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.