Craig’s Questions – Sand and Atoms

Alright, here it is, the first instalment of – the highly anticipated – Craig’s Questions. The First question came about following a conversation with someone who is studying maths. He (Andy) casually dropped the following phrase into the conversation about numbers, as a statement meant to inspire wonder. The statement did more than just that for me though, it raised my curiosity and I felt compelled to sit down and work it out for myself. But here’s the thing to consider before we go any further, numbers, beyond a certain point, lose their meaning to us. I don’t really think our brain works well with visualising numbers beyond the thousands and it probably struggles even with that. For example, I know that I can’t visualise 10,000 apples. I understand the concept of the number but I couldn’t form an accurate picture of it in my head. Would it be as tall as me if they were still in their cases? (Probably.) How wide would it be if we staked them to only my height (6 ft)? These answers just elude my intuition and, I suspect, you’re no different. The following question takes advantage of that and forces us into the realms of Avogadro’s number, maths and straight up comparisons. At first these types of statements or questions seem impossible to answer and if anyone delivered an answer confidently enough one way or another, you might just be inclined to believe them and move on with your day. Hopefully you’ll realise that working it out is more fun.

Read this question, think about it and have a guess (no cheating or working it out for yourself, we’ll run through the maths together later on). I’d love to know what you thought. To make this even more fun, comment (below) or tweet me (@Sci_McInnes) your intuitive guess now before we move on. I’d genuinely love to know what you think!

So here we go, the first question:

“Is it true that there are more atoms in a grain of sand than there are grains of sand on the Earth?”


Damn, that sand looks nice. Image credit: Craig McCubbin

So, first off, to the (chemist’s) easy part: how many atoms are there in a grain of sand?

To do this, we need to know about Avogadro’s number (nice video). This number tells us how many atoms there are in one mole of a substance (i.e. how many atoms there are in 12 grams of carbon-12, for example); the answer is 6.022×1023. That’s a big number. We use Avogadro’s number to give us the number of atoms in a grain of sand in the following way (pssst, skip this if you don’t like maths, just look for the other blue “pssst”.):

        Avogadro’s number               =number of molecules in gram of sand (1.004×1022)

Weight of one molecule of sand

We then multiply this by three as there are three atoms in every molecule. The answer is 3.012×1022.

So now we know the number of atoms in a gram of sand, we’ve got to figure out how many grains of sand there are in a gram and multiply it by the number of atoms in that same weight.

If a medium grain of sand takes up 0.5 mm of space (0.0005 cm3) and 1 cm3 of sand weighs ~2.8 g then one medium grain of sand weighs about 0.0014 g (1.4 mg)

Now: number of atoms per gram x number of grains per gram = number of atoms in one grain

0.0014 x 3.012×1022 = 4.33×1019

(Pssst, pay attention here) That means that there are 43 quintillion atoms in one grain of sand. Damn, that’s a big number.

Now, how many grains of sand are there on the Earth?


Image credits: Craig McCubbin (wikimedia)

This bit was a little trickier. I couldn’t just straight out guess it because I don’t have a map or any concept of how deep the grains of sand go in a desert, or a beach, or even a sandpit for an Olympic game of beach volleyball. So I had to look it up and the estimates vary from between 7.5×1018 throughto 7×1021. It seems that all of these estimates are ignoring the deserts and the ocean, so I think that we can say that even the upper estimate here is quite conservative. So let’s compare the two numbers and see which is bigger; 7 sextillion or 43 quintillion? That’s right, you guessed it, it’s 7 sextillion (7×1021).

So that means that, even being fairly conservative with our estimates, and to answer our original question, there are more grains of sand on the Earth than there are atoms in one grain of sand, by at least three orders of magnitude. Mind blowing! I have to say, regardless of the outcome, the mere fact that we can contemplate these questions with some degree of precision is, really, the truly mind-blowing thing and that’s why I decided to write about it today; science is awesome.

Thanks for the constant slew of “Craig’s Questions” go to Sam (@_whitewashed) and the many interesting conversations with Kieran and Andy. If you have a question that you’d like me to answer, tweet me (@Sci_McInnes) or email me c (dot) mcinnes (dot) chem (at) gmail (dot) com and I’ll do my best to answer them.

A Ripple Effect

I’ve been careful to (mostly) follow people on twitter that are scientists, science communicators or generally witty people with clever things to say. I do this so that twitter is a genuine networking tool and not an intravenous mainline of gossip, scandal and Justin Beiber. So when twitter knee-jerks itself into a schism, brand new outrage or trends its way up the “ladder of fury” hovering in the lower left-hand-side of my screen, I tend to be fairly immune. Immune to all the public outrage and responses being directed at and retorted from celebrity chiefs, popstars or any other tabloid victim, for that matter and I get on with my life. I use twitter (mostly) for talking about, and discovering, interesting science.

