On another note, I've heard that the first thing you need to fabricate (beyond basic hand tools) is a lathe. Once you have that, you can make a better lathe, which can make various other machine shop tools, etc. until you have a whole workshop created. Although this probably assumes that you still have access to modern (as in the last couple hundred years) materials to work with.

It is information like this that makes you realize how incredibly fragile our civilization's tech stack is. Most of our physical tech stack is read-only executable code: there isn't a civilizational "source code" that shows from first principles how to build up to our current technology layer. For that matter, not even from first principles to turn of the 20th century technology level. We take a most of our tech stack for granted. This would matter if we had a civilization-wide energy crash, so if the catastrophic-scale climate change or oil crash predictions come true then this would be more than a passing interest for just the recreational primitive tech hobbyists.

Unfortunately during a collapse of society you very rarely find hospitable environments. By the time society itself recovers and has the resources to spare everyone who knew of the old world is dead and a lot of the artifacts are ruined or destroyed.

Seed vaults, storing equipment and books in salt mines, etc should prove extremely helpful if such a dire situation arises. It might take a lot longer to rebuild though because there won't be any cheap, easy oil to burn.

The winning strategy so far seems to be duplication, so it's about time we get some colonies on other planets to help ensure continuation of the metaspecies.

With a fertility rate of 1.3 among the intelligent (read: technologically capable) peoples of the world, we are far more likely to run out of people to maintain the technology than we are to run out of the energy to power it.

Indeed, if you walk into any utility company or similar, who do you see doing all the work? Middle-aged-to-old working-class white men. What happens when those men retire? Who is going to hold the infrastructure together?

Unlike a civilization-wide energy crash, this is not merely a rhetorical question.

Are you using the number of 1.3 from people with university education in the rich world? It seems a very narrow window through which to view humanity'a 'capable' people, who exist in all shapes and forms, all colours, on all continents, and often arise from deep poverty without any formal education, my grandfather for instance

IQ is substantially heritable. A child's IQ is (more or less) the average of his four grandparents. The IQ of his four grandparents is largely the result of cognitive assortment within a breeding population with a certain mean IQ.

If a population's mean IQ is 70, the percentage of people with an IQ above 130 is 0 (out to four decimal places).

If 85, 0.1%.

If 100, 2.2%.

If 115, 15.9%.

The mean IQ of the white race is about 100. The mean IQ of SS Africans is about 70. The mean IQ of Arabs is about 85. The mean IQ of Chinese is 105 or so. The mean IQ of Ashkenazi Jews is 110-115, depending on how you measure it (they are a special case).

There are probably more people possessing IQs of 130 or above in Israel than in all of Africa.

The number 1.3 comes from a rough average of the fertility of the white nations and of the high-end Asian countries, namely Japan, Singapore, Hong Kong, and to a somewhat lesser extent mainland China.

Apart from being hilarious and great fun, it's also a suprisingly serious study of just how much technology, and I'm not talking about the modern stuff, is based on a huge pyramid of other skills and technologies which you simply can't leapfrog.

Mild spoilers follow:

Our hero, after being flung back in time to Rome in the year 535, is trying to prevent the fall of the late Roman Empire when it gets conquered by the Byzantines (actually the story's a lot more complex than that, so that's simplified). He tries to reinvent all sort of different pieces of military technology, and fails utterly --- turns out reliable gunpowder is really hard to make. His clocks won't keep time, his lenses aren't round, and he doesn't even both with electricity.

The innovations he eventually ends up successfully introducing? Distilled spirits (a great money-maker!), Arabic notation, double-entry notekeeping, and semaphores.

Sure this is just one example, but it is what comes to mind given TFA's subject matter. Without access to iron-working, I suppose a less durable rim material like e.g. hemp could be used, which would introduce some more complications involved in tightening. If solid rather than spoked wheels were acceptable, an out-of-round wheel on an axle can be marked with a piece of chalk-rock held in place while spinning the wheel, and then abrasive stones can be used to true the wheel to the chalk mark.

That is a rudimentary lathe.

For bonus points I'd give them the decimal number system.

This says much more about how we dismiss ancient civilizations as inferior than it does about ancient civilizations themselves.

The fact is, the geocentric model was an excellent one, able to explain all observations at the time in a sensible and straightforward way. Admittedly, more data helped to develop the heliocentric model, but there were valid scientific criticisms against that model at the time. In particular, it took Kepler to provide truly sensible and strong arguments in favor of heliocentrism.

