# How much can we learn from a grain of sand?

I've wondered about this for years. Reading one of the books in the Inheritance Cycle, I came across a stipulation. It stated that if observed enough, a grain of sand could render to the viewer the deep secrets of the universe. Of course, that's a little far fetched, if not outright preposterous. I hasten to add that I am not asking if this is true, but it did occur to me to ask:

What, based on the tools we currently have, can we discern about the planet, chemistry, and physics in general, from a grain of sand?

Limitations:

• Don't be funny and blindingly obvious, e.g. "It's a grain of sand."
• Older tools are usable.
• Observations may include the use of other matter, obviously, but not in excess.
• Not a brainstorm, try to include the most verifiable points you can.
• It's an ordinary, 2mm diameter, slightly oblong, sand grain.
• You are (technically) allowed to use other objects as controls, preferably also sand grains.
• This is something I've wondered about too after reading (what was it, Brisingr?) – fi12 Mar 18 '16 at 0:54
• This doesn't seem to be about WB, more a question about physics, biology, and (maybe) philosophy. What are you trying to build? – Frostfyre Mar 18 '16 at 1:33
• @Frostfyre where would you suggest he put it? – White Fang Mar 18 '16 at 1:55
• @WhiteFang I don't know, but that doesn't inherently mean it belongs here. – Frostfyre Mar 18 '16 at 2:03
• @fi12 brisingr... That sounds really familiar. What is it? – Aarthew III Mar 18 '16 at 4:11

I would imagine we could discern the following things (but this is far from a complete list):

• The scale of our planet $\rightarrow$ If a sand grain is considered small and a beach is made of trillions of sand grains, then we have a general idea of how much larger things are on our planet
• Gravity on our planet $\rightarrow$ $g = -\frac{GM}{r^{2}}$, where:

$g$ is the acceleration of gravity at a particular point

$G$ is the universal gravitational constant = $6.67 \cdot 10^{-11}~\text{N}\frac{\text{m}^{2}}{\text{kg}^{2}}$

$M$ is the mass of the object

$r$ is the distance from the center of the gravitating body. For the surface of the Earth, $r$ is approximately $6.38 \cdot 10^{6}~\text{m}$.

Obviously you'd need to know $r$ in this case, but dropping the sand grain and seeing how long it takes to reach the floor could give us an idea of how relatively powerful our gravity is.

• Since hypothetically, extraterrestrial bodies could "maybe" not be composed of atoms, by analyzing the sand grain in detail, you can realize that everything here on Earth is indeed made of atoms

• Sand grains are made of quartz and feldspar, so knowing the composition of a grain of sand helps determine what minerals are present here on Earth

• The fact that every sand grain in the world is unique when looked at under a microscope goes to show that through weathering and constant battering, our powerful oceans will never allow 2 sand grains to be identical. At the same time, this also shows we have powerful weather forces: wind, water, freezing/thawing, etc.

• And probably the biggest inference you can make: there is life on Earth. According to this article:

The animals living in the sand are often less than a millimeter long and sometimes as small as $\frac{1}{20}$th of a millimeter. They make up for size with numbers: Scientists estimate that a bucket of sand might hold thousands of these tiny creatures; in a few square yards of beach, there might be millions.

This is by no means a comprehensive list and I'm still editing my answer searching for more possibilities.

• Any reason for the downvotes? – fi12 Sep 12 '17 at 1:29

Yes, a grain of sand can enlighten you about some deep secrets of our universe ... if you look at it deeply enough, and leave all your scientific, religious and philosophical biases aside.

# It exists!

Hold the grain of sand on the tip of your index finger and think "Why does this grain of sand exist?" Where did it come from? Where did everything come from? Why do things exist? Was there a moment of creation which created everything we see? Have things existed forever without any creative force?

Ponder on these lines and it will lead you to one of the models about the creation$^1$ of universe or how things came to be.

# It Falls!

Carefully drop that grain of sand from your fingertip on the palm of your other hand and notice how it falls down! Isn't that amazing? Why does it fall? What is falling? What makes the grain of sand fall? Move to a different location and repeat the experiment. Does it always fall down? What is down? Why does the grain of sand always fall towards Earth? Is Earth pulling on that grain of sand? Jump upwards and see if you can go into space like that. Can you? Does Earth pull on you too? Does Earth pull on everything? Why does Earth pull on everything? Why is it easier to lift lighter things than heavier things? What makes things light and heavy?

Think and if you think deep enough and clearly enough, you will start to form an idea about mass and matter and how gravity works.

# It shines!

Carefully rotate the grain of sand in sunlight and notice how it starts to shine at one point/angle. What makes it shine? Why doesn't it always shine at all angles? Does it have something to do with the alignment of the sun, the grain and your eyes? Does the grain of sand shine by itself or does it reflect the light of sun?

