> neutrino signalling could make it faster

you need a nuclear reactor for transmission and a deep array of detectors buried underground for reception...

And somehow distinguish between the signal and the flood of solar neutrinos.

> thanks to them we have shorter fiber routes across the atlantic at least.

Can you explain how HFT caused a shorter fiber route across the Atlantic? Is this route open to the non-HFT public?

I read Flash Boys and am aware of a custom fiber link between Weehauken, NJ and Chicago, IL, but I thought they are were moving to microwave. I thought there were some HFT links (fiber or microwave) within Europe.

There are microwave links across Europe:

https://sniperinmahwah.wordpress.com/2016/01/26/hft-in-the-b...

There are apparently shortwave links across the Atlantic:

https://sniperinmahwah.wordpress.com/2018/05/07/shortwave-tr...

https://sniperinmahwah.wordpress.com/2018/07/16/shortwave-tr...

These should have a lower latency than fibre links although the shortwave link will probably have rather a low data rate.

Microwave is great for latency, but the bandwidth sucks. When you need bandwidth & low latency, you need a more direct fiber link.

I recall a new transatlantic cable constructed a few years ago being advertised as shaving off a few milliseconds. Trading and cloud providers were mentioned as target customers. I don't know whether they also route public internet traffic.