When you’re in a hole, stop digging!

Somebody made a comment at Scientific American on Ken Shulman’s article pointing to my criticism and providing a link. Not unexpectedly, Mr Shulman has reacted and posted a sort of defence of his excruciating piece on the history of astronomy. He did not join the comments column here to post his retort but did so under his article at Scientific American. As I have no desire to register at Scientific American in order to be allowed to respond I have transferred the whole of Mr Shulman’s latest screed here where I shall subject it to the same careful analysis with which I rewarded his original effort.

Thony Christie’s writes that words fail him, but in truth they merely betray his as rash and mostly wrong.

Yes! Slapdash, ill considered, rash and without a doubt wrong! Guilty as charged your honour. Somebody spends a long-time and expends a lot of effort carefully analysing why your text is factually wrong and the best you can do Mr Shulman is to dismiss it as rash! A rather weak level of criticism for a professional journalist. However you do go on to make some specific comments; let’s see what you think I got wrong. Before doing so I would point out that you have only answered some and by no means all of my criticisms. Does that mean all the others are right?

For starters: 

Cambridge University records show Jeremiah Horrocks entering Emmanuel College on May 18, 1632 as a sizar–a student who supplemented his tuition by performing menial tasks. Why would a wealthy father subject a gifted son to this indignity? And as far as the nature and location of Horrocks’ observatory, we can only speculate, although they were clearly not as elaborate as Tycho’s.

The Horrocks-Aspinwall clan, his mother was an Aspinwall, were strict and active puritans, which also explains why he studied at Emmanuel College Cambridge, as this was the leading Puritan educational establishment of the age. Given their beliefs and their moral attitudes it would in fact be more than probable that they would expect their son to work his way through college. There is another very good example of another leading seventeenth century British astronomer with a Puritan background entering Cambridge as a sizar, although his family were wealthy, Isaac Newton. Before anybody says that he was only the son of a farmer I will point out that when Newton inherited the family estate after the death of his mother it generated an income of £600 p.a. This at a time when the annual income of John Flamsteed, the Astronomer Royal, was only £100. Newton’s family could more than afford to pay for his studies.

You were the one claiming to know that Horrocks observed from a cottage. I pointed out that his place of observation is not known. It is however known that Horrocks did not possess or use an observatory, again as I have already pointed out, just like nearly all of his fellow contemporary astronomers.

The device Gassendi used during the 1631 transit of Mercury is properly defined as a camera obscura.

I would direct your attention to the exchange between Rebekah “Becky” Higgitt and myself at the start of the comments to my post criticising you article. It is a debatable point of terminology, as to whether the sun focussed through a telescope should be referred to as a camera obscura or not. Kepler who coined the term camera obscura would almost certainly have said no, as he discriminates in his writings between camera obscuras and telescopes. This, as I have already pointed out in my remarks in the comments, is not the central point of my criticism. Due to your form of expression you definitely imply, intentionally or unintentionally (and I’m not sure, which is worse) that Gassendi’s mode of transit observation was different and inferior to Horrocks’. As I pointed out it wasn’t they both utilised the same method of observation.

Keeping track of dates can be difficult for one who straddles centuries. Every author deserves at least one mulligan. I offer one here for Mr. Christie. Copernicus published De Revolutionibus in 1543 (although he had circulated draft versions of his heliocentric theory to friends and colleagues on or before 1514.) Both dates fall well within the 16th century. Again, the 16th century. Kepler worked with Tycho Brahe in 1600, published Astronomia Nova in 1609,and his third law in 1619. His major contributions all occur in the 17th century, the one in which Kepler lived from age 28 until his death in 1630. 