The geocentric model is so good that even today it is often the sensible model to use when thinking about some astronomical problems. I hate to hear it being dismissed as 'wrong' - because from a physical perspective the two are simply geometrical transformations of one another, they are both 'right'. It's simply that one of them is simpler than the other for most problems.

But most of all, I hate hearing people say it 'held back thinking', because I assure you that the people doing the thinking back then were just as capable of doing good, logical, rational thinking as we are today, and didn't need anyone to claim they were too stupid to think critically for themselves about the scientific understanding of the time.

Not really, at least if you want to keep simplicity of Newton's laws which are formulated for inertial reference frames. The reference frame in the heliocentric model is inertial, while in the geocentric one it is not.

As a point of comparison, who discovered the existence of North America? Was it Christopher Columbus in 1492? Or was it the Vikings in 900 AD? Or was it some mix of people who first melded together in Beringia, somewhere around 20,000 BC?

Has a fact been discovered if one person learns of it? Or is it only discovered if the news spreads to all of society? If the latter, then science is a social process, not an individual one.

The historian Fernand Braudel points out that an Italian engineer, wanting to show off his skills, built an automated saw mill in Italy, back during the 1200s. The logs were slotted automatically and run through the mill automatically. This engineer had created an important part of the Industrial Revolution, 500 years early!!! Did it matter? No. The project was merely a demonstration. The abundance of wood was never used. How could it be? There was no system of transportation for the abundance of wood, there was no finance to cover operating expenses, nor any finance to support a building boom that might use the wood, nor any modern labor market from which the mill owner could hire more workers to do the initial cutting of trees, nor was there the modern strictness regarding contracts, nor were commoners allowed to bring civil suits against the nobility (in case of default, supposing a nobleman contracted to have a manor built), nor was the judiciary independent, nor... In other words, the Industrial Revolution was a social process, involving the creation of dozens of important modern institutions, and the public's acceptance of the legitimacy of those institutions. No single engineer, however brilliant, could jump start the process.

People deeply overestimate the value of any single insight, and largely forget about the dozens of mundane but non-trivial details a successful implementation relies on. Great entrepreneurs understand this and know how to solve enough of those "little problems" to enable a big idea to thrive, and that's the magic of it. Bad ones obsess over the idea itself.

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

From their perspective the map looks like this: https://en.m.wikipedia.org/wiki/Circumpolar_peoples

From their perspective North America is simply yet another settled area.

1 or 100,000 the point is people who made the crossing did not get a popup saying "achievement unlocked: new continent!" And then run around telling everyone about it.

Yes, European mapmakers did not known about such crossings, but being a very remote area in 1400's they probably never asked. And from an oral history perspective it would not be anything unusual because a 50 mile ocean crossing is just a regular thing to sea going populations.

Also, DNA evidence is going to be sketchy because it's really hard to say if someone migrated 400 years ago vs 600 years ago.

PS: I am not saying this 100% happened, but it seems very likely.

"1 or 100,000 the point is people who made the crossing did not get a popup saying 'achievement unlocked: new continent!'"

Yes, that is the point that I made above. The people had no idea.

Likewise an interest free loan would be permissible, though there wouldn't be great incentives to offer them except to family members, for example.

(It works up to a point, but it's hard to scale. You can emulate a loan contract between two parties, but you can't have a bond market because the "loans" aren't tradeable)

Slightly relevant, what information would you send to the past if you had a phone that could communicate backwards in time? But there's a catch, any idea you send is converted to the closest analogue in ancient times. So if you tell them about the scientific method, they will just think about religion. http://lesswrong.com/lw/h5/archimedess_chronophone/

All that being said, assuming the chronophone will let me, I'd bring their attention to the idea of the printing press. It's easily made, the benefit is obvious, and the effect is dramatic. Kind of amazing it wasn't invented earlier.

How do you think that held us back? Do you think heliocentrism, which is similarly wrong, has/is holding us back?

Telescopes and semaphores would get you very far at a fraction of the cost.

Runners, horses, ships moved communications fast enough. Even if you knew ceaser was coming to Rome, transport speed meant you couldnt do much with that. And yes we with hindsight cab cherry pick situations where it would help. But it was not worth cost to create, train and maintain such a system for hundreds if years for the fee.tumes it provided marginal benefit.

