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Friday, 3 August 2012

Tech Laws we should all know about - #TechLaws

In many different events and conferences, these laws get quoted so I decided to collect them all in a place.

Moore's law: The law is named after Intel co-founder Gordon E. Moore, who described the trend in his 1965 paper.

Moore's law is the observation that over the history of computing hardware, the number of transistors on integrated circuits doubles approximately every two years. The period often quoted as "18 months" is due to Intel executive David House, who predicted that period for a doubling in chip performance (being a combination of the effect of more transistors and their being faster).

Gordon Moore himself predicts that Moore's Law, as applied to integrated circuits, will no longer be applicable after about 2020 - when IC geometry will be about one atom thick. However, recent technology announcements about 3-D silicon, single-atom and spin transistors gives another twenty years of conventional doublings before the electronics limit is reached. Inevitably, other technologies, such as biochips and nanotechnology will come to the forefront to move the equivalent of Moore's Law inexorably forward.

See Also: Transistor Wars: Rival architectures face off in a bid to keep Moore's Law alive


Koomey's Law:  The number of computations per joule of energy dissipated has been doubling approximately every 1.57 years. This trend has been remarkably stable since the 1950s (R2 of over 98%) and has actually been somewhat faster than Moore’s law. Jonathan Koomey articulated the trend as follows: “at a fixed computing load, the amount of battery you need will fall by a factor of two every year and a half.”

See Also: See Also: A New and Improved Moore's Law


Metcalfe's lawAttributed to Robert Metcalfe, originator of Ethernet and founder of 3COM: the value of a network is proportional to the square of the number of nodes; so, as a network grows, the value of being connected to it grows exponentially, while the cost per user remains the same or even reduces.

Within the context of social networks, many, including Metcalfe himself, have proposed modified models using (n × log n) proportionality rather than n2 proportionality.

See Also: Wikipedia


Gilder's Law: proposed by George Gilder, prolific author and prophet of the new technology age - the total bandwidth of communication systems triples every twelve months (some refer to the period as eighteen months). New developments seem to confirm that bandwidth availability will continue to expand at a rate that supports Gilder's Law.

See Also: Technology Needs for 40G–100G Network-Centric Operations & Warfare


Nielsen's Law: Network connection speeds for high-end home users would increase 50% per year, or double every 21 months. As a corollary, he noted that, since this growth rate is slower than that predicted by Moore's Law of processor power, user experience would remain bandwidth-bound.


Cooper's Law:



Cooper has found that the ability to transmit different radio communications at one time and in the same place has grown with the same pace since Guglielmo Marconi's first transmissions in 1895. The number of such communications being theoretically possible has doubled every 30 months, from then, for 104 years. This fact has been dubbed Cooper's Law.

See Also: ArrayComm: Cooper’s Law


Edholm's Law of Bandwidth: Edholm sets out three categories of communications – wired, wireless and nomadic. Nomadic is a form of wireless where the communicator is stationary during the period of communications. According to Edholm’s Law, data rates for these three telecommunications categories increase on similar exponential curves, the slower rates trailing the faster ones by a predictable time lag.



The chart above shows data rates plotted logarithmically against time. When drawn like this, it is possible to fit straight lines to each of the categories. The lines are almost parallel, although nomadic and wireless technologies gradually converge at around 2030. For example, in 2000 2G delivered around 10kbits/s, W-LANs connected to dial up delivered 56kbits/s, and the typical office local area network (LAN) provided 10Mbits/s. Today, 3G delivers 100kbits/s, a home wireless LAN with DSL or cable broadband access is about 1Mb/s and typical office LAN data rates are 100 Mbits/s. Edholm’s Law predicts that in 2010 3G wireless will deliver 1 Mbits/s, Wi-Fi connected via a faster backhaul 10 Mbits/s, and office networks 1Gbit/s.

Edholm’s Law overlaps with Guilder’s on the fixed bandwidth side and to some degree with Cooper’s on the wireless side. But perhaps key is its prediction that wired and wireless will maintain a near-constant differential in data rate terms.


Shannon's law (Shannon–Hartley theorem)In information theory, the Shannon–Hartley theorem tells the maximum rate at which information can be transmitted over a communications channel of a specified bandwidth in the presence of noise. 

Considering all possible multi-level and multi-phase encoding techniques, the Shannon–Hartley theorem states the channel capacity C, meaning the theoretical tightest upper bound on the information rate (excluding error correcting codes) of clean (or arbitrarily low bit error rate) data that can be sent with a given average signal power S through an analog communication channel subject to additive white Gaussian noise of power N, is:

 C =  B \log_2 \left( 1+\frac{S}{N} \right)

where
C is the channel capacity in bits per second;
B is the bandwidth of the channel in hertz (passband bandwidth in case of a modulated signal);
S is the average received signal power over the bandwidth (in case of a modulated signal, often denoted C, i.e. modulated carrier), measured in watts (or volts squared);
N is the average noise or interference power over the bandwidth, measured in watts (or volts squared); and
S/N is the signal-to-noise ratio (SNR) or the carrier-to-noise ratio (CNR) of the communication signal to the Gaussian noise interference expressed as a linear power ratio (not as logarithmic decibels).


Finally,

Murphy's Law: Anything that can possibly go wrong, does


Further reading:

Please feel free to add any others you may know of in the comments and if they are popular I will add them in the blog post.

2 comments:

Tsahi Levent-Levi said...

Atwood's Law: any application that can be written in JavaScript, will eventually be written in JavaScript.

Taken from here: http://www.codinghorror.com/blog/2007/07/the-principle-of-least-power.html

Anonymous said...

Fremer's Law of Dissemination and Citation

I don't think this will rise to the level where it makes the list but here is Fremer's Law:

If you use the label "Law" to describe almost any interesting phenomenon, it will be more widely quoted and cited.

I have also noted that if you can come up with lists of ten as opposed to nine, eleven, or any other number it will be easier to get the session describing a presentation containing your list of ten accepted at a conference or cited by your peers.

So coming up with ten laws and so naming your list of ten laws would boost readership a great deal.