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What is geometry?
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I wish to know what geometers and other mathematicians consider geometry.
About the AuthorPeter Sloterdijk (b. 1947) is one of the best known and widely read German
intellectuals writing today. His 1983 publication of Critique of Cynical Reason
(published in English in 1988) became the best-selling German book of
philosophy since World War II. He became president of the State Academy
of Design at the Center for Art and Media in Karlsruhe in 2001. He has
been cohost of a discussion program, Das Philosophische Quartett
(Philosophical Quartet) on German television since 2002.
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I'd be interested to learn more about the influence the Ray Kurzweil
transhumanism in Continental circles or is that memeplex more
parochial to the Anglophones. Also, have you studied Ken Wilbur?
Kirby
PS: interesting to learn how MathOverflow has become so central among
those of a mathematical bent (dint?) of mind. StackOverflow has achieved
a lot of providence in CS circles, which claims to be math on pseudo-random
days of the year based on some opaque #DeepLearning curve."
"What should I study? you ask." Study the circle as compression from
spherical unity. There is nothing more comprehensive and inclusive. It is the biggest playing field you can step into and you get to pick any position you want to play. To be more
precise, as Maria said, geometry is “like laughter or song or dream.” Left
field is great place to do that. There are not too many of us out here, the pay is lousy and you don't get much action.
As to
Kirby’s question, since I do not consider myself a geometer, only a left fielder, I am unable to give a reasonable answer.
Yes, John, ordinary people, I’m with you on that generalization.
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I'd be interested to see how you thinking might be shaped by an encounter
with the new Germanic blend, coming from the Globes, Bubbles and Foam
volumes. We have at least one serious reader of that material in 97214
(an Asylum District zip code **).
https://mitpress.mit.edu/books/bubblesAbout the AuthorPeter Sloterdijk (b. 1947) is one of the best known and widely read German
intellectuals writing today. His 1983 publication of Critique of Cynical Reason
(published in English in 1988) became the best-selling German book of
philosophy since World War II. He became president of the State Academy
of Design at the Center for Art and Media in Karlsruhe in 2001. He has
been cohost of a discussion program, Das Philosophische Quartett
(Philosophical Quartet) on German television since 2002.
Kirby, Thank you for your analysis. It's interesting to know that Peter Slojterdik's "Spheres" (Bubbles!) is finally in English. I have a volume in Spanish but have not read much from it. Maybe I should look again but I'm not sure if there is any meaningful idea there. Is there? I read Ken Wilbur's book "The Theory of Everything"
On Jun 27, 2016, at 2:40 AM, Andrius Kulikauskas <m...@ms.lt> wrote:I'm really interested to figure out the "six transformations" that I mention below and in my essay. I think that Clifford algebras will provide useful insights. I look forward to studying that together.
On Jul 6, 2016, at 4:47 PM, Andrius Kulikauskas <m...@ms.lt> wrote:I'm also reading about Clifford algebras... I'm intrigued by their connection with Pascal's triangle.
https://slehar.wordpress.com/2014/03/18/clifford-algebra-a-visual-introduction/
For example, Steven Lehar says the complex numbers can be identified with the row 1-2-1. I'm wondering if the quaternions can be related with the row 1-3-3-1. And so on?
Pascal's triangle seems very basic. At the heart is a recursion relation. One way it appears is as in Euler's characteristic, the formula that Vertices - Edges + Faces = 2. If we add the unique Center and the unique Totality (the Volume), and we change the signs around, then we get:
Center - Vertices + Edges - Faces + Totality = 0
By setting P=5 in the expression 2PF^2+2, the number of spheres in each successive layer of the cuboctahedron may be derived. F stands for "frequency" and is the number of intervals between spheres along any edge of the cuboctahedron or, alternatively, is the number of intervals along any radius between a corner sphere and the central one.
In a virus, the RNA-protecting shell or capsid is made from sub-units called capsomeres. By taking F as the number of between-capsomere intervals, and using 10F^2+2 on capsid "shell frequencies" of 1,2,3,4,5 and 6, we obtain corresponding counts of 12, 42, 92, 162, 252 and 812 capsomeres. "All of these numbers are in fact found in actual viruses, 12 for certain bacteriophages, 42 for wart viruses, 92 for reovirus, 162 for herpesvirus, 252 for adenovirus and 812 for a virus attacking crane-flies (Tipula or daddy-long-legs)" - The Natural History of Viruses by C.H. Andrews (W.W. Norton R Co., 1967).
Kirby,
It will be very interesting to go through your detailed letter. I was struck by your operations +2 and x2, so I want to share my thought on that.
First, I want to quickly explain what I mean by the "Center" and the "Totality" which you asked about. It all started with my interest in the "simplex" which came from my interest in trying to understand the "field with one element". A basic situation where the latter comes up is when we count the number of k-dimensional subspaces of an n-dimensional vector space over a finite field with q elements. That number is given by the Gaussian binomial coefficient which is a polynomial in q. And when q=1 we get the usual binomial coefficients, given by Pascal's triangle, which count the number of subsets of size k of a set of size n. The upshot of which is that underlying vector spaces is an intrinsically ordered basis e1, e2, ..., en. But when you only have one choice of scalar (the field has size 1), then you really don't have a choice, and so the order of the basis doesn't matter, and so we get subsets of an (unordered) set instead of sublists of an (ordered) list.
Now the "field with one element" also comes up in all kinds of algebraic geometry questions, which is how I learned about the simplex. And when I read about the simplex, I saw that its parts (its sub-simplexes), are counted by Pascal's triangle. See the table here:
https://en.wikipedia.org/wiki/Simplex
Also, I was interested because the simplex is a generalization of the tetrahedron, which you've been championing. Indeed, note that we can read off from Pascal's triangle that a tetrahedron has: 1 (what?) 4 vertices 6 edges 4 faces 1 volume. So what is the "what"? Note that:
* each vertex is a zero-dimensional 0-simplex
* each edge is a one-dimensional 1-simplex with 2 vertices connected to each other
* each face is a two-dimensional 2-simplex, a triangle with 3 vertices connected to each other in all possible ways
* the volume is a three-dimensional 3-simplex, a tetrahedron with 4 vertices connected to each other in all possible ways.
I was struck by your operations +2 and x2. I realized that the cross-polytopes are built up by the operation +2. We keep adding a pair of vertices (like a particle and anti-particle, or like the two rays of a line). For the cube, we keep multiplying the vertices by 2 as we build it. I suppose we can think of this version of Pascal's triangle as interpolating between +2 and x2. That is, the cross-polytopes and cubes are defined by the same version of Pascal's triangle, just from opposite sides.
Does this help make more sense of what I mean by "center" and "totality"?