I can’t believe that while I was writing recently about how ancient civilizations managed to figure out how to move massive stones over large distances to create monuments such as the Pyramids of Egypt and the palaces and temples of the Forbidden City in China, I completely forgot to inform readers of Eddie Izzard’s reflections on how Stonehenge came to be built in England. (Language advisory) [Read more…]
In the Forbidden City, a city within the city of Beijing consisting of massive palaces and temples built in the 15th and 16th centuries, some of the stone slabs used in the construction weigh 100 tons or more. According to contemporary records they were quarried 70 kilometers away. [Read more…]
If someone fires a gun at you, can you dodge the bullet by jumping aside? If the target is a loved one or you are someone’s bodyguard whose job it is to protect some major figure like the US president, can you jump in front of the other person to take the bullet instead of them? [Read more…]
When wind power is spoken of in the US, it is as a source of unreliable auxiliary power that supplies a small fraction of the total energy needs. Hence I had always viewed it as a fringe source of power that did not have the long term potential of solar power as an alternative to fossil fuels. [Read more…]
The surprising discovery that the universe is not just expanding but that the rate of expansion is increasing is what led to the idea of dark energy as the cause of that acceleration. But explaining in non-mathematical terms to a lay audience why dark energy leads to an accelerating expansion is not easy and introducing the idea that dark energy creates a negative pressure does not help much either. [Read more…]
Angular momentum is a hard concept to teach in introductory physics courses. This is partly because it is a quantity known as a vector that has both a magnitude and a direction, and adding and subtracting and multiplying vectors is more complicated than with scalars, like mass. Other things like force and velocity are also vectors but in those cases the directionality at least is intuitively obvious. The direction of the force vector is in the direction along which the force acts and the direction of the velocity vector is the direction in which the object is moving. [Read more…]
I was sorry to learn that Stanford professor Clifford Nass died unexpectedly this week at the age of just 55. He studied the ways in which technology and human beings interacted. [Read more…]
The ‘good news, bad news’ set up is often used in jokes. But apart from humor, I bet that almost all of us have at some point been asked by someone the above question when they were about to tell us something. I hate being asked it and would much prefer the person just tell me in whatever order they like. [Read more…]
A bicycle is a good example of something that is commonplace and yet quite extraordinary. It seems such an unlikely mode of transportation. One has to wonder how someone came up with the bizarre idea that by sitting astride a bar that connects two wheels one behind the other, one could propel oneself forward without falling. And yet everyone who has ridden a bike knows that it feels remarkably stable and as long as it is moving, it stays upright and seems to almost ride itself. ‘Look, no hands’ is the common exultation expressed by new learners as they discover for themselves that the bike can be ridden with minimal action on their part other than to keep it moving. [Read more…]
In a document obtained by Al Jazeera under the Freedom of Information Act, the NSA urges its officials to use 9/11 as a sound bite to deflect any questions about their snooping programs, giving them explicit language to use. And sure enough, NSA director Keith Alexander used it in his congressional testimony. [Read more…]