Tuesday, February 7, 2006

Physics as Danish enterprise

Physics, in the usual sense, started with the refined models of the Solar system, and it can be interpreted - with a slight stretch of imagination - as a Danish science.

First of all, some math had to be known before physics could smoothly develop. The letters "Dan" sound almost like "Tan". Who discovered the tangent? Yes, it was Thomas Fincke who was Danish.

Classical mechanics was the first successful discipline of physics as we know it today. Newton's equations could only be found because Kepler's laws of planetary motion were already known. Why were they known?

As Einstein always emphasized, Kepler could only find his laws because of huge Excel files describing the planetary motion and produced by Tycho de Brahe. Although Tycho de Brahe did his important work in Prague under Rudolph II, a great sponsor of arts, sciences, and alchemy, he was born in Copenhagen. Although his Tychonic model was kind of geocentric, it combined the Ptolemaic model with the virtues of the Copernican one and agreed with the available high-precision data.

With Tycho's accurate data, it was straightforward to discover Kepler's laws and Newton's laws, and the rest of classical mechanics quickly followed.

At this point, it should be clear that the rest of the world was just helping to complete some Danish discoveries that initiated classical mechanics. What is the next important milestone in the history of physics? Yes, you're right, it's field theory - especially electromagnetism.

Electromagnetism - the relation between electricity and magnetism - was discovered by Hans Christian Ørsted. Needless to say, he was Danish, too. In 1820 he observed that the needle of his compass was moving whenever the battery was turned on or off. Electromagnetism was born and several other physicists completed the details. As Wikipedia explains, Ørsted never hesitated to promote radical views. For example, he encouraged the greatest writer of fairy-tales, Hans Christian Andersen of Denmark, to write more stuff. :-) Quite a radical set of books.

The rest of electromagnetism was straightforward and it had many obvious implications such as the discovery of special relativity (and consequently also general relativity).

You may think that I am skimming over a lot of other physics to create a false impression that physics is mostly a Danish science. For example, there is also optics. Who discovered the relations between the index of refraction and the density of a gas? Yes, it was Ludwig Lorenz from the University of Copenhagen in 1869. The Dutchman Hendrik Lorentz discovered it independently in 1870, which is why we often call it the Lorentz-Lorenz formula.

I guess that 92% of the readers have not been able to distinguish Lorentz from Lorenz and the Dutchmen from Danes before they read this article. ;-) Do you think that the figure 92% is exaggerated? Do you think that I am incorrectly assuming that all the readers have the IQ of Quantoken? No, I am not! Do you remember the gauge invariance in the theory of Ørsted's electromagnetism? We can fix the ambiguity, can't we? For example, the most natural relativistic gauge-fixing requires that

  • partial A^mu / partial x^mu = 0

Do you know whose condition it is and what was his nationality? It's the Lorentz's condition and Lorentz was Dutch, 92% of the readers will say. Nope! It is actually the Lorenz condition and the author was Danish. The Danes are so modest (or ignorant) that they never protest against the typo.

Do you still think that 92% was an exaggeration? Not at all. At scholar.google.com, you will find 3,620 wrong papers :-) that describe the Lorentz gauge. The list of the authors who are wrong includes Schwinger, Guralnik, Kibble, as well as most other physicists you know. On the other hand, only 295 papers talk about the correct Lorenz gauge. You can do the math.

There are two more revolutions in the 20th century physics waiting for us.

The more important one - so far - seems to be quantum mechanics. After introducing the old quantum mechanics, Niels Bohr of Copenhagen became the spiritual leader of the young generation of quantum mechanicians. The orthodox interpretation or quantum mechanics was called the Copenhagen interpretation, to emphasize Bohr's key contributions to the community.

What is the final revolution of the 20th century physics? Yes, it is string theory. Who discovered that there were any strings to talk about in particle physics? You may have seen the TV program about our friend who got drunk when his paper was rejected. But he was not the only one. One of the two other co-discoverers of string theory was Holger Nielsen. We are pretty much near the current state of theoretical physics.

Once again, many readers may protest that I only focused on a single line of reasoning in physics and that there are many other disciplines in physics. For example, self-organized criticality. Well, yes, you're right. Self-organized criticality was invented by Per Bak, another Dane. At this moment, some people will become a bit nervous and argue that biochemistry can't be Danish. Someone had to discover things like the vitamin K and get a Nobel prize for it. Yes, it was Henrik Dam of Denmark.

The feminists will object that all the physicists above were male and the ratio should have been 50:50. Well, I can't offer you this number. But I can tell you that one of the Nobel prize candidates may be Denmark's Lene Hau of Harvard University who was able to stop the light. She may become the first female physics Nobel prize winner after more than 40 years.

Dear Muslim friends, it is now up to you to multiply the discoveries above by a factor of 250 in order to give the humankind the same contribution per person as the Danes. If you can't do it, then we will have to conclude that at least at the level of natural science, neither Allah nor Mohammed (PBUH) works right.

And that's the memo.