Greetings, everyone. Today I’m going to continue where I left off last time. I had planned to examine the saying, “There are more stars in the sky than all of the grains of sand on all of the beaches of the world”, or however it goes. When I was researching this topic, there was so much mindless drivel to wade through that I was appalled. I got so disgusted that I threw a slipper at the cat.
Hmph. I try not to get so worked up anymore, but sometime I just reach my limit and,…wait, do I have a cat? I used to have a cat, but I haven’t seen him in at least 10 years, so it probably wasn’t him, hmmm. Well, I threw a slipper at something the size of a cat, anyway. And I see that I am wearing both of my slippers. Then what did I throw? Bah, it doesn’t matter. Where was I? Oh yes, sand and stars.
So, are there more stars than grains of sand yada yada yada? The short answer is: yes.
The long answer is a little more involved, but not so long that you’ll get bored and wander off, looking for more coffee and something nice to go along with it. I’ve been having vanilla wafers with my coffee lately, and they’ve been quite tasty. My wife doesn’t normally let me eat such things and constantly hides them from me, the tyrant! “They have too much sugar in them”, she says, and “do you want to go on insulin?” Bah! She’s always nagging, but those sugarless things that she brings home are bloody awful, the texture is more like clay than cookie, and…and
Ahem. The calculations are pretty straightforward once you’ve arrived at your base values.
The first thing we need is the number of sand grains on all of the beaches blah blah, and it just so happens that someone at the University of Hawaii has come up with just such a calculation. You can look at the equations themselves here:
Leave it to the scoundrels at U of H to come up with a project that involves going down to the beach, probably with some pretty graduate students, and playing in the sand. There was probably a subsection that called for drinking beer until you could no longer count, too. Hmph.
The value they arrived at is 7.5 x 1018 or 7.5 billion billion grains of sand. Sounds about right.
Next, we need the number of stars in a galaxy, and since the Milky Way is right there, we’ll use it. The estimates for the number stars in our galaxy varies all over the place, from 75 billion all the way to 400 billion, and the Milky Way is considered a small galaxy once you start looking. The accepted estimate for the Milky Way for a long time was 100 billion, or 1011 so we’ll double that to 2 x 1011 and call it good for now.
Now we need the number of galaxies in the visible universe. The estimates for this value are all over the place too, and it grows every time the Hubble space telescope takes a long exposure photograph. The most recent number I’ve read about is 4 x 1011 or 400 billion galaxies, so that’s what we’ll use.
A simple calculation:
(2 x 1011) x (4 x 1011) = 8 x 1022 or 80 billion trillion, and remember, this figure is probably quite low.
Since 8 x 1022 > 7.5 x 1018, we can safely say that there are more stars than grains of sand yada blah. A lot more, like 1000 stars per grain of sand more.
And there you have it.
An interesting side note: While I was researching this topic I came across someone who calculated it differently, but I can’t find the article again. He got some sand, sifted it so that all the particles were uniform, and figured out how many grains would fit in a cubic millimeter. He then took the number of stars in the visible universe, and calculated how many cubic millimeters they would make as sand, and mapped it over the surface area of the Earth. He figured that sand would bury the Earth to a depth of 450 kilometers or so. Since that isn’t the case, QED. I thought it was novel.
Google answers, of all places.