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Sprawling Mayan network discovered under Guatemala jungle

bbc.com

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Re: Sprawling Mayan network discovered under Guatemala jungle

#41
post #16

Earlier quoted context omitted.

A few hints from the article: 810 sq miles mapped, a three year project and lidar flying by helicopter. Another giveaway is the search for MH370. In some dimensions Earth is still huge!

I wonder how much city life biases us to think the planet is smaller than it is. Perhaps it explains fears of overpopulation.

It’s both bigger and smaller than we often think.

In a straight line, it’s smaller than we might expect: People can (and do) walk across continents, sail across oceans in one-person boats, fly all the way around in 2 days, visit every country at least once during their life, etc.

But of course the surface is two-dimensional, we can’t see very far at a time. The land surface is about 150 million square kilometers. (For reference, New York’s Central Park is about 3.4 square kilometers.)

It’s also “fractal”, in the sense that as we look at smaller and smaller pieces, we keep noticing more and more details. Every little patch of soil is teeming with tiny animals, plants, fungi, and bacteria.

Or if you like, there are probably at least 10 million restaurants in the world (maybe an order of magnitude more, it’s hard to guess). If you eat at 3 different restaurants every day for your whole life, it will take more than 100 lifetimes to eat at all of them. Then there are the 150 million books to read. Etc.

Re: Sprawling Mayan network discovered under Guatemala jungle

#42

Earlier quoted context omitted.

> And it also says things like horses, chariots, steel, and other anachronistic things existed in the pre-Columbian Americas. There is no evidence (to date) to support any of those claims. Horses definitively existed in (far enough) precolumbian America. The dominant belief seems to be that they died out (perhaps due to human hunting) at or shortly after the end of the Pleistocene, ca. 10-12kya, but there is some evi…

I should have qualified that with "during the Book of Mormon timeline".

3kya is just about at the Book of Mormon timeline.

Re: Sprawling Mayan network discovered under Guatemala jungle

#43

The is one thing I don't understand. The article reports the use of lasers to map the ground, yet they mention the presence of foliage in situ . Assuming that they use optical or infrared lasers, foliage should be completely opaque at these wavelengths. How did they manage to map the asperities and characteristics of the ground?

A filter that takes the most deepest z-value you get, considering all else in a square meter as noise- or foliage?

Re: Sprawling Mayan network discovered under Guatemala jungle

#44
post #6

Reminds me of the recent finding that the Amazon River basin was much more cultivated in the ancient past than was thought: https://www.theatlantic.com/science/archive/2017/03/its-now-...

Which in turn reminds me of Richard Feynman describing the Mayan Calendar in his famous lectures on quantum mechanics, as an example of how the Mayans understood how the planets moved by looking, that they even figured out a number of patterns and predictions, but that they still did not know why the planets moved as they did, his point being that current understanding of quantum mechanics is very similar to this[0].…

And the reason that there are only a few surviving books is that the Spanish conquerors plucked those out to send back to Europe as curios before they burned down all the libraries.

Re: Sprawling Mayan network discovered under Guatemala jungle

#45

Earlier quoted context omitted.

Which in turn reminds me of Richard Feynman describing the Mayan Calendar in his famous lectures on quantum mechanics, as an example of how the Mayans understood how the planets moved by looking, that they even figured out a number of patterns and predictions, but that they still did not know why the planets moved as they did, his point being that current understanding of quantum mechanics is very similar to this[0].…

This is why liberals are sometimes using the term genocide more broadly in a way conservatives don’t like. They reference things like “black genocide” and conservatives get mad because the actual slayings are too few to be considered “genocide”. Yet in terms of lost culture, putting a high enough percentage of individuals in prison, and confining enough of the others to ghettos, while driving them out of historical c…

> Of course the culture is born again in a different form, as Native American culture endures today

Well, a culture is born again; culture just tends to happen if you put people together, it's in our blood. The question is whether it flourishes. I am from Europe so cannot say this for certain, but I get the impression that all over both American continents, Native Americans are still very much an ethnic minority whose rights are being trampled over.

Re: Sprawling Mayan network discovered under Guatemala jungle

#46
post #28

The link below may be interesting to look at (or laugh at?) since the LDS church's famous book claims to be about 3 civilizations that lived somewhere in north,central or south america. As far as I understand, one or more LDS leaders years ago decided (for arguably valid reasons) that all of the Book of Mormon events occurred between 600 BC to about AD 400. This has made it more difficult for the church to say "look,…

The Book of Mormon never claims that everyone died in the Americas at AD ~400. Nor does it claim that its account of the peoples there is comprehensive. In fact, it says the opposite: that splinter groups settled elsewhere, that there were other bands of people in the land, and that after the destruction of the Nephites, the millions of remaining Lamanites continued to sprawl over the land.