Keeping track of dates is the bread and butter of historical research. I’m quite happy to admit that my original comment on the short centuries in the Early Modern Period was a cheap shot that I would not normally have taken if the rest of your article were not so atrocious. However I find it somewhat strange that you now admit that I’m right whilst at the same time trying rather lamely to justify yourself. You claimed incorrectly in your article that Tycho and Kepler worked together in the 1590s, which I corrected and despite the fact that I supplied you with the right information you still get it wrong. They only worked together in 1601. If we are going to be picky Kepler published his Mysterium Cosmographicum, which he considered, right up to his death, to be his most important work in 1596 so not all of his major contributions occur in the seventeenth century.

Sure, Copernicus explained retrograde motion. So did Ptolemy, and Aristotle. They just didn’t explain it right. Of course the heliocentric model is light years better than those with jury-rigged epicycles or nesting spheres to illustrate why planets seem to move backwards in their orbits. But the phenomenon of retrograde motion wasn’t fully understood until Kepler.

We now come to the reason for the title of this post. You, Mr Shulman are deep down in a hole and don’t realise it and so go on digging like the Duracell Bunny*. It was this, quite frankly, bizarre claim that led me to criticise your article in the first place and you go on insisting that it’s correct. Just for your benefit a short discourse on the cause of retrograde motion and its explanation.

Retrograde motion is an illusion observed in heliocentric planetary systems. All planets travel in the same directions on their orbits but inner planets travel faster than outer planets. When an inner planet overtakes an outer planet the outer planet first appears to halt then to reverse its direction of travel, to stop again and then continue in the original direction. These apparent loops are retrograde motion and are as I say an illusion. The Eudoxian homocentric system, which was the one propagated by Aristotle and the Ptolemaic deferent epicycle system, both of them geocentric, produced geometrical models that were capable of reproducing the retrograde motion but not of explaining it. All heliocentric systems automatically explain retrograde motion irrelevant of the shape of the orbits. Copernicus’ system completely explains retrograde motion and none of the changes that Kepler introduced in his heliocentric system added anything to that explanation. If you can’t or wont accept that then you definitely should not be writing about the history of astronomy.

As far as Galileo goes, my bad. Mr. Galilei worked with the 10x scopes in 1608. By 1610, during his observation of the phases of Venus, he did have a 30x. And it is true that in 17th century astronomy the known bodies were referred to as stars. But these bodies were divided into two categories: Galileo himself refers to fixed stars (still known as stars,) and wandering stars (known today as planets) in Sidereus Nuncius. In a 1610 letter to Cosimo II, Grand Duke of Tuscany, he refers to the moons of Jupiter as planets, and later as Medician stars. I’m happy to parse the language further, but the matter here is that Galileo’s observations of the phases of Venus confirmed that Venus orbited the sun and was, just like the earth, a planet. 

The Duracell Bunny* is still shovelling away with no regard for the depth of the hole. The status of Venus as a wandering star, i.e. planet (Greek for wanderer), had never been in doubt since sometime deep in antiquity and your claims that Galileo proved it was a planet and not a star are just ridiculous. Your last half sentence also displays a lack of historical sensitivity as when Galileo, Harriot, Lembo and Marius observed the phases of Venus the Earth was not regarded by the majority of astronomers as a planet; it didn’t wander but sat at the middle of the universe. Turning the Earth into a planet is the essence of the so-called Copernican Revolution, which didn’t become the accepted majority view amongst astronomers until after 1660.

I don’t think I’m telling Mr. Christie anything he doesn’t already know. But I will tell him if he cares as much about the stars and the truth as he professes to, he certainly should know better.

Unlike yourself Mr Shulman I do know better and as a historian of astronomy I actually know what I’m talking about something that could not be said about yourself on the evidence available.

* My readers, who are much better informed than I am, have told me that the “Duracell Bunny” is known as the “Energizer Bunny” in the US of A.


Filed under Book Reviews, History of Astronomy, History of science, Renaissance Science

13 responses to “When you’re in a hole, stop digging!

  1. Pingback: When you’re in a hole, stop digging! | Whewell's Ghost

  2. I notice that he didn’t even try to defend the passage I found the bizarre of all:
    “…others included eclipses and planetary conjunctions that should not have occurred if the Copernican model of the solar system was accurate.”

