Ice is Nice!!!

extreme-ice-fishing

Today, I spent a while in my front yard shoveling the foot or so (let’s use 3 decimeters…that sounds much cooler) snow out of my driveway.  As I was LOLing at my neighbors who were all stuck in snow drifts because it is apparently against the law to plow my street, I started to think about how ridiculous snow is.  One day you go outside and there’s a blanket of ice shards as far as the eye can see.  It really is a bizarre phenomena.  So, it seemed fitting to go on about how awesome ice actually is.

Thank Goodness for Hydrogen Bonding

The thing that makes ice specifically, and water in general, pretty awesome is the hydrogen bond.  Regardless of how much science you’ve been exposed to in your life, everyone knows that water is H2O; two hydrogen molecules attached to a single oxygen molecule.

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The whole idea of bonding in chemistry of the sharing of electrons.  Hydrogen has one lone electron and an inferiority complex; it really wants to be like its buddy helium, which has two electrons.  It wants this because, with two electrons, it will be essentially non-reactive (the outer shell of electrons will be full), and this is energetically favorable.  Nature enjoys things that are energetically favorable.  Likewise, oxygen, which has six eight electrons, really wants to be like its buddy neon because, like helium, neon’s outer shell of electrons is full, making it fairly non-reactive.  So, when two hydrogen atoms and one oxygen atom get together, they strike a deal.  Oxygen, the ring leader, says “Tell you what…if you two hang out close enough to me, I’ll let you ‘borrow’ a couple of my electrons, so you can be like helium, and in return, you’ll let me ‘borrow’ your electrons so I can be like neon…win-win for everyone!”  Thus, we have water.

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However, the shape of water is important.  The fact that it is bent slightly makes the charge distribution just a little asymmetric and the molecule acts like something called a dipole.  One the whole, the molecule as a whole is electrically neutral.  But, since the positive and negative charges are separated a bit, the negative part can be attracted to a positive charge nearby and the positive part can be attracted to a negative charge nearby.  This will cause the molecule to rotate into alignment with an electric field.  Indeed, this is how your microwave works; as the microwaves pass through the object and the polarity of the wave switches back and forth from positive to negative, the water dipoles rotate back and forth, creating a kind of friction that heats the material.

If you put a bunch of water molecules together, they don’t just float around in any old way.  The positive parts of each molecule attract the negative parts of other molecules.  This action is known as hydrogen bonding.  It is much weaker than the covalent bonding that holds the water together, but it is responsible for most of the awesome properties of water and ice.  For instance, water is “wet” because of hydrogen bonding…hydrogen bonds are created between the water and the molecules of whatever it’s on,  making it atomically “sticky” when you get it on your skin.  If you’ve every played with mercury from a thermometer, you may have noticed that it doesn’t wet anything, it just rolls around.  This is because there are no hydrogen bonds present.

Fantastic…but why does this make ice nifty?  The molecules in liquid water have enough kinetic energy to constantly break the hydrogen bonds and move around.  This is what makes water, well…water.  It’s viscous because of hydrogen bonds, far more viscous than it would be without them.  If you add heat, the molecules speed up, gaining kinetic energy, and eventually all hydrogen bonds break and the molecules fly apart…STEAM!!!  In fact, one interesting fact is that if hydrogen bonding did not exist, liquid water would boil at around -90°C!  Considering how important water is to life and its development, it’s a good thing this is not the case.

If you remove heat, the molecules loose energy and hydrogen bonding becomes a more dominant process.  At the freezing point, the molecules no longer have enough energy to break the hydrogen bonds and “flow”.  The water then crystallizes into ice.

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The hydrogen bonding forces the molecules into layers of rippled hexagons; I added the little copper rods in the picture above to represent this bonding.  This brings be to something waaaaaay cool.

Snowflakes

The hexagonal structure imposed in normal ice is what is primarily responsible for the hexagonal symmetry seen in snowflakes.  A snowflake is an individual crystal of ice that forms when a small droplet of water in the atmosphere supercools around a nucleus, something like a dust particle or our ever-present smog.  Once this nucleus forms, the surrounding vapor droplets freeze and aggregate onto the crystal.  However, the hydrogen bonding imposes symmetry onto the deposition…so we get the familiar snowflake.

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This image was taken of an ice crystal with a scanning electron microscope; the colors were added afterwards to increase contrast.

So, the thing that really makes water interesting is this hydrogen bonding.  Without it, we wouldn’t have liquid water at the normal temperature of the Earth and we wouldn’t have bazillions of amazing snowflakes with unique shapes falling onto our tongues…and onto our walkways and roads…at 2 am…that we have to plow and shovel.

There is another interesting consequence to hydrogen bonding, though.  As the water freezes and takes on this hexagonal structure, the overall effect is to push the molecules away from each other into the rigid pattern of ice.  The result is that ice is less dense than liquid water and, as we all know, floats in water.  This is actually quite remarkable; there are very few substances whose solid phase is less dense than it’s liquid.  An example of a very not-water example of something else that has this property, check out gallium.

This fact has had profound impact on Earth.  If ice was like every other solid and was more dense, then the freezing process would start from the bottom up.  If this were the case, then the oceans, lakes, and streams of our planet would freeze from bottom up, destroying life.  The hydrogen bonding in ice is what has made it possible for life evolve; without it, all of our water would have frozen long ago and life could never have developed in the oceans for billions of years.  Erosion from freezing and thawing would also not exist, as water would not expand as it froze.  