However, there have been a few notable exceptions; I was quietly intrigued when Jonah Lehrer was ousted as a fraud and a liar (and a bloody successful one at that), I “lost my absolute shit” when he tried to make his comeback at the Knight Foundation with what, I thought, was a contrived, self-indulgent, non-apology of a mea culpa. Most irksomely, it appeared as if it was a public re-launching of his career and an inevitable return to spreading misinformation.

More recently, I was drawn into gawking at another twitter-mediated scandal as Bora Zivkovic (AKA @BoraZ) was publicly accused of (more than once), and then publicly admitted to, sexual harassment. For those that don’t know, Bora was probably the most prolific tweeter in the science communication field. He earned the name “blogfather” for helping to develop people’s writing and communication skills, he was on a variety of sci comm boards and set up and helped run the Science Online conferences, which are so dear to so many (to name but a few things). He cast a wide (professional) net and one, in which, I find myself. We were/are connected via twitter (along with about twenty five thousand other people). The most visitors ever directed to my blog came from one retweet sent out, by him, to the masses. A connection that at the time I thought was potentially very useful, and later found out to be useless as he (rightfully) stepped away from the online world.

Yesterday, and rather out of the blue, I spotted that faintly familiar “retweeted by Bora Zivkovic” appear in my timeline. It’s no exaggeration when I say, I knew that my little corner of twitter was about to go into meltdown…again. Bora’s return to online life has brought with it a mix of emotions and decisions for many in the field. Some have remained his friend and stood by him. His wife called for the entire conversation to be handled offline (though I wonder how likely that is considering Bora had so much influence online).

More importantly, the victims of the harassment and those closely involved with the Science online community seem wholly unimpressed with Boras return to online life and potentially Sci Comm conferences (though Bora has now reiterated that he will not be attending SciOx events).

When it comes to the “what to do about Bora?” question, I feel like it’s important to stay out of this argument directly as I’m very much an outsider in this community. In fact the only connection I have to it, is a mutual following on twitter with Kathleen Raven (along with around four thousand others, I might add). So while I don’t think it’s appropriate for me to tell a community what they should do, I do think I’d like to make one point (hang on in there, we’re almost there). Something that popped into my head as a result of watching this shit-storm unfold. Something that might well be a tiny bit of positivity to come from this mass swathe of negativity and perhaps something to consider when all of this is over.

A void has been left in the absence of Bora from twitter. A void that, strangely, I hadn’t thought about until today – perhaps I was too caught up in the original downfall to fully appreciate this seemingly obvious fact. (Perhaps I have been too busy trying to get a job to care! Actually that’s almost certainly 90% of it right there.) Relatively-new and unrecognised communicators, like myself, who relied upon the retweet of a seemingly benevolent giant in the community, might feel like we need a replacement. There are others out there who have the impact and demonstrate the willingness to search for new and exciting talent (Kathleen Raven and Khalil Cassimally come to mind). But I suspect that having a replacement Bora is a silly idea. After all, he was always online and who needs but one tenuous link to a community anyway? This leads me to my point. No matter how big or small we are, or how closely affiliated we were to the Science Online community, we’re all a part of the bigger science communication collective that exists online (and off). We all have an impact and we can all be of use to others. As a result of that, I’m asking others to dive in and fill the void left by Bora, even if he has returned to online life.

Of course, if I’m asking others to take note of and promote the talents of new and interesting writers, I better be willing to do the same myself. You’ll be glad to know that I am. I lead by example. So it’s as a ripple effect of Bora’s return to twitter that I have decided to do my bit and publicise good science communication as and when I see it. I’d like to introduce/hijack the hashtag #RippleEffects. I would like to start this off by pointing you in the general direction of Kat Day who writes an excellent chemistry inspired blog, and in particular I’d like you to have a little read of her Christmas Chemist piece, at the tail end of this festive season, go check it out. I will, of course, tweet all good content as I see it but perhaps I’ll make more of an effort to blog about it too.

Twitter frequently goes into a meltdown, even when you think you’re surrounded by and follow only the smartest people out there, we are not immune. Occasionally (as with this example) the meltdown is justified. Regardless of this fact, and from a swarm of fury, confusion and lines in the sand, something useful can emerge; I hope this attitude (and perhaps the hashtag – though I’ll latch onto others just as easily) is one of those things.

Happy New Year and happy reading.

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