In other words most technology is synergistic. It really isn't awesome unless bunch other tech is at sufficient level to exploitmkit

The local HFT community would probably pay for a semaphore system. A lot of money could be made on knowing the outcome of events earlier than others.

On the other hand, "trees are plentiful" probably meant that sight lines were awful. Maybe, a semaphore only becomes feasible after one has cut down most of the trees.

The difference between steam engines is that steam engines were very difficult to build. Semaphore is very simple and a trial system wouldn't be expensive to set up.

The Romans did use crude fire signals, so I think that proves that they would find it useful.

Roman legions mounted in bikes could be everywhere. Their roads already were a force multiplier. Combined with being able to feed them and have them not die of disease simple wounds. We'd all be speaking Latin.

We all know, Rome is center of the universe. :)

The Romans had wheels and carts that seemed to work. It doesn't seem like a huge leap to put a human on them.

As for manufacturing lenses, you can get by without many tools with cunning techniques. Molten glass naturally forms curved shapes and can be polished by fire. Leeuwenhoek made tiny lenses in the 1600s, although no one knows for sure exactly how (he made a point of not sharing) - one technique that's known to work is drawing the glass into a fine thread, snapping the thread, and heating the end so it forms a tiny ball.

I wonder the same. If I was suddenly teleported to the middle of a forest, without anything, not even my shoes and clothes, and no chance of any contact with civilization again, what SHOULD my first few tasks even be??

Imagine a modern human, ideal in health and strength and faculties, and immune to disease or aging, teleported butt-naked to a copy of the planet Earth where there never had been any humans — so no chance of radio, or rescue choppers seeing your smoke signals, or finding any technology that you didn't make yourself.

The only thing that person has is a version of Wikipedia in their brain, so they know how everything is built and how nature works.

How long will it take for them to resch current levels of technology, and be able to construct a device like the one you're reading this on? Would two people make a significant difference?

How would you fare in that situation?

Transporting a man and a woman doesn't help much either because there probably wouldn't be sufficient genetic variety to produce a viable species. I think I read you need thousands of humans to do that, and then there's enough spare capacity beyond mere survival to ensure that knowledge gets passed on.

There is a book about all this (a rather depressing book actually): https://www.theguardian.com/books/2014/apr/03/knowledge-how-...

Of course the daily grind there is probably food production and medical issues.

1. What are the chances of any us surviving outside of human civilization if all technology was stripped from us, even if we had memorized all of humanity's combined knowledge?

2. How long would it take to replicate current technology from scratch, if all the research was already done for you, and you were basically immortal?

By "from scratch" I mean skipping the creating-the-universe part, just starting without any preexisting tools other than what you may find in nature.

Maintenance is a killer. There comes a point, fairly early in technological development, where it's simply impossible for any single person to keep everything working and still have time to improve on the situation.

That's true for even the most benign of environments. Hana, unfortunately, was stuck in a rather damp jungle.

(And to preempt the possibly inevitable question, find it at https://forums.sufficientvelocity.com/threads/song-in-the-fo.... Read if you feel like; I like to think it's cute.)

(In that setting, you can build a very simple machine --- powered by a potato, which actually makes sense in context --- which can take you to a parallel Earth. You can take what you can carry with you; but not iron, which stays behind. Turns out that setting up a society from scratch using only hand tools and brain power is kinda hard.)

It would be an effort, but I think we could retool to bootstrap industry mainly using aluminium and copper alloys (engineering bronzes particularly are great materials). Some titanium and nickel alloys in the mix.

I'm still not sure I want to read the last two. I swore of solo Baxter books after getting burnt by Titan.

And vice versa.

We spend most of our time either learning to be a cog in society's machine, or being that cog.

Most of today's cogs are useless in ancient times. "What is this 'full stack' you speak of, stranger?"

Most of the past's cogs are useless today. "So you're good with sticks on wet clay? Cool story bro."

Either stranger could adapt to the times, but they'd be very inefficient because they'd never be fully integrated to the larger machine, having to relearn every interaction that a native just takes for "the way things are."

Also, I would highly recommend "The Cross Time Engineer" series as it's this same scenario but works through how he's able to apply his modern knowledge as leverage to work up from a boatman earning pennies to running the country.

1 - https://www.amazon.com/Cross-Time-Engineer-Adventures-Conrad...