lectures and courses. These were a source of entertainment and edification. We've already seen the Gresham College was a college founded in London in the late 16th century that did not have any students that existed purely to give public lectures, to educate the citizenry of London. These lectures were popular at the time. Remember, this is in the days before video games, and films, and movies, and TV. They attracted audiences in the hundreds and sometimes thousands. There were also demonstrations, spectacularly showing the public experimental science for the first time. Some of these forums were also places where women could participate, and learn science and become scientists. Remember at this time, because of their particular tradition from religious circles and closed circles, most universities were not open to women. We also see popular scientific books aimed at the non-scientists, and the translation of previous Latin texts into common languages. Women in Science is a big topic, and we can't give it its full due, just briefly here. But the history of science, as we've already seen, is largely and sadly devoid of women until the 20th century. Even then, their representation has grown only slowly. Women and people of color are even more dramatically underrepresented. There are many cultural and political reasons for this asymmetry, but none that can be ascribed to any intrinsic differences or proclivity towards science or skill at science. We can pick out just a few examples. Caroline Herschel, who we'll talk about in more detail, was an astronomer and instrument maker and prominent intellectual of her time. There was Laura Bassi who was a physics professor, the second woman to have a PhD in her country and other people such as the director of the Imperial Academy, Marie-Anne Pierrette Paulze, who is the chemist, wife of Lavoisier, and a major scientists in her own ride. We have Eva Ekeblad, agronomist and chemist who introduced widespread use of the potato as a cash crop, Lady Mary Wortley Montagu, who introduced smallpox inoculation, and the woman pictured here on the right, Emilie du Chatelet, who died sadly at the age of 43, who is an extraordinarily broad scientist, a physicist, develop the ideas of kinetic energy and momentum, translated Newton's Principia into French and added some derivations including the conservation of energy and of course, since then, the number of women in science has grown. Here in kinetic form we see a montage of a number of them from the 20th century. Meanwhile, there are ideas and philosophers who also provide a backdrop for the ideas of science. We see John Locke with his influential essay concerning human understanding. He categorized three kinds of knowledge, the intuitive, obvious knowledge, understanding angles in a triangle, for example, the demonstrative knowledge, where you have to arrive at it through reasoning where Pythagoras's theorem is an example. Then sensitive knowledge. Knowledge arrived through the senses and not necessarily purely intellectually. He thought that all these ideas do derive ultimately from experience. But since we have limited knowledge of what causes sensation, we can make a direct connection between our senses and the true essence of external things. George Berkeley was an important idea minded person here who rebelled against essentialism or platonic forms. He was a skeptic and he held to what we call radical immaterialism, saying that only ideas are real and not abstract ideas but concrete instances. For example, you can't really think of a triangle without thinking of a particular triangle. He got into the meaning of language in science, that it gets its meaning from association with experience and he was very aware of the distinction that is central to all science that correlation is not the same as causation. We have David Hume, a remarkable figure who was known to have spoken five or six languages before the age of five, including ancient Greek. He argued that passions rule reason, and we have to suppress them to be able to be rational people. He thought that deductive reasoning and causality cannot actually be justified rationally since they rely on uncertain matters of fact, an unreliable perception. That's a common theme among these philosophers and they're only habits of thought. He agreed with the other thinkers just mentioned, that we cannot have a reliable notion of external reality and so again, adhered to the principle of skepticism, which is at the heart of all science. Adam Smith is another important thinker, mainly in the field of economics, who was a close friend of Hume. Then Mary Wollstonecraft is an important figure too who is an advocate of republicanism and the rights of women and recognized that social order founded in reason would treat both men and women as equally capable rational beings. Emmanuel Kant is an important thinker of this time and in the history of philosophy. His book, The Critique of Pure Reason, is a hugely influential texts in the history of philosophy. He argued that Locke was not careful enough in his classification of knowledge and so he got into the details making distinctions between analysis, the idea that red is a color, the form of subject and predicate of explaining things in a logical argument versus synthetic, the fact that red, for example, angers bulls, where you have a subject that's independent of the predicate and so is informative, adding knowledge from experience. He was also very careful to make distinctions between a priori and a posteriori reasoning. A priori means it's based on reason alone from first principles and universal, like Pythagoras's theorem, a posteriori might, for example, mean that spiral nebulae are made of stars. This is an inference based on experience or observation, and it's necessarily uncertain or limited. Pierre-Simon Laplace was another important thinker of these times, a mathematician who developed major tools of statistics, probability, including partial differential equations and linear algebra methods that are foundational to mathematics as it's taught today. He was also a physicist who did major work on celestial mechanics and hydrodynamics and developed a theory of tides that went far beyond what Newton had done. Laplace had the idea of a demon, a subversive mental form that could refute freewill. He worried a lot about the idea of a mechanistic universe, the clockwork universe. He thought that given initial conditions and enough calculation power, you could predict all future events and so you're faced with the problem of freewill. What happens to freewill if we have sufficient knowledge to predict all future events of the universe. He recognized that saving freewill would imply some extra component like randomness and so he worked on statistical physics and the ideas of chaos and dynamics. He also anticipated quantum mechanics, although this was before quantum theory. He also imagined that we might simply not have a big enough computer. Computers of course didn't exist, but mechanical calculators did. We might not have a big enough computer to calculate all future events and so we could say freewill that way. That's the end of this topic.
