HN Explorer

Challenge HN: Convince an ancient Greek that you are from the future

41 points by lisper ↗ HN
I'm writing a book about the scientific method targeted to a lay audience. As part of the dramatic narrative I came up with the following puzzle: imagine you have built a time machine and you want to go back to ancient Greece and try to convince someone that you are from the future. The time machine operates under Terminator rules: it can only transport your body, no artifacts. (Some provision is made for you to acquire period clothing once you arrive, but that's it.) So the only thing you can take back with you is information that you are able to memorize. You can study for as long as you want before you go (so, for example, you can, and probably should, learn to speak ancient Greek) but once you go there is no coming back.

Mark Twain used a similar scenario as a plot point in his book, "A Connecticut Yankee in King Arthur's Court." In that book the protagonist solves the problem by predicting an eclipse of the sun, but that isn't very interesting so I am adding the following two conditions to the puzzle:

1. There is some uncertainty about exactly when and where you will arrive. The time uncertainty is many decades, and the space uncertainty is many tens of kilometers.

2. You have to convince them within a small number of weeks, otherwise they will just decide you are crazy and throw you in the loony bin.

So predicting a solar eclipse doesn't work because solar eclipses are very rare at any particular point on the ground, so the odds of you appearing someplace where there will be a solar eclipse to predict are vanishingly small. Even if you did get lucky enough to end up somewhere that an eclipse would happen within a few weeks, you would have to either memorize the exact time and location of all of the solar eclipse events in Greece over a multi-decade period, or learn how to calculate them on the fly by hand. You would also have to somehow figure out exactly when and where you had arrived. You can't just go buy a newspaper and look at the masthead.

Some other things that won't work:

1. Predicting a lunar eclipse. The ancient Greeks knew how to do that so this would not impress them.

2. Predicting a historical event, for all of the same reasons that predicting a solar eclipse wouldn't work.

The puzzle is designed to nudge you towards an approach where you try to reproduce some scientific or technological advance towards which you can leverage the knowledge you bring with you from the future.

I have not been able to come up with a solution.

38 comments

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tomrod
Assuming you know the local language and can translate symbols, your best best is to get the buy in of mathematicians and engineers. Predictive power of Newtonian physics and utility of modern mathematics through calculus generally.

Euclidean geometry as a starting point would blow their minds.

Proving sqrt(2) is irrational might get you martyred though, be careful.

lisper
> Predictive power of Newtonian physics

The problem with that is that this predictive power only manifests itself when you can make precision measurements of celestial objects, and the Greeks could not because they didn't have telescopes. (Hm, inventing the telescope might be an answer. Did the Greeks have lens-making technology?)

> Euclidean geometry as a starting point would blow their minds.

Sure, but that wouldn't prove you were from the future any more than it proved that Euclid was from the future.

travisjungroth
> Sure, but that wouldn't prove you were from the future any more than it proved that Euclid was from the future.

By that standard it doesn't seem like any scientific or technological knowledge could prove you're from the future, either.

The only way to show you're from the future that can't also be explained by being from the present and having great knowledge/intelligence is to predict the unpredictable. But, you've narrowed the time constraint (a few weeks) and widened the range (a few years) so that predicting the immediate and unknowable isn't an option. Seems to be what you're going for also. So, I don't think you're left with anything.

lisper
"Prove" is too strong a word and I shouldn't have used it. That's why the challenge is "convince", not "prove". But I don't think anyone ever even suspected that Euclid was from the future.
travisjungroth
I think by those standards it would depend as much on persuasiveness as anything else. It seems really hard to differentiate between “from the future” and “from somewhere else more advanced”, especially with your constraints.

Even if you loosen some of the constraints it’s hard. You could show up with a Jeep and some people would think you’re from the future and some would think you’re just from somewhere else. Even if your predict their future that may not convince someone! Predict an eclipse and they might say eclipses are predictable (of course, they’re right), predict the outcome of a battle and they’ll say you can see the future but that doesn’t mean you’ve been there.

riskpeep
I'm pretty sure they didn't have lenses. Lenses need optically clear glass. Clear glass came along around 100AD, but it took another 1000 years before it was sufficiently clear that you could make good lenses with it.

Glassmaking would be a good one because the chemistry is based on available materials and with sufficient knowledge you would walk them through the history of glassmaking up to a simple lens and make eyeglasses.

ArtWomb
You could do something along the lines of Mendel's pea pods. Predict a recessive trait appearing in offspring. An explanation of hybridization to Ancient ears could be enough to trigger a Baconian revolution ;)
riskpeep
A functional glider would do nicely I think. (Doh, they had those with Daedaleus and Icarus).

I was going to suggest a boat or a hot air balloon, but Archimedes figured that one out.

Another thought would be a simple steam engine. The Greeks had iron and knew how to work it. All the rest is knowledge that wouldn't surprise them, but they'd not put it all together.

