Here is another example of a fourfold, in the mathematics of Fourier Analysis. Here the four elements of our investigation resolve into Discrete Time, Continuous Time, the Fourier Series, and the Fourier Transform.

From the three dualities of Time – Frequency, Periodic – Aperiodic, and Discrete – Continuous, we obtain the four combinations Discrete Time/Periodic Frequency, Continuous Time/Aperiodic Frequency, the Fourier Series (Periodic Time/Discrete Frequency), and the Fourier Transform (Aperiodic Time/Continuous Frequency).

In the table below, T stands for Time and f for Frequency. The subscripts denote the attributes of each: D for Discrete, C for Continuous, P for Periodic, and A for Aperiodic. So T subscript C, f subscript A means that when Time is Continuous, Frequency is Aperiodic, etc. Please see Steve Tjoa’s web site for the equations for the Fourier Series and the Fourier Transform in Continuous and Discrete Time.

References:

http://stevetjoa.com/633

http://en.wikipedia.org/wiki/Fourier_analysis

http://en.wikipedia.org/wiki/Fourier_series

http://en.wikipedia.org/wiki/Fourier_transform

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evolution, fourfolds, Science

The Theory of Evolution

June 8, 2012 Martin K. Jones 2 Comments

“I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection”

— Charles Darwin

Can we cast the theory of evolution into a fourfold? I propose that the following four processes can serve as an abstract model for evolution: generation, variation, speciation, and selection. These four entities are similar to the fourfold of Structure-Function, currently in development. By my analogy which will be explained later, Generation is action, Variation is part, Speciation is structure, and Selection is function. A more familiar analogy matches these four processes to Aristotle’s Four Causes: Generation is efficient cause, Variation is material cause, Speciation is formal cause, and Selection is final cause.

Generation: Offspring are like their parents by and large, except when made different by processes of variation. Mainly the act of reproduction, procreation, or replication, but includes the ordinary evolutionary factors of descent and heredity.

Variation: Offspring can be different than parents. Includes the factors of genetic variation, mutation, sexual reproduction, and genetic drift.

Speciation: Includes the factors which keep species separated and differentiated from each other.

Selection: Really natural selection. I always thought this was a negative process, where species become extinct or are selected out if they are ill adapted to their environment. Apparently the original meaning was that the fittest organisms and their traits continue: that is, they are selected to survive by nature because of their adaptive traits.

As a process of change, evolution has been suggested by scientists to operate at many levels of nature, not just for the biological. One such scientist is Eric Chaisson, who has written many books on his idea of “cosmic evolution”.

References:

http://en.wikipedia.org/wiki/Evolution

http://en.wikipedia.org/wiki/Reproduction

http://en.wikipedia.org/wiki/Genetic_variation

http://en.wikipedia.org/wiki/Speciation

http://en.wikipedia.org/wiki/Natural_selection

https://www.cfa.harvard.edu/~ejchaisson/cosmic_evolution/docs/splash.html

Eric Chaisson / Epic of Evolution: seven ages of the cosmos (2005)

Note:

Also note the similarity between this fourfold and the fourfold I have drawn for Kevin Kelly’s Philosophy of Technology. In “What Technology Wants”, Kelly claims that technology develops in an evolutionary manner.

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