Kepler’s Discovery of God’s Cosmic Blueprint

Science as an act of worship

Image: Johannes Kepler, tonsoffacts.com

Philosopher and intellectual historian Hans Blumenberg once reflected that “the origins of the modern scientific worldview lie in medieval mysticism.”¹ For Early Modern Scientists, the study of nature and mathematics was a way to encounter the mystery of God. This was certainly the case for Johannes Kepler—the Father of Physical Astronomy, one of the first defenders of Copernicanism, and the discoverer of the first scientific laws of planetary motion. An inspiration to Isaac Newton and a contemporary of Galileo, Kepler was also a religiously devout mystic who sincerely believed that his science was revealing the mind of God as manifest in creation. Through all of his scientific research and brilliant insights into nature, Kepler always affirmed that he was “merely striving to think God's thoughts after Him.”²

Tycho Brahe and the End of the Ptolemaic-Aristotelian Cosmos

For over 1500 years, Aristotle’s and Ptolemy’s understanding of the Universe reigned supreme in the West. According to this model, the universe was conceptualized as a spherical cosmic nesting doll with Earth at the center. In the Aristotelian-Ptolemaic representation of the cosmos, the sun and planets were fixed onto solid transparent crystalline spheres in concentric circles around the sphere of Earth, and a corona of fixed stars on another solid sphere orbited the circumference of the planetary spheres once per day.

When Nicolas Copernicus first proposed his heliocentric theory of the Earth’s motion in 1514, he largely accepted Aristotle’s model of the solid spheres, but he replaced the center sphere with the Sun instead of the Earth. Much of Copernicus’s motivation for doing this was theological and he knew that there were still many scientific problems that needed to be solved—such as the problem of the lack of stellar parallax—before his theory could be seen as an accurate physical description of the cosmos.

Thirty years after Copernicus published his On the Revolutions of the Heavenly Spheres, Tycho Brahe, Danish nobleman and Court Astronomer to the Holy Roman Emperor, made a series of observations that eventually led him to reject the Aristotelian-Ptolemaic geocentric model of the solar system. Brahe’s observation, however, also contradicted the heliocentric model of the cosmos that was proposed by Copernicus. Brahe observed a supernova in 1572 and comets in 1577 and 1585 which, contrary to both the Ptolemaic and Copernican models, appeared—according to Brahe’s precise calculations—to be located far above the sphere of the moon that—in the Aristotelian-Ptolemaic system—orbited the sun.³

Moreover, it appeared that these comets had passed right through the solid crystalline spheres that had been standard in both the Aristotelian-Ptolemaic and Copernican models. As a result, Tycho abandoned the idea that each of the planets was supported by a solid crystalline orb. As an alternative he “concluded that the substance of the heavens was a continuous fluid of some sort, that the planets moved freely through this medium, and that the orbs of the planets were not physical objects but geometrical constructions representing boundaries in this medium.” ⁴

Convinced by both common sense and the empirical observation—given the perceived absence of stellar parallax—that the Earth is not moving, Tycho constructed an alternative model of the solar system which placed the Sun at the center of the orbits of Mercury, Venus, Mars, Jupiter, and Saturn while the orbits of the Sun and the Moon revolved around a stationary Earth at the center of the cosmos. This geoheliocentric model of the solar system had two rotational centers and it could predict stellar phenomenon just as accurately as the Copernican system while avoiding the issue of stellar parallax.

In the eyes of his contemporaries, Tycho had “proven clearly…the fact that for Saturn, Jupiter, Mars, Venus, and Mercury the center of the earth is not their center.”⁵ Indeed, in the year 1601—thirty-one years before the publication of Galileo’s Dialogue Concerning the Two Chief World Systems—Kepler  remarked that “today there is practically no one who would doubt what is common to the Copernican and Tychonic hypotheses, namely that the sun is the center of motion of the five planets.”⁶

Kepler’s Discovery of God’s Mathematical Model for the Cosmos

Image: Tycho Brahe, historiasdelahistoria.com

Kepler became Tycho’s assistant and scientific collaborator in 1600 under a mutually beneficial arraignment. Tycho needed an expert to crunch numbers and he had heard of Kepler’s reputation as an excellent theoretician and mathematician. Kepler, in turn, needed raw data, and he had heard that Tycho made unprecedentedly accurate observations (using new instruments that Tycho himself had designed). Kepler had become a convinced Copernican for theological reasons in the 1590s and his life goal was to show that Copernicus's theologically beautiful understanding of the solar system was nothing less than God's plan for the world.

While Kepler found that Copernicus’s calculations of the movements of the heavens were close to his own data, close was not good enough for Kepler because he was in pursuit of the mind of God. Kepler needed much more accurate observations so he could discern whether his own calculations “would fit as precisely as God had made them.”⁷ Because Tycho was wary of Kepler’s Copernicanism, he permitted Kepler to see and use only his data on Mars, thereby giving Kepler the task of working out the orbit of the most difficult of the planets. Even when Tycho died a year later, and Kepler took his place as Royal Court Astronomer, Tycho’s heirs continued to restrict Keper’s access to Tycho’s data. 

Kepler remarked that ‘he could have died ten times’ while trying to solve the orbit of Mars, yet he continued his work undaunted and eventually realized that the only orbit of Mars that would fit Tycho’s data was an ellipse. Kepler then worked out precise elliptical orbits for all of the planets and published his findings in his work New Astronomy Based on Causes (1609). In this work, Kepler also described the first two of his famous three laws of planetary motion—laws that are still valid and taught to astronomers to this day.

