How is Musk's tunnel in Las Vegas better than a normal train tunnel.

To answer this, we are going to use what computer scientists call "big-O notation". Tunnels are 𝑶(𝑛²) -- so Musk's trick is to create narrow tunnels. https://twitter.com/GordonJohnson19/status/1380344687874166784

The effort to dig tunnels depends upon the size of the tunnel -- but this grows faster than you think. Twice the width of the tunnel means FOUR TIMES the effort to dig it. You can see that with the following circles: the larger is twice the width of the 4 smaller ones

Subway tunnels to fit rail cars are often around 28 feet, Elon's trying to get his tunnels below 14 feet. This means creating tunnels with ¼ the effort, a quarter of the cost. Instead of $200million for the Las Vegas project, $50million.

The point of this thread is to explain Big O notation by explaining Elon's Boring Company. He's a computer geek who understands 𝑶(𝑛²) and how to exploit that.