Ethan Siegel is an astrophysicist, but he is better known as a highly successful science populariser, who even has his own Wikipedia page. He first rose to fame as the author of the blog Starts With a Bang, which he launched in 2008. He expanded his brand, with the publication of popular books on physics. He expanded still further, making podcasts and writing posts under his brand name on Medium, Forbes, and Big Think. He is today one of the biggest names on the Internet in popularisation of physics. Here I’m going to look at his latest publication on Big Think. Big Think is a multiplatform, multimedia Internet organisation who in their own words state:
Our mission is to make you smater, faster. At Big Think, we introduce you to the brightest minds and boldest ideas of our time, inviting viewers to explore new ways to work, live, and understand our ever-changing world.
“Big Think challenges common sense assumptions and gives people permission to think in new ways.”
I’m sorry, but to my ears that sounds like those windy ads on the Internet that say, “Take our three-week course of our seminars once a week and you will be earning $100,000 a month within a year!”
So, what is the post of Dr Siegel on Big Think that has attracted the attention of The Renaissance Mathematicus and why? Our intrepid astrophysicist and physics populariser has decided to try his hand at history of science and has written a post about Johannes Kepler, Why Johannes Kepler is a scientist’s best role model. After all our author is a scientist and a successful science populariser, who has even won prestigious awards for his work, what could possibly go wrong, when he tries a bit of history of science? Unfortunately, as with other scientists and science populariser, who think they can do history of science, without investing serious time and effort in the discipline, almost everything.
So why does Siegel think that the good Johannes should be every scientist’s role model? He tells us in his lede:
- The annals of history are filled with scientists who had incredible, revolutionary ideas, sought out and found the evidence to support them, and initiated a scientific revolution.
- But much rarer is someone who has a brilliant idea, discovers that the evidence doesn’t quite fit, and instead of doggedly pursuing it, tosses it aside in favor of a newer, better, more successful idea.
- That’s exactly what separates Johannes Kepler from all of the other great scientists throughout history, and why, if we have to choose a scientific role model, we should admire him so thoroughly.
He then delivers four examples of famous scientists, who could admit they were wrong:
- Albert Einstein could never accept quantum indeterminism as a fundamental property of nature.
- Arthur Eddington could never accept quantum degeneracy as a source for holding white dwarfs up against gravitational collapse.
- Newton could never accept the experiments that demonstrated the wave nature of light, including interference and diffraction.
- And Fred Hoyle could never accept the Big Bang as the correct story of our cosmic origins, even nearly 40 years after the critical evidence, in the form of the Cosmic Microwave Background, was discovered.
I already have a couple of comments here. Niels Bohr is on record as saying that Einstein through his intelligent, astute, and penetrating criticisms of quantum theory that demanded answers contributed more to the development of that theory than almost anybody else. Not least Bell’s theorem, one of the key developments in quantum theory, was based on his analysis of the Einstein–Podolsky–Rosen paradox. Opposition to theories based on knowledge are important to the evolution of those theories.
Newton did in fact reject a wave theory of light in favour of a particle theory. However, he was able with his theory to explain all the known optical phenomenon. Moreover, when Hooke rejected his theory of colour saying that it wouldn’t work in a wave theory, Newton developed a wave theory, that was more advanced than those of Hooke and Huygens, to show that his theory of colour did work in a wave theory. Lastly, as I love to point out, Einstein won the Nobel Prize for physics, not for relativity, but for demonstrating that light consists of particles, so Newton wasn’t so wrong after all.
More generally, there is a famous quote from Max Planck about the development of new theories in science:
A new scientific truth does not generally triumph by persuading its opponents and getting them to admit their errors, but rather by its opponents gradually dying out and giving way to a new generation that is raised on it.
He then goes on to tell us why Kepler was a spectacular exception. First, we get a popular rundown of the observable phenomena of the cosmos and why that led to a geocentric model. On the whole OK but littered with small errors. For example, he tells us:
The Earth was big, and its diameter had been measured precisely [my emphasis] by Eratosthenes in the 3rd century B.C.E.
This is, unfortunately, typical of Siegel’s hyperbolic style. Depending on which value for the stadium one takes, Eratosthenes’ estimate of the size of the earth was relatively close to the real value but by no means precise. Also, in antiquity no one knew how correct it was and most people actually accepted other values.
We then get a description of the deferent/epicycle model for the planets and Spiegel tells us that Ptolemy made the best, most successful model of the Solar system that incorporated epicycles. Nothing to criticise here but there follows immediately a small misstep, he writes:
Going all the way back to ancient times, there was some evidence — from Archimedes and Aristarchus, among others — that a Sun-centered model for planetary motion was considered.
