Comment by iamelgringo | Hacker News Reader

Comment by iamelgringo | Hacker News Reader

Here's what I would suggest:

Take a bunch of fibrous, cellulosic material, pound it into a pulp and then squeeze it into very thin, flexible sheets of material. Let them dry.

Then, take some form of pigment or dye, and with a very fine stylus impregnated with the dye, visually encode the data on the cellulosic sheets using a set of graphemes. Each grapheme would roughly represent a phoneme in a spoken language.

It would take quite a while to encode all that data. I'd suggest building some type of mechanical to automate the task of transferring dye on to the cellulosic sheets. I'd also want to bundle these individual cellulosic sheets into stacks of 200-500 for organization's sake. I'd probably cover them with a more durable material such as animal hide or perhaps a thicker layer of cellulosic material.

I'd then take all these bundles of data laded cellulosic material, and I'd build a structure to protect these bundles from the elements. Developing a cataloging or indexing system for these bundles shouldn't be too hard. I'm sure it's been done before.

Regardless, you could either preserve the materials or let the public have free access to the information. You'd run the risk of damaging the data, but if you had a mechanical replication system, you could simply make multiple copies of each data set, and ensure the safety of the data that way.

Sheets of fibrous, cellulosic material should last several thousand years if kept in the right environment.

You know. Now that I think about it. It's probably much too complex a system to handle something like that. I really don't think it would work.

It is important to remove the lingin from your fibrous material, or otherwise ensure the flexible sheets have a basic pH, else the sheets will deteriorate.

Out of curiosity, how large would the time capsule need to be to contain 5TB of data encoded that way?

http://searchstorage.techtarget.com/sDefinition/0,,sid5_gci9...

So roughly half a Library of Congress.

The storage density of A-format mass market paperbacks containing dense UTF-8 text is roughly 4Mb/Kg. (A 400 page novel weighs around 250 grams and contains roughly 1Mb. Source: I went and weighed one of my novels, of known word count.) We can up the density somewhat by bzip2-compressing and then uuencoding (or similar); maybe 10Mb/kg is achievable.

Normal A-format paperbacks use acidic wood pulp for paper, but acid-free paper doesn't add a whole lot to the cost. So we get roughly 10Gb/ton, and the whole kaboodle comes in at roughly 500 tons. As the density of wood pulp is close to that of water, this approximates to a 10 x 10 x 5 metre lump. Quite a large time capsule, but not unmanagable :)

However. If we posit the availability of decent optical scanners in 50 years' time, there's no reason not to go denser.

We can print the data as a bitmap at 300dpi and be reasonably sure of retrieving it using a 2400dpi scanner. Let's approximate 300dpi to 254dpi, and call it 10 bits/mm. Printed on reasonable quality acid-free paper, we can get 100mbits/square metre, and that square metre will weigh around 80 grams (it's 80gsm paper -- same as your laser printer runs on). Call it 1.1 mb/gram. At this density, we can print the whole 5Tb (or 40tbits) on just 40 tons of paper, without compression; with compression, call it 20 tons. That's a 2.71 metre cube; just under 9' on an edge.

This assumes a monochrome bitmap. If we go to colour and use archival-quality inks we can probably -- conservatively -- retrieve one bit each of red/blue/green per dot, and it's probably not unreasonable to expect to get a whole byte out in place of each bit in our mono bitmap. So we can probably shrink our archive to roughly 2.5 tons of paper -- a pallet-load.

I wonder if anyone has actually attempted this and seen how dense you can pack it and reliably recover. I imagine you would need measures to counter small misalignments when rescanning and imperfections in the physical media.

200kb per A4 page using a 600dpi b/w laser printer: http://ronja.twibright.com/optar/

Take a look at http://www.ollydbg.de/Paperbak/index.html It encodes the binary onto paper and uses Reed-Solomon ECC to restore unreadable data.

I've tested it out myself, and it's only after you start to crumple it together that it stops working. I tested it with an inkjet printer though. A laser printer may stand up better.

Hah, I'm building a time capsule right now. Acid-free paper, laser printed, and encased in epoxy resin. I'm targeting 300 to 500 years.

Eventually I want to do the same thing with a 20ft cargo container and a bunch of concrete.

ha, yeah right.

no way that would ever work.

I know nothing about this topic. Would you care to elaborate on this point so the rest of us can learn?

paper

Well that's embarrassing. Thanks, now I know.

Paper, books, printing presses and libraries.

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