Circles to Circles

Using stereographic projection, you create a distorted image of the surface of a sphere, stretched out to cover an infinite plane. Each point on the sphere is mapped to a point in the equatorial plane by a projection ray starting at a pole of the sphere. Draw a circle on the sphere, e.g. by intersecting … Continue reading Circles to Circles

Vintage Covectors

Covectors in the Dual Space. This sounds like an alien tribe living in a parallel universe hitherto unknown to humans. In this lectures on General Relativity, Prof. Frederic Schuller says: Now comes a much-feared topic: Dual vector space. And it's totally unclear why this is such a feared topic! A vector feels familiar: three numbers … Continue reading Vintage Covectors

Peter M. Schuster on History of Science

The late Dr. Peter M. Schuster was a physicist and historian of science. After a career in industry, he founded a laser technology startup. Recovering from severe illness, he sold his company and became an author, science writer, and historian. He founded echophysics - the European Center for the History of Physics - in Pöllau … Continue reading Peter M. Schuster on History of Science

Poets Who Speak of Jupiter

In the third chapter of the first volume of his legendary physics lectures, Richard Feynman discusses the relation of physics to other sciences. He says that astronomy got physics started, and its most remarkable discovery is that stars are made of atoms of the same kind as those on the earth. He adds this famous … Continue reading Poets Who Speak of Jupiter

Gödel’s Proof

Gödel's proof is the (meta-)mathematical counterpart of the paradoxical statement This sentence is false. In his epic 1979 debut book Gödel, Escher, Bach Douglas Hofstadter intertwines computer science, math, art, biology with a simplified version of the proof. In 2007 he revisits these ideas in I Am a Strange Loop. Hofstadter writes: ... at age … Continue reading Gödel’s Proof

The RSA Algorithm

You want this: Encrypt a message to somebody else - using information that is publicly available. Somebody else should then be able to decrypt the message, using only information they have; nobody else should be able to read this information. The public key cryptography algorithm RSA does achieve this. This article is my way of … Continue reading The RSA Algorithm

The Solar Self-Building Movement

Every year the International Energy Agency publishes a detailed report on worldwide usage of solar thermal energy. The last one from 2019 is based on data from 2017. Countries are ranked by their installed capacity: Collectors' thermal heating power under standard operating conditions is linked to their area: 0.7 kWth (kilo Watt thermal) per square … Continue reading The Solar Self-Building Movement

Computers, Science, and History Thereof

I am reading three online resources in parallel - on the history and the basics of computing, computer science, software engineering, and the related culture and 'philosophy'. An accidental combination I find most enjoyable. Joel on Software: Joel Spolsky's blog - a collection of classic essays. What every developer needs to know about Unicode. New terms … Continue reading Computers, Science, and History Thereof

Peter von Rittinger’s Steam Pump (AKA: The First Heat Pump)

Peter von Rittinger's biography reads like a success story created by a Victorian novelist, and his invention was a text-book example of innovation triggered by scarcity ( Bio DE / EN). Born 1811, he was poor and became an orphan early. Yet he was able to study mathematics and physics as his secondary education had … Continue reading Peter von Rittinger’s Steam Pump (AKA: The First Heat Pump)

Lest We Forget the Pioneer: Ottokar Tumlirz and His Early Demo of the Coriolis Effect

Two years ago I wrote an article about The Myth of the Toilet Flush, comparing the angular rotation caused by the earth's rotation to the typical rotation in experiments with garden hoses that make it easy to observe the Coriolis effect. There are several orders of magnitude in difference, and the effect can only be … Continue reading Lest We Forget the Pioneer: Ottokar Tumlirz and His Early Demo of the Coriolis Effect