[blintzing]

But sometimes the connection between "beautiful art project" and "practical tools" is totally unexpected. We often invest time in projects that seem simply like "beautiful art", and then much later stumble upon something practical.

I think a great example of this is cryptography. The foundations of it come from number theory (prime numbers, modular arithmetic, elliptic curves), but the subject of number theory, before the advent of computing, was possibly the most useless kinds of mathematical 'art' that could have existed. I imagine it was the mathematical equivalent of frolicking in the fields.

Mathematicians explored Fermat's little theorem starting in 1640, but they didn't do it because they knew it'd be useful several hundred years later in RSA. They did it simply because math is worth exploring in itself.

Even if you don't subscribe to the idea that we should pursue math for math's sake, history shows us that it's very difficult to know what parts of math will be useful to humanity, especially hundreds of years later. Since people work best on what they find interesting, mathematicians should continue exploring the topics that most interest them, because we really can't say with any certainty what will prove useful (or even essential) to future generations.

[Houshalter]

That's a popular meme but its mostly false. See http://lesswrong.com/lw/4kt/the_value_of_theoretical_researc...

The vast majority of "useless" mathematics really do turn out to be useless. In the rare exceptions, there's not much evidence that doing the work beforehand is actually an advantage. E.g. Einstein wasn't aware of most of the work on non-Euclidian geometry before developing relativity IIRC.

Stuff like prime numbers have eaten up millions of brain hours of highly intelligent people. I remember thinking it was weird that so many project Euler problems were about prime numbers. And I looked up what the applications of them were and couldn't find anything significant beyond cryptography.

And they seem to have been chosen for cryptography simply because it was a well studied problem with certain properties. Not because cryptography inherently needs prime numbers and would be impossible without centuries of previous work studying them.

[blintzing]

> Stuff like prime numbers have eaten up millions of brain hours of highly intelligent people

I think the idea that brilliant minds have been 'wasted' on prime numbers is nonsense. Don't 'highly intelligent people' have the right to pursue what interests them, and even disregarding that, won't they do their best work on problems that interest them?

Even further, is learning anything that is not practical or useful a 'waste'? Certainly not. Calculus might not be of the utmost importance career-wise for an aspiring musician, but learning it helps us think in new ways.

> The vast majority of "useless" mathematics really do turn out to be useless.

That's fine! So long as we strike gold every once in a while (cryptography, which is pretty essential to the internet functioning as anything more than a bulletin board), math is doing it's job.

[coliveira]

> Einstein wasn't aware of most of the work on non-Euclidian geometry before developing relativity IIRC.

That's the worst example you could find, because Einstein didn't develop the mathematics for general relativity. He relied on the math invented in the XIX century for non-Euclidian geometry. If nobody had though about such a "sillY' geometry with "no practical value" it would probably take much longer because the necessary results would be out of the reach for Einstein.

[sdenton4]

Riemann's contribution is overlooked far far too often. The early non-Euclidean geometries were spaces of constant curvature - spherical and hyperbolic - and Riemann brought the idea of a manifold, and the notion of having a geometry that changes as you move around the space. And he did it in a fantastic lecture with only one equation in 1854, a good 50 years before special relativity.

Einstein was also definitely familiar with the work of Helmholtz, who did some fascinating work on non-Euclidean geometry in the context of ophthalmology: Lenses change the amount of curvature we perceive in space (think of fish-eye lenses), and provide a great jumping off point for the notion that the universe might not be as flat as it appears.

The Dover book 'Beyond Geometry' collects a bunch of the major papers in non-Euclidean geometry leading up to relativity, and is a fantastic read.

[Houshalter]

He figured out that spacetime may be non-Euclidean before he was aware that the math had been extensively studied. Then he learned about the preexisting work.

It's true it probably would have been much harder for him to work out the math on his own. But he and/or others eventually would have done it.

[shas3]

I think you are needlessly generalizing the personal argument of the LessWrong post to apply to general epistemology. As a person who is a utilitarian, you cannot fully justify studying pure math. However, at a societal level, you do need critical mass in terms of enough people working on math for practically useful insights to emerge. So 'don't do pure math' (or art, or music, or theoretical CS) is good as a personal goal for someone with utilitarian aspirations, but is inappropriate 'public policy'.

Consider this: a vast majority of mutations are useless, but for this reason, if there were no mutations at all, and mutations somehow willed themselves out of existence, then there would only be primitive lifeforms on earth.

[goolulusaurs]

That is nonsense. We have have no idea what math will turn out to be useful in the future. To say that it has already turned out to be useless presupposes that we already know all uses we might put it to in the future, which we clearly don't.

[Houshalter]

Well empirically most math developed in the past turned out to be useless up until now. Are you suggesting that it will suddenly become useful in the (near) future? Are the past few centuries not enough time for you to generalize from?

[goolulusaurs]

I think it is very plausible that a large portion of mathematics that is not very useful presently could be very useful for problems we have yet to tackle. As science progresses it will be less and less able to make grand unified theories and increasingly focus on the manifold particular. I can imagine much of math being useful only for problems we haven't even identified yet, like algebraic topology being used to study social dynamics, or engineering problems at strange scales. Even beyond that I think it may be the case that much of mathematics will become useful for reasons unforeseen. Unknown unknowns always seem to be where new science pops up.

[tsotha]

>And I looked up what the applications of them were and couldn't find anything significant beyond cryptography.

Cryptography is a pretty big deal, though. You can't run a modern economy without it.

[moonchrome]

>But sometimes the connection between "beautiful art project" and "practical tools" is totally unexpected. We often invest time in projects that seem simply like "beautiful art", and then much later stumble upon something practical.

That's like saying that we should randomly start drilling holes in the ground because sometimes we will strike oil.

people arguing for it usually ignore the silent evidence of research that lead nowhere and also, more importantly, the potential research accomplishments those people could have acheived if guided to work on different problems.

[zardo]

>That's like saying that we should randomly start drilling holes in the ground because sometimes we will strike oil.

Unless you have better tools for locating the oil, that's not a bad strategy.

[moonchrome]

I would argue that if you didn't have better tools for locating oil or determining viable research areas you shouldn't be digging/funding it in the first place because unless you have a high probability of finding something (and we've left the times of early science when there was a bunch of low hanging fruit) the cost of failed attempts will outweigh the benefits of the success stories.

[dllthomas]

Your broader point - that we're a lot more likely to find useful things using some guidance as to where useful things are likely to be than in proceeding randomly - is important.

A crucial difference between digging for oil and doing math, however, is the nature of the externalities. In either case, you're burning some work that could be spent somewhere better, but with oil you're left with a hole that you probably want not to be there and there's no good way to put it back. In both drilling and math, "drilling" helps us refine our methods. In the case of math exploring more of the ramifications of our axioms also helps raise our confidence that they're not subtly inconsistent.

And of course, math is generally less expensive than an oil well.

I don't know where the cost-benefit analysis puts work on math when we don't yet see practical application. And I think that's often over-romanticized. However, I do think there are a lot of reasons we should expect the analysis to come out more favorably than for drilling random holes.