Isegoria

Thomas of Protokol2020 shares some bits of rocket science:

1. The most economic angle to launch a rocket from an airless planet is at 0 degrees elevation, direction to the east. The next time you’re returning from Moon, just go east young man!
2. The most economical launching pad on Earth in the terms of rocket fuel is Chimborazo mountain, Ecuador.
3. Fuel costs are not very significant in overall costs.
4. A coal, wood or wax rocket could reach the orbit.  Even a rocket propelled by compressed air could. It would simply require a few more stages.
5. The more g, the less fuel is needed to reach the orbit. A super cannon could launch cheaply, if there were no people and no delicate instruments on board and if there was no atmosphere. A Moon based horizontal cannon would be very good.
6. An Earth based launching cannon could not be chemical, but electromagnetic for example. You can shoot a bullet from some special military guns from the Moon to the Earth. Not the other way around.
7. An Earth based space cannon would require a heat shield all the way up through the atmosphere. Rockets don’t need that, since they start very slowly. For the same reason they are not very energy efficient.
8. With the space lift the minimal energy needed to leave the planet is negative! You actually get a lot of energy by launching a kilogram of mass from the Earth’s surface. The space lift must be tall  enough, but still less than the Moon is high in the sky.
9. As the Moon slowly moves away from Earth, both go away from the Sun! We are on a collision course with Jupiter. Jupiter is on a collision course with the Sun, but our collision is scheduled first.
10. Our Solar system is very unusual. Too many gas giants and planet orbits that are too circular. But don’t worry, it’s normalizing slowly, becoming inhospitable.
11. There might be some objects in space, leftovers from the nuclear detonations after WW2. Ulam’s doors (remains?) could be farther away than Voyagers and Pioneers.

(Hat tip to our Slovenian guest, who calls Thomas of Protokol2020 “the smartest Slovenian I know of” and “a skeptic par excellence“.)

Modern dentistry is mildly unpleasant, with a terrible reputation that goes back centuries:

Most of us will have had cavities at some point in our lives. Some of us are even old enough to have had them filled with amalgam: a mixture of mercury, silver, tin and copper. But in earlier periods, having a cavity filled was not an option. Once a tooth began to rot, one had little choice but to have it pulled, without anaesthetic.

Of course, the loss of a tooth could leave a person aesthetically challenged. The wealthy were increasingly unhappy to go around in public with missing teeth. In the 18th century, surgeons began experimenting with implants. Patients who could afford it might choose between “live” or “dead” teeth. With the former, the recipient would have his or her rotten tooth removed before a selection of donors, who would then have their own teeth extracted until one was found that was deemed acceptable in appearance. Afterwards, the tooth was inserted into the empty socket and fixed using a silver wire or silk ligatures.

Although desirable, having a “live” tooth implanted into one’s mouth was a costly endeavour. For the thrifty consumer, teeth extracted from the mouths of the dead proved cheaper. According to one body-snatcher: “It is the constant practice to take the teeth out first … because if the body be lost, the teeth are saved.” During the 19th century, a good set of teeth could fetch as much as five guineas, or roughly £400 today.

As time progressed, the prevalence of tooth decay increased as sugar and tobacco became more readily available, creating a market for dentures. Early versions were made of ivory or animal bone, and typically incorporated the teeth of executed criminals or exhumed bodies.

When George Washington was inaugurated as the first president of the United States in 1789, he only had one remaining tooth left in his mouth. Dr John Greenwood — a dentist from New York, and a former soldier in the war of independence — fashioned a set of dentures from hippopotamus ivory, using gold wire springs and brass screws to hold together the human teeth he had procured. There was even a hole left for his one remaining tooth.

Contraptions like this were cumbersome and painful to wear. But more so, these teeth were often plucked from the mouths of those who had died from syphilis, thus infecting their new owners when contaminated tissue came into contact with open wounds in the mouth.

What practitioners really needed was access to young, healthy teeth. That opportunity presented itself during the battle of Waterloo in 1815, which led to the deaths of 51,000 men. “Waterloo teeth”, as they were known, referred to any teeth stolen from the mouths of dead soldiers in the 19th century, and was a term employed during the Crimean and American civil wars. Body-snatchers followed armies into battle, and returned home with bagfuls of teeth that they sold to dentists and surgeons at inflated prices.

Gwern performs a life-extension cost-benefit of metformin, the diabetes drug that may have more general anti-aging properties, and finds that metformin use is probably “profitable” for a 30-year-old.