First off you really shouldn’t use an expression like “ancient times.” We know that both Archimedes and Aristarchus lived and worked in the third century BCE, so we can say that. The expression “there was some evidence from Archimedes and Aristarchus, among others” is a load of waffle, which doesn’t actually tell the reader anything. According to a couple of secondary sources Aristarchus of Samos devised a heliocentric system. We don’t have anything about it from Aristarchus himself. Archimedes is one of the secondary sources but not in a work on astronomy or cosmology. Archimedes wrote a work on calculating and expressing large numbers, The Sand Reckoner, in which he calculated the number of grains of sand needed to fill the cosmos. He used Aristarchus’ heliocentric model, which he only mentions in passing, because the heliocentric cosmos is considered to be larger the than the geocentric one.
Siegel now moves onto Copernicus and once again delivers up historical rubbish:
Copernicus was frustrated to discover that his model gave less successful predictions when compared against Ptolemy’s. The only way Copernicus could devise to equal Ptolemy’s successes, in fact, relied on employing the same ad hoc fix: by adding epicycles, or small circles, atop his planetary orbits!
As stated, this is rubbish. From the very beginning Copernicus used deferent/epicycle models for the planetary orbits. He didn’t add epicycles as an ad hoc solution because his model gave less successful predictions when compared against Ptolemy’s. In fact, Copernicus didn’t produce any planetary tables before he died in the year that his De revolutionibus was published, so he couldn’t know about the comparative predictive powers of his and Ptolemy’s system. When Erasmus Reinhold (1511–1553) did produce his Prutenic Tables (1551), the first ones based on Copernicus’ model, it turned out that in some cases the predictions were better than in tables based on Ptolemy and in some cases worse. This was because Copernicus used the same, in the meantime corrupted through frequent copying, basic data for his models as Ptolemy. This problem was recognised by Tycho Brahe, which is why he set up his massive astronomical observation programme, on the island of Hven, in order to provide new basic data. It is to Tycho that Siegel now turns.
Tycho Brahe, for example, constructed the best naked eye astronomy setup in history, measuring the planets as precisely as human vision allows: to within one arc-minute (1/60th of a degree) during every night that planets were visible towards the end of the 1500s. His assistant, Johannes Kepler, attempted to make a glorious, beautiful model that fit the data precisely.
This is Siegel’s introduction to Kepler’s Mysterium Cosmographicum published in 1596, four years before he even met Tycho and began to work with him! Siegel now gives a brief description of the model presented in the Mysterium Cosmographicumand follows it up with a pile of absolute garbage.
Maybe our astrophysicist author has slipped into a parallel universe because what he presents here is hyperbollocks, an assorted collection of made-up “facts” thrown together in a narrative that bears absolutely no relation to what really happened in history. As a Kepler fan when I read this and the following paragraphs eight days ago, I began banging my head against the wall and haven’t stopped since. No pain can blot out the stupidity presented here.
Kepler formulated this model in the 1590s, and Brahe boasted that only his observations could put such a model to the test. But no matter how Kepler did his calculations, not only did disagreements with observation remain, but Ptolemy’s geocentric model still made superior predictions.
Tycho made no such boast, that is simply made up and in fact he was not in any way interested in Kepler’s model. Kepler wanted to work with Tycho to get access to his data to fine tune his model, Tycho wanted to employ Kepler to do the mathematics necessary to turn his data into models for the planets orbits in his own geo-heliocentric model. When Kepler arrived in Prague, Tycho refused him access to the data he wanted out of fear of being plagiarised. Instead, he set Kepler to write a paper proving the Ursus had plagiarised him. The resulting essay is brilliant, was however first published in the nineteenth century, and has been described by Cambridge historian of science, Nicholas Jardine as The Birth of History and Philosophy of Science (CUP, 2nd rev. ed. 1988). Following this he was given the task of determining the orbit of Mars using Tycho’s data, to which I will return in a minute.
At this point in his life Kepler made no attempt to improve his geometrical model. The phrase, Ptolemy’s geocentric model still made superior predictions is quite simple mind boggling for anybody who knows what they are talking about. The geometric model that Kepler presents in his Mysterium Cosmographicum is his answer to the question, why are there exactly six planets? Kepler argues that his completely ration God, who is a geometer, designed his cosmos rationally and geometrically and there are exactly six planets because there are only five regular Platonic solids to fill the spaces between them. Not our idea of rational but Kepler was mighty pleased with his “discovery.” This model makes no predictions of any kind!
Now we get to the crux of Siegel’s whole argument, Kepler admitting he was wrong:
In the face of this, what do you think Kepler did?
- Did he tweak his model, attempting to save it?
- Did he distrust the critical observations, demanding new, superior ones?
- Did he make additional postulates that could explain what was truly occurring, even if it was unseen, in the context of his model?
No. Kepler did none of these. Instead, he did something revolutionary: he put his own ideas and his own favored model aside, and looked at the data to see if there was a better explanation that could be derived from demanding that any model needed to agree with the full suite of observational data.
Kepler didn’t tweak his model, at this time, attempting to save it, he certainly didn’t mistrust Tycho’s data, and he didn’t at this time add any postulates. He did put his model aside but not to look at the data to see if there was a better explanation that could be derived from demanding that any model needed to agree with the full suite of observational data. He was too busy doing other thing, things that served other purposes.
