[ksec]

I know a lot is focusing on the Bandwidth. But are we making any progress on Long Distance Subsea Cable using Hollow Core Cable, achieving close to maximum speed of light for theoretical lowest latency possible? Imagine cutting latency from West Coast US to Hong Kong by 50ms!

Light is only traveling at around 2/3 of speed within Fibre.

The previous decades have been around Bandwidth. Is time we shift out focus to latency. 5G is already part of that , and 6G is further pushing it as standard feature. I wish other part of network start thinking about Latency too.

May be not network, but everything. From out input devices to Display. We need to enter the new age of Minimal Latency Computing.

[idlewords]

You gotta bore for that sweet latency win. A chord tunnel between San Francisco and Hong Kong would save 1300 miles (20% improvement right there), and if you drill it straight enough, you won't even need a cable.

[BelenusMordred]

Please don't give the HFT's ideas, they'll probably do it and cause a half dozen tsunamis in the process.

[ISL]

If you don't like HFTs, this is an idea you'd probably like to give them. Nobody has ever drilled through the Mohorovicic. It is unclear whether or not it is possible to do so.

The most-likely outcome is a few happy geologists/geophysicists and a number of very-sad HFT underwriters.

https://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_disconti...

[oAlbe]

It says it's 10 to 20 km below the ocean floor. Are we as humans been digging in the ocean floor that deep, or even at all? That sounds like sci-fi to me, I'd love to learn more if that's actually feasible.

[krallja]

USSR, land, 12,262 metres: https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole

US, sea, 183 m below the sea floor in 3,600 m of water: https://en.wikipedia.org/wiki/Project_Mohole

[baud147258]

Apparently the deepest oil well at sea was 10km deep, in the Mexico Gulf, drilled by the Deepwater Horizon rig

[potiuper]

https://www.wsj.com/articles/high-frequency-traders-push-clo...

[pm90]

You know, if HFT's will be the agents of future MegaInfrastructure spend, so be it.

I long for the days when the US loved building infrastructure.

[TuringNYC]

Anyone interested in the topic, this is a great movie — fiction but very close to reality:

https://en.wikipedia.org/wiki/The_Hummingbird_Project

[hinkley]

...and create a supervolcano.

[ethbr0]

We already have one of those on land in the US.

[Talanes]

We have two. I suspect that you are thinking of Yellowstone, but there is also the Long Valley Caldera in Eastern California. The Mammoth Mountain area.

[jeffbee]

Heh baby steps maybe? The existing cables aren’t even short paths along great circles. The Oregon-Japan cable google owns is 12000 km along a 7500-km path.

[extropy]

Need to have lava shields for that.

[LargoLasskhyfv]

Who cares? Would be totally worth it because of unlimited geothermal energy!

[idlewords]

The photons go through fast enough that they won't get very hot.

[bmcahren]

Remember: You want your photons crispy around the edges, not charred.

[leprechaun1066]

I take my photons medium-rare.

[craftinator]

Not to make light of these puns, but they aren't very coherent...

[uticus]

Medium-rare with a light salad

[samstave]

I only use recycled photons, so my light is green.

[rorykoehler]

How deep would this bore tunnel be at the centre most point if it was perfectly straight? Would it go into the mantle?

[potiuper]

d=r(1/cos(s/(2r))-1)=3958(1/cos(6906/7916)-1)~=2198 mi; Yes, into the lower mantle with only 692 mi to go to the outer core. What I would love the internetz to explain is how to justify the h8 for HFT, yet the luv for Musk since he is the one in the driver's seat at the moment for this stuff with StarLink and the Boring company.

[koheripbal]

One of the important components of online hate is that it requires zero justification or logical consistency.

It just needs to feel gratifying.

[wmf]

Because HFT helps the rich AF get richer but Starlink benefits normal people?

[potiuper]

Satellite internet already exists; StarLink's defining feature is lower latency both by being in a lower orbit and inter-satellite links. It does benefit consumers by introducing another satellite internet competitor, but how many "normal" people want to rely on satellite internet or, if they do, care about a few extra 100s of ms of latency? (Inter)-National wireless companies have a tendency to consolidate and lobby out smaller companies and municipalities who have less incentive to build out fiber and landline companies, if any, have further justification to cut cords. StarLink is the now the leading solution for global low latency connections for HFT by being in a near vacuum in low orbit. The case for HFT benefiting non-professional trader Mrs. Mainstreet is that she no longer has to eat the larger spread offered by the big bank market maker every pay cycle when the 401K contribution hits with HFTraders providing liquidity. The opportunity for smaller traders to make the market is no longer there, but the odds that they would had a chance to begin with have been stacked against them for a long time with the cost of the fastest connection being marginal to now near insignificant.

