# How many atoms/molecules in the universe? **URL:** \ **Category:** Factual Questions\ **Created:** [February 26, 2004, 9:30pm UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357 "2004-02-26T21:30:54Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Paddle](https://avatars.discourse-cdn.com/v4/letter/p/f19dbf/32.png) [@Paddle](https://boards.straightdope.com/u/Paddle)\ **Post date:** [February 26, 2004, 9:30pm UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/1 "2004-02-26T21:30:54Z")
I think the answer is somewhere in the region of a googol molecules (101 digits), but was wondering how much varience there is in different approximations. How about atoms? Protons/Neautrons/electrons? Quarks? The reason I ask is that I’ve been asked by my project supervisor to write a program dealing with 2^2^m possibilities and he wants me to be able to deal with n=20. This gives a number with several thousand digits. Paddle. ps. Sorry if this has been dealt with, but I searched unsuccessfully. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [February 26, 2004, 9:37pm UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/2 "2004-02-26T21:37:23Z")
[This page](http://van.hep.uiuc.edu/van/qa/section/Stuff_about_Space/The_Rest_of_the_Universe/982241844.htm) gives some some numbers. There aren’t a googol of _anything_ in the universe. Even the number of photons falls short by a factor of something like 10[sup]12[/sup]. That’s 12 orders of magnitude, folks! ---
**Author:** ![owlofcreamcheese](https://avatars.discourse-cdn.com/v4/letter/o/97f17d/32.png) [@owlofcreamcheese](https://boards.straightdope.com/u/owlofcreamcheese)\ **Post date:** [February 26, 2004, 10:06pm UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/3 "2004-02-26T22:06:32Z")
all of them ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [February 26, 2004, 10:23pm UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/4 "2004-02-26T22:23:02Z")
> [@Q.E.D.](#): > > [This page](http://van.hep.uiuc.edu/van/qa/section/Stuff_about_Space/The_Rest_of_the_Universe/982241844.htm) gives some some numbers. The numbers on that page agree with what I’ve heard, but I think the answer man is a little confused. “No, don’t keep arguing”, and then he attaches something that explains why the questioner is right! And then he titles the column “Lots and Lots of Atoms in the Universe” when the point of the article is that it’s _less_ than a googol. 🙂 Incidentally, the number of molecules in the universe is equal to the number of protons, or the number of atoms, to within an order of magnitude. ---
**Author:** ![Wearia](https://avatars.discourse-cdn.com/v4/letter/w/13edae/32.png) [@Wearia](https://boards.straightdope.com/u/Wearia)\ **Post date:** [February 26, 2004, 11:29pm UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/5 "2004-02-26T23:29:51Z")
> [@Q.E.D.](#): > > [This page](http://van.hep.uiuc.edu/van/qa/section/Stuff_about_Space/The_Rest_of_the_Universe/982241844.htm) gives some some numbers. There aren’t a googol of _anything_ in the universe. Even the number of photons falls short by a factor of something like 10[sup]12[/sup]. That’s 12 orders of magnitude, folks! This strikes me as more than a little bit odd. As far as anyone knows the universe is infinite in space. How do you go about calculating how much matter is present in an infinite volume? For example, lets say for every cubic(?) lightyear of space you have one atom. Infinite space means that even with only 1 atom per lightyear^3 you still have infinite atoms. The case that your cite seems to make (correct me if I’m wrong, which I just might be) is that going by the big bang theory the universe started at a single point and since it is just expanding, the mass remains the same. The problem with that is, how do we have any idea how much mass was present in the big bang? ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [February 26, 2004, 11:41pm UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/6 "2004-02-26T23:41:46Z")
> [@Wearia](#): > > The case that your cite seems to make (correct me if I’m wrong, which I just might be) is that going by the big bang theory the universe started at a single point and since it is just expanding, the mass remains the same. The problem with that is, how do we have any idea how much mass was present in the big bang? I may be misreading, but that’s not what the cite says at all. He emphasizes the fact that he’s talking about the _observable_ universe, the current proper volume of a light-cone starting at the Big Bang with us at center (in our frame). Using that and the local proper number density of photons, you can get the total number of photons in the observable universe. As for the mass, you use cosmological observations to get Omega[sub]M[/sub] and H[sub]0[/sub], which gives you the proper mass density, which you can use along with the proper volume to get the total mass. ---