If only we could all be so brave, so brilliant, and at the same time, so humble before the Universe itself! Kepler calculated that ellipses, not circles, would better fit the data that Brahe had so painstakingly acquired. Although it defied his intuition, his common sense, and even his personal preferences for how he felt the Universe ought to have behaved — indeed, he thought that the Mysterium Cosmographicum was a divine epiphany that had revealed God’s geometrical plan for the Universe to him — Kepler was successfully able to abandon his notion of “circles and spheres” and instead used what seemed to him to be an imperfect solution: ellipses.
Here without explicitly naming it, Seigel is referencing Kepler’s work on the orbit of Mars that he published in his Astronomia Nova in 1609. It was during the many years of his “War with Mars”, his own description, that he finally discovered his first two laws of planetary motion: 1: Planetary orbits are ellipses with the Sun at one focus of the ellipse 2: A line from the Sun to the planet sweeps out equal areas in equal periods of time. For a good description of the route to the Astronomia Nova, I recommend James R. Voelkel’s excellent The Composition of Kepler’s Astronomia nova (Princeton University Press, 2001).
Siegel apparently thinks that this refutes Kepler’s Mysterium Cosmographicum, it doesn’t. The Mysterium Cosmographicum doesn’t deal with the shape of orbits at all. His model has the Platonic solids filling the spaces between the spheres. In the Ptolemaic deferent/epicycle system the orbits are not simple circle because of the epicycle. Ptolemy in his Planetary Hypothesis embedded the deferent/epicycle in a sphere but the book that got lost and was only rediscovered in the 1960s in a single Arabic copy. However, Peuerbach (1423–1461), which is almost certainly based on a now lost copy of the Planetary Hypothesis, revived this model in his Theoricae Novae Planetarum (written in 1454, published by Regiomontanus in 1472) with illustrations.
Copernicus’ heliocentric system, which also uses the deferent/epicycle models would suffer from the same problem and it is between these spheres that Kepler places his Platonic solids, irrespective of the orbit inside the sphere. The system would work equally well for elliptical orbits, so Kepler’s discovery of them had no effect on his Mysterium Cosmographicum.
Siegel gives a table of Tycho’s Mars observations with the following caption:
Tycho Brahe conducted some of the best observations of Mars prior to the invention of the telescope, and Kepler’s work largely leveraged that data. Here, Brahe’s observations of Mars’s orbit, particularly during retrograde episodes, provided an exquisite confirmation of Kepler’s elliptical orbit theory. [my emphasis]
Kepler used Tycho’s Mars data to derive his first two laws, so they can’t be used by him as confirmation. In fact, at the beginning he didn’t actual confirm his theory, simple assuming it applied to all the planets. It wasn’t until his Epitome Astronomiae Copernicanae published in three volumes from 1618 to 1621, after he had discovered his third law and done a substantial amount of the work reducing Tycho’s observational data to planetary tables, the Rudolphine Tables published in 1627 and on which he had begun to work as Tycho was still alive, that he demonstrated all three laws for all the known planets.
I will now return to that third law and the Harmonice mundi (1619) in which it first appeared. Kepler had already suggested the possibility of fine tuning the Mysterium Cosmographicum model with the Pythagorean concept of a harmony of the spheres and this is what his magnus opus Harmonice mundi was. He had already conceived it in the late 1590s but because of other commitments didn’t actually get round to writing it until the second decade of the seventeenth century.
Having created his harmony of the spheres, in 1621 Kepler published an expanded second edition of Mysterium Cosmographicum, half as long again as the first, detailing in footnotes the corrections and improvements he had achieved in the 25 years since its first publication, so far from abandoning his first theory to produce his elliptical orbits as Seigel claims, Kepler spent his whole life working to improve it.
What is truly bizarre is that Seigel appears to be aware of this fact. He writes:
It cannot be emphasized enough what an achievement this is for science. Yes, there are many reasons to be critical of Kepler. He continued to promote his Mysterium Cosmographicum even though it was clear ellipses fit the data better. He continued to mix astronomy with astrology, becoming the most famous astrologer of his time.
As already explained in detail, he didn’t just promote his Mysterium Cosmographicum, he worked very hard for many years to improve it. The statement, becoming the most famous astrologer of his time is another example of hyperbollocks. Kepler was a well-known astrologer in Southern Germany and Austria but the most famous astrologer of his time I hardly think so. I would also note that the modern astro-scientists disdain for astrology, as displayed here by Seigel, displays their ignorance of the history of their own discipline. Astrology was the driving force behind the developments in astronomy for its first three thousand years of its existence.
Seigel, like many scientists, who think they can write history of science without doing the detailed research, has taken a set of half facts, embroidered them with stuff that he simply made up and created a nice fairy tale that has very little to do with real history of science. A fairy tale that will be swallowed by his large fan base, who will believe it and make life difficult for real historians of science.