Thursday, January 11, 2007

Kepler's Supernova


The Chandra X-ray observatory gave us this new view of SN 1604, discovered by Johannes Kepler. Once upon a time, supernova discoveries were so rare that you could name them by the year. Kepler studied at a number of universities, and was planning to be a minister when he was asked to take a teaching job. He would hold many jobs in his lifetime before becoming Tycho Brahe’s last assistant.

Tycho had discovered his own supernova in 1572. The king of Denmark gave Tycho funds and an island to build an observatory. Tycho’s many observations of planets provided Kepler with ample data to explore their motion. Kepler himself was known for his meticulous mathematical tables. Kepler believed, like Pythagoras, that mathematical relations underlie all of nature. Unlike Tycho, Kepler believed in the Copernican system, and sought to find a principle behind it.

For much of Kepler’s life, the Platonic solids fascinated him. These five shapes--tetrahedron, cube, octahedron, dodecahedron and icosahedron were known since at least the time of Pythagoras. Plato tried to relate them to the Earth and its elements. Kepler tried to explain orbits as ratios these solids, with only limited success. He had greater success with a theory of ellipses.

Starting from the principle of planets orbiting the Sun, Kepler came up with three laws:
1) Planetary orbits are elliptical with the Sun as one focus.
2) Orbits sweep out equal areas in equal amounts of time.
3) The period of a planetary orbit is proportional to its long axis raised to the 3/2 power.
These laws described the motion of planets far better than any epicycle theory. Kepler’s laws allowed him to predict the transit of Venus in 1631, providing a crucial proof. A full expalanation would come from Newton's gravity.

Galileo and Kepler kept up a correspondence. “Here at Padua,” Galileo complained in one letter, "is the principal professor of philosophy whom I have repeatedly and urgently requested to look at the moon and planets through my glass, which he pertinaciously refuses to do.” Even 400 years ago, learned minds literally refused to look at the truth. Today's cosmologists need to spend more time looking at nature. The truth can be quite beautiful.

UPDATE: New information indicates that Kepler's supernova was a Type Ia.

7 Comments:

Blogger serge said...

"A full expalanation would come from Newton's gravity." I'm no expert but it seems to me, and please correct me if I'm wrong, that Newton's gravity equations are a re-arrangement of Kepler's, with different concepts maybe but the information in the math of both Kepler and Newton are equivalent, i.e., Newton did not add information to Kepler's discoveries.

4:03 PM  
Blogger L. Riofrio said...

Kepler came up with elliptical orbits, but Newton produced a full law of gravitation, GMm/(r^2). One could consider that a very creative re-arrangement of Kepler.

4:08 PM  
Blogger serge said...

"learned minds literally refused to look at the truth." - Well put. In all our history, including pre-history, a scientific mind does not equal a learned mind, as a scientific mind is one that knows that it's not learned, always striving to learn more, to find and appreciate beauty. This character of our mind is one of our best qualities, and it is associated with another one of our best qualities, our capacity to love the world, including our normal co-travellers.

Now if we could only learn how to deal with our abnormal co-travellers, learned or not, then we'd be happy campers, wouldn't we?

4:22 PM  
Blogger serge said...

"GMm/(r^2)" - Thanks Louise. Yes, Newton was good at coming up with nice little equations that worked. No small feat, then ... and now.

4:27 PM  
Blogger CarlBrannen said...

serge, I think it's important that Newton came up with simple equations that work. What Kepler did was find simple symmetries that work.

Now physics is once again based on simple symmetries rather than simple equations and it awaits recasting in equation form.

11:18 PM  
Blogger nige said...

That supernova looks a bit like a tangled string! I bet it will get all the cosmic string theorists excited...

4:39 AM  
Blogger serge said...

Carl: "Now physics is once again based on simple symmetries rather than simple equations and it awaits recasting in equation form." - well put Carl and thanks for the concise view of current physics. I'll take your word for it.

One precision on the imprecise term 'abnormal' that I used for the members of our species who do not seem to operate within normal parameter values: they are unfortunately 'normal' (even if their mind is not healthy) for two reasons: 1) they are the vast majority of the current population, 2) their behavior was originally part of our survival repertoire. Unfortunately, some tend to go to extremes and this is when these and their behavior should be called 'sick' or 'in an unhealthy state'. And this is where the healthy people should try harder to find effective remedies to cure our species in the near future. My proposition for a component of a cure is to have some form of communication with dolphins, no matter how limited, in order to break the isolation and illusion brought about by our belief that we are the superior species, the alpha species. If we just started to see that we are not superior, then we may see that we as a species are sick, and then we may be half-way to curing ourselves. In other words, we will probably cure ourselves not by trying to change ourselves physically but by changing our view of ourselves, by replacing an single invalid hypothesis with a valid one. The effect would be automatic, yet difficult for living individuals, because the entire world-view then needs to be rebuild, and the instability of this process is very freighful. But this should be easier for future generation if they are educated before their superiority belief becomes well established. Talking with another species could be a trigger, in time.

2:51 PM  

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