Comments on: Stars and Sand Grains

By: Ben Burress

Ben Burress — Wed, 18 Apr 2012 18:58:00 +0000

A LOT different :). My estimate of sand grains on beaches alone assumes a narrow strip of sand–and even though it takes into account the length of all coastline in the world, the estimate of sand grains would go up enormously if it starts taking into account land areas of deserts–just the Sahara alone is huge–and the bottoms of the oceans. And since my estimate is not only calculated very conservatively, but also only puts only 5 times as many stars in the Universe, it doesn't take much to put the estimate well over that, I think.

By: Joanengirls

Joanengirls — Wed, 18 Apr 2012 18:01:00 +0000

So what if you add all sand grains. Like the ones on the ocean floor,
and the desert sand? Would your conclusion be different?

By: Chris McCarthy

Chris McCarthy — Fri, 13 Apr 2012 17:31:00 +0000

Take this kiss upon the brow!
And, in parting from you now,
Thus much let me avow–
You are not wrong, who deem
That my days have been a dream;
Yet if hope has flown away
In a night, or in a day,
In a vision, or in none,
Is it therefore the less gone?
All that we see or seem
Is but a dream within a dream.

I stand amid the roar
Of a surf-tormented shore,
And I hold within my hand
Grains of the golden sand–
How few! yet how they creep
Through my fingers to the deep,
While I weep–while I weep!
O God! can I not grasp
Them with a tighter clasp?
O God! can I not save
One from the pitiless wave?
Is all that we see or seem
But a dream within a dream?

E.A. Poe

By: Rvaldez4108

Rvaldez4108 — Tue, 03 Jan 2012 09:08:00 +0000

Oops…I was trying to recall the numbers but more acurrately, it would be: first two grains, half-mile, third grain representing furthest star in milky galaxy, 125 miles, fourth in Andromeda – 3,125 miles and finally, fifth representing furthest star in the universe, 17.5 million miles away. Or 700 times around the Earth. At the size of a grain of sand – pretty impressive.

By: Rvaldez4108

Rvaldez4108 — Tue, 03 Jan 2012 08:06:00 +0000

So I next asked her to imagine that two of the grains we held in our hand (one representing our sun and one the nearest star) were placed at proportional distances from each other. She'd have to walk the grain a half-mile down the beach. I was doing the numbers in my head so they're very rough. If we took a third grain representing the furthest star in our galaxy, she'd have to walk 13.5 miles. Take a fourth representing a star in Andromeda, and she'd have to fly 338 miles away. Take a fifth representing the furthest star and she'd have to be 1.9 million miles away. She lost interest at 338 miles. ;)

By: Rvaldez4108

Rvaldez4108 — Tue, 03 Jan 2012 06:49:00 +0000

This is so cool! One of the best summaries I've seen on the subject of sand grains versus star counts. Mind boggling until you mention the water molecules being 3000x! But your's is one of the few with depth defined. I told my daughter about this "fact" last summer when we were at the beach and she said "but how deep?". Oops...I hadn't read that anywhere.

By: fatalflaw

fatalflaw — Thu, 15 Dec 2011 05:57:00 +0000

http://www.youtube.com/watch?v=7wwZ2OQ8WNA

By: George Whaley

George Whaley — Fri, 02 Oct 2009 16:57:03 +0000

I take your point about considering only beaches. It is clearly an important difference as many instances of this question being discussed do fail to make the distinction.
In any case the visible universe is only a fraction of the (unknowable?) total so the universe may well win out.

By: Ben Burress

Ben Burress — Fri, 02 Oct 2009 14:50:20 +0000

There are many ways to slice and dice this calculation. In my own, I was confining my example to only the sand of Earth's beaches (not deserts), and taking every opportunity to use conservative estimates for the variables. But the point of my estimation was not so much to try to calculate how many grains of sand there are, but demonstrate the number of stars in the Universe. Even if you regard my conservative beaches with their coarse sand grains, the fact is, that's a heck of a lot of sand! And if my (maybe unrealistically) conservative sand sum is in the ballpark of the Universal star-sum, as long as I've achieved mind-boggledom, I'm satisfied….

By: George Whaley

George Whaley — Fri, 02 Oct 2009 12:32:39 +0000

This longstanding issue has been discussed again recently (on BBC)and notwithstanding many web pages giving calculations I am deeply distrusting of the maths. I have just measured (roughly) some garden sand and reckon it at 100 grains per mm^3. 10^22 (stars) = 100×1000^3×1000^3×100 =100 km^3 of garden sand.
The sandy region of the Sahara desert (alone) is some 2.5 million km^2 which is 2500 km^3 or 25 universes per metre depth.
As to the rest of the world's deserts, beaches…

Or have I missed something?