Computers are getting smaller, faster, and
more powerful all the time. That’s awesome for a lot of reasons, but
it’s creating a problem: most of our computers store data pretty much the same way they have
for decades, and that technology is starting to run into fundamental physical limits on
just how small and fast it can be. Which is why a lot of researchers are working
on newer tech to take its place. And someday, you might be saving that fanfiction
you’re writing about Sherlock and Watson to a tiny glass disk that could last billions
of years, or storing it as a hologram. You might even be able to hardcode it into
DNA. You probably know that files on your computer
are stored as lists of ones and zeros. But we haven’t really talked about how those ones and zeros are actually stored in your computer. The usual explanation is that ones are ‘on’
and zeros are ‘off’, but that doesn’t explain how computers keep track of them without
power. Nothing’s really on
when you shut down your computer, but all your songs and documents stay saved anyway. That’s because computers don’t permanently
store data in patterns of ‘on’ and ‘off’. Instead, ones and zeros, called bits, are
stored in different ways, like in magnetic patterns on a hard disk drive. Computers read a hard drive’s data by spinning
the disks to the right place and reading the pattern with a tiny magnetic head. It’s kind of like how old record players
worked, but the head is way smaller and hovers above the disk instead of rubbing against
it. And you might remember floppy disks, which
were a portable version of this technology. We’ve been permanently storing data on hard
drives for decades, since the days when a file the size of a song would fill most of
a computer the size of a fridge. Today’s hard drives only need a few hundredths
of a millionth of a square meter to hold thirty million or so bits in an average song, but the technology
is still pretty similar, just smaller. We keep using these hard drives because they’re
pretty stable. Data stored as magnetic patterns generally
stays that way for years, if not decades. But those stored bits keep getting smaller
and smaller, and there are limits to how small bits can get before they start changing the
bits around them. Spinning hard disks at thousands of revolutions
per minute also takes a lot of energy, and all those rapidly moving parts can break or
wear out. Optical disks like CDs and DVDs also store
data in patterns, although they use physical patterns of bumps on their surfaces, which computers read by bouncing
a laser off the bumps. But there’s still a limit to how many bumps
you can cram together, since each kind of laser only reads bumps above a certain size, and smaller bumps generally need
more expensive lasers. Computers can also store data with transistors,
which are basically little switches where the ones and zeros really are ‘ons’ and
‘offs’. When you open a file, for instance, it gets
copied over to random access memory, or RAM. RAM is made of transistors that either block
electric current for a ‘zero’ or let it through for a ‘one’. Transistors don’t have any moving parts, so they can quickly change
between different states. It’s also a lot faster to read and write
data to transistors, since there’s no spinning disk involved. But you can’t use RAM for permanent storage
because without power, the transistors are reset to the ‘off’ position. Instead, you can permanently store data on
solid state drives, or SSDs, which use different kinds of transistors that don’t need constant
power to store data. That’s because they can let a charge build
up and get stuck in parts of the transistors. A transistor with a charge represents a “zero”,
and a transistor with no charge is a “one”. And the charges stay stuck even when there’s
no power. Another advantage of SSDs is they don’t
have any spinning disks or other moving parts that will break. SSDs are still much less common than traditional
hard drives, but they’ve become more popular over the last few years as they’ve gotten
bigger and cheaper. They’re faster, and even though the transistors
in SSDs can wear out if they’ve been used enough times, they’ll usually
take longer to wear down than it’ll take you to replace your computer. SSDs have seemed like the wave
of the future for the past few years, but someday they might be
as obsolete as the floppy disk. Because scientists are working on completely
different ways of storing data. In 2013, a team at the
University of Southampton in the UK came up with what they’re calling
five-dimensional data storage. They’re thumb-sized disks
with patterns etched into them, a lot like how CDs and DVDs
have data imprinted on their surfaces. But CDs, like most modern data storage technologies,
mostly just store information in two dimensions. DVDs can do a little better, since they can
actually have two different patterns, one on the surface, and one slightly underneath it. But these disks take that to another level. They have patterns cut into them with ultra-fast
lasers in three different layers, and each layer has two different patterns in it. So lasers reading these disks
can focus in one of five different ways, and each way they’ll read
completely different information. This is where the “five-dimensional” part
comes from. With all of these dimensions available,
the researchers estimate that each disk can hold 360 terabytes of data. That’s about three quadrillion bits,
or enough to store the entire Library of Congress
on fourteen little disks. Plus, these disks are made of glass, which
is one of the most stable materials we have. If we’re lucky, data on some of today’s
permanent storage devices might last between a few years and a few decades. But glass can withstand
really high temperatures and pressures, and it’s stable around lots of different chemicals. Thanks to that glass, data on these disks
could stay intact for billions of years! So computers of the future might come with
these tiny glass disks inside them, and tons of storage space. Then there’s stuff that just sounds like
science fiction. Take holographic storage. It's called "holographic" because it uses
holography, where the interference of light encodes data, and it would work a little bit
like a CD or one of those 5D glass disks: To read something in holographic storage, you’d shine a laser on something
with a pattern in it. But there are a couple big differences. For one thing, there wouldn’t just be
one or three patterned layers; there might be thousands. The laser would go through whatever crystal
or other material had the pattern, instead of bouncing off of it, so it could be focused
on one layer after another throughout the entire thing. It also wouldn’t have to read one bump or
scratch at a time, like you have to with CDs or glass disks, or even hard drives and SSDs. Instead, the laser would shine through the
crystal onto something like a camera, which would capture the pattern
of the entire layer at once. So instead of reading one bit after another
like our computers do today, computers with holographic storage might be able to read
sixty thousand bits at a time. But our computers mainly work by analyzing
one bit at a time, which means we’d have to rework the way that our computers themselves
approach information. So it’s still far off in the future, but
holographic storage is in the works. But maybe you want permanent storage that
feels a little more personal than eternal glass disks or patterns in crystals. Well, you’re in luck. Your DNA is made of
chemical compounds called nucleotides that tell your body
what kinds of molecules to make. And scientists have been working on
ways of arranging those nucleotides to encode data that computers can work with. Nucleotides are smaller than the smallest
magnetic bits or transistors that computers use to store data today. So if each nucleotide in a strand of DNA represented
one bit of information, DNA could be way more efficient than anything else in the world
right now. We’re talking storing the entire world’s
data in just a teaspoon of DNA. And DNA could also be more stable than a lot
of other current methods we use. It’s not age-of-the-universe stable,
but it might be able to last for hundreds of years longer
than hard drives or SSDs. DNA storage has only been around
for about twenty years, so it hasn’t quite reached its potential yet. Scientists are still figuring out how to get
these incredibly tiny nucleotides in exactly the right order along an entire strand of DNA so that each one can represent
a bit of information. The current record is from a team that stored
about two hundred megabytes (about 1.6 billion bits, or about sixty songs’ worth of data)
on short DNA strands. It’s also hard to find ways of reading DNA
at a particular random spot, which is what computers have to do whenever they open a
file. If researchers work out these problems, though, there could be a day when you
really do have music in your DNA. Or, at least, in your computer’s DNA. For more in-depth science
behind the technology that runs our world, check out our recent mini-series
on the history of the internet. And if you’re new to SciShow,
don’t forget to subscribe!
