Talk:The Sand Reckoner

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[edit] Comments

In Names of large numbers it is said that a myriad is 10⁸ however in this article it is said a myriad is 10,000. Which is correct? Answer: The Names of large numbers page actually says that a myriad myriads is 10⁸, consistent with the statement here that a myriad is 10⁴ (i.e. 10000). Niels Ø 00:41, Nov 29, 2004 (UTC)

I missed that, thanks.

[edit] Accuracy?

The resulting estimate is that the radius of the universe is about one light year which is consistent with current estimates for the radius of the solar system. Archimedes' final estimate gives an upper bound of 10⁶⁴ for the number of grains of sand in a filled universe.

It would be interesting to have an estimate of the actual number of grains that would fit in a one-light-year universe. — Johan the Ghost _seance 04:55, 26 August 2006 (UTC)

[edit] Universe size?

I've not seen the estimate of 10^14 stadia for the diameter of Archimede's universe reinforced elsewhere: a more common number thrown about seems to be 10^9 stadia, which doesn't even encompass the majority of our solar system.

Haven't changed anything -- I'm not sure if my references are worth citing -- but I'm bringing attention to the discrepancy —Preceding unsigned comment added by 196.2.161.80 (talk) 19:24, 13 September 2007 (UTC)

As Archimedes explains in The Sand Reckoner, he uses the term universe (Greek: κόσμος) to denote a sphere whose radius is equal to the distance of the Earth from the Sun. He estimates the diameter of this sphere to be no more than 10¹⁰ stadia. In the heliocentric model he is using, however, the fixed stars are much further away from the Sun than the Earth is, so this sphere does not encompass everything observable. The much larger sphere of the fixed stars, which is estimated to have diameter no more than 10¹⁴ stadia, is the only sphere which can encompass everything observable, so it is the sphere which fits the modern usage of the word universe. Spacepotato 19:43, 13 September 2007 (UTC)