
Glass discs that can store 360TB and remain intact for billions of years (2016) - elorant
https://www.disclose.tv/these-5d-glass-discs-store-360-tb-of-data-for-138-billion-years-370041
======
YayamiOmate
I dunno, but it seems to me universities increasingly focus on press releases
and marketing departments...

5D and 13.8 billion years? Phony. I know no sane scientist or enigneer that
would say they use more than 3D physics. Sounds like catch phrases to sell.
With such logic plain old HDD is at least 4D, because it uses CHS coordinates
and magnetic orientation, to store data.

To me such communication style undermines the real scine behind it. Do they
have nothing better to brag about than excuses to call invention 5D? Why
introduce such noise?

~~~
lvh
Yes, 13.8Gy is the approximate age of the universe and yes the researchers
used that number. But it's not like they made this up ("phony", as you put
it)!

Turns out the biggest decay factor is nanograting and the biggest contributing
physical quantity is temperature. They plotted what decay would look like on
an Arrhenius plot. They both computed estimates and measured to confirm: the
measurements are quite accurate. The specific claim is that they computed that
it would last 13.8Gy at a some reasonably high temperature (462K). They
could've picked any other point on the time/temp scale, like "here's how long
it would last at room temperature" or "here's how hot you could store it if
you only cared about it for a billion years".

They did not, however, simply make up a number with no justification, let
alone commit straight-up academic fraud, as you're implying.

The paper is here:
[https://www.researchgate.net/publication/297892219_Eternal_5...](https://www.researchgate.net/publication/297892219_Eternal_5..).

~~~
gnode
I don't think they meant it was fraud, just that it's sensationalist drivel.
It's choosing a way to interpret results for the sake of sounding impressive,
rather than improving understanding.

Choosing a temperature in order to say "this will last as long as the
universe's current age", or finding ways to count extra dimensions is the
behaviour of marketeers, not academics.

~~~
lvh
And yet, I pulled those claims out of the paper, which I linked. Are you
suggesting Peter G. Kazansky, a research professor with over two decades of
experience in optics, does not count as an academic? Or are you saying the
paper doesn't make those claims? Or are you saying the paper also isn't a real
academic paper and just marketeer noise?

(I'm not quoting the other authors, who are of course also distinguished
scholars :-))

~~~
sombremesa
The complaint here appears specifically to be a lamentation that academics are
behaving this way, so in attempting to prove their priors you're only
strengthening the argument. Your tone seems to be adversarial, so I'm guessing
that's not your goal...

~~~
lvh
"The paper isn't a real academic paper and itself also marketeer noise" is one
of the options I've outlined as a debate position. But let's be clear: we
started by calling research "phony" over something that would've been
trivially clarified by reading a short paper. In order to even get to that
point, I have to acknowledge that maybe you get to call research "phony"
without seriously implying fraud. I have a hard time taking that as a serious,
bona-fide argument.

~~~
airesearcher
There are actual papers. Press releases and popularizations are not the same
thing. If you look you can find the actual papers.

~~~
lvh
It appears you’re agreeing with me? I’m suggesting the confusion would have
been alleviated by reading the actual paper.

------
notacoward
There's a long and mostly bad history of claims around 3D storage. About
twenty years ago I followed a company called Constellation 3D, later Terastor.
They made many strikingly similar claims, smaller absolute numbers but a
similar multiplier vs. what was already in the market. At least they only
claimed three dimensions. I can sort of accept orientation as an effective
fourth dimension, but size seems like a real stretch. In any case,
C3D/Terastor struggled along for a few years, with more claims and more
excuses, before they turned into the predictable smoking crater. I've seen
several more _just_ like them come and go since then, so I think I'll wait for
more concrete proof that this particular technology can work at scale in the
real world instead of just once in a lab.

BTW, if you want to go even further back, who else remembers the promises
about bubble memory?

~~~
Robotbeat
Or what if it's a niche technology that works just fine at scale in the real
world but nobody cares enough for super long lifetimes to pay the higher price
for the equipment?

No "bad history of claims," just niche technology.

Not everything has to be "fake news" or "phony" just because it doesn't take
over the world.

