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Thursday, March 23, 2017

About Infinity...


I blurbed a little bit earlier about Eugenia Cheng’s new book “Beyond Infinity.” Very much enjoying it, now that I’m farther in (…but do realize it’s an entire book about infinity — so you need a significant interest in the topic to enjoy it; the typical popular math book might only have a chapter or two on infinity, touching a few highlights; this volume goes deeper).
For now just wanted to mention one small matter that came up:
Quite awhile back on Twitter I asked if there was any sort of “proof” that aleph-null must in fact be the ‘smallest’ infinity; i.e. infinity is full of so many counterintuitive outcomes, and the whole question of whether aleph1 really is the second infinity is so complicated, that I wondered how we could even be sure that the natural numbers, for example, represent the lowest degree of infinity.
The few replies I got implied that the minimalness of aleph-null was axiomatic or established by definition. BUT Dr. Cheng does offer a short form of something like a proof in her volume. Her basic argument is simply to indicate that there is no subset of the natural numbers that can be put into one-to-one correspondence with the natural numbers and have anything leftover (sort of a reversed diagonalization argument). Or as she concludes, “This means that every subset of natural numbers is either finite or has the same cardinality as the natural numbers. There is no infinity in between. So we have found the smallest possible infinity: it’s the size of the natural numbers.”
I don’t know if I’m quite fully convinced (that there is much more than tautology or definition at work here), but I was glad to at least see an argument put forth. Dr. Cheng herself admits “This is not quite a proof, but is the idea of a proof…” It’s at least better than saying that the natural numbers are the lowest infinity by edict ;)
A lot of the difficulty in wrapping one’s brain around infinity lies in our deep-seated entrenchment in one view of what “numbers” are. As Cheng writes at one point, “Infinity isn’t a natural number, an integer, a rational number, or a real number. Infinity is a cardinal number and an ordinal number. Cardinal and ordinal numbers do not have to obey all the rules that earlier types of number obey.” 
I still have several chapters to go, and they look like they will be quite good. As with her earlier work ("How To Bake Pi") Dr. Cheng writes in an off-hand, almost conversational style meant to draw readers in to sometimes difficult or abstract ideas. I don't think she is always successful, but admire her making the effort. And her own passion for her subject-matter is clear.

Sunday, March 19, 2017

The Universe as a Mathematically-designed Machine


"To the divine understanding, all phenomena are coexisting and are comprehended in one mathematical structure. The senses, however, recognize events one by one and regard some as the causes of others. We can understand now, said Descartes, why mathematical prediction of the future is possible; it is because the mathematical relationships are preexisting. The mathematical relationship is the clearest physical explanation of a relationship. In brief, the real world is the totality of mathematically expressible motions of objects in space and time, and the entire universe is a great, harmonious, and mathematically designed machine. Moreover, many philosophers, including Descartes, insisted that these mathematical laws are fixed because God had so designed the universe and God's will is invariable. Whether or not humans could decipher God's will or penetrate God's design, the world functioned according to law, and lawfulness was undeniable, at least until the 1800s."

-- Morris Kline (in "Mathematics and the Search For Knowledge")

Tuesday, March 14, 2017

Just For Fun

Just for fun today, some simple arithmetic….

Math Tricks” blog put up the somewhat classic '30-cows-in-a-field' riddle yesterday, and I’ll post another video of it here today for any not familiar with it:


(what I love about this is that it is simple, appropriate for all ages, and nicely demonstrates language/speech ambiguity)


Sunday, March 12, 2017

Atoms and Primes


 Beginning of Edward Scheinerman's new book, "The Mathematics Lover's Companion":
"The physicist Richard Feynman believed that if humanity were to be faced with the loss of all scientific knowledge but was able to pass on just one sentence about science to this postapocalyptic world, that sentence should describe how matter is composed of atoms. In that spirit, if we could pass on only one bit of mathematics to the next generation, it should be the solution to the problem: How many prime numbers are there?"
[...he goes on to describe some of the proofs for the infinity of primes, before embarking on a wide array of other topics throughout the book.] 


Wednesday, March 8, 2017

"Experimental Math"... never-ending explorations


ICYMI, John Horgan interviewed Stephen Wolfram recently at his blog:

That was followed up shortly by a long, interesting post from Wolfram himself on “experimental mathematics,” iteration, cellular automata, Mathematica, etc. (h/t to Mike Lawler):

...and then Mike Lawler followed that up incorporating some of Stephen's inventive ideas into his own "Family Math" series:


Sunday, March 5, 2017

Sunday With Hermann


Sunday reflection from a 2014 paper on mathematical neural correlates:
"Hermann Weyl is recorded as having said, 'My work always tried to unite the true with the beautiful; but when I had to choose one or the other, I usually chose the beautiful.' Relevant here is the story of Weyl's mathematical formulations, which tried to reconcile electromagnetism with relativity. Rejected at first (by Einstein) because it was thought to conflict with experimental evidence, it came subsequently to be accepted but only after the advent of quantum mechanics, which led to a new interpretation of Weyl's equations. Hence the perceived beauty of his mathematical formulations ultimately predicted truths even before the full facts were known."

Wednesday, March 1, 2017

Evelyn Lamb Serves Up Her Mathiness From 'Hard-hitting' February


The 2nd edition of Evelyn Lamb's new newsletter is out... GREAT place to keep up with Dr. Lamb's writings (since she shows up in multiple outlets), as well as other things on her mind:

http://tinyletter.com/evelynjlamb/letters/stuff-evelyn-wants-you-to-read-2

If you're not already a subscriber I encourage you to become one (so you don't have to rely on me pointing out each new issue):  https://tinyletter.com/evelynjlamb