austern

I saw the traveling _Gods in Color_ exhibit when it came to San Francisco, which is where some or all of the images in this article come from. I don't think the exhibit glossed over the fact that these reconstructions are speculative, and that we can't know for sure what the originals looked like.

One quote I remember from the exhibit, which I looked up to make sure I got the wording right, was an anecdote about one of the most famous Greek sculptors, as recorded by Pliny: "When asked which of his works in marble he liked the most, Praxiteles used to say: ‘Those to which Nikias has set his hand’—so highly did he esteem his coloring of the surface."

One takeaway from that quote is the obvious: one reason we know that ancient statues were painted is that ancient authors said so. Another takeaway is that the painters, not just the sculptors, were famous, and the ancients recognized that some were better than others.

Barbed wire worked well for human soldiers in WWI. It was part of a security system that also included trenches, artillery, machine guns, and active counterattacks, but it was a crucial part.

I was going to make the same recommendation. In particular I'd recommend her new book, _The Joy of Abstraction_. It's a real textbook that goes up through the Yoneda Lemma, but it isn't too scary and it doesn't assume that the reader already knows any theoretical math.

It's interesting to note that this blog post was written in 2003, and that a lot of the arguments we've seen in this thread, both for and against dynamically typed languages, are exactly the same arguments people might have used back then. One question to ask is whether there's anything we know today about this question that we didn't already know 20 years ago.

My suggested answers: 1. We now know, 20 years later, that dynamic-typing languages have not replaced static-typing languages. All of the languages from that '03 blog post are still heavily used. If we look at more recently introduced languages, some are statically typed and some are dynamically typed. Evidently programmers still see value in both of those ideas, and neither looks like it's replacing the other. 2. We now know that it's possible to add type deduction to statically typed languages and type annotation to dynamically typed languages, even older languages like C++ and Java and Python.

I think some of the people responding to the comment about solving the energy problem are missing the point. There's solving the energy problem in the sense of finding an energy source that can power human civilization (preferably without melting the planet I live on, but that's a discussion for another thread). Then there's solving the energy problem in the sense of accelerating a spaceship to ultrarelativistic speeds. The latter is a very hard problem.

A good rule of thumb to remember is that if you're going fast enough to experience large time dilation, then your kinetic energy is to be large compared to your rest mass. It's the same factor of γ=1/√(1-v²/c²) either way. So if you're traveling 1000 years in 15 years ship time, you've got γ=67 and your kinetic energy is 66 times your rest mass. Ouch! (And here I'm making the incredibly optimistic assumption that you aren't carrying your fuel with you, because if you are then you also have to expend energy to accelerate your fuel, and to accelerate the fuel you use to accelerate your fuel, etc.)

If the rest mass of your ship is about the same as that of an aircraft carrier (the USS Enterprise, CVN-65, seems appropriate), then 66 × 86000000kg × (3×10×⁸ m/s)² = 5×10²⁶J. That's a lot.

Nuclear energy in the ordinary sense is nowhere close to enough. This is thousands of times more energy than we could get with all the U-235 on Earth. Or we could imagine getting this energy from fusion, using the big fusion reactor located a cozy 8.5 light-minutes away from us. Earth gets about 123000TW from the Sun, so another way of looking at this number is that if we captured 100% of that energy, it would take us 130 years to get enough for the ship's kinetic energy.

Accelerating big things to ultrarelativistic speeds isn't easy.