**Author:** ![sibyl](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@sibyl](https://boards.straightdope.com/u/sibyl)\ **Post date:** [February 26, 2004, 11:47pm UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/7 "2004-02-26T23:47:54Z")
How about the number of possible ways the universe could be arranged? 😃 ---
**Author:** ![adirondack\_mike](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@adirondack\_mike](https://boards.straightdope.com/u/adirondack_mike)\ **Post date:** [February 27, 2004, 12:03am UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/8 "2004-02-27T00:03:26Z")
from this [page](http://home.earthlink.net/~mrob/pub/math/numbers-10.html#l_p1_4932_07): 3.149…x10^79 - Eddington number - the number of particles in the universe, 1x10^97 - larger estimates for the number of particles. and in a reference to the [Straightdope](http://www.straightdope.com/mailbag/mgoogol.html) 1x10^110 - the total number of protons if the universe was completely filled with them. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [February 27, 2004, 3:58am UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/9 "2004-02-27T03:58:28Z")
How are you going to count them? ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [February 27, 2004, 4:05am UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/10 "2004-02-27T04:05:40Z")
You don’t “count” them. You “reckon” them. Calculating the number of particles to fill the universe is known as “reckoning”. It’s tradition! ---
**Author:** ![Sublight](https://avatars.discourse-cdn.com/v4/letter/s/439d5e/32.png) [@Sublight](https://boards.straightdope.com/u/Sublight)\ **Post date:** [February 27, 2004, 4:19am UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/11 "2004-02-27T04:19:03Z")
> [@sibyl](#): > > How about the number of possible ways the universe could be arranged? 😃 _Scientific American_ had an article on parallel universes last year (Feb or March 2003, I think) that brought this up. There are a large, but finite, number of Planck volumes in the observable universe, so therefore there are a finite number of possible arrangements they can all be in (somewhere in the neighborhood of 10^10^100). Given an infinite universe, this means that there must be other volumes of space with exactly the same arrangement as our observable universe. Same milky way, same sun, same earth, same people, same SDMB. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [February 27, 2004, 2:49pm UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/12 "2004-02-27T14:49:29Z")
> [@Sublight](#): > > _Scientific American_ had an article on parallel universes last year (Feb or March 2003, I think) that brought this up. There are a large, but finite, number of Planck volumes in the observable universe, so therefore there are a finite number of possible arrangements they can all be in (somewhere in the neighborhood of 10^10^100). Given an infinite universe, this means that there must be other volumes of space with exactly the same arrangement as our observable universe. Same milky way, same sun, same earth, same people, same SDMB. We’ve been through this over and over in previous threads. An infinite universe in no way shape or form implies that all arrangements must occur. The power set of a set is vastly larger than the set. Vastly larger. You can’t put them into one-to-one correspondence so most combinations will _never_ occur. And by “most” I mean as close to nearly all as you could probably think of. ---
**Author:** ![dylan\_73](https://avatars.discourse-cdn.com/v4/letter/d/ecccb3/32.png) [@dylan\_73](https://boards.straightdope.com/u/dylan_73)\ **Post date:** [February 27, 2004, 4:23pm UTC](https://boards.straightdope.com/t/how-many-atoms-molecules-in-the-universe/231357/13 "2004-02-27T16:23:04Z")
> [@ftg](#): > > most combinations will _never_ occur. And by “most” I mean as close to nearly all as you could probably think of. Any reality you may be experiencing is just a statistical anomoly and may safely be ignored, eh? 😉