Thermodynamicist

There's no great disadvantage to modern humans (we spend relatively little time outside compared with our ancestors, and we have access to a bewildering variety of hats), and therefore head hair isn't a strongly conserved trait in the male human population.

Likewise, we still have genes in our genome which code for the receptors necessary to have a dog-like sense of smell. But we don't need that capability, and therefore that part of our genome isn't aggressively conserved by natural selection.

As a result, the Second Law has done its thing and random mutations have gradually degraded our sense of smell.

It's a very different matter for sniffer dogs, and a sniffer dog with a poor sense of smell is going to be quite rapidly removed from the sniffer-dog gene pool.

The same sort of thing applies to vision. I don't need perfect vision, because I can wear glasses. Imperfect vision therefore doesn't dramatically affect my chances of reproductive success, and therefore perfect vision isn't strongly selected for in the human population.

On the other hand, birds of prey tend to have very good eyesight, because the ones which don't rapidly starve to death and so good eyesight is highly conserved within e.g. the Hawk population.

Solution.

The key to this sort of problem is to calculate the ram temperature rise. It's just like the burrito problem also in this thread.

In reality, this sort of simple total temperature calculation only applies to the flow at the stagnation point, and represents a maximum temperature, but it's useful for somewhat conservative design calculations.

The CP of dry air is about 1005 J/kg/K between about 200 and 400 K, rising above that temperature, which means that you can just use a fixed CP for ram temperature rise problems up to about Mach 2 with an error of about 1% or less.

You'll find that fixed CP assumptions fall to bits once the flow is hypersonic, and then the v² term bites quite rapidly, meaning that you have to start considering that the flow is reacting, and may be quite far from chemical equilibrium from Mach numbers past about 6 (depending upon altitude, because it all gets pressure dependent), especially if the object around which the air is flowing is fairly small.

At this stage, rigorous calculation becomes tedious.

Old-school mechanical film cameras would be fine - just look at all the nuclear test footage made from the 1940s to the test ban.

In the distant future, when all of this is somewhere in the depths of the wayback machine, you should get the studio to persuade the curators of the archive to edit your post out of the archive, and replace it with a massive *.gif of the movie, so that the whole meta-story of it all is encapsulated in one thread, for Internet historians.

1. Have you pre-submitted this AMA to the nominative determinism section of New Scientist?
2. What are your thoughts on the recent paper about an Occupational Depression Inventory [Link to paper] [Link to reddit thread]?
   • To what extent do you think that stress is intrinsic to individuals, rather than being a function of their social environment (whether at home or work)?
3. Adam, you mention work/life balance. What are your thoughts on the aphorism "Do what you love, and you'll never work a day in your life."?