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Comment by woeirua | Hacker News Reader

Radar does not penetrate through brine water. Other remote sensing techniques have such poor resolution that they are relatively useless for this task. Unfortunately, sonar based bathymetry is really the best tool for this task and that means you have to run around with a surface ship mapping out the sea. As you can imagine the Chinese are not a big fan of American ships doing that in waters that they claim to be theirs.

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> As you can imagine the Chinese are not a big fan of American ships doing that in waters that they claim to be theirs.

Why does anyone (besides China) care? Nobody in that region recognizes those claims.

> Why does anyone (besides China) care? Nobody in that region recognizes those claims.

China has power, military and economic, and thus can't be ignored. If Fiji claimed a region of the Pacific, it wouldn't matter (in this respect).

>> Why does anyone (besides China) care? Nobody in that region recognizes those claims.

> China has power, military and economic, and thus can't be ignored. If Fiji claimed a region of the Pacific, it wouldn't matter (in this respect).

It isn't ignored, but that doesn't mean those claims are recognized. The US (at least) takes actions to specifically show that:

https://en.wikipedia.org/wiki/Freedom_of_navigation#Freedom_...

> It isn't ignored, but that doesn't mean those claims are recognized.

Agreed. The GGP was asking if anyone cared. People certainly care about the claims, even if they don't recognize them.

Because China happens to have nukes, probably.

> sonar based bathymetry is really the best tool for this task and that means you have to run around with a surface ship

Why can't it be done from a plane or satellite? I can imagine answers (e.g., sound doesn't travel as well through air), but does anyone know?

> the Chinese are not a big fan of American ships doing that in waters that they claim to be theirs

I'd be surprised if that stopped the US in this circumstance. They regularly conduct operations in the South China Sea.

The air / water interface makes it impossible to get any useful sonar data from an aircraft. Some military helicopters carry dipping sonar that they can temporarily lower into the water, and specialized aircraft can also drop sonar buoys, but those are designed for detecting submarines and are mostly useless for bathymetry.

The US Navy does regularly operate in the South China Sea. In fact the USNS Mary Spears oceanography research vessel was there recently, presumably gathering bathymetry and other data.

https://www.marinevesseltraffic.com/vessels/USNS-Mary-Sears-...

Thanks.

(I'd upvote you but for some reason votes don't stick, on comments and stories: When I reload the page, the arrows return, as if I hadn't voted. flag/vouch behaves normally. Perhaps a mod will read this.)

Votes typically take a few seconds to resolve, possibly longer under load. HN's JS indicates them immediately when you're on the page.

Check your profile's upvoted comments / posts link (https://news.ycombinator.com/upvoted?id=wolverine876&comment... -- that's private for you only) to see if your upvotes have been registered.

If not, drop a line to hn@ycombinator.com as I suspect they'll be interested.

Thank you. No upvotes in 2 days via that link and I'm not that stingy! I upvoted your comment just before I wrote this.

I'm confirming either no upvotes (or at least balanced ones) on my GP comment above.

What browser are you using? We changed hn.js a few days ago to use the Fetch API - I wonder if this is related.

It's probably not a configuration you test against (and almost certainly not worth testing against), both an unusual and an old browser used for compatibility with something else.

  Tor Browser 8.5.5
  - built on Firefox 60.9.0 ESR
  NoScript 11.2.11
  - ycombinator.com is 'trusted', which has always
    been sufficient for voting to work

So I'm not filing a bug report, so to speak, but if it helps you track down something useful:

* It happened once before, I think sometime in 2020 (sorry I don't recall more precisely), and it likely would have been in the same browser. I forget what fixed it but it went away eventually. Possibly it was just restarting the browser, which I can try if that will help (but that will lose the current state, of course, and Tor Browser deletes a lot of the current state on a restart; it may create a new profile).

* The top comment on my upvote page is this one from 2 days ago: https://news.ycombinator.com/item?id=29062312

* I don't know the precise times of my comments, of course, but if you see I was commenting then I was very likely voting (though my voting slowed a bit in the last day or two when I noticed they weren't registering).

