Entropy in our Everyday Lives: Active Stability

Because things naturally move to disorder over time, we can position ourselves to create stability. There are two types of stability: active and passive. Consider a ship, which, if designed well, should be able to sail through a storm without intervention. This is passive stability. A fighter jet, in contrast, requires active stability. The plane can’t fly for more than a few seconds without having to adjust its wings. This adjustment happens so fast that it’s controlled by software. Ther...

 Hold Expertise in Esteem

Facts, evidence, reason, logic, an understanding of science -- these are good things. (Applause.) These are qualities you want in people making policy. These are qualities you want to continue to cultivate in yourselves as citizens. (Applause.) That might seem obvious. (Laughter.) That's why we honor Bill Moyers or Dr. Burnell. We traditionally have valued those things. But if you were listening to today's political debate, you might wonder where this strain of anti-intellectualism ca...

 Flatland Science: Dimensions

What and where is Flatland? A Square gives us several interesting answers, many of th contradictory. We know that it’s flat, big (but how big?), and very thin, the most important question of all is “how thin?” A lot depends on the answer… A Square himself eliminates the version that’s easiest for three-dimensional readers to understand; a world that’s thin – maybe only a few atoms thick - but nevertheless has some physical height. It would have some sort of solid or semi-solid ...

 The One-Electron Universe

I received a telephone call one day at the graduate college at Princeton from Professor Wheeler, in which he said, "Feynman, I know why all electrons have the same charge and the same mass" "Why?" "Because, they are all the same electron!" And, then he explained on the telephone, "suppose that the world lines which we were ordinarily considering before in time and space - instead of only going up in time were a tremendous knot, and then, when we cut through the knot, by the pl...

 Hydrogen Levels in the Universe

Our Sun is significantly enriched, having formed when the Universe was more than 9 billion years old in the plane of a spiral galaxy, one of the most enriched places in the Universe. Yet, when our Sun formed, it was still made out of — by mass — 71% hydrogen, 27% helium, and about 2% “other” stuff. If we convert that into “number of atoms” and treat the Sun as typical of the Universe, that means, over the first 9.3 billion years of the Universe, the fraction of hydrogen ha...

 Reason Comes After a Plan

When Galileo caused balls, the weights of which he had himself previously determined, to roll down an inclined plane; when Torricelli made the air carry a weight which he had calculated beforehand to be equal to that of a definite volume of water; or in more recent times, when Stahl changed metal into lime, and lime back into metal, by withdrawing something and then restoring it, a light broke upon all students of nature. They learned that reason has insight only into that which it produces a...

 Pendulum Moves East to West

The observations, so numerous and so important, of the pendulum as object are especially relevant to the length of its oscillations. Those that I propose to make known to the [Paris] Academy [of Sciences] are principally addressed to the direction of the plane of its oscillation, which, moving gradually from east to west, provides evidence to the senses of the diurnal movement of the terrestrial globe.

 Focusing Light Increases Heat Where Focused

The sun's rays proceed from the sun along straight lines and are reflected from every polished object at equal angles, i.e. the reflected ray subtends, together with the line tangential to the polished object which is in the plane of the reflected ray, two equal angles. Hence it follows that the ray reflected from the spherical surface, together with the circumference of the circle which is in the plane of the ray, subtends two equal angles. From this it also follows that the reflected ray, t...

 Peter Norvig: How Well Does the Program Run When it Isn't...

And think about failure modes—I remember one of the great lessons I got about programming was when I showed up at the airport at Heathrow, and there was a power failure and none of the computers were working. But my plane was on time. Somehow they had gotten print-outs of all the flights. 1 don't know where—there must have been some computer off-site, i don't know whether they printed them that morning or if they had a procedure of always printing them the night before and sending them ...