Tangentially related, but I wonder how long before HFT harnesses neutrino transmission to send market data directly through the earth? The MINOS [1] project is underway to send neutrinos from Fermilab in Illinois to detectors in northern Minnesota. Straight through the earth's crust. Detecting neutrinos is hard, and modulating data on them will probably be even more difficult, but if it shaves a few micro/millisecond…
Maybe less infrastructure required.