The Greek's theory of chemistry was all kinds of messed up. There are likely lots of examples there that could be used as well.

gus_massa
Go with Archimedes and teach him calculus. He will understand https://en.wikipedia.org/wiki/Quadrature_of_the_Parabola
hbrav
Well first you'd have to teach him algebra, and even that would probably be impressive. Have you ever read Euclid's Elements? The notation is horrific, way harder to work with than modern algebra.
Qem
I was going to suggest that too.
unkeptbarista
Pretty sure the Greeks have all the materials for these.

Create batteries from dissimilar metals, using clay pots, weak organic acids, and copper wire. Once you have batteries, wind copper wire around a small, rough rod of iron to create a weak magnet.

A mineral acid will produce stronger batteries, but require access to things like salammoniac and blue vitrol and the knowledge of how to heat them together and pass the resulting gases through water.

hbrav
Copper _wire_ requires you to be able to draw wire, not just refine copper. I'm not sure if the ancient Greeks knew how to do that.
unkeptbarista
I'll admit that I was assuming that since many civilizations at that time knew how to make gold and silver filigree, that copper wire was also possible. One can probably replace the copper wire with gold wire, but you might have a hard time convincing the locals to loan you some for demonstration.
pvaldes
Funding your own oracle or acting as a physician with modern knowledge about microbes and what causes disease would be a much more profitable enterprise. Disclosing that you are from the future (a future without Greek gods, none less) would be a disastrous move. You simply couldn't tell the truth and remain alive
nudpiedo
Show them the reduction to absurd of square root two. Tell them that one day their culture will eventually come to an end and but will be forever remembered like Homer’s Odysee, however large parts of it will be lost, therefore they should keep some of their best written manuscripts hidden on some caves which I will visit when I am back, to the future, lol.

Also I don’t like to change the past, but someone should pass a note there saying that aside of Persia eventually the Arabian peninsula will create an even greater enemy.

animal_spirits
My idea would be to first study in depth every hallucinogenic plant and mushroom that could have grown during the time period, as well as common tactics of charismatic public speaking. After traveling backwards I’d quickly gather up as many of those plants as possible and prepare them in ways that can be easily ingested by the common folk through teas and what not. Then I’d sell them to the common folk as ways to see and talk with the gods, and hope to gain a cult following. That way I can actually have people listen to me without disregarding me. Then I suppose I’d have to teach them how to build as complicated of a technology out of simple materials, maybe a simple plane like the wright brothers, and go on to teach complex mathematics or something.

The first step is to just get people to listen to you. But I suppose that won’t help with your opening story haha

lisper
Indeed not, but I like that plan a lot nonetheless! :-)
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detritus
I guess start by describing what I know of orbital mechanics and how the solar system works.

After that, build a small furnace with an exhaust that can shift a propellor shaft.

After that, a flushing toilet.

Then describe a manual Blockchain and mint the world's first NFT.

satori99
> build a small furnace with an exhaust that can shift a propellor shaft.

The Aeolipile was described shortly before the common era, but it took another 1600 years before anyone could build a steam engine capable of real work.

https://en.wikipedia.org/wiki/Aeolipile

0-_-0
And then convince them to mine bitcoin with pen and paper.
blitz_skull
I almost choked on my coffee at the blockchain / NFT comment. Well-played.
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joezydeco
Build a simple barometer and predict the weather.

Falling pressure = storms arriving, rising pressure = clearing skies.

somebodynew
I think that my goal would be to demonstrate electrical devices starting with simple components and scale up progressively as people become more convinced.

As a starting point with minimal material requirements, I would build Faraday's rotating motor using: coins made of two different base metals and cloth soaked in saltwater for a battery, a lodestone as a natural permanent magnet, and wire or thin beaten sheet of any non-ferrous metal with a saltwater pool. Demonstrating continuous electromagnetic motion will hopefully be enough to secure some patience to request materials for further construction.

Radio demonstration would need to settle for morse code transmission because all of the components necessary for a basic radio receiver/transmitter are simple except for an amplifier. The leap in difficulty to construct a triode vacuum tube amplifier seems too far to expect to progress to voice transmission quickly. I would hope that a local ruler would understand the value after seeing a wireless telegraph in action.

The priorities from here would be to use the accumulated prestige to request smiths to make copper wire, to requisition the more exotic but already known sulfuric acid, construct lead-acid batteries, and short them through a copper coil containing an iron bar to make strong permanent magnets for use in practical motors and generators.

Once you get a bit of support, you can progress as far as needed through nineteenth century electrical development until they are convinced.

randomhodler84
Teach them binary, Boolean logic, basic logic circuits. Algorithms. Batteries, electronics. Bootstrap Silicon industry from first principals.
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f0e4c2f7
I would look for historical information on shallow deposits of gold within Greece, or if I could not find any start my own expedition to discover one.

Then I would go back in time and announce that I knew where the deposit was to anyone who would listen and lead them there to dig it up.

Then I'd break the news to them about time travel.

mikewarot
I can't do it in weeks, it would take years. I'd set up a blacksmith shop, then work up the chain to a machine shop with thread cutting lathe, planer, etc. I'd be making involute gears within a decade.

Once you've got a machine shop, you can make movable type, and work towards a printing press.

