[NhanH]

I was about to disagree with you (citing that the change of 1815-1915 is much less than the change of 1915-2015). But then I realized that for certain places on Earth, the norm of technology might not be that much more advance than 1915 (this is a bit of a stretch, but you get the point) -- and I 'm not sure those people won't be able to adapt if they got move to the US.

[Chinjut]

The technological change of 1815 to 1915 is pretty drastic: railways, the automobile, the airplane, the telegraph, the telephone, the phonograph, photography, moving pictures, radio transmission, refrigeration, plastics, lightbulbs, x-rays, anesthetic surgery, the work of Semmelweis/Snow/Pasteur/Lister on medical hygiene/sanitation(/the germ theory of disease!), the spread of indoor plumbing and the flush toilet, ...

And culturally? Well, for one (U.S.-focused) example, there's that whole Civil War/end-of-slavery thing smack dab in the middle of it.

It's by no means clear to me that the changes of 1915 - 2015 somehow completely outstrip the changes of 1815 - 1915.

(I see that you agree with my general point, and with good illustration, too. I just wanted to point this out as well.)

[TheOtherHobbes]

Problem: a lot of those items/techniques were exclusively available to the very rich in 1915.

The UK still had slums with limited indoor plumbing during the 1950s. It wasn't until the slum clearances of the 1960s that the standard became an indoor bathroom in a house with central heating.

The big change between 1915 and 2015 is that the technological GINI coefficient has shrunk so much.

Being rich gets you few technological perks. You can buy a supercar or a private jet, but that's a difference of degree, not a difference in absolute access.

Most people have cars, and almost everyone can afford to fly. And all but the very poorest have Internet and electronic media access.

Likewise for cultural differences. Sexual morality - at least as publicly presented - is completely different now.

Work culture is somewhat different. Politics and finance have probably changed least of all.

The point being that someone from 1915 may just about be able to understand the Internet and computing. But they're going to have a really tough time learning how to parse Buzzfeed or TechCrunch or Reddit. Never mind what happens when they find PornHub or Tinder.

There are three things to learn, not one. The first is what the technology does. The second is the vocabulary of new names and the new concepts used to describe. The last is the social scripting that defines appropriate and inappropriate behaviour.

Those last two will take longest and be hardest.

I'd expect similar challenges in 2115, with the difference that there's likely to be much more social and political change, and not less.

It would surprise me if the definition of "human" hadn't changed fundamentally by then, together with almost everything we think we know today about culture, politics, and economics.