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Comment by hammock | Hacker News Reader

Incredible, great info. We are now living in the Diamond Age.

Well, not quite. They were making diamond windows from atmospheric carbon dioxide at room temperature in household machines or machines you could rent at the post office. We’re a ways off from that yet.

Also the whole aerostat thing where you make a diamond "balloon" full of vacuum that floats in air, using the strength of the rigid diamond to avoid it being crushed and popped.

I'm no materials-scientist, but I did some napkin-math on that once and it came out to some ridiculously-thin-sounding layer of diamond.

Redoing the napkin math because I can't find the original and I've somehow nerd-sniped [0] myself. Assume a sphere that contains a cubic meter of air and is neutrally buoyant:

    Vacuum volume           1.00        m^3
    Vacuum radius           0.62        m
    Air density             1.23        kg/m^3
    Displaced mass          1.23        kg
    Diamond density         3250        kg/m^3
    Diamond volume          3.77E-04    m^3
    Sphere surface area     4.84E+00    m^2
    (Thin shells can be approximated by ignoring curvature)
    Shell thickness         7.79E-05    m
    Shell thickness         77.94       μm (microns)
    Human hair thickness    17 to 181   μm (microns)

So the big vacuum-ball somehow needs to withstand crushing using only the strength of a diamond skin, and that skin is around as thick as (some) human hairs. It has to be thinner if you want it to float with a payload.

Remember: The walls of party-balloons and soap-bubbles are a very different situation: They can have extremely thin skins because the gas inside is doing almost all the "don't get crushed" work, the skin is really just there to keep the two gases from mixing.

[0] https://xkcd.com/356/

Perhaps they use a diamond frame filled in with graphene instead. Still seems pretty unlikely though. And probably too easy to puncture, ruining the vacuum.

Or perhaps they just build surfaces out of more complicated things than carbon. Hydrocarbons could be as easily assembled as diamond with similar techniques, and are a lot lighter than pure carbon. Plus they would want to put electronic advertising on the surface of the ball anyway, so it’s got to have a bit more going on to form LEDs and whatnot.

I was thinking about smaller bubbles and aerogels, but when the volume changes by a factor of 0.10, the thickness-budget only changes by a factor of ~0.46.

So while many smaller spheres--or pockets sharing walls--might be easier to engineer, the square-cube law [0] eats away at your lifting-power as everything becomes mostly-diamond with very little air-displacing vacuum.

[0] https://en.wikipedia.org/wiki/Square%E2%80%93cube_law

Yup, the scaling works the wrong way for small objects. A vacuum–zeppelin makes a lot more sense than a beach ball.

Exactly. That’s why a cubic meter of air is probably not the right range to look at. Something several magnitudes larger might do better.

Likely, but even a cubic meter is already a large step up from the scales in the book, ex:

> Each aerostat in the dog pod grid was a mirror-surfaced, aerodynamic teardrop just wide enough, at its widest part, to have contained a pingpong ball.

It doesn't say they aren't relying on some kind of down-thrust, but at that point I'd wager it's much easier to skip the whole marginal buoyancy part entirely. Use those conductive diamonds for an ionic thruster or something.

Buckling would be a problem.

so I guess it needs to be like 1/4th the thickness of the latex in a balloon (diamond is 4x the density). Vacuum gives you a bit more lift than helium but not that much. Yeah, seems pretty thin.

The pressure across a latex balloon is only about 0.5% that of maintaining a vacuum in earths atmosphere. I’m guessing the diamond would need to be much more than 1/4 the thickness of a latex balloon.

Yea, a bit of artistic license on the author’s part. You could make things quite light though.

I guess there is some sci-fi book everyone has read but me?

Yes!

It’s called “The Diamond Age, or a Young Lady’s Illustrated Primer” by Neal Stephenson. I definitely recommend it.

Literally The Diamond Age.

Where's my magic book then. And my atomic fabbers! Lemme 3d print a phone.

eBook readers exist, and with a bit of jiggery you could have programmatic content.

One of the hibernation screens for one of my ebook readers reads "Don't Panic", for all the obvious reasons. (Different franchise, similar concept.)

Magic book = iPad or Remarkable

Atomic fabber = chip fabs making things on ~10 atom scales

3D printing homes is possible now, just a bit niche

And yet we’re not really there yet. The book wasn't just a tablet computer; it was programmed to continually analyze everything happening around it and relate those events back to the education of the owner. It shocked a bully who was playing keep–away with it. It noticed that the owner was eating junk food, and taught her a better diet. It taught her to read, as well as manners and exercises and elocution. Later a constable unobtrusively scanned it and then very carefully explained (so that it wouldn’t shock him) that nobody would try to take it away from her during her visit, so long as she didn’t show it to anybody or try to interface it with a printer. It told her stories that aided her in running away from an abusive father, in avoiding police patrols so she could sleep in a public park undisturbed, etc, etc. It invented new stories with fractal depth, allowing her to ask questions and get more and more detailed information. Its pages were both a sophisticated microscope and telescope. She used it to design and print a nanotech sword and later to infiltrate a hive–mind society.

And it also contained the text of every other book ever written, of course.

And arguably it was that character’s mother too.

I’m going to have to reread this one soon; it’s such a good story.

When I first read Diamond Age is was 90% science fiction, now it's seemingly far less than that.

Environmental sensing is a little weak in our own devices, but in theory your cell phone could listen to everything you do and (externally) analyze it for things like a bad diet. You'd have to point the camera intentionally at things you're doing for it to capture that information.

Now, no one is going to make a product that shocks people holding it, yet this isn't an impossibility. Failing to login, or having the camera capture the wrong person is using could very easily be designed in to the product. No one is going to do that for fear of lawsuits.

Yea, I agree that it’s a little less science fiction than it used to be.

But remember the subtlety of it; the constable didn’t have his face recognized, or log in, he literally made a promise to the book while pretending to talk to the owner. It’s still mostly science fiction :)

About 70% of those are covered by the Internet especially if you include ChatGPT.

I think you are overestimating ChatGPT, but perhaps one day. And the book was capable of doing all of this while off line. Again, perhaps one day :)

A Bambu P1S will let anyone just print a phone case with no fuss, so we're on the way there!

I already got an A1 mini to trial the brand, looking at replacing my Ender 5 Plus. Not bad Bambu, not bad at all.

“You wouldn’t download some RAM”

Not yet, not even diamond phone screens are here. And tax evasion has not killed the nation-states yet.

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