On this entire planet, approximately how many atoms are there?
2[sup]170[/sup] (1.4965776766268445882405732687015e+51) Number of atoms in the planet. From Bruce Schneier’s “Applied Cryptography”, first edition.
While I’m at it:
How many grains of sand are there?
At least 100, even 1,000 probably many more.
I was sure the answer was less than 50.
I’d like to see how he arrives at that number. That’s awfully close to the number I remember for the number of atoms in the known universe. I don’t have a cite, I just remember having worked it out in physical organic many years ago. We were trying to decide if, based on the pKa of methane, there were any ionized methane molecules out there. The answer was no. Your number would change that answer.
Pencil and paper? Calculator (really good one though)? Pulled out of his ass?
The number of atoms in the known Universe is more in the region of 10^80, or 10^85, from what I’ve read.
The Earth weighs 3.75E51 daltons, so thats the max number of atoms it could have if it was completely made out of Hydrogen. So 1.4E51 seems like its in the right ballpark.
I’d think the average atomic weight of the earth is going to be more than 2pointsomething. Sure there’s a fair amount of hydrogen, but more oxygen, silicon and iron. So, if the 3.75e51 number is right, the 1.4e51 seems high by maybe half to one order of magnitude?
(But it’s probably close enough; what’s the difference between 51 and 49.5 after all?)
Taking the weight of the earth 5.98x10^27g, the composition of the earth 32.1% iron etc. and the atomic weights of these elements I come up with aproximately 1.37x10^50 atoms.
element, adundance, mass (g), atomic wt, atoms
Iron, 0.321, 1.92E+27, 55.84, 2.07E+49
Oxygen, 0.301, 1.80E+27, 16.0 , 6.77E+49
Silocon, 0.151, 9.03E+26, 28.09, 1.94E+49
Magnesium,0.139, 8.31E+26, 24.3 , 2.06E+49
sulfur, 0.029, 1.73E+26, 32.07, 3.26E+48
Nickel, 0.018, 1.07E+26, 58.69, 1.10E+48
Calcium, 0.015, 8.97E+25, 40.08, 1.35E+48
Aluminum, 0.014, 8.37E+25, 26.98, 1.87E+48
Others, 0.012, 7.18E+25, 35.26*, 1.22E+48
Total 1.37E+50
*atomc weight of trace elements was taken to be average of other atomic weights
Isn’t matter continually being added to earth from meteorites, space dust, etc.? Then you have to subtract the atoms we’ve shot out of the atmosphere. How many atoms in the Voyagers, the Mars rovers, Lunar Modules. . .?
We need to be precise here.
ISTR an email that was making the rounds a few years ago, claiming that there were only something like 1069 (or 1080, or 10xx) atoms in the universe. It was supposed to depict how stupid scientists are, since they put the number somewhat higher. Of course it was a C&P thing, and the superscript format didn’t copy.
Does anyone have a link to it, or at least know the purported number?
There are only 93 atoms in the universe. However, owing to the freakishness of quantum physices, those atoms are in many places at the same time.
OK, since I posted 50 minutes ago
The new current answer must be
1.3700000000000000000003x10^50 atoms 
Odly enough, I was just reading about the one electron universe the other day:
The implications of this would be absolutely tremendous. Current estimates suggest there’s about 10^80 atoms in the observable universe, so let’s use that same figure for the number of electrons. (Actually, since the vast majority of those are one-electron hydrogen atoms anyway, that isn’t much of a stretch.) The universe is already nearly 14 billion years old, but it will last far, far longer than that, although the ultimate age of the universe depends on which theory of its final fate you subscribe to.
This is what I remember Carl Sagan saying in his Cosmos show. He was talking about how ridiculously huge the numbers Googal and Googal-plex are (10[sup]100[/sup] & 10[sup]Googal[/sup] respectively) and he pointed out how they were higher than the number of atoms in the universe. He went a big step further and said that even if the entire universe were packed solid with neutrons it would exceed a Googal but be nowhere near a Googal-plex (would be something like 10[sup]127[/sup] neutrons I think).
People forget how exponents work…