I can't help but think we're cheapening the idea of fraud when we accuse every
company or technology of fraud just because they don't wildly succeed.

~~~
notacoward
I think you're overreacting, or perhaps going off on a bit of a tangent from
what I actually said. I didn't accuse anyone of fraud. I even offered kudos.
I'm just trying to adjust expectations because the history is indeed bad even
if nobody did any wrong. Would it have been better if I'd said "sad" or
"unfortunate" instead?

A medium that really has these kinds of density and survivability traits is
indeed a great thing, but "niche" is a bit of an understatement. Adding it to
the payload of a multi-million dollar rocket is _definitely_ a publicity
stunt, so I think it's entirely fair to point out that it might be good for
little else depending on how further development plays out.

~~~
kragen
If you don't launch it into space, it will be destroyed when the sun engulfs
the earth in only six billion years, if not earlier. There's a dismayingly
large chance that the only thing surviving from our entire culture in only a
few million years will be a mass extinction in the fossil record, a halo of
geosynchronous metal debris, and whatever data is encoded in such stable forms
as these glass discs.

In that context, describing it as "a publicity stunt" seems short-sighted to
the point of self-parody, like a small child who thinks that the main
distinguishing feature of money is that you can buy candy with it. In a very
short time, it is likely that the only things humanity has done that are even
detectable are the launching of satellites, a mass extinction, and the
launching of such archival media.

~~~
notacoward
I know it's fun to call people short-sighted and compare them to children, but
grow up yourself. Sending something in _this particular medium_ was a
publicity stunt, and it worked. You think we're talking about it here for any
other reason than Elon Musk was (tangentially) involved? Sending some sort of
beacon or memorial into space is such a great idea we've done it many times
before, with better-tested media. If we wanted to try something newer, a
Rosetta Project disk would have been a much more obvious choice.

Practicality wasn't the point. Publicity was.

~~~
hilbert42
"Practicality wasn't the point. Publicity was."

The real issues involved here are the Laws of Thermodynamics, Entropy and
'Glass' (Crystals) being the the most stable state of matter in the universe.
All of these indicate that such longevity is possible (see my main post).

Clearly, the reason that '13.8 Gy' is used here is that it's a well known time
interval and it puts the longevity of this technology into perspective in ways
that many will understand.

If actually achieved in practical terms then we ought to be hailing this work
as a remarkable effort—not quibbling about trivia and silly incidentals.

~~~
kragen
Glass is the opposite of crystals. Crystals would presumably be longer-lived,
but their anisotropy makes them somewhat trickier to work with. Otherwise I
agree, and like you, I'm profoundly disappointed by the level of
"notacoward"'s comments in this thread so far.

~~~
hilbert42
You're right of course. I've assumed the stuff would necessarily be
crystalline (and would have to be to have such longevity). The word 'glass'
here being used for easier digestion by the public. (See my longer post for
more details.)

------
toyg
Seems a bit of a waste to dedicate an entire 360TB disc to a single text
document like a bible, which is probably just a few KBs... /s

More seriously, they don't talk about reading capabilities (retrieval speed
etc). And what if it gets scratched? What is the error tolerance? At that
density, a single speck of dust could have dramatic implications...

I hope this reaches industrial viability, because we desperately need a
digital format that can approximate the lifespan of simple paper. At the
moment we are chained to a maintenance nightmare of periodic hops between
formats, with deadly consequences any time we miss a single jump.

~~~
orbital-decay
Yeah, actual museum-grade archival is so much more than just having an aging-
resistant media. You also need to be able to read and decode it many years
into the future, which is really tricky to guarantee - you can't assume the
future generations will know how to make a reading device and remember your
formats/encodings. So it's a bit like _unzip.zip_ problem.

~~~
mapcars
>You also need to be able to read and decode it many years into the future,
which is really tricky to guarantee

