I not long ago read a book titled "Time Travel in Einstein's Universe." and I was no more than a 1/4 of the way into it before I was saying to myself, "I have no idea what is being said here" Much of the maths that was being used was way over my head, and I had always considered myself reasonably competent with maths, since I was trained as an engineer, and have been tutoring first year maths at our local university for a few years. So I can see that much of what we, as in western civilization takes for granted now would have been inconceivable to those living a mere 500 years ago, and to those living in another 500 years time our understanding will become the bywash of history.

Mathematics. Big surprise, but it's definitely one of the big ones. The simple fact that we cannot divide by zero - except for Chuck Norris - is telling of the ultimately arbitrary design. One of these days we're gonna go, "It served us well, but was intrinsically a wrong way to measure, define, and prove natural phenomenon." Aliens gonna be like: "Y'all still use math, wut a bunch o' simpletins..."

It could be mans curse to destroy knowledge it can't accept or understand because it doesn't fit his current frame of reference only to have later generations rediscover that knowledge and find out that it was useful and true after all.

Thanks, I’ll look that book up. Your comment made me think of Newton. He is considered by many to be one of the most intelligent people who ever lived yet because of indoctrination he spent more time on alchemy than on physics. Even during the renaissance it would have been a death sentence to speak out against the church. People were as intelligent as we but they just lacked education and information and the church did everything they could to keep it that way. Now we have people that call themselves conservatives and those who are progressive. Conservatives, especially social conservatives, tend to want to return to the days of ignorance while progressive look to the future. I have real problems with those who look back at the ancient world and find magical knowledge that was lost. I have never found evidence of that in any literature that I have ever read. People were ingenious but they had no “hidden knowledge that was lost.” The holy books have bronze age thinking permeating their pages and it is useful historically to learn how those people thought but because so much of those books is pure myth, it certainly is not useful as factual history and the contents are not scientific and they contain very little morality.

A lost of science was known at one time, but "lost" due to religious suppression leading to a "dark age". The suppression of Greek and Roman Knowledge kept mos to fEurope in the dark ages for over 1,000 years.

When Cortez conquered the Aztecs he found they had sources for artificial light that didn't require heat or flames. The technology was lost and may never be rediscovered. Several Native American tribes of central and South America had done successful brain surgeries, but that knowledge was lost too, and was nto rediscovered until the 20th century.

Every abandoned ancient city or settlement may have had knowledge that was lost to us, either due to disease, war, or destruction of local ecologists. Destruction of local ecologists is what weakened the Incas and Mayans in South America and also was the reason for the Abandonment of Anchor Watt in Cambodia. They had knowledge to build great cities, but did not realize how they changing their local environment would impact them over the long run.

Now we are changing environment on a global scale. Global warming and climate change is a logical outcome if you understand what has been done and what is still beign done.