Isn't helium potentially in short supply? https://www.cbc.ca/news/business/helium-smartphones-fibre-optic-cable-mri-internet-scuba-1.5084212 https://www.cbc.ca

Isn't helium potentially in short supply? https://www.cbc.ca/news/business/helium-smartphones-fibre-optic-cable-mri-internet-scuba-1.5084212 https://www.cbc.ca/news/business/helium-smartphones-fibre-op... Pressurizing train tunnels with significant amounts of helium which would constantly need to replenished may be impractical