-   Prime Gap Searches (
-   -   2^64 is not a big number! (

Viliam Furik 2021-06-01 14:05

[QUOTE=xilman;579653]I'd like to see you walk from the Earth to the Moon.[/QUOTE]

Note the usage of words - "walking [B]distance[/B]".

LaurV 2021-06-01 14:17

[QUOTE=xilman;579653]I'd like to see you walk from the Earth to the Moon.[/QUOTE]
Give me the time...

Bobby Jacobs 2021-06-03 17:23

Light travels 0.3 Micrometers (1/1000 of a millimeter) in 1 femtosecond.
Light will travel more than 18446 Light-Years in 2^64 femtoseconds. This is more than 4000 times the distance to the closest stars to our sun.

Actually, light travels about 18446 light-seconds in 2[SUP]64[/SUP] femtoseconds. That is less than a light-year.

a1call 2021-06-03 20:59

Thank you very much for the correction :smile:

[CODE]2^64*0.3 micrometers = 5534023222112865484.8 micrometers = 5534023222112.8654848 m = 5534023222.1128654848 km = 0.00058493005201488906931613994292358101681 ly

a1call 2021-06-03 22:55

The "back half of the chessboard" is a reference to the old story about the inventor of chess. As the story goes, when chess was presented to a great king, the king offered the inventor any reward that he wanted. The inventor asked that a single grain of rice be placed on the first square of the chessboard. Then two grains on the second square, four grains on the third, and so on. Doubling each time.

The king, baffled by such a small price for a wonderful game, immediately agreed, and ordered the treasurer to pay the agreed upon sum. A week later, the inventor went before the king and asked why he had not received his reward. The king, outraged that the treasurer had disobeyed him, immediately summoned him and demanded to know why the inventor had not been paid. The treasurer explained that the sum could not be paid - by the time you got even halfway through the chessboard, the amount of grain required was more than the entire kingdom possessed.

The king took in this information and thought for a while. Then he did the only rational thing a king could do in those circumstances. He had the inventor killed, as an object lesson in the perils of trying to outwit the king.


robert44444uk 2021-06-05 06:54

[QUOTE=LaurV;579667]Give me the time...[/QUOTE]

I feel confident that there are people who do the distance in a lifetime. But probably not most specimens of homo sapiens species.

People are encouraged to do 10,000 steps a day in the UK, and an average step is about 70 cm. Allowing for pre toddler days and bedridden days at the far end, a good mobile life (say the top 10%-15% of the population) is 85 years in G20 countries.

So a first approximation:

85*365.25*10000*0.7/1000 = 217,300 km in a lifetime

The moon is Km 356,500 closest distance from the earth centre to centre, or approx. 348,400 km surface to surface.

There will be fit pastoralists in Africa who achieve this, I am sure. Not so sure about us car-obsessed people in the G20. Some will though.

Bobby Jacobs 2021-06-07 19:49

I recall the story of the grains of rice. The first square on the chessboard had 1 grain of rice, the second square had 2 grains, the third square had 4 grains, ..., the last square had 2[SUP]63[/SUP]=9223372036854775808 grains. In all, there were 2[SUP]64[/SUP]-1=18446744073709551615 grains of rice. That might seem like a lot of rice, but there are more atoms in a single grain of rice than the number of grains of rice in that story.

chalsall 2021-06-07 20:05

[QUOTE=Bobby Jacobs;580264]...but there are more atoms in a single grain of rice than the number of grains of rice in that story.[/QUOTE]

There are more possible positions in the game of Go than there are atoms in the Universe.

That's why [URL=""]AlphaGo[/URL] was so impressive. And scary (for those who like humans).

All times are UTC. The time now is 22:39.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.