[roomey]

We used to manage a remote branch over geo stationary satellite, it was an excersise in pain. We used to check the local weather forecast to see if it was raining before doing any work on the servers. Geo internet is awful, I think you are underestimating how much usability difference there would be between LEO and GEO latencies and bandwidth (because geo bandwidth was awful too)

[p1necone]

Current satellite internet is really bad. ~600ms of latency is very noticeable even just loading webpages, and the throughput isn't great either.

Also multiplayer gaming is rather popular, and that's just not possible with that much latency.

VOIP is a pretty terrible experience with that much latency too.

[Seanambers]

" care about a few extra 100s of ms of latency?"

Well, as someone who grew up in the modem era(90's) and was trying to play online fps games. I cared quite a bit about latency. Normal people also like things to be quick you know :)

Based on that experience in the 90s to this day i want my internet connectivity to be as fast as possible and i'm willing to pay.

Low latency enables video/audio chat amongst other things and just a better experience.

A quick google search gives 600 ms latency for satellites(not Starlink) thats quite a alot. Also bandwidth is a issue with existing providers i think.

[Retric]

The ping on satellite internet is usually around 640 ms as it’s a ~45,000 mile round trip, worse the bandwidth is terrible. That kind of latency breaks a lot of assumptions in the modern web. Dropping to ~20ms and dramatically upping the bandwidth is a huge win for rural internet users.

PS: I am on the waiting list for starlink.

[samstave]

And tell me how one would service any problems that arise either by tectonic movements or breaching an alien/breakaway civilization hollow earth chamber?

[potiuper]

Repair it like any other tunnel that requires maintenance?

[m463]

> if you drill it straight enough, you won't even need a cable.

Well, yes and no. I recall they wanted to pursue hollow cables in the early days of optical cabling, but it turned out solid fiber was the answer.

(sorry, can't find a good reference)

So FTTC (Fiber Through The Core) is what you want.

[dekhn]

couldn't you start experiments using the Alameda-Weekhauken tunnel?

[jodrellblank]

Alameda enterprises excited by rumours of new chord tunnel Thursday, low latency burrito delivery futures up 5%.

[kstrauser]

Currently posting from Alameda. If you cause a local surge in demand that means I have to outbid a Manhattanite for a good burrito, I will cut someone.

[throw_away]

BagelRail was dual use before the fiasco

[simoneau]

And they are heated along the way!

[idlewords]

We have the technology!

[thomaslangston]

More feasible would be transmitting neutrinos or some other signal that would not be blocked by the Earth.

[jxcl]

> More feasible

If they don't interact with the thousands of miles of earth between the source and the destination, they probably also won't interact with the receiver! :p Imagine the retransmission rates!

https://en.wikipedia.org/wiki/Neutrino_detector

[retzkek]

The MINERvA experiment at Fermilab already demonstrated communication with neutrinos, admittedly over short distance: "The link achieved a decoded data rate of 0.1 bits/sec with a bit error rate of 1% over a distance of 1.035 km, including 240 m of earth."

https://arxiv.org/abs/1203.2847

Anyone from an HFT firm who wants to look into a partnership researching a neutrino link to the CME data center feel free to reach out :)

[cameldrv]

There has been a lot of progress in the past 20 years on antineutrino detection. Antineutrinos are produced by fission and so there's been a fair bit of interest in detecting them to detect covert nuclear tests as well as potentially a new modality of detecting nuclear submarines.

I think it could become possible before too long to use this to transmit data. It would probably be a ~billion dollar project, but the HFT arbitrage market is essentially winner-take-all, and may be large enough to support this size investment.

[atonse]

And you'd also have to ignore all the insane amounts of noise coming from regular neutrinos wizzing about in the universe.

[parineum]

If you've built a reliable detector, you've already built something that can intercept them. You just need to make a shroud around your detector and a tube facing your transmitter out of the same material.

[ISL]

There are ~65,000,000,000 neutrinos from the sun passing through each square centimeter of your hands every second as you read this. There are no materials on Earth that can reliably stop any given neutrino. For that, one needs densities greater than those generally found in stellar cores.

Neutrino detectors work by maximizing dumb luck through being both very large and very, very clean (low radioactivity). The transmitter-detector systems work by sending oodles of very energetic neutrinos at a well-defined time and looking for a rare coincident flash in the detector.

[ISL]

If you're sending neutrinos at a known energy from a known location and in a narrow time-coincidence window, you can hammer most backgrounds way down.

The low detection rate isn't so terrible either -- one only needs the bits that are detected to be tradably-correct almost-all the time.

The hard part is arranging to make enough money to fund the accelerator and detector.

[Arrath]

Dear god the packet loss.

[O5vYtytb]

My bet is on tech like Starlink with inter-satellite communication. Starlink should have lower latency with space lasers compared to fiber.