[deleted]

Re: Sprawling Mayan network discovered under Guatemala jungle

#47
post #16

Earlier quoted context omitted.

A few hints from the article: 810 sq miles mapped, a three year project and lidar flying by helicopter. Another giveaway is the search for MH370. In some dimensions Earth is still huge!

I wonder how much city life biases us to think the planet is smaller than it is. Perhaps it explains fears of overpopulation.

I would say quite a lot.

A private small-aircraft flight over any populated area (other than the biggest cities) reveals just how sparse most towns are. Travel almost any direction away from a main highway and in a minute or two you'll be looking at trees, trees, trees (or desert/mountains/fields).

It helps give one an entirely new perspective when we're used to traveling along roads and seeing unyielding flows of civilization, when the reality is those are mere ribbons of development criss-crossing what is still mostly empty, disinterested nature.

Re: Sprawling Mayan network discovered under Guatemala jungle

#48

Earlier quoted context omitted.

I should have qualified that with "during the Book of Mormon timeline".

3kya is just about at the Book of Mormon timeline.

Just about is fair but still short by ~400 years, unless you count the Jaredites. They purportedly fled the Old World around the time of the Tower of Babel (~2000 BCE IIRC?).

EDIT: I wasn't sure if the Book of Ether even mentioned horses, but it did, along with elephants. [1]

[1] https://www.lds.org/scriptures/bofm/ether/9.19?lang=eng&clan...

Re: Sprawling Mayan network discovered under Guatemala jungle

#49

This highly corroborates Charles C Mann's book 1491: https://en.m.wikipedia.org/wiki/1491:_New_Revelations_of_the... From wikipedia: The book presents recent research findings in different fields that suggest human populations in the Western Hemisphere—that is, the indigenous peoples of the Americas—were more numerous, had arrived earlier, were more sophisticated culturally, and controlled and shaped the natural land…

This is not my field of expertise, but why wouldn't we just run LIDAR scans of as much of the earth's surface as possible? Is it prohibitively expensive at this point? Is the computation [relatively] expensive? Is there a sound reason we don't race to do more? I get the feeling this kind of data could inspire generations of new archaeologists and historians. There are also some pseudo-archeological and pseudo-histori…

LiDAR collection is pretty dense from a data perspective. When I was working with helicopter collection teams we would regularly collect 1TB of point data per day at around 120 points per square meter. Based on the density of the canopy in Central America, the teams are probably using a density greater than that, and are using "multiple return" depth mapping so that they can see through the forest.

Processing LiDAR data is also quite expensive in terms of the hardware required and expertise of the people needed to correct the data back at the office. Typically LiDAR processing workstations have around 128-256 GB of RAM and a large RAID array of SSDs to quickly perform corrections interactively.

After the initial correction, most of the data is thrown out or "filtered" down to just the points of interest to save on space. Since it's quite easy to end up with hundreds of TBs worth of point data within a few months of collection. If the team is using colorized LiDAR, orthographic, and oblique images then that can take up even more space.

So the short answer to why more of the world hasn't been mapped with LiDAR techniques is money, time, and storage space. But with self driving cars now making LiDAR more prevalent, and storage space becoming more affordable every year, mapping whole regions with LiDAR is a more reasonable task.

NOTE: One of my former jobs was working with aerial LiDAR collection teams to manage the data and processing of the collected assets. This was around 2012 so some of the numbers may have changed since then.

Re: Sprawling Mayan network discovered under Guatemala jungle

#50
post #16

Earlier quoted context omitted.

A few hints from the article: 810 sq miles mapped, a three year project and lidar flying by helicopter. Another giveaway is the search for MH370. In some dimensions Earth is still huge!

I guess I'll just have to study up on the tech. IIRC there was a fairly quick LIDAR demo put on by a team at MIT that scanned the campus and surrounding areas in a relatively brief amount of time using a drone, I think. My ignorance on the subject of LIDAR has me wondering why we can't use a faster traveling vehicle, or would it be possible to do perform scans with something like a fleet of balloons that stream the d…

Some rudimentary googling, MIT campus is 168 acres or .26 sq miles. So the 810 sq miles in 3 years is still pretty impressive.
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