- published: 09 Apr 2016
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In mathematics, and in particular set theory, the aleph numbers are a sequence of numbers used to represent the cardinality (or size) of infinite sets. They are named after the symbol used to denote them, the Hebrew letter aleph () (though in older mathematics books the letter aleph is often printed upside down by accident, partly because a Monotype matrix for aleph was mistakenly constructed the wrong way up ).
The cardinality of the natural numbers is (read aleph-naught or aleph-zero; the German term aleph-null is also sometimes used), the next larger cardinality is aleph-one , then and so on. Continuing in this manner, it is possible to define a cardinal number for every ordinal number α, as described below.
The concept goes back to Georg Cantor, who defined the notion of cardinality and realized that infinite sets can have different cardinalities.
The aleph numbers differ from the infinity (∞) commonly found in algebra and calculus. Alephs measure the sizes of sets; infinity, on the other hand, is commonly defined as an extreme limit of the real number line (applied to a function or sequence that "diverges to infinity" or "increases without bound"), or an extreme point of the extended real number line.
Vote for Vsauce in the WEBBYS! https://pv.webbyawards.com/2016/online-film-video/video-channels-and-networks/science-education Sources and links to learn more below! I’m very grateful to mathematician Hugh Woodin, Professor of Philosophy and Mathematics at Harvard, for taking the time on multiple occasions to discuss this topic with me and help me wrap my (finite) head around it. I’m also grateful to David Eisenbud, the Director of the Mathematical Sciences Research Institute (MSRI) and professor of mathematics at the University of California, Berkeley, for his help and for connecting me with Hugh Woodin. And of course, big thanks to Brady Haran who created the “mile of pi” seen in this video and connected me with all these mathematicians in the first place. His channel, Numberphile, i...
Sometimes infinity is even bigger than you think... Dr James Grime explains with a little help from Georg Cantor. Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile tweets: https://twitter.com/numberphile James Grime: http://singingbanana.com/ Videos by Brady Haran Minute Physics video on this topic http://www.youtube.com/watch?v=A-QoutHCu4o (somewhat more fast-paced... but we did film ours BEFORE his was uploaded, so similarities are coincidental... well actually, no they are not... we are all building upon Cantor's work!!)
In set theory, a discipline within mathematics, the aleph numbers are a sequence of numbers used to represent the cardinality of infinite sets. They are named after the symbol used to denote them, the Hebrew letter aleph. The cardinality of the natural numbers is , the next larger cardinality is aleph-one , then and so on. Continuing in this manner, it is possible to define a cardinal number for every ordinal number α, as described below. This video is targeted to blind users. Attribution: Article text available under CC-BY-SA Creative Commons image source in video
Aleph number In set theory, a discipline within mathematics, the aleph numbers are a sequence of numbers used to represent the cardinality (or size) of infinite sets.They are named after the symbol used to denote them, the Hebrew letter aleph () (though in older mathematics books the letter aleph is often printed upside down by accident, partly because a Monotype matrix for aleph was mistakenly constructed the wrong way up ). -Video is targeted to blind users Attribution: Article text available under CC-BY-SA image source in video https://www.youtube.com/watch?v=_wFxi22PF9w
This video presents Cantor's argument that there exist different infinities by demonstrating a set that is uncountable. It will only make sense if you have watched the previous video, Part 5, which defines countable sets. In essence, the size, or cardinality, of the rational numbers (fractions) is the smallest infinity: aleph null (or aleph zero). The cardinality of the real numbers, aleph one, is probably the next largest infinity, but that fact (the continuum hypothesis) has been shown to be impossible to prove under the current axioms of set theory.
The guys from Corvus Belli, creators of Infinity, give us the run down on one of the most mysterious factions in the Infinity game. The techno-organic ALEPH.
Infinity is one of the most interesting concepts in mathematics, and while most people have some idea of what it is as a concept, many only know of an extremely simplified version of this idea - the simple concept of "the biggest number". With so many ideas at the forefront of science relying heavily on this supposedly useless number (the study of black holes and quantum mechanics being just a few), it seems a shame to reduce this incredibly important and complex topic down to just a single sentence. Concepts discussed: Aleph Null: https://en.wikipedia.org/wiki/Aleph_number Hilbert's Paradox of the Grand Hotel: https://en.wikipedia.org/wiki/Hilbert%27s_paradox_of_the_Grand_Hotel Uncountable sets: https://en.wikipedia.org/wiki/Uncountable_set Cantor's Diagonal Argument: https://en.wikipedi...