Date: 18 Apr 1995 15:43:43 -0400 From: Scott T Cramer Subject: Q: name for infinity symbol Dr Math, I got your address from the WWW. If this is appropriate, I'd appreciate your reply. My question is: What is the name for the infinity symbol (the on-its-side figure eight)? Or is there no name for it? Thanks in advance. Scott
Date: 19 Apr 1995 15:43:34 -0400 From: Dr. Ken Subject: Re: Q: name for infinity symbol Hello there! Well, I thought I'd just write to let you know that we're working on your question. I'll have an opportunity to do more research on it a little bit later, but here's what I think I remember: the modern symbol for infinity was an invention of some English mathematician, and I don't think it was used as a symbol before that. I'll have to check on that, though. Anyway, I've never heard of a name for it before; sometimes people call it "the sideways 8" or "the infinity symbol" or things like that. I'll let you know what else I find out. -Ken "Dr." Math
Date: 19 Apr 1995 17:01:04 -0400 From: Scott T Cramer Subject: Re: Q: name for infinity symbol Ken, Thank you for your efforts in naming the infinity symbol. I have also posted the query to Usenet and have received a few replies of "lazy eight" and one of "lemniscate". I've looked in several math and symbol dictionaries and all of them simply define the symbol as "infinity". I managed to find lemniscate, but its definition was that of an "algebraic curve" which, although it looks (when plotted) like the infinity symbol, doesn't seem to have much to do with the concept of infinity. Your historical info sparked my interest too. Any idea on when the symbol was first used? (Well, now I really am off on a tangent :-) Anyway, thanks again. It's strange how seemingly trival details can gnaw away at one's attention. Scott
From: Dr. Ken Subject: Re: Q: name for infinity symbol Date: 19 Apr 1995 19:23:59 -0400 Hey there. I found this in Florian Cajori's "A History of Mathematical Notations": The sign [infinity] to signify infinite number was introduced by John Wallis in 1655 in his "De sectionibus conicus" in this manner: "Esto enim [infinity] nota numeri infiniti." The conjecture has been made that Wallis, who was a classical scholar, adopted this sign from the late Roman symbol [infinity] for 1000. So that's as much as I find. It goes on to say where the symbol was subsequently used, and how it was used, and so on. Hope this hits your interest. -Ken "Dr." Math The Math Forum Check out our web site http://mathforum.org/dr.math/
From: Dr. Ian Subject: Re: Q: name for infinity symbol Date: 21 Nov 2001 11:47:00 -0400 Hi, Jerry Jelincic has pointed out that according to http://www.geocities.com/Paris/Rue/1861/etyindex.html the symbol introduced by Wallis may have been a variant of the Greek letter omega, which to me seems more plausible than using the Roman symbol for 1000. Thanks, Jerry! -Dr. Ian http://mathforum.org/dr.math/
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