In a 2000 paper, Dr. Seth Lloyd examined the computational capacity of the ultimate physically possible computer weighing one kilogram and occupying one liter of space. There’s only one problem, this ultimate laptop is going to have to contain a small black hole.
His approach is based on viewing the universe itself as a vast quantum computer. He states that “A computer made up of all the energy in the entire known universe (that is, within the visible ‘horizon’ of 42 billion light-years) can store about 1092 bits of information and can perform 10105 computations/second”
And Lloyd demonstrates that by applying quantum mechanics, he can calculate a simple answer to the question of how fast information can be processed using a given amount of energy matter and space, specifically about the size of a small laptop weighing one kilogram and occupying one liter of space.
According to Lloyd’s calculations, the ultimate black hole laptop is capable of 1051 operations per second and can store around 1031 bits. Current laptops deliver on the order of 1010 operations per second and store about 1010 bits.
Lloyd states, “Conventional laptops operate much more slowly than the ultimate laptop. There are two reasons for this inefficiency. First, most of the energy is locked up in the mass of the particles of which the computer is constructed, leaving only an infinitesimal fraction for performing logic. Second, a conventional computer employs many degrees of freedom (billions and billions of electrons) for registering a single bit. ”
Making a micro black hole might seem problematic but Lloyd and others believe it can be done although how one would sustain it, contain it, and program it remain speculative. For one thing these tiny black holes might tend to evaporate. But don’t worry, they won’t destroy the universe.
Using a black hole computer isn’t exactly like using the machine you are used to. With a black home computer, computations are performed by properly preparing the material that falls into the hole, and Lloyd states that it is possible to get this system to perform any desired computation.
“At the greater extremes of a black hole computer, we assumed that whatever theory (string theory, M theory?) turns out to be the correct theory of quantum matter and gravity, it is possible to prepare initial states of such systems that causes their natural time evolution to carry out a computation.”
However, Lloyd then asks “What assurance do we have that such preparations exist, even in principle?”
He goes on to argue it can be done and to list known physical systems that can be shown to be computationally universal, that is, they can programmed to perform arbitrary digital computations. Although computational universality might at first seem to be a stringent requirement, there are a wide variety of known physical systems including nearest neighbor Ising models, quantum electrodynamics, and conformal field theories which are known to be computationally universal.
“Even though the ultimate physical limit to how much information can be stored in a kilogram of matter in a liter volume is unlikely to be attained, it may nonetheless be possible to get a fair way along the road to such bit densities. In other words, the ultimate limits to memory space may prove easier to approach than the ultimate limits to speed. Following Moore’s law, the density of bits in a computer has gone down from approximately one per cm2 fifty years ago to one per µm2 today, an improvement of a factor of 108 . It is not inconceivable that a similar improvement is possible over the course of the next fifty years. In particular, there is no physical reason why it should not be possible to store one bit of information per atom.”
Conventionally, in familiar three-dimensional gravity, the minimum energy of a microscopic black hole is 1019 GeV, which would have to be condensed into a region on the order of the Planck length. However recent research suggests that micro black holes might be formed with much lower energies. But no one really knows if it is possible to create, sustain, and confine micro black holes long enough to use them.
Recent experiments with a table top colliders demonstrate that relatively small systems can produce the needed energy levels. Physicists at The University of Texas at Austin have built a table top particle accelerator that can generate energies and speeds previously reached only at facilities that are hundreds of meters long.
“We have accelerated about half a billion electrons to 2 gigaelectronvolts over a distance of about 1 inch,” said Mike Downer, professor of physics in the College of Natural Sciences. “Until now that degree of energy and focus has required a conventional accelerator that stretches more than the length of two football fields. It’s a downsizing of a factor of approximately 10,000.”
Downer said that now that he and his team have demonstrated the workability of the 2 GeV accelerator, it should be only a matter of time until 10 GeV accelerators are built.
While table top accelerators aren’t small enough to fit in a laptop, and they don’t yet come close to the needed energy levels to create micro black holes, it isn’t too much of a stretch to imagine a device like this that could create a microscopic black hole for use as a computational resource.
Perhaps eventually your future black hole laptop will even tap into the gigantic galactic black hole computer at the center of our galaxy.
Faux Apple concept art from http://gadgets.infoniac.com/apple-black-hope-holographic-device.html