Not really, those future people don't just come out of nowhere. It's a
gradual, incremental change as there are still systems using tape storage the
technology or formats are not lost but migrated.

~~~
orbital-decay
That depends on the time scales we're talking about. 30 years? Probably (and
even then there are problems with abandoned/little-documented formats like
Word 3.x). 300 years, and a historian will have a hard time decoding a digital
file from the year 2019, even assuming the media is still intact. 3000 years
and a nuclear war can make a weird shiny disc appear as a currency or a cult
item for an archaeologist, not as a knowledge storage.

------
Robotbeat
A small prototype of this technology already flew in the glovebox of the Tesla
Roadster launched to deep space on the Falcon Heavy’s inaugural launch (third
launch just succeeded this morning):

[https://medium.com/arch-mission-foundation/arch-mission-
foun...](https://medium.com/arch-mission-foundation/arch-mission-foundation-
announces-our-payload-on-spacex-falcon-heavy-c4c9908d5dd1)

...it (appropriately) contained Asimov’s Foundation Trilogy.

> _The Arch library that was included on the Falcon Heavy today was created
> using a new technology, 5D optical storage in quartz, developed by our
> advisor Dr. Peter Kazansky and his team, at the University of Southampton,
> Optoelectronics Research Centre._

------
theclaw
Link to source (University of Southamton):
[https://www.southampton.ac.uk/news/2016/02/5d-data-
storage-u...](https://www.southampton.ac.uk/news/2016/02/5d-data-storage-
update.page)

------
totaldude87
This keeps repeating every few years i guess.

[https://www.theverge.com/2016/2/16/11018018/5d-data-
storage-...](https://www.theverge.com/2016/2/16/11018018/5d-data-storage-
glass)

[https://www.extremetech.com/extreme/160928-five-
dimensional-...](https://www.extremetech.com/extreme/160928-five-dimensional-
glass-memory-can-store-360tb-per-disc-rugged-enough-to-outlive-the-human-race)

[https://www.extremetech.com/extreme/92892-five-
dimensional-g...](https://www.extremetech.com/extreme/92892-five-dimensional-
glass-storage-could-revolutionize-medical-imaging-computing)

or did we capture its evolution :)

------
rolleiflex
Interesting side effect, this also gives us some clue about what kind of ...
information storage devices we should be looking for in other heavenly bodies.

Had we found a bunch of silicate glass pebbles in Europa, we'd have considered
them a curiosity. After this, we have good reason to find a way to ship it
back and have another look.

~~~
tokai
Somebody should take another look at those moon glass beads.

------
SoylentOrange
I have a question for anyone here who understands how this works: is the glass
from the article resilient to physical shocks like falling/shaking/heat/other
mechanical stress?

Documents that are meant to last a long time used to be written on vellum
because it is a very physically durable material. I understand that this glass
method beats existing digital storage methods for resilience, but does it best
traditional analog/legacy techniques?

~~~
kragen
Yes, fused quartz has roughly the mechanical durability of granite, and it
doesn't melt until a considerably higher temperature than ordinary glass
(though lower than the 1650° temperature at which crystalline quartz melts).

Vellum and other leathers have a lifespan of under 10000 years under ideal
conditions, like those under which Ötzi was preserved. Under such conditions,
the researchers extrapolate from accelerated-aging measurements that their
medium will last 3×10²⁰ years, which is 3×10¹⁴ times as long. That is, this
glass disc will last 300,000,000,000,000 times as long as a vellum document
will, unless it's subjected to high heat.

They also extrapolate that at 462 K (189°, or, in obsolete units, 372°F) it
will last the current age of the universe, some 10–100 billion years. At 189°
I think vellum's lifetime is a few minutes.

~~~
SoylentOrange
Thanks for the answer. Can the durability of the fused quartz be compared to
the durability of this storage format though?

(from a more detailed article [1])

> The information encoding is realised in five dimensions: the size and
> orientation in addition to the three dimensional position of these
> nanostructures.

Is the idea that these nanostructures are themselves hyper-resilient? Or would
a significant impact alter them so as to render them unreadable?

[1]: [https://www.southampton.ac.uk/news/2016/02/5d-data-
storage-u...](https://www.southampton.ac.uk/news/2016/02/5d-data-storage-
update.page)

~~~
kragen
Well, there are a couple of different questions here. One is about resilience
to physical shocks such as falling and mechanical stress, which could destroy
the disc but won't do anything to the nanogratings. The other is about
gradual, continuous decay processes — over a sufficiently long period of time,
random thermal fluctuations will destroy any solid object, and analogous but
larger-scale relaxation processes will destroy galaxies as well. Such
processes could cause the nanogratings to decay long before the fused quartz
itself evaporates.

The nanogratings do have a certain amount of built-in redundancy; they're
holographic phenomena.

------
kijin
It looks like somebody just said "it will last as long as the universe" and
someone else translated it into an actual number using too many significant
digits.

How long can we realistically expect glass to last, judging from e.g. beads of
volcanic glass embedded in the geological record?

~~~
lstodd
Not much, regular glass transitions to crystal quite fast compared to those
geological timescales. And who knows what the transition will do to the data
stored at these densities.

Nothing in the article states what kind of glass is used (which blows the
bullshit detector right there).

If they use crystalline quartz, it should last indefinitely. If it's regular
glass, then 50 years if you're lucky, controlled conditions, etc, etc.