[xoa]

OP is talking about photonic bandgap fiber I think, or perhaps another kind of photonic-crystal fiber. At any rate, whereas in regular fiber guiding light via differences in refractive index the speed of light is only about 70% c, photonic bandgap fiber can reach something like 99.7% c, which is close enough to c in vacuum as to essentially eliminate the difference vs a free space EM link (particularly for space-based ones which face an extra minimum RTT distance penalty). Last I checked though 3-4 years ago they needed fairly frequent repeaters, were harder to mass produce, etc.

I don't know of any being deployed long distance, though in principle they'd be really valuable for intercontinental backbones. Starlink fills a huge gap in existing infra, and there are places that won't see any sort of fiber, let alone fancy microstructured fiber, for the foreseeable future (or ever, obviously in the case of ships/aircraft). But the bandwidth isn't great. Each current sat does I think 20 Gbps, and though no doubt that'll increase over time that's literally orders of magnitude from this single cable alone. Having the sats support direct ground optical links for backbone usage might be interesting someday, but weather attenuation will never stop being a problem with that. Starlink is filling in the gaps for fiber infrastructure, not replacing it. They're complementary.

So I agree it would be great to see more advanced fiber deployed long distances and start to shrink latency for everyone, and interesting to know what technical obstacles remain if any (maybe a lot remain?). A 40% speed boost while still having massive bandwidth isn't nothing.

[baybal2]

Now...

How do you splice a hollow optic fibre?

[mmmBacon]

Starlink satellites are in orbit 550km high. So any journey would add at least 1100km. Moreover not sure that a single satellite would be able to hit another one across transpacific distances and may need to go through multiple hops to get there.

Each hop will add latency since signal needs regeneration. So it’s not clear to me a swarm of satellites is a real winner from a latency POV. Furthermore, given costs to put the constellation up there, it’s extremely expensive on a $/bit basis and not sure how it could compete against fiber.

The value of Starlink is providing service in areas lacking existing broadband infrastructure where the cost to provide service exceeds the cost of Starlink.

[mrtnmcc]

>> Starlink satellites are in orbit 550km high. So any journey would add at least 1100km

Might want to check with Pythagoras on that one..

[ptudan]

Meh, he said at least. There could be cases where you beam up then down nearly vertically (same city).

[function_seven]

So, "at most" then, right?

The further you are from the other end, the less additional distance the satellite adds on.

[jamessb]

But the correct statement is "no more than" not "at least".

Consider a right-angled triangle with base length d and height 550, corresponding to transmission from a base-station to a satellite. The hypotenuse has length sqrt(d^2 + 550^2), so the difference in length between the hypotenuse and base is sqrt(d^2 + 550^2) - d.

This has a maximum of 550 when d=0 (i.e., shooting straight up), and decreases as d increases: https://www.wolframalpha.com/input/?i=plot+sqrt%28d%5E2+%2B+...

Alternatively, consider the triangle inequality: the sum of the lengths of any two sides must be greater than or equal to the length of the remaining side. This directly implies that the difference in length between the hypotenuse and base is less than or equal the height [base + height >= hypotenuse implies height >= hypotenuse - base].

[sliken]

Er, no, "the difference in length between the hypotenuse and base is sqrt(d^2 + 550^2) - d".

The hypotenuse is cos(angle)*base.

If you think about it at a minute if a sat is 500 miles up directly overhead that's the closest it ever will be, as it flies off the hypotenuse gets longer, not shorter.

So ideally you bounce off a sat overhead, (distance of 1100), any single hop will be longer, and to get across an ocean you'll likely need more than one hop.

Basically the sin(beam path) will will never be less than 550 and the length of the beam will never be less than 550.

[imoverclocked]

Are all base stations directly underneath a satellite?

I think this is an over-simplification if we are chasing pedantics; There are cases where it will be more and others less so the slightly more precise wording might actually be "about 1100km."

To the larger picture: it seems we often lose that order of length on the ground due to existing network topologies and geographical limitations.

[russdill]

1100km / c is 3.7ms. In free air, light speed is 50% faster. So long as the distance you are covering is more than 2200km, you'll overcome that. Of course, there's also the consideration that there can also be a lot of hops in terrestrial links and it's often very far from a straight line path.

[LargoLasskhyfv]

Are you sure about the necessary regeneration? Let me hand wave from the dark skies here for a moment:

1.) Think of the precision mirrors in the so often mentioned EUV-lithography equipment from ASML for latest generation chips from TSMC.

2.) Now imagine something like that on board of a satellite, maybe smaller.

3.) Have 2.) moveable with sufficient precision to bounce the rays from satellite to satellite in realtime, without having to regenerate them in any way for about 4 to 5 hops.

4.) problem solved by purely 'optical' mesh while signal is 'in orbit'.

kthxbaiiii!