Another approach would be to make a slide ruler, showing them logarithms. I've done that by hand, in a crude manner. Decimal numbers would be among the lessons required to make it useful.

ncmncm
Seems like the clock shouldn't start ticking until you actually start trying to convince somebody. So, take your time making the equipment you need to demonstrate the photoelectric effect, and c, and the moons of Mars, Jupiter and Saturn (and existence of Uranus and Neptune), and electromagnetic induction.

But maybe all you really need is to solve quadratic equations and demonstrate integral calculus, and maybe disprove some famous conjectures. Show that pi is transcendental, and introduce e, non-integral powers and logarithms, and infinite sums. And (la pièce de résistance) zero. You will need zero to explain limits.

MaybeItsMia
Of the top of my head, without studying:

I could make soap and biodiesel from wood ash and olive oil... Though I'm not sure which one, lol.

I could also make some batteries, a basic generator/motor, etc.

Some basic chemistry. I could make hydrogen which I'm sure would be a crowd pleaser.

I could most likely muddle through my math to contribute some stuff that's unknown at the time, I could definitely "invent" a bunch of algorithms, data structures, encodings. I could also atleast describe a functioning CPU/computer. Maybe I could figure out how to make vacuum tubes? I'm sure I could find a glass blower to make the tubes themselves, but I'm not sure what material you'd need for the filaments, or how to pull a vacuum. I could most likely make a mechanical computer, or even adder/counter with enough time. Introducing Arab numerals could be big.

I could make a telegraph If I get steady electricity figured out, hell, maybe even a telephone. Sadly I'm not really sure how radio works.

Some basic economics/astronomy/cosmology/philosophy/sociology/political theory/evolution might not be immediately relevant, but if I write it down folks might find it interesting in a few hundred years after the fact.

I could also describe a nuclear reactor and nuclear bomb in broad strokes, along with firearms I suppose. I'm pretty sure gunpowder is charcoal and something with nitrogen right, potash, or is it a nitrogen containing mineral you dig out of the ground right? You can make a type of solid rocket fuel with sugar and iron rust, right? Maybe I could make chlorine gas, since that's just hydrolyzing molten salt, right?.

I think I could make a laythe? And therefore a piston which I could use to make a steam engine, put that on tracks or a boat. And y'know of course Cannons if I get gunpowder figured out.

You can mass produce steel or iron by pumping air through iron ore and coal/charcoal right?

I could make a simple printing press, maybe even a rotary one. Oh yeah, and paper making!

Maybe I could make a telescope, use the moon's of Jupiter to get accurate time keeping and do accurate cartography, along with knowing about the Americas, general Asian geography, Australia, etc. Maybe I could make a somewhat accurate maritime clock knowing that the guy who originally made one used strips of metal to adjust the clock speed at different temperatures to handle thermal expansion of components? That would help help solve the longitude problem? How accurate are capacitor clocks?

I'm also mid transition Trans, so I'm not sure how that would go down. Hopefully the Greeks are less witch burny. You can make HRT with concentrated female horse urine, right?

Convincing folks to brush there teeth could be big. Ntm washing hands and a germ theory of medicine. To bad I have no idea how to make anti-biotics, but maybe I could set others in the right direction. Though it's fairly simple to make petri dishes and isolate cultures right? The petri dish is just boiled gelatin made with sugar and beef broth poured into a container which can be somewhat easily sealed, maybe with wax?

If I have the resources sending some folks to the new world to pick up potatoes, corn, and beans would be great. Some basic nutrition advice could be good, the importance of vitamin C, vitamin A, macronutrients etc.

Maybe I could make some sheepskin condoms and introduce some family planning concepts/ plus some basic sex ed?

I might be able to organize a few manufactureries using division of labor/production lines with the help of some local artisans, then maybe do some light mechanization using water power atleast, or steam power if I get that figured out. Also ntm designing based on replaceable parts could be big.

Maybe I could make a mechanical loom if I tinker away at it?

I know how an ic engine works in principal, but I'm not sure I could make one without a machine shop. Maybe I could make an electric tr...

MaybeItsMia
Oh and outlining refrigeration/air conditioning, though I'm not what I could use as a refrigerant. Pasteurization and even canning high pH foods would be pretty easy in the grand scheme of things.

Oh! And Newtonian physics, throw some stuff off a cliff to demonstrate that heavier things don't fall faster.

Also obviously I'd want to ferment a slave rebellion at some point to get rid of the ruling class of slave owning aristocrats who waste a bunch of education and resources sitting around drinking all day.

Organizing a basic army based on slings/primitive firearms, shield walls/formations, guerilla warfare, a meritocratic officer corps, and explosives if I could produce them could definitely be effective against most militaries of the time. A hot air balloon with primitive bombs, maybe someone would still have the recipe for Greek fire, could be effective.

laxmin
Nothing impresses as much as a deadly weapon.

Learn to make Gunpowder.

If there were wise men, teach them the value of Zero.

If everything else fails, claim to be a prophet and produce a book with some vague moral values. Make the claim that you are from the future, one of the cardinal dogmas.