From MIT Technology Review · · 3m
How far can we push computing?
Computing's physical limits reveal 35 orders of magnitude gap to ultimate speed.
In brief
Computing's physical limits reveal 35 orders of magnitude gap to ultimate speed. Computing can grow 35 orders of magnitude faster than current tech before hitting quantum physics limits. Originally reported by MIT Technology Review.
Feynman's 1959 vision
In 1959, physicist Richard Feynman argued we could write the entire Encyclopædia Britannica on a pinhead or store all books in a dust speck.
“There’s Plenty of Room at the Bottom”
Transistor revolution
The transistor halved in size repeatedly, doubling chip density until computers fit in watches.
“The transistor, the switch at the heart of computer chips, repeatedly halved in size so that chips doubled in density”
Current scaling slowdown
Six hyperscalers plan to spend over $700 billion this year on computing infrastructure, twice the 2025 record.
“Six of the biggest hyperscalers, the companies that run the world’s largest such facilities, are on track to spend more than $700 billion this year on computing infrastructure”
Moore's Law slowing
Moore's Law, tracking transistor density on chips, has slowed down after decades of doubling every year.
“Moore’s Law, which plots how densely transistors can be constructed on silicon, has slowed down”
Dennard scaling ended
Dennard scaling, which allowed chips to switch faster and draw less power, stopped around 2004.
“Dennard’s Law, which states that power consumption in a given patch of computer chip stays the same even as it gets more and more packed with smaller and smaller transistors, has ended”
Koomey's Law flagging
Koomey's Law, tracking computation per joule of energy, has begun to flag as efficiency plateaus.
“Koomey’s Law, which traces how much computation we can wring from each joule of energy, has begun to flag”
The physical limits
Quantum mechanics, general relativity, and information theory set fundamental limits for computing and communications.
“The physical limits of computing and communications, dictated by quantum mechanics, general relativity, and information theory, lie far below anything in a data center today”
Feynman's first prize
Feynman offered $1,000 for a motor smaller than a 0.4-millimeter cube, won by William McLellan in 1960.
“One would go to the first person to build a working electric motor smaller than a 0.4-millimeter cube”
Feynman's second prize
Feynman's second prize for shrinking text by 25,000x was won by Tom Newman in 1985.
“It was finally won in 1985 by Tom Newman, a Stanford graduate student who used an electron-beam lithography machine”
The transistor breakthrough
Jack Kilby built the first integrated circuit from a single germanium sliver in 1962.
“Jack Kilby, newly hired at Texas Instruments and with no vacation yet to take, spent that July nearly alone in the lab while his colleagues enjoyed time off, and by that September he had wired together a transistor, a capacitor, and three resistors, all made from a single sliver of germanium”
Moore's Law origin
Gordon Moore observed in 1965 that the number of components on a chip doubled at a steady pace.
“Gordon Moore, in a 1965 trade-magazine article, simply drew a line through the trend and extended it into the future”
The 10 orders of magnitude
Transistor density has grown by 10 orders of magnitude since the first transistor.
“In the nearly eight decades since the first transistor, the density of transistors on a chip has grown by 10 orders of magnitude, a 1 followed by 10 zeros, or a factor of 10 billion”
The 12 orders of magnitude
Computational speed has grown by 12 orders of magnitude since the 1940s.
“Computational speed has grown even more, by 12 orders of magnitude, or a factor of a trillion”
The 17 orders of magnitude
Energy per operation has fallen 17 orders of magnitude from early vacuum-tube machines.
“Energy per operation has fallen 17 orders of magnitude, from about 100 joules for an early vacuum-tube machine down to a femtojoule, one-quadrillionth of a joule, for a single switch of a logic gate”
Seth Lloyd's ultimate laptop
MIT physicist Seth Lloyd calculated that a kilogram of matter could theoretically compute 5 ×10 50 operations per second.
“In a 2000 paper in Nature titled 'Ultimate physical limits to computation,' he worked out the answer and called the imaginary machine the ultimate laptop”
The 35 orders of magnitude gap
Current computing is 35 orders of magnitude slower than the quantum physics limit.
“The biggest gap exists for computational speed: Our current chips are some 35 orders of magnitude, that’s a 1 followed by 35 zeros, short of what quantum mechanics allows for a one-kilogram computer”
Landauer's limit
Erasing a single bit must release at least 2.9 ×10 -21 joules of heat at room temperature.
“In 1961, Rolf Landauer, a physicist at IBM, showed that information and thermodynamics are bound together: Erasing a single bit must release a minimum quantity of heat, about 2.9 ×10 -21 joules at room temperature”
Bekenstein's bound
A cubic millimeter can hold about 10 42 bits, 10 36 to a cubic millimeter.
“For a region the size of Lloyd’s ultimate laptop, that comes to about 10 42 bits, some 10 36 to a cubic millimeter, nearly 30 orders of magnitude beyond what a device that size can store today”
Holevo's limit
A single channel carrying one watt can deliver 10 17 bits per second at the quantum limit.
“In 1973, the Soviet mathematician Alexander Holevo determined the ultimate limit on how much information a stream of quanta can convey. A watt of light delivers only so many photons each second, and quantum mechanics fixes how many distinguishable ways they can arrive, how many messages a receiver could ever tell apart”
The next frontier
Quantum computers could bridge the gap by converting every atom into a computing element.
“Quantum computers could get us part of the way there if they could convert every degree of freedom in a lump of matter, every atom, and every way it can move or spin, into a computing element that we could reliably manipulate”
What matters most
Computing can grow 35 orders of magnitude faster than current tech before hitting quantum physics limits.