Place the sand grain at different angles and notice at which angle it shines. Think about the alignment of the sun, the sand grain and your eyes. Does it tell you something about the laws of reflection? If you want to think deeper, think about the nature of light. What is light? Where does it originate from? How does it enable us to see?

# What is sand?

So then. Why do we call it sand? What is the difference between yourself and the sand gain? How is it different from air? Can we take the grain of sand apart and see what it is made of? How do we take it apart? If we heat it enough, can we split it into its parts?

Try heating the sand grain and notice how it changes color. Heat it more and you will see it melts! If you heat it enough, you will see it reduces to a grayish colored substance. What does this mean? If you keep heating this grayish substance, it only melts and then vaporizes, but does not reduce to anything else. What does it mean? Is that grayish substance the core part of sand? What is the other part that must combine with it to form the sand grain?

Think on these lines and you will start to form an idea about basic chemistry, thermal decomposition and additive reactions.

Si + O$_2$ =======> SiO$_2$

I could go on and on with with this, but i think the point has been made.

1. By creation I mean the moment when everything came into existence. No bias intended towards creationism. Creation of the universe from God or without God is a completely different (and unrelated) discussion.

Looking at what we know how sand forms, we can be sure of multiple things.

• The planet is(or was) tectonically active. Because sand particles forms when earth slowly cools down.
• The planet's crust contains Silicon and Oxygen, because sand is SiO2
• We can roughly tell composition of the soil based on the size of the sand particle, because other components need to solidify first for sand particles to form in the remaining space.
• Some form of erosion happens. Either wind or water breaks down the soil and frees the sand particles.
• The weathering effect is not aggressive, either physically or chemically, to destroy or change the sand particles

It depends greatly on which grain of sand we're talking about, not all sand is created equal when it comes to diagnostic information. A reasonably "new" grain of Quartz/Feldspar isn't going to tell you that much, on the other hand, the oldest sand grains on Earth are Zircons from Australia's Simpson Desert, they tell us a great number of things, firstly they give us a most recent occurrence date for the Earth's crust cooling to below approximately 1200K (a little over 4.4 billion years B.P.) and since the grains were themselves found in sedimentary rocks with younger igneous intrusions dated to 3.2 billion years B.P. we can also say with some certainty that there were erosive processes occurring by then and that they probably involved liquid water. Careful analysis of their exact composition tells us about the chemical environment and temperature at which they crystallised and also gives an isotopic benchmark for analysis of other minerals. The way that sand minerals in general crystallise at the atomic level can tell us a lot about Ionic, Metallic, and Polar Bonding as well as giving clues about solid solutions, which is useful for alloy chemistry.

Grain morphology the shape and surface features of the grain can tell you a lot about the physical environment that reduced your and grain from a large crystal to it's present diminutive size. Thermal Stress, Frost Wedging, Wave Action, Salt Wedging, Pressure Release Foliation, and Wind Erosion all leave telltale marks on the individual grains. Wind or water transportation other markers, sand moved by the wind turns red from Iron oxidisation while the same sand moved by water action turns blue also because of the Iron but due to reduction. The environment of deposition whether Alluvial, Marine, or Subaerial will also leave traces on the grains and also within the deposits they form.

Of course as other people have pointed out you can also work out any number of Physical (as in the science) quantities and constants using a sand grain for a measuring stick.

I'm impressed by the book The Force of Symmetry. One line remarks “Next time you put some salt in your soup, remember how its properties are related to the rotational symmetries of space!”

Not only the existance of atoms and the various choices of elements, but their chemical properties and large-scale bulk characteristics all emerge due to some fundimental properties of the universe.

A grain of sand will have a few possible minerals in it. This summarizes the basic laws of the Universe. The fact that you have a few kinds of atoms and examples of chemical bonds will tell you pretty much everything about physics.

That there are a few kinds of atoms will tell you about the history of the universe. That stars existed and died, and new stars with planets formed.

• You could learn a lot of about physics, but not "everything". Not GR v. Newtonian gravity, and not a lot of the high energy physics of the Standard Model (e.g. particles beyond the first generation and probably not neutrino physics either). Not the Big Bang theory or nucleosynthesis. – ohwilleke Sep 11 '17 at 18:48

You can learn a lot from a grain of sand itself as the other answers tell you. But depending on where and how do you find the grain of sand you'll learn even more.

For an example, you can learn about volcanic eruptions that occured a long time ago. As explained here, thin little particles such as ashes or grains of sand are sent into the atmosphere during powerful volcanic eruptions.

Some of the particles end up falling to the groud. When they land on ice and a new ice layer form, the particles become stuck in the ice. The deeper you dig in ice, the older the information get. And then by some geology magic, we can find where do the particles originate.

This is how a simple particle such as a grain of sand can bear information about the past events that happened on earth.