------
hmhrex
I just mentioned this to a co-worker last week. This was news here 4 years ago
-
[https://news.ycombinator.com/item?id=11140033](https://news.ycombinator.com/item?id=11140033)

------
nitin_flanker
I don't know but the article does not talk about the credibility of the claim.
I mean even the way they have described the whole thing feels more like a
marketing attempt than an actual scientific breakthrough.

If you look at other articles of this website, they will seem more like a lame
attempt at getting traffic than to provide something useful.

They have articles titled like - "Ladies Get dose of Radiation From Government
UFO" and "Hackers, UFO's and Secret Space Programs - Oh My!"

I mean, this does not feel like an information source I'll trust.

Edit: As others are mentioning in this thread. From a researcher's
perspective, they should have also talked about the read/write capabilities.

------
lwhi
I remember chatting to someone working on the project at the University of
Southampton years ago .. I think it was back in 2004. Great to hear it's come
to fruition.

The length of time this type of project takes amazes me.

~~~
yorwba
This is about research published in 2013:
[https://eprints.soton.ac.uk/364916/](https://eprints.soton.ac.uk/364916/)

It was recycled for a university press release in 2016:
[https://www.southampton.ac.uk/news/2016/02/5d-data-
storage-u...](https://www.southampton.ac.uk/news/2016/02/5d-data-storage-
update.page)

Then that press release was recycled for this HN submission.

~~~
lwhi
In that case, I'll be amazed about the lifecycle of a news release instead ;)

------
bastawhiz
These articles pop up every few years, and it always makes me shake my head.
Such storage solves no market need. Technology hardly lasts five years let
alone fifty years let alone five billion years. Virtually nobody is worried
about being able to read their media 500 years out.

And even if that was a reason to pursue a technology, the actual storage
capacity is meaningless on its own. 360TB of spinning disks isn't very
expensive to buy, rack, or run. And you can read and write to them at a decent
clip. Managing failures is fairly predictable. What benefit does a magical
glass (or, in previous incarnations, quartz or other crystal) disk have?
Optical media isn't known for its amazing random access speeds. Write-once
media has very limited use and is almost never fast to write to.

So who's buying this? Who has data that needs to last that long, or needs to
store lots of permanently immutable data that's read back sequentially? I
honestly can't think of a market for this. The article says "museums" but I
don't know of any museums that would prefer glass disks for their backups over
an S3 bucket. This is "on prem backup" taken to a comical extreme.

I can see the academic value of exploring the technology, but this space has
been exhausted many times over. I remember seeing similar articles in
Technology Review and Scientific American about identical developments twenty
years ago. It's just not a good idea.

~~~
gnode
Being able to store data densely on a commodity material such as quartz is
great for archival storage (e.g. Amazon Glacier). If the storage media is
cheap, then it tends not to matter if it can be reused.

For random access, rapidly created and destroyed data, SSD and HDDs will
continue to dominate. But for the growing use case of hoarding data forever,
this is a good fit.

------
fredsted
What happens at 13.9B years?

~~~
simonh
I'm guessing that's the estimated time it would take for entropy in the
material to render the data unreadable. They specify at room temperature, so
I'm pretty sure they're talking about entropic disruption of the structure due
to thermal effects.

Note that 'glass' is a hugely varied class of materials, so without knowing
much more we can't make spot judgements about the validity of the claim.

~~~
kragen
No, 10–100 billion years is at 462 K, which is a lot hotter than room
temperature. At room temperature the estimated lifespan (or, really, the time
constant τ) is 3×10²⁰ years.

~~~
simonh
That's really great, precise information. Where did you get it from? Also
which exact material is that for? As I said, there are a lot of different
things called 'glass'.

~~~
kragen
From the paper:
[https://www.researchgate.net/profile/Ausra_Cerkauskaite2/pub...](https://www.researchgate.net/profile/Ausra_Cerkauskaite2/publication/297892219_Eternal_5D_data_storage_via_ultrafast-
laser_writing_in_glass/links/59fb2de00f7e9b9968b962dd/Eternal-5D-data-storage-
via-ultrafast-laser-writing-in-glass.pdf?origin=publication_detail)

They're using fused quartz, as one does. I'm guessing it would be a bit easier
to use soda-lime glass, and also reasonably stable, but considerably _less_
stable.

------
gpmcadam
Hello people from the future looking back at this thread reminiscing about the
old days when this claim was incredible to us.

------
Dangeranger
Does anyone know a resource which explains the theoretical limit for
retrievable, durable, information storage?

I would assume the most dense medium possible would be a collection of
neutrons, since neutron stars are the most dense object other than a black
hole, but retrieving information from them doesn’t seem feasible.

