FromQuarkstoQuasars

Immanuel Kant: Discoverer of Nebulae and the Multi-galaxy Universe

FuturismFebruary 18th 2014
Kant
Image via Wikimedia Commons (In the public domain)

In the past, we have covered various scientists and their contributions to their respective professions, but we’ve never touched based on professors of philosophy. Not until now, that is.

Immanuel Kant was born 22 April 1724, and he died almost 80 years later on 12 February 1804 in the town of Königsberg; at the time, this area belonged to East Prussia. During the course of his life, Kant never left Eastern Prussia. Moreover, her rarely left his own home. Kant only owned one piece of artwork, supporting the absence of passion in favor of logic. This philosophy was also reflected in his most famous works, such as “Critique of Pure Reason,” “Critique of Practical Reason,” and “Logic” among many others.

Quite generally regarded as one of history’s truly great thinkers, Kant is known for the historical combination of his transcendental method, which brought together the two major components competing at the time of the Enlightenment Era of Philosophy (the metaphysical approach and the empirical approach). The metaphysical approach is the branch of philosophy that attempts to answer two basic questions in the broadest possible terms: “What is there?” and “What is it like?” While the empirical approach is the branch of philosophy which states that knowledge comes from sensory experience, what you see for example.

The Winds of Change:

Through his “Copernican revolution,” Kant moved the criterion of truth from assertions about an external reality to the immediacy of knowing yourself. His contribution practically put an end to philosophical speculation as it had been practiced for centuries. It established a firm basis for factual knowledge (in particular, the scientific method), but it also opened the way to agnosticism on ultimate issues. For better or for worse, his legacy has never been entirely transcended.

So why am I talking about Kant? Why is this Philosopher being recognized on the awesomest of awesome science pages? Because of two theories that some of you may or may not know about, but are now known as Kant’s theory.

Despite being a well-known Philosopher, his early works focused more on geology, astronomy, and physics. In his 1755 work, “The Universal Natural History and Theories of the Heavens,” Kant talks about astronomy and two noteworthy theories about the Heavens. The first is his “Nebular Hypothesis” on star and planetary formations, where he theorized that thin, dim clouds of dust and gas out in the cosmos would collapse in on themselves under the force of gravity, causing them to spin to form a disk. From this spinning disk, stars and planets would form, and from this type of formation, the rotation of Earth and the other planets would be explained.

Unlike the earlier great German philosophers, such as Gottfried Wilhelm Leibniz, Kant was not a mathematician in any way, shape, or form, so his nebular hypothesis was not given a mathematical equation until a French mathematician by the name of Pierre-Simon Laplace looked over Kant’s theory and figured it out. Ultimately, his theory became the well accepted model of star and planet formation. Today, we can even see this happening in stellar nurseries like the Orion Molecular Cloud. Despite this, some astronomy textbooks give the credit of the Nebular Hypothesis to Laplace only, and not the Kant-Laplace theory.

The First Nebula: 

The second theory that Kant made also has to do with nebulae…sort of. Along with the bright, dark, and planetary nebulae, there are also spiral nebulae (though early telescopes could not really see these clearly enough to discern them as actual spirals). Rather, they looked like “die neblichten Sterne,” or nebulous stars. However, Kant distinguished these nebulae as their own species…as galaxies

The Milky Way through a fish eye lens with Comet Hyakutake
The Milky Way through a fish eye lens with Comet Hyakutake

In 1750, Thomas Wright had suggested that the Milky Way, our own Galaxy, was a vast spinning disk, consisting of stars, planets, nebula etc. He claimed that the Earth was part of this system. Kant had read a report of this theory, and he used it to form a hypothesis about the existence of other galaxies. Ultimately, his use of this theory actually brought it to general attention. An observational confirmation of it came from the great astronomer William Herschel in 1785. Kant’s idea was that the dim, tiny nebulae were themselves external galaxies or “island universes” — independent of the Milky Way. He said:

“It is far more natural and conceivable to regard them as being not such enormous single stars but systems of many, whose distance presents them in such a narrow space that the light, which is individually imperceptible from each of them, reaches us on account of their immense multitude in a uniform pale glimmer. Their analogy with the stellar system in which we find ourselves, their shape, which is just what it ought to be according to our theory, the feebleness of their light which demands a presupposed infinite distance: all this is in perfect harmony with the view that these elliptical figures are just universes and, so to speak, Milky Ways, like those whose constitution we have just unfolded.”

[Reference: Shapley’s Scientific Record]

Cepheid Variable Stars in Andromeda (Click for a larger image)
Cepheid Variable Stars in Andromeda (Click for a larger image)

Again, Kant did not have a scientific background, thus most of his theories were built on guesswork and speculation. But, guess or not, it sparked a huge debate. This debate started in the late 1700’s. Laplace viewed these spiral nebula as the Nebular Hypothesis in action. And many astronomers subscribed to Laplacean’s belief that spiral nebulae were stellar nurseries, while others held Kant’s view of a multi-galaxy universe.

It wasn’t put to rest until Edwin Hubble came onto the scene in the 1920’s. Using the brand new Mount Wilson 100 inch telescope in the San Gabriel mountain range, Hubble was able to identify Cepheid variable stars in the nearby Great Spiral Nebula in Andromeda (now known to bea galaxy), which lies a staggering 2.38 million light-years away. Not only is it our closest celestial neighbor, but its full extent covers a 3 seconds of arc in the sky, making it about six times the size of the Moon and the Sun. Despite its now known size, the rest of the galaxy remains elusive to stargazers, as only the brightly-lit core is visible to the naked eye, with a few prominent stars. These stars were much, much farther than any of the stars in the Milky Way. Kant was right, yet again.

With all things considered, how much credit can we actually give him? As it turns out, a lot. Most great ideas in any science field begin as guesses, a little more than speculation… sometimes with very little, or contrary evidence behind them (as with the case with Nicklaus Copernicus). More importantly, if we ask who the first person was to think of the form of the universe as we now see it, filled with “billions and billions” of galaxies (10 points to who gets that reference!), the answer is— Immanuel Kant, a man who never left East Prussia and who had never even seen a mountain.

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