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Comment by Bluecobra | Hacker News Reader

Even microwave is slow, they are using shortwave radio for certain signals. Maybe neutrinos are next?

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

I'm not sure what's going on with this comment so let me make three observations:

The speed (latency) of the EM spectrum is the effective celerity of the medium: this doesn't differ in the air between microwave and shortwave in any meaningful way.

The speed (throughput) achievable on a given frequency is limited by the period of that frequence, high wavelengths can modulate more signal. Microwaves are higher frequency than radio by definition, so they have a higher throughput.

Neutrinos don't exceed the speed of light, and make a very bad medium of transmission given the near-complete lack of interaction with baryonic matter.

Neutrinos don’t need to go around the earth, so in theory you have a pi/2 advantage over an EM signal when sending to an antipodal location, for instance. In practice of course, throughput is utterly horrible for the reason you indicate.

All you need is a couple bits, but yeah, making sure it’s the neutrino your buddy sent and not some other one is where it gets complicated.

I think neutrino detectors capture at best something like 10 neutrinos per year or so, so the throughput would be severely limited.

This assumes that neutrinos aren't slowed by a dense medium as light is.

That's a maybe. Still, good point.

We already fire neutrino beams through the Earth's crust, and they travel at the speed of light, and the core isn't that much more dense.

Latency would also be degraded by the interaction property. The probability that you detect the first packet of neutrinos is extremely low.

Shortwave radio can be transmitted around the curve of Earth by ionospheric reflection and refraction so fewer repeaters are needed. This allows crossing vast oceans where microwave infrastructure might not be possible.

As you say the downside is available bandwidth and throughput.

That’s why most markets close during night time.

No it isn’t.

Most markets, in terms of their daily volume, are open at night, but very thinly traded until EU hours, but some do see action in Asia hours. It’s just about liquidity.

Maybe you’re thinking of single name equity markets, which are a fraction of daily trading.

I think they’re probably asking about US markets. Afaik those do close at business hours and I’m not sure how after hours trading happens but it might not be available to most people.

I think the one of the main reasons is government concerns about shenanigans happen overnight without oversight / flash crash. That being said I presume all the breakers that would halt trading activity are probably automatic but potentially not all of them (I think the US did things like that during the housing collapse).

Another good point, and one I thought about before replying, but that doesn't make microwaves slower, it makes them inapplicable.

In theory having fewer repeaters improves latency, probably in the range of 100ns per repeater. I don't know how much of a practical effect that has, likely very minimal with modern implementations.

Either way it's more sensible to build high throughput microwave networks given the tiny amount of shortwave bandwidth we have.

I bet it's way lower than 100ms for this application. Single digits. Maybe less.

I wrote 100ns, and meant an analog repeater. Full digital regeneration is probably in the 1-10μs range.

The game is repeaters and path lengths, not the speed of the medium itself

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