[morei]

Those 'precision EUV mirrors' achieve a reflectance of about 70% i.e. they aborb ~30% of the EUV light that reaches them. :)

More seriously, those mirrors are special because they use bragg reflectors to handle 13.5nm light. They're not special for their precision, nor their reflectance.

Setting that aside, the major problem with your proposal is that laser still have significant bream spreading. So the mirrors would need to be large enough to encompass a spread beam at every step, which adds weight and volume for both the mirror and the tracking mechanism. The tracking mechanism is particularly problematic because moving mass on a satellite affect the attitude, so you either need precision counterweights to null it out, or large reaction wheels.

Using MEMS mirrors instead would solve some of the mass issues, but MEMS mirrors have very limited tracking (typically limited to a single axis) which would probably render them impractical.

Far, far easier to just send and receive the signal at every step.

[LargoLasskhyfv]

Hrm. Taken from https://www.asml.com/en/technology/lithography-principles/le... :

> Flatness is crucial. The mirrors are polished to a smoothness of less than one atom’s thickness. To put that in perspective, if the mirrors were the size of Germany, the tallest ‘mountain’ would be just 1 mm high.

edit: What I meant to say was rather something with that precision reflecting whichever wavelengths are used for laser communications. Which would be infrared, I guess? Or are we talking Maser?

[mmmBacon]

While an interesting idea, I think you’ve greatly understated the problem. First, lasers and coherent light beams diverge, light cannot stay perfectly collimated and it’s not really possible to collimate well over such long distances. So the receiver, >10,000km away, will “see” only a small cross-section of beam. The efficiency of this is defined by something called the overlap integral between the areas of the beam and the detector. Think of it like the amount of light from a flashlight that gets through a pinhole in a sheet of paper. This reduces the available signal power significantly. If you introduce mirrors you have the mirror loss plus the vignetting losses for each bounce. This is likely much worse.

[LargoLasskhyfv]

But the reciever won't be be > 10,000km away in the configuration I mentioned. 4 to 5 'hops', remember?

edit: arrgh, forget it... one beam, reflected multiple times until 'end of the line', got it...(sigh)

[ballenf]

So slightly concave mirrors?

[m_eiman]

Won't they be at low enough altitude that they'll need more hops than fiber to get around the globe, where each hop adds at least some delay?

[xoa]

Not sure what you mean by "hops" here? The current beta sats mostly act as "bent pipes", where they relay directly between user terminals and ground stations which then go to out to the regular net from there. But the final deployment sats are intended to have free space optical links between satellites (these are currently deployed and testing on the most recent polar orbit ones), so a connection can go entirely through the mesh in space until it reaches the nearest physical ground station (probably with some weighting for congestion and priority of course). The orbital RTT penalty will only be paid once, and with tens of thousands of sats the optical route will actually be much more direct for many people when crossing oceans than going through whatever undersea fiber links there are. Compared to regular fiber, final Starlink will definitely win on latency over sufficient distances.

But Starlink will never match the bandwidth and reliability that fiber can do, nor is it meant to. So it's not a replacement, just another awesome option.

[xoa]

Also just to run the math on an example for "actually be much more direct for many people when crossing oceans": say someone is somewhere on the southern coast of Alaska, be it more towards King's Cove or back towards Newhalen, and want to talk to someone in Sapporo Japan. As the bird flies that's something like a 2500-3000 mile distance. But in practice there is no undersea cable direct linking Alaska and Asia (unless that's changed in the last year or two). Instead a connection probably has to go to Anchorage, then to Seattle, then probably to Tokyo, and then out to the rest of Japan from there. This could easily turn a 2500 mile path into a 7300 mile path. Starlink satellites in the current plan AFAIK are going to heavily be in shells 214 to 350 miles high (including Ku/Ka band current ones and future V-band ones). At 350 mi orbit, so maybe a 700-1000 mile up/down penalty, total distance could still be half the cable distance in this example, even before latency advantages.

[0xffff2]

When you're traveling at the full speed of light in vacuum, compared to 2/3rds in fiber, even a few extra hops can leave you with significantly lower latency.

[mrtnmcc]

Right, if they are using standard OTN framing, the hop latency should be ~3 microsecond (which is <1km of light propogation)

[sneak]

I agree, but we can start on our local machines first. Most of the latency of modern computers isn't related to the network.

[ksec]

Yes. Keyboard, Mousepad, Display, Sound, Graphics.

I mean input lag [1] is easily 50ms. But some of them requires software changes. And any thing software is expensive. The cost of this new Cable is only $300M. Hardware innovation is getting faster and cheaper than Software.

[1] https://danluu.com/input-lag/

[sunbum]

Latency reduction like that would mostly be relevant for traders.

[KptMarchewa]

And games.