-Even though his work was very data intensive, Kepler’s scientific discussions in A New Astronomy were grounded in the conviction that God has created the world according to an intelligible plan and that he, Kepler, had discovered this plan. Having found the cause for the number and distances of planets, and uncovering “a geometrical structure to the heavens whose elegant beauty served as the best proof yet of the Copernican system,” Kepler believed that he “had uncovered the mathematical blueprint by which God constructed the heavens.”⁸

Still striving to think God’s thoughts after Him, Kepler asked himself, “Why God would have chosen ellipsoids instead of spheres” and “Why would he have chosen to make planets speed up and slow down when he could have arranged for them to move uniformly?”⁹ To answer these questions Kepler’s New Astronomy drew heavily on the English physicist William Gilbert’s work on magnets. To offer a physical causal explanation of how planets move—an explanation that took into account both the elliptical orbits and the variation in speed—Kepler proposed that the Sun, the Earth, and all of the other planets acted like giant magnets. This meant that magnet-like forces “linked the Sun to each of the planets, and as the Sun rotated on its axis it swept the planets around with it.”¹⁰

Because the magnetic force diminished over distance according to an inverse square law, planets further from the Sun would move slower than those closest to the Sun. Moreover, the magnetic force between the Sun and each planet was affected by the orientation of the planet in relation to the other planets. Kepler’s magnetic world system accounted for the precise details of the elliptical orbits of the planets and the fact that they continuously sped up and slowed down. Kepler also suggested that the moon exerted the same type of attractive force upon the Earth and that this force was responsible for the tides. Without calling it such, Kepler had discovered what Isaac Newton would later describe as the Universal Law of Gravity.

The Faith of a Physicist

Through all of his scientific undertakings, Kepler was “a deeply religious man who had an unswerving faith in God as the Creator who worked according to a plan for the Universe with all its objects and creatures.”¹¹ Kepler’s understanding of the scientific method “was grounded in the conviction that God had created the universe according to ‘number, weight and measure’ and therefore according to mathematical laws.”¹² As a brilliant mathematician and astronomer—and a man of deep faith—Kepler “endeavored to know the order of creation because by faith he believed that the God who had created the heavens and the earth could be known in that creation.”¹³

The fire that enlivened Kepler’s equations was “an abiding belief of purpose and mathematical perfection in the Universe.” ¹⁴ To discover how these relationships reflected the Mind of God was the quest of his entire life, and this underlying theme can be seen throughout all of his works. Kepler saw his scientific work as being in perfect harmony with Scripture’s theological understanding of creation, and thus Kepler saw his science “as an act of worship.”¹⁵ Believing that “from the love of God towards mankind many causes of things in the world may be deduced,” Kepler affirmed that “God is the beginning and end of all scientific research and striving.”¹⁶

1.  Hans Blumenberg cited in Dermot Moran “Nicholas of Cusa and modern philosophy” in James Hankins, ed., The Cambridge Companion to Renaissance Philosophy (Cambridge University Press, 2007) 176-177.

2.  Johannes Kepler, quoted in John Henry, A Short History of Scientific Thought (Palgrave Macmillan, 2012), 102.

3. In the case of the supernova, “Tycho established that the new light in the sky had no parallax and must, therefore, be in the region of the heavens, and not below the Moon, as it would be if it was an atmospheric phenomenon. Inspired by this, he also decided to check the parallax of a comet which appeared in 1577. Sure enough, Brahe was able to establish that comets had no parallax and so must in fact be heavenly phenomena. What’s more, he established that they followed a path which meant they must be cutting through the planetary spheres. This seemed to suggest that the spheres may not exist—certainly they did not exist as solid crystalline spheres.” Henry, 101.

4. Peter Barker and Bernard R. Goldstein, “Theological Foundations of Kepler’s Astronomy,” in Science in Theistic Contexts: Cognitive Dimensions, Osiris 16, ed. John H. Brooke, M.J. Osler, J.M. Van der Meer (University of Chicago Press, 2001), 93

5. Noah J. Efron and Menachem Fisch, “Astronomical Exegesis An Early Modern Jewish Interpretation of the Heavens,” in Science in Theistic Contexts: Cognitive Dimensions, Osiris 16, ed. John H. Brooke, M.J. Osler, J.M. Van der Meer (University of Chicago Press, 2001), 74.

6. Nicholas Jardine, The Birth of History and the Philosophy of Science: Kepler’s A Defense of Tycho against Ursus with Essays on its Provenance and Significance (Cambridge: Cambridge University Press, 1984), 147.

7. Kepler quoted in Henry, 101.

8.  Lawrence Principe, The Scientific Revolution: A Very Short Introduction (Oxford University Press, 2011), 57.

9.  Kepler quoted in Henry, 102.

10.  Kepler quoted in Henry, 104.

11.  Anton Postl, “Kepler, mystic and scientist,” Vistas in Astronomy, Volume 18 (1975), 453

12.  Ann Blair, “Natural Philosophy,” in The Cambridge History of Science: Volume 3, Early Modern Science, ed. Katharine Park and Lorraine Daston (Cambridge: Cambridge University Press, 2003), 401.

13. Édith Weber, “Musica Christi: A Lutheran Aesthetic,” Church History and Religious Culture, (2007) 87(3), 423-424.

14.  Postl, “Kepler, mystic and scientist,”, 454

15.  Jürgen Hübner, “Natural science as praise of the Creator,” Vistas in Astronomy, Volume 18 (1975), 383.

16.  Johannes Kepler, Mysterium Cosmographicum, Chapter 4.