Scott MacLeod's Anthropology of Information Technology & Counterculture: Ashoka 9 - November 4, 2016

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Nov 4, 2016

Yogically, what happens to our consciousness when we read, watch and understand Yonatan's post here? (http://worlduniversity.wikia.com/wiki/Yoga & http://worlduniversity.wikia.com/wiki/Consciousness) ... and how would this work in a realistic virtual earth - re a Harbin warm pool in Google Street View, for example (and at the neuronal and atomic levels)?

Originally shared by Yonatan Zunger - 93 comments

Today, a simple illustration of physics. You might wonder why so much liquid splashes backwards; you can see what's happening most clearly with the water bottle (second from the bottom). The bullet strikes the liquid and starts transferring energy to it. (That energy transfer is why a bullet damages things) This, in turn, pushes a wave forward, moving faster than the bullet until it strikes the front wall and begins to break it. That breakage will be amplified by the bullet's impact a moment later, but before that, the wave has started to bounce back -- until shortly afterwards, it strikes the back wall, already damaged by the bullet hole, and blows it open.

All of this works because the bullet is travelling slower than the speed of sound in the liquid. (The speed of sound in liquid is much higher than it is in air) If the bullet were travelling much faster, around 3,400mph, then you would see a different reaction: the bullet would strike the front wall before the wave did, and by the time the wave hit it there would be much less for it to bounce against. Almost all of the splatter would fly forward, in that case.

If the bullet were travelling faster still, at around 11,000mph, it would be going faster than the speed of sound in glass, and things would change even more: the bullet would make it out of the glass before the shock waves from the impact had a chance to spread, and it would punch a fairly clean hole through it rather than shattering it. Of course, the impact of the water wave (if it were a filled bottle target) would then shatter the glass anyway.

I know this thanks to Prof. Bob Laughlin, a slightly mad physicist (and Nobel laureate) for whom I TA'd for many years. He asked a version of this question on the qualifying exam for the PhD, asking students to design a new "Star Wars"-type defense system called Brilliant Potroast. The idea (an improvement, no doubt, over the real "brilliant pebbles" design) was that we would attach rocket engines to a bunch of pot roasts, put them in orbit, and then fire them at incoming ICBM's; students were tasked with doing all the calculations for this, from calculating fuel needs to describing what would happen when a pot roast struck a nuclear missile.

The correct answer turned out to depend on the angle and position of impact, because (given orbital speeds and so on) the relative speed of the pot roast and the missile could fall anywhere above or below the speeds of sound in pot roast, structural Aluminum, and Plutonium. In almost all the cases, though, the effect would look sort of like a "water balloon:" the pot roast would punch a hole almost straight through the missile, and splatter outwards as it flew like a water balloon hitting, well, an ICBM.

Hopefully, this would damage critical components of the missile, and/or make it aerodynamically unstable once it reentered the atmosphere. Alternatively, you could design the flying meatsacks to deliberately hit the missile at an angle so that it would always be below the speed of sound in structural metals, and cause much more shattering along the length of the missile.

As a footnote: When Prof. Laughlin won the Nobel, the department held a party for him. A bunch of students got together and got him a very large pot roast as a gift.

h/t +Steven Flaeck and +İsmet D. İstanbul for the wonderful image.

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Scott MacLeod's Anthropology of Information Technology & Counterculture

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Ashoka 9 - November 4, 2016 - August 24, 2016

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