My recent post questioning the Giordano Bruno segment in the first episode of the new Cosmos has attracted a gratifying amount of attention, both on this site and elsewhere around the web. It has also prompted a heartfelt reply from Steven Soter, a resident research associate at the American Museum of Natural history and Cosmos‘s co-writer (along with Ann Druyan).
It is very much in the spirit of Cosmos, and of the scientific process in general, to engage in debate in the search for deeper truths. It is also a powerful tribute to the new series that so many people are now discussing Bruno, Thomas Digges, and the intertwined relationship of science and religion during the 16th century–not your usual day-after TV conversations. In that spirit, I am pleased to present Steven Soter’s essay here in full, followed by a response from me. Soter, in turn, will soon provide some additional closing thoughts.
The Cosmos of Giordano Bruno by Steven Soter
Corey S. Powell takes the new Cosmos series to task for telling the story of Giordano Bruno in the opening episode. Bruno was burned at the stake in Rome in 1600 for various heresies, including his belief in other worlds.
Powell’s critique dwells on the well-known facts that Bruno was a mystic and an extremely difficult person. Well, so was Isaac Newton, who devoted as much time to alchemy and biblical numerology as to physics. But that has no bearing whatever on the value of his good ideas.
Powell writes that the new Cosmos is “downright wrong” because “Bruno was not the first to link the idea of infinite space with the infinite glory of God.” But the script never says that. Bruno got the idea of infinite space from Lucretius, but he also read Nicolas of Cusa, who related the concept to an infinite God.
Bruno’s originality lay elsewhere. He was indisputably the first person to grasp that the Sun is a star and the stars are other suns with their own planets. That is arguably the greatest idea in the history of astronomy. Before Bruno, none of the other Copernicans ever imagined it.
Powell suggests that Cosmos should have featured the English astronomer Thomas Digges instead of Bruno. The great contribution of Digges was to realize that the Copernican system allowed the stars to extend out to infinite distances, because they no longer had to make a daily revolution around the Earth. But Digges regarded the stars as “the court of the celestial angels”, not as the suns of other material earths. And that was a big step backward. In contrast, Bruno wrote, “the composition of our own star and world is the same as that of as many other stars and worlds as we can see.” His profound intuition had to wait three centuries to be verified by the spectroscope.
Powell writes that neither Kepler nor Galileo thought much of Bruno. It is true that Kepler recoiled from Bruno’s infinite universe of worlds and found it frightful, but his reasoning was based in part on a mystical obsession. He rejected the existence of any planets beyond the six allowed by his notion of a perfect Pythagorean solar system. The naming of the Kepler space telescope, dedicated to the discovery of planets around other stars, is perhaps somewhat ironic.
Here is what Kepler wrote (in De Stella Nova, 1604) about Bruno’s infinite universe: “This very cogitation carries with it I don’t know what secret hidden horror . . . Well, let us seek the remedy in Astronomy herself, so that by her arts and soothing blandishments this madness of the philosophers . . . might be led back within the bounds of the world and its prisons. Surely, it is not good to wander through that infinity.” Kepler was a very great man, but not for this.
While Kepler rejected an infinite universe, he was a good enough scientist to recognize that Galileo’s discoveries with the telescope lent support to some of Bruno’s ideas. Writing to Galileo in 1610, Kepler was impressed by the observation that stars seen through the telescope still sparkled, in contrast to the circular appearance of planets. He asked:
“What other conclusion shall we draw from this difference, Galileo, than that the fixed stars generate their light from within, whereas the planets, being opaque, are illuminated from without; that is, to use Bruno’s terms, the former are suns, the latter, moons, or earths?”
Galileo never once mentioned Bruno’s name. Of course in the land of the Inquisition he had good reason. But in his Dialogue on the Two Chief World Systems (the book that got him into deep trouble), he discretely accepted Bruno’s greatest idea, writing that the fixed stars are other suns.
It does not matter in the least where correct scientific ideas come from. Once out there, they can be tested. The important thing is not to suppress ideas. Freedom of thought is the life blood of science. That’s why Bruno’s story is important.
Corey S. Powell responds:
This may sound strange, but I’m going to start by disagreeing about some of what we disagree about.
You say: The fact that Bruno was a mystic and a difficult person does not discredit his ideas. I completely agree with this, and never argued otherwise. You say: Bruno got his idea of infinite space from Lucretius and the idea of an infinite God from Nicolas of Cusa. I agree on these points as well. The treatment of Bruno’s reading of Lucretius is handled beautifully in Cosmos.
Here are the two main areas where I think the Cosmos episode went awry, and why it really matters.
First, the depiction of Bruno as a lone wolf (“…for one man, Copernicus did not go far enough…”) is historically inaccurate and—more important, to my mind—it misrepresents the collaborative and cumulative way that science operates. As I noted, the notion of infinite space beyond our solar system originated with Thomas Digges, whom Bruno undoubted read and may have met during his time in England. Even the idea that other stars are suns has possible precedent a century earlier in the work of Nicolas of Cusa, who wrote this remarkable passage [with the emphasis mine]:
… it would always seem to each person (whether he were on the earth, the sun, or another star) that he was at the “immovable” center, so to speak, and that all other things were moved…if he were on the sun, he would fix a set of poles in relation to himself; if on the earth, another; on the moon, another; on Mars, another; and so on.
Second, Cosmos confusingly depicts Bruno’s infinite cosmology as a physical theory of the universe (in praise of God, yes, but physical all the same). Reading Bruno’s most relevant works—On the Infinite Universe and Worlds and The Ash Wednesday Supper—is eye-opening. Thank you for inspiring me to do it. Bruno’s vision of an infinite space, containing infinite populated worlds, is thrilling and beautiful. Interpreting it primarily in physical terms is anachronistic, however.
Bruno imagines all planets and stars having souls (part of what he means by them all having the same “composition”), and he uses his cosmology as a tool for advancing an animist or Pandeist theology. See historian Stanley Jaki’s translation of Ash Wednesday, with highly critical commentary.
True, Bruno takes a big step forward from Copernicus in speaking explicitly about the infinite, and about the existence of other planets and suns; but he takes a big step backward by interpreting the universe more in theological than mathematical terms. You justly write, “It does not matter in the least where correct scientific ideas come from,” but my point is that Bruno’s cosmology was not a correct scientific idea, nor was it even a “guess” as Cosmos asserts. It was a religious and philosophical statement, one that sparked a great deal of stimulating debate in the 17th century but not one that advanced the broader cause of rationalism.
That is why I say that religion, not science, caused Bruno’s deadly clash with the Church. And that is why I spoke up on behalf of the forgotten British astronomer Thomas Digges. Digges, far more than Bruno, built on the tradition of Copernicus and sought to bring more of the universe into the grasp of math and geometry; far more than Bruno, he sought to create a whole community of Copernicans who could keep that process going. Digges at least banished the angels to the distant, starry realm. Interestingly, he was also the first to consider how the night sky can be dark in an infinite universe (a question now known as Olbers’ Paradox).
Back to where we agree: “Freedom of thought is the life blood of science.” I admire the way Cosmos tells this aspect of the Bruno story—and just to be clear, I greatly admire the entire Cosmos project, which is why I am being so critical here.
I just wish that, with this rare opportunity to present a pivotal historical era to a broad audience, Cosmos could portrayed Bruno not just as a victim of the “thought police” but as a complex, inspired, paradoxical participant in the grand struggle to create our modern view of the universe.