~~~
bookofjoe
"'Dragon's Egg' is a 1980 hard science fiction novel by Robert L. Forward. In
the story, Dragon's Egg is a neutron star with a surface gravity 67 billion
times that of Earth, and inhabited by cheela, intelligent creatures the size
of a sesame seed who live, think, and develop a million times faster than
humans. Most of the novel, from May to June 2050, chronicles the cheela
civilization beginning with its discovery of agriculture to advanced
technology and its first face-to-face contact with humans, who are observing
the hyper-rapid evolution of the cheela civilization from orbit around
Dragon's Egg.

"The novel is regarded as a landmark in hard science fiction. As is typical of
the genre, 'Dragon's Egg' attempts to communicate unfamiliar ideas and
imaginative scenes while giving adequate attention to the known scientific
principles involved."

[https://en.wikipedia.org/wiki/Dragon%27s_Egg](https://en.wikipedia.org/wiki/Dragon%27s_Egg)

Superb.

~~~
dotancohen
I absolutely loved this book. However, isn't it curious that the humans arrive
just as the cheela are reaching the level of technology needed to communicate?
In terms of human time, they could have come a year earlier, or a year later.

~~~
slm_HN
As I remember the book it was the humans probing the neutron star with
something (x-rays?) in order to survey/study the star that triggered the
evolutionary advances in the cheela. So no, it wasn't curious timing, the
humans precipitated the rise of the cheela.

Great book btw, hope I'm remembering it correctly.

------
leshokunin
Interesting. If we ignore whether or not this specific implementation will
work, this would actually be a great way to store data for the Permaweb. I
would imagine such resilient data would be a great asset when combined with
content hashing!

------
vmurthy
Given that the sun will die in about 5B Years, this is a bit of a gimmick :-D

~~~
JulianMorrison
By then we could probably tow Sol over to a comparable system using a Shkadov
thruster and jump ship to a new sun.

~~~
TheSpiceIsLife
_After one billion years, the speed would be 20 km /s and the displacement
34,000 light-years, a little over a third of the estimated width of the Milky
Way galaxy._

[https://en.wikipedia.org/wiki/Stellar_engine](https://en.wikipedia.org/wiki/Stellar_engine)

------
13of40
So if one of these discs was dug up by a civilization with the level of
technology we had in, say, the 70's, would they be able to tell what it was,
much less make something to read it?

~~~
sudhirj
They'd likely know it had information on it, even if they couldn't necessarily
read it immediately. Anyone storing information is likely to mark it or
arrange it in some non-natural way, otherwise it'll just look like rocks.

~~~
chii
so how do you know that the crystalline structure of some rocks aren't
encoding some information?

Alternatively, information encoded in rocks could've been encrypted. And
encrypted information should be indistinguishable from random noise.

~~~
jdironman
Our bodies are coded with DNA and rocks and geo formations are encoded with
the earth's history.

------
supermatt
Im always sceptical about these claims of archive longevity. IIRC when CD-Rs
were first available, they were touted as suitable for century long archives.
The reality was far from that.

~~~
simonh
High quality discs are capable of that, the problem is the drives to read them
all broke down. For an ultra-long term storage medium like this that's moot.
If someone wants to read one of these in a billion years, they'll just have to
develop the tech, but that would be true of any such long term mass storage
medium. It's not necessarily a strike against this particular implementation.

~~~
Wowfunhappy
> High quality discs are capable of that, the problem is the drives to read
> them all broke down.

What are you referring to? I assume you're not just talking about "high
quality" compact discs, since we have plenty of readers for those.

~~~
chii
The OP meant the drives would've broken down before the disks would degrade.

~~~
simonh
I think the original comment about optical disks was talking about very early
formats, before CDs were standardised, such as the drives used for the
Doomsday Project.

[https://en.wikipedia.org/wiki/BBC_Domesday_Project](https://en.wikipedia.org/wiki/BBC_Domesday_Project)

------
ksec
Facebook uses BluRay RW Disc for Cold Storage ( Not sure if that is still the
case ).

The question is nearly 4 years later are they anywhere close to production?

------
iandanforth
I guess I'll have to buy the White Album again.

------
JVIDEL
Is this another tech that's "just around the corner" like holo-memory from the
late 90's?

------
myfonj
TIL glass is not supercooled liquid after all.

