# Size of the universe vs. the amount of atoms in earth **URL:** \ **Category:** Factual Questions\ **Created:** [March 2, 2003, 4:50am UTC](https://boards.straightdope.com/t/size-of-the-universe-vs-the-amount-of-atoms-in-earth/158534 "2003-03-02T04:50:51Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Neonfish07](https://avatars.discourse-cdn.com/v4/letter/n/5f9b8f/32.png) [@Neonfish07](https://boards.straightdope.com/u/Neonfish07)\ **Post date:** [March 2, 2003, 4:50am UTC](https://boards.straightdope.com/t/size-of-the-universe-vs-the-amount-of-atoms-in-earth/158534/1 "2003-03-02T04:50:51Z")
Heres a question raised during lunchtime: If all the atoms in the planet earth, where the size of the earth as we know it, how much of the universe would it take up? just curious =] ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [March 2, 2003, 4:58am UTC](https://boards.straightdope.com/t/size-of-the-universe-vs-the-amount-of-atoms-in-earth/158534/2 "2003-03-02T04:58:16Z")
One-millionth of one percent. ---
**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:** [March 2, 2003, 5:19am UTC](https://boards.straightdope.com/t/size-of-the-universe-vs-the-amount-of-atoms-in-earth/158534/3 "2003-03-02T05:19:55Z")
Given the average atomic diameter of 2.5 x 10[sup]-10[/sup] meters, and the diameter of the Earth is 1.2756 x 10[sup]7[/sup] meters, the Earth would be 6.880 x 10[sup]7[/sup] light years in diameter if all its atoms were expanded to the size of the Earth currently. If the diameter of the universe is 20[sup]26[/sup] meters, then the expanded Earth would take up 4.0703 x 10[sup]-57[/sup]% of the universe’s volume. ---
**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:** [March 2, 2003, 5:25am UTC](https://boards.straightdope.com/t/size-of-the-universe-vs-the-amount-of-atoms-in-earth/158534/4 "2003-03-02T05:25:52Z")
Only off by 8 orders of magnitude, **Achernar**. 😛 ---
**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:** [March 2, 2003, 5:27am UTC](https://boards.straightdope.com/t/size-of-the-universe-vs-the-amount-of-atoms-in-earth/158534/5 "2003-03-02T05:27:34Z")
Silly me…I divided by mistake. Should be 50 orders of magnitude. :smack: ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [March 2, 2003, 5:44am UTC](https://boards.straightdope.com/t/size-of-the-universe-vs-the-amount-of-atoms-in-earth/158534/6 "2003-03-02T05:44:13Z")
Check your math, and don’t mix up light-years with meters. I think you’ll find your answer is about 27 times larger than mine. A factor of 8 is due to my using the radius of the universe where you used diameter. A factor of 1.3[sup]3[/sup] = 2.2 is due to my universe’s dimension being bigger (13.7 Glyr). The remaining 1.5 is due to our assumptions about the [atoms in the earth](http://pages.prodigy.net/jhonig/bignum/qaearth.html). I agree with you on the first difference, so I change my answer to: eight-millionths of one percent. ---
**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:** [March 2, 2003, 5:53am UTC](https://boards.straightdope.com/t/size-of-the-universe-vs-the-amount-of-atoms-in-earth/158534/7 "2003-03-02T05:53:43Z")
You’re right. I had anticipated finding a diameter of the universe in light-years, so I converted to that first. Surprisingly I found one in meters, and used that, but did not convert back. The new, corrected result is 2.76 x 10[sup]-8[/sup]%, or about 27-millionths of a percent. Most of the measures came from [this site.](http://math.ucr.edu/home/baez/distances.html)