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Moore’s law describes a long-term trend in the history of computing hardware, in which the number of transistors that can be placed inexpensively on an integrated circuit has doubled approximately every two years. [see image nearby]
The capabilities of many digital electronic devices are strongly linked to Moore’s law: processing speed, memory capacity, sensors and even the number and size of pixels in digital cameras. All of these are improving at (roughly) exponential rates as well. This has dramatically increased the usefulness of digital electronics in nearly every segment of the world economy. Moore’s law precisely describes a driving force of technological and social change in the late 20th and early 21st centuries. The trend has continued for more than half a century and is not expected to stop until 2015 or later.
The law is named after Intel co-founder Gordon E. Moore, who introduced the concept in a 1965 paper. It has since been used in the semiconductor industry to guide long term planning and to set targets for research and development.
- 1 History
- 2 Other formulations and similar laws
- 3 As a target for industry and a self-fulfilling prophecy
- 4 Future trends
- 5 Consequences and limitations
- 6 See also
- 7 References and notes
- 8 Further reading
- 9 External links
The term “Moore’s law” was coined around 1970 by the Caltech professor, VLSI pioneer, and entrepreneur Carver Mead. Predictions of similar increases in computer power had existed years prior. Alan Turing in a 1950 paper had predicted that by the turn of the millennium, computers would have a billion words of memory. Moore may have heard Douglas Engelbart, a co-inventor of today’s mechanical computer mouse, discuss the projected downscaling of integrated circuit size in a 1960 lecture.A New York Times article published August 31, 2009, credits Engelbart as having made the prediction in 1959.The complexity for minimum component costs has increased at a rate of roughly a factor of two per year … Certainly over the short term this rate can be expected to continue, if not to increase. Over the longer term, the rate of increase is a bit more uncertain, although there is no reason to believe it will not remain nearly constant for at least 10 years. That means by 1975, the number of components per integrated circuit for minimum cost will be 65,000. I believe that such a large circuit can be built on a single wafer.
Moore slightly altered the formulation of the law over time, bolstering the perceived accuracy of Moore’s law in retrospect. Most notably, in 1975, Moore altered his projection to a doubling every two years . Despite popular misconception, he is adamant that he did not predict a doubling “every 18 months”. However, an Intel colleague had factored in the increasing performance of transistors to conclude that integrated circuits would double in performance every 18 months.
 Future trends
Computer industry technology “road maps” predict (as of 2001[update]) that Moore’s law will continue for several chip generations. Depending on and after the doubling time used in the calculations, this could mean up to a hundredfold increase in transistor count per chip within a decade. The semiconductor industry technology roadmap uses a three-year doubling time for microprocessors, leading to a tenfold increase in the next decade. Intel was reported in 2005 as stating that the downsizing of silicon chips with good economics can continue during the next decade and in 2008 as predicting the trend through 2029.
Some of the new directions in research that may allow Moore’s law to continue are:
- Researchers from IBM and Georgia Tech created a new speed record when they ran a silicon/germanium helium supercooled transistor at 500 gigahertz (GHz). The transistor operated above 500 GHz at 4.5 K (−451 °F/−268.65 °C) and simulations showed that it could likely run at 1 THz (1,000 GHz). However, this trial only tested a single transistor.
- In early 2006, IBM researchers announced that they had developed a technique to print circuitry only 29.9 nm wide using deep-ultraviolet (DUV, 193-nanometer) optical lithography. IBM claims that this technique may allow chipmakers to use current methods for seven years while continuing to achieve results forecast by Moore’s law. New methods that can achieve smaller circuits are expected to be substantially more expensive.
- In April 2008, researchers at HP Labs announced the creation of a working “memristor“: a fourth basic passive circuit element whose existence had previously only been theorized. The memristor’s unique properties allow for the creation of smaller and better-performing electronic devices. This memristor bears some resemblance to resistive memory (CBRAM or RRAM) developed independently and recently by other groups for non-volatile memory applications.
 Ultimate limits of the law
On 13 April 2005, Gordon Moore stated in an interview that the law cannot be sustained indefinitely: “It can’t continue forever. The nature of exponentials is that you push them out and eventually disaster happens.” He also noted that transistors would eventually reach the limits of miniaturization at atomic levels:In terms of size [of transistors] you can see that we’re approaching the size of atoms which is a fundamental barrier, but it’ll be two or three generations before we get that far—but that’s as far out as we’ve ever been able to see. We have another 10 to 20 years before we reach a fundamental limit. By then they’ll be able to make bigger chips and have transistor budgets in the billions.
In January 1995, the Digital Alpha 21164 microprocessor had 9.3 million transistors. This 64-bit processor was a technological spearhead at the time, even if the circuit’s market share remained average. Six years later, a state of the art microprocessor contained more than 40 million transistors. It is theorised that with further miniaturisation, by 2015 these processors should contain more than 15 billion transistors, and by 2020 will be in molecular scale production, where each molecule can be individually positioned. 
In 2003 Intel predicted the end would come between 2013 and 2018 with 16 nanometer manufacturing processes and 5 nanometer gates, due to quantum tunneling, although others suggested chips could just get bigger, or become layered. In 2008 it was noted that for the last 30 years it has been predicted that Moore’s law would last at least another decade.
Some see the limits of the law as being far in the distant future. Lawrence Krauss and Glenn D. Starkman announced an ultimate limit of around 600 years in their paper, based on rigorous estimation of total information-processing capacity of any system in the Universe.
Then again, the law has often met obstacles that first appeared insurmountable but were indeed surmounted before long. In that sense, Moore says he now sees his law as more beautiful than he had realized: “Moore’s law is a violation of Murphy’s law. Everything gets better and better.”
 Futurists and Moore’s law
Futurists such as Vernor Vinge, Bruce Sterling, and Ray Kurzweil believe that the exponential improvement described by Moore’s law will ultimately lead to a technological singularity: a period where progress in technology occurs almost instantly.Moore’s law of Integrated Circuits was not the first, but the fifth paradigm to forecast accelerating price-performance ratios. Computing devices have been consistently multiplying in power (per unit of time) from the mechanical calculating devices used in the 1890 U.S. Census, to [Newman‘s] relay-based “[Heath] Robinson” machine that cracked the Nazi [Lorenz cipher], to the CBS vacuum tube computer that predicted the election of Eisenhower, to the transistor-based machines used in the first space launches, to the integrated-circuit-based personal computer.
Kurzweil speculates that it is likely that some new type of technology (possibly optical or quantum computers) will replace current integrated-circuit technology, and that Moore’s Law will hold true long after 2020.Lloyd shows how the potential computing capacity of a kilogram of matter equals pi times energy divided by Planck’s constant. Since the energy in such a large number and Planks’s constant is so small, this equation generates an extremely large number: about 5.0 * 1050 operations per second.
He believes that the exponential growth of Moore’s law will continue beyond the use of integrated circuits into technologies that will lead to the technological singularity. The Law of Accelerating Returns described by Ray Kurzweil has in many ways altered the public’s perception of Moore’s Law. It is a common (but mistaken) belief that Moore’s Law makes predictions regarding all forms of technology, when it actually only concerns semiconductor circuits. Many futurists still use the term “Moore’s law” in this broader sense to describe ideas like those put forth by Kurzweil.
Moore himself, who never intended his eponymous law to be interpreted so broadly, has quipped: