If pykrete is such a cheap strong material, why don’t we use it for regular buildings?
Probably because we have the option of tunnelling into regular ground instead for subways. But tunnelling in general is underutilized and overpriced, likely due to lack of innovation, risk aversion, high time preference, property rights problems, NIMBYism etc etc etc. Elon is absolutely right that Tunnels would solve traffic, and tunnelling into rock is better than making a pykrete megastructure.
But you certainly could make a pykrete structure on rock foundations (which are not everywhere!) and have a pretty economically valuable and affordable megastructure in the form of a multilayer city. I tentatively suspect that tunnelling the lower layers and then building skyscrapers (like Manhattan Island) is the superior option though.
In general, megastructures are underbuilt for political economics reasons. Things like The Hoover Dam and the US Highway System would probably be illegal to build today because of NIMBYism. Most of Manhattan Island would be illegal today too.
Also we have aging and shrinking populations in The West so there’s immense social pressure to run things as a form of managed decline rather than innovate and build. Old people have lots of capital and limited life left, so they want to make everything quiet and static and peaceful, and they throw their monetary and political capital around to keep things that way.
Probably because we have the option of tunnelling into regular ground instead for subways. But tunnelling in general is underutilized and overpriced, likely due to lack of innovation, risk aversion, high time preference, property rights problems, NIMBYism etc etc etc. Elon is absolutely right that Tunnels would solve traffic, and tunnelling into rock is better than making a pykrete megastructure.
But you certainly could make a pykrete structure on rock foundations (which are not everywhere!) and have a pretty economically valuable and affordable megastructure in the form of a multilayer city. I tentatively suspect that tunnelling the lower layers and then building skyscrapers (like Manhattan Island) is the superior option though.
In general, megastructures are underbuilt for political economics reasons. Things like The Hoover Dam and the US Highway System would probably be illegal to build today because of NIMBYism. Most of Manhattan Island would be illegal today too.
Also we have aging and shrinking populations in The West so there’s immense social pressure to run things as a form of managed decline rather than innovate and build. Old people have lots of capital and limited life left, so they want to make everything quiet and static and peaceful, and they throw their monetary and political capital around to keep things that way.