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On the (Small) Number of Atoms in the Universe

norvig.com

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Re: On the (Small) Number of Atoms in the Universe

#41

Post by yk »

creshal wrote: post #26
onion2k wrote: post #25

There is a theory that states the number of atoms (well, electrons) in the universe is exactly 1. https://en.wikipedia.org/wiki/One-electron_universe

But electrons interact with each other, don't they? How'd that work?

The electron goes forward and backward in time and interacts with itself. (In quantum field theory you can replace a positron with an electron going backwards in time). Regrettably the theory does not work, since it would predict the same number of electrons and positrons in the universe.

Re: On the (Small) Number of Atoms in the Universe

#43

Post by Retric »

boredguy8 wrote: post #29

I like how Ken Jennings dealt with the 'Go complexity' analogy: "Go is famously a more complex game than chess, with its larger board, longer games, and many more pieces. Google’s DeepMind artificial intelligence team likes to say that there are more possible Go boards than atoms in the known universe, but that vastly understates the computational problem. There are about 10^170 board positions in Go, and only 10^80…

Don't conflate the "Observable Universe" with the actual Universe. We flat out don't know how big the actual Universe is. So, it could be 10^80, 10^800, or even A(10, 80)* Atoms.

*https://en.wikipedia.org/wiki/Ackermann_function

Re: On the (Small) Number of Atoms in the Universe

#45

Post by dsfuoi »

Retric wrote: post #43
boredguy8 wrote: post #29

I like how Ken Jennings dealt with the 'Go complexity' analogy: "Go is famously a more complex game than chess, with its larger board, longer games, and many more pieces. Google’s DeepMind artificial intelligence team likes to say that there are more possible Go boards than atoms in the known universe, but that vastly understates the computational problem. There are about 10^170 board positions in Go, and only 10^80…

Don't conflate the "Observable Universe" with the actual Universe. We flat out don't know how big the actual Universe is. So, it could be 10^80, 10^800, or even A(10, 80)* Atoms. * https://en.wikipedia.org/wiki/Ackermann_function

It could be infinite.

Re: On the (Small) Number of Atoms in the Universe

#46

Post by andy_ppp »

ChicagoBoy11 wrote: post #34

I'm curious how the author found the link to this - I looked at Norvig's home page but could not find it, which made me wonder how many more goodies he's got up there that we don't know about!

https://www.google.co.uk/search?q=norvig.com&oq=norvig.com&a...

There's a few interesting things on there!

Re: On the (Small) Number of Atoms in the Universe

#47

Post by d_theorist »

marai2 wrote: post #22

Scott Aaronson's blog post on large numbers is also a very interesting read: http://www.scottaaronson.com/writings/bignumbers.html

Very enjoyable.

However, I think I found a mistake:

"For example, ‘5 tetrated to the 3’ means 5 raised to its own power 3 times, or 5^5^5"

(I am paraphrasing slightly here because the essay uses an image to show 5^5^5 in normal notation (http://www.scottaaronson.com/cgi-bin/mimetex.cgi?5^{5^5}))

However, shouldn't this be 5^5^5^5, if we're raising 5 to its own power three times?

Re: On the (Small) Number of Atoms in the Universe

#48

Post by pdabbadabba »

nitrogen wrote: post #38
lisper wrote: post #11

Earlier quoted context omitted.

The earth is small. If you build a scale model of the solar system the size of a football field, with the sun and one end and Neptune at the other (Pluto has been laid off as a planet) then the sun will be about the size of a ping pong ball and the earth will be the size of a poppy seed (and it will be about ten feet from the sun). Jupiter is about the size of a pea at this scale. Alpha Centauri is about four miles a…

Planets seem like a really big waste of mass in that sense. Computational dust in a cloud around a sun would be a more efficient allocation.

Ha! Relative to what goal, exactly, are planets a waste of mass?

Re: On the (Small) Number of Atoms in the Universe

#49

Post by nitrogen »

pdabbadabba wrote: post #48
nitrogen wrote: post #38

Earlier quoted context omitted.

Planets seem like a really big waste of mass in that sense. Computational dust in a cloud around a sun would be a more efficient allocation.

Ha! Relative to what goal, exactly, are planets a waste of mass?

To the goal of sustaining intelligent life. I'm being semi-facetious of course, but scifi authors and futurists have discussed dismantling the planets to build more mass-efficient structures for a long time.

Re: On the (Small) Number of Atoms in the Universe

#50

Post by aardvark179 »

d_theorist wrote: post #47
marai2 wrote: post #22

Scott Aaronson's blog post on large numbers is also a very interesting read: http://www.scottaaronson.com/writings/bignumbers.html

Very enjoyable. However, I think I found a mistake: "For example, ‘5 tetrated to the 3’ means 5 raised to its own power 3 times, or 5^5^5" (I am paraphrasing slightly here because the essay uses an image to show 5^5^5 in normal notation ( http://www.scottaaronson.com/cgi-bin/mimetex.cgi?5^{5^5}) ) However, shouldn't this be 5^5^5^5, if we're raising 5 to its own power three times?

Nope, see the description of titration on on wikipedia.
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