The only decisions being made at the nanosecond level are whether to quote at 148.23 or 148.24. So yes, that’s enough time for trivial decisions like those to be made.

A computer can do in a few nanoseconds calculations that would take a human days.

I don't that's true. Single clock-cycles of CPUs are measured in nano-seconds, and human's aren't that slow.

That comment was obviously a metaphor choosing "nano" as it's the coolest prefix, but since this is Hacker news I suppose now we have to fact-check a metaphor.

A Geforce 1080, at the high end of "normal" computing claims about 350 gigaflops. Divide through and we get 350 floating point calculations per nanosecond as an absolute maximum. Depending on what the numbers actually are and what method we make the human use (expert abacus users are surprisingly fast) that looks more like an hour's work for the human.

This just highlights how absolutely tiny a nanosecond is, though. Those speeds are only valid for numbers already within the processor; fetching from DRAM could be hundreds of nanoseconds. Also recall Grace Hopper's excellent video with a nanosecond of cable length, which is about a foot long.

> This just highlights how absolutely tiny a nanosecond is, though. Those speeds are only valid for numbers already within the processor; fetching from DRAM could be hundreds of nanoseconds. Also recall Grace Hopper's excellent video with a nanosecond of cable length, which is about a foot long.

This is exactly what I was intending to highlight. The speeds at which High-Frequency Trading operates are so ridiculously fast that even a computer can't put much "thought" (let alone more considered "wisdom") into a problem.

pico seconds might be a better measurement of modern high end clock speeds