[qurren]

Some good points. However:

> replacing the majority of air travel with high speed rail

I absolutely LOVE high speed rail, but I will note that it is correlated with far more light pollution than air traffic. I say correlated because typically high speed rail is routed through high-density population centers, but if there aren't population centers, you'll have to have plans to create them in order to support the rail system itself.

Basically there is nowhere in the world that has both high speed rail AND suitable for astronomy. If you want to find dark skies in China for example you have to get far away from all the high speed rail areas of the country.

[adamsb6]

My wife's hometown in China used to have two options to reach from Shanghai - high speed rail (top speed ~ 200MPH) that takes about six hours or a roughly one hour flight.

Rail travel has stops and slowdowns in more populated areas that make it a bit slower than the advertised top speeds.

[computably]

That's a backwards argument. Flights in California between SF and LA will obviously travel a continuous line across California. Yes, the populated areas have light pollution, but that's because they're, y'know, populated areas. HSR itself would add nearly no light pollution outside of the existing population centers, in contrast to flights.

[qurren]

Right, the California HSR route doesn't travel through any really dark sky regions anyway.

My point was that if you want replace, say, San Francisco <-> Las Vegas with HSR you're going to inevitably have to wreck a chunk of Bortle 1 dark skies in the Sierra or Death Valley.

Doesn't mean I'm against HSR but it has to be done thoughtfully.

[oblio]

> but if there aren't population centers, you'll have to have plans to create them in order to support the rail system itself.

This is such a misanthropic point of view.

Nobody "creates" population centers. People aren't created out of raw clay, they already exist.

If population centers are "created" it's because people already exist and want to live in a specific place, often time urban.

And if they wouldn't go to these population centers they wouldn't live in caves in the dark. They would be spread over many more places, yes, creating lower levels of light pollution but lots more of them, covering a lot more land.

[t-3]

Many cities and settlements have been created intentionally rather than as a result of populations organically reproducing on the spot. Colonies, chartered towns/cities/etc, company towns, etc. It's a very common thing throughout history to the present day.

[oblio]

And... the people? Where do they come from? Mars?

All you're describing is population redistribution, not population creation. Urban centers have very low fertility rates, which actually reduces populations...

[t-3]

Yes, the people come from other places. The "population center" is very often made by people with intention though. The global population is still rising, so conjecture about the effect of cities on fertility rates is irrelevant. Humans aren't going extinct any time soon.

[oblio]

Did you read my previous comment in detail?

People don't live in caves, they will create light pollution everywhere, anyway. Might as well put them in small and dense population centers.

I hate reading comprehension these days :-)

[t-3]

You said: "Nobody "creates" population centers."

That's demonstrably false, population centers are created all the time. The fact that populations don't spontaneously appear is irrelevant.