~~~
wongarsu
There's a good Veratasium video about that [1]. But the short version is that
glas is pretty much a solid, and lead is much more liquid at room temperature
than glas.

1:
[https://www.youtube.com/watch?v=c6wuh0NRG1s](https://www.youtube.com/watch?v=c6wuh0NRG1s)

------
RenRav
How does glass being amorphous affect the data integrity? What 'glass'
specifically is being used?

~~~
kragen
Presumably the amorphous nature of glass lowers the energy barrier to
disrupting the stored information. They're using fused quartz glass, as one
does.

------
jody2
article from 2016 [https://petapixel.com/2016/02/16/glass-disc-can-
store-360-tb...](https://petapixel.com/2016/02/16/glass-disc-can-store-360-tb-
photos-13-8-billion-years/)

------
nmstoker
Looks like we need a bit more clarity on what they mean by "glass".

If you look at glass in medieval glass windows it's heavily distorted by
gravity (fatter at the bottom than the top) and that's after ~900 years, so
presumably they're actually meaning something more robust than that!

~~~
keiru
Turned out it was a mistaken belief. Basically, thickness invariance in
medieval glass had to do with the manufacturing process, and the viscosity of
glass is not observable in a human timeline.

[https://ceramics.org/ceramic-tech-today/glass-viscosity-
calc...](https://ceramics.org/ceramic-tech-today/glass-viscosity-calculations-
definitively-debunk-the-myth-of-observable-flow-in-medieval-windows)

~~~
nmstoker
That's great - I hadn't heard about that, thanks for putting me right.

------
tudorw
would this offer a safe haven for instructional code on a space ship?

------
camillomiller
Why is this here now? The piece of news is from three years ago

------
ConfusedDog
The pitch sounds very cool. For all the information given, it could well
possible take 13.8 billion years to write 360 TB of data and always in the lab
environment that needed to be funded. They seem to be avoiding specifics.

------
meerita
I wonder how many years our file systems will remain usable.

------
social_quotient
So it’s like a Craftsman tools warranty.

------
schpaencoder
I still remember the promise of the CD-Rom. Billions of years.

~~~
wongarsu
You could probably build CD-ROMs that last millions of years if you really
tried. You can buy regular CD-Rs that are estimated to last hundreeds of
years. But of course most people buy whatever is cheapest, and the cheapest
CD-Rs won't last you a decade.

------
masters3d
Minority Report?

------
ChrisArchitect
please add (2016) to this title, old news

~~~
ChrisArchitect
[https://news.ycombinator.com/item?id=11140033](https://news.ycombinator.com/item?id=11140033)

------
mrmondo
dd if=/dev/data | tee >(dd of=/dev/glass1) | dd of=/dev/glass2

20:20 optical replication ;)

------
benj111
Can I rant about the 5D?

"It's been dubbed five-dimensional (5D) digital data because, in addition to
the position of the data, the size and orientation are extremely important
too"

Orientation is inherently important anyway. Have you ever tried reading a book
upside down, and what does size bring? Other than lowering density. And
obviously position is important, it's the difference between data and
randomness.

~~~
simonh
Books only have one orientation, so they're not actually making use of that
dimension to encode data.

The rest of your points... oh my. None of the dimensions count at all, really?
So rant away, but it's nice if the sound and fury at least signifies
_something_.

~~~
benj111
No 2 dimensions are important at least :)

Regarding orientation, are you saying they printed half the book over the
first half, but at right angles over the top? Ie you _see_ different data from
different orientations?

Ps I've seen old (18th century?) letters where they wrote at 0, 90 and 45
degrees to get more on one page. Postage was charged by the page so it made
sense. Newspaper also used to be taxed by the page (in the UK at least) so you
had origami like folding of one sheet of paper into a newspaper, not aware of
them 'double printing' in this way though. I assume that's why 'broadsheets'
were so massive up until relatively recently.

~~~
simonh
I think they encode the data as asymmetric marks in the material, with
different orientations of the marks corresponding to different values.

Imagine you could print a page containing just a grid of 100x100 numbers. If
you can orient those numbers so the top of each digit could be facing up,
down, left or right and use those 40 different glyphs to encode in base 40
instead of base 10, now you can fit 4x as much data into the same two
dimensional area.