  3. Benjamin Goldberg

    Dr Christie, thanks for taking the time to correct these errors. I wonder though if you have any thoughts on the larger issue here: popular histories of science. Are they good or bad? What place do they have in our intellectual life, if any?

    I am myself a historian of science (I work on early modern natural philosophy and anatomy), and I have come to detest many popular works of science history. They perpetuate various origin myths about the sciences, as well as ideas about the nature of science and history that we in the HPS and STS community have worked hard to undermine and replace–such as the idea that you can explain the discovery and acceptance of a scientific theory or fact by its truth value (e.g., Aristotle was rejected because he was wrong). I’m thinking, for instance, about Mr. Shulman’s rather naive remarks about ‘really understanding’ retrograde motion, as if understanding is not indexed to particular time periods and deeply entwined with all sorts of larger social, cultural, historical and epistemological ideas. I am reminded of nothing so much as the error filled, triumphalist histories of medicine written in the late 19th/early 20th century by retired doctors, arguing, for instance, that Harvey was a mechanist and experimentalist and not, as he is in fact, a rather conservative and ecclectic Aristotelian of the Renaissance variety. Perhaps these works by retired doctors (or astronomers or other scientists) is still a popular genre, I do not know–I promised myself after the first year of my dissertation research never to read another one!

    One of the best things about your blog, and others like it, is that I can now point my non specialist friends to places where they can learn about the history of science in a way that is both easy to understand for the layperson, but still historically accurate and historiographically sound. My deepest thanks, and please keep up the excellent work!

    • Benjamin Goldberg

      Ack – I meant, “…Perhaps these works…ARE still a popular genre.” Please excuse my grammar mistake(s). Sigh.

  4. Nick

    “All heliocentric systems automatically explain retrograde motion irrelevant of the shape of the orbits.”

    The shape of the orbits *might* be irrelevant, but surely speed of orbit *is* relevant, so the above statement is not literally true? We need to know that “inner planets travel faster than outer planets” — and why. Kepler provided part of the “why”; Newton went further.

    • Hypothetically if the outer planet was faster than the inner one you would still experience retrograde motion when it overtakes. It’s the effect of one planet overtaking the other that counts. Even if they both travelled at the same speed it would still take place because the orbit of the inner planet is shorter and so it would still overtake the outer one.

      • Nick

        Sure, angular velocity is the significant factor, and it was Kepler (and, more fundamentally, Newton) who explained why inner planets have a higher angular velocity. Not all heliocentric systems have this property and thus explain retrograde motion.

      • Peter R.

        I can’t seem to reply directly to Nick, but the distinction I see here is that heliocentrism itself explains the appearance of retrograde motion (as do the epicycles). What Kepler (and Newton) did was explain the different velocities of the planets in dynamic terms. So far as I know (this isn’t my specialty, Copernicus took the differential velocities as a given to explain retrograde motion itself. Kepler and Newton went a further step back in causation. Perhaps this is what you are saying anyways.

        What Shulman doesn’t seem to appreciate is that what *counted* as an acceptable explanation changed. Copernicus wasn’t actually better than Ptolemy at prediction (only Kepler was).

  5. DiMono

    “like the *Duracell* Bunny”


    • Naturally. Why do you ask?

      • Paul Hutchinson

        He’s probably in the USA, most of us over here only know of the Energizer Bunny. Duracell forgot to renew its USA trademark and the Eveready company seized the opportunity to make their own trademarked battery bunny. Duracell does not use a bunny at all in USA advertising.

        PS – thanks for all your effort smacking down the bad science history.

  6. Bob O'H

    Keeping track of dates can be difficult for one who straddles centuries.

    Yes, it’s so difficult to do sums. 1619 – 1543 = ?
    Get that man a Barbie.

    Hm, I’ve straddled centuries, does this mean I’m 100 years old?

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