* I just upvoted your comment at 22:44:07 UTC

I think the problem is that our JS now does this:

  fetch(url);

where it used to do this:

  new Image().src = url;

... and that seems to breaking a few edge cases of older browsers.

Can you try collapsing a comment somewhere and then refreshing the page to see if it stays collapsed? If it doesn't stay collapsed, that's another sign that fetch() calls aren't making it to the server.

> Can you try collapsing a comment somewhere and then refreshing the page to see if it stays collapsed?

I tried a few times on a couple pages, and they don't stay collapsed after refresh.

EDIT: Using another browser on this computer, I just logged into HN, and upvotes and collapsed threads seem to stick. I upvoted your comment (i.e., the parent to this one I'm writing) at 00:27:49 UTC.

This browser (another old and unusual one, but much more recent):

   Brave Version 1.25.72
   - built on: Chromium: 91.0.4472.101

It looks like you managed to upvote https://news.ycombinator.com/item?id=29101929 - did you do anything different to get that to work? e.g. different browser or turn JS off?

Yes, different browser. See my edit in the GP (which seems to have crossed on the wire with your comment).

I reverted the change for voting and collapsing. Does it work now?

Yup, both upvoting and collapsing work. Thanks! Though I wouldn't want to be the edge case that stands in the way of an update. I can workaround it pretty easily.

Another user had emailed to complain of something similar. Where there are two there are probably many, so I think we can leave it this way—it's no big deal. One question though: do 'hide' links on stories work, e.g. on the front page or /newest? I suspect they probably won't, because I didn't revert that part of the change.

> One question though: do 'hide' links on stories work, e.g. on the front page or /newest? I suspect they probably won't, because I didn't revert that part of the change.

I've never used that feature so I don't know what's supposed to happen ...

1. On /newest, under a story, click "hide"

2. Story disappears, stories beneath it are renumbered, an additional story appears at the bottom of the list.

3. Reload page (F5)

4. Hidden story reappears

EDIT: Also, I just noticed that when I upvote a story, the points displayed under the story don't increment until I reload. For all I know it's always been that way, but at the moment, of course, I'm a bit more attentive. Not a problem for me, but maybe useful for you.

Sound doesn't travel as well through the air, but it still does. The primary reason that you can't do it from the air is that the surface of the ocean is a big irregular reflector of acoustic energy from the air, so the overwhelming majority of the energy will be lost. It just would never be practical.

It might be possible to use airborne gravity gradiometry to map seaborne mounts. I'd never considered that before, but I see no reason to think it wouldn't work.

I'm finding it hard to believe that satellite and/or local gravimetry would entirely miss an underwater mountain.

Sound doesn't transmit well at all between air and water in either direction. It just bounces off. You can't hear what's going on underwater when you're out of the water and you can't hear what's going on above water when you're underwater.

How do anti-glare coatings on lenses work? Could something similar be devised for the air-water interface?

Sure. You just need to apply your anti-glare coating to the world's oceans.

I mean for acoustic waves. Alternatively/similarly, could an aerial sonar waveform be matched to the ocean surface waves to cause constructive interference below the surface, and destructive above it? Would it be possible to recover the reflections afterward?

https://en.wikipedia.org/wiki/Anti-reflective_coating

> Layer thicknesses are chosen to produce destructive interference in the beams reflected from the interfaces, and constructive interference in the corresponding transmitted beams. This makes the structure's performance change with wavelength and incident angle, so that color effects often appear at oblique angles.

The kind of sensors you can put on a plane or satellite simply can’t penetrate seawater effectively. It absorbs radar, dissipates heat and light. Sonar sound waves in air mostly just bounce off the ocean surface.

This is why submarines are so stealthy and therefore militarily useful. As long as they stay quiet they’re almost impossible to detect without using relatively short range active sonar.

Water isn’t air? Even air can become opaque.

A good techno-thriller might be some group of hackers nab the Chinese bathymetry database, which then finds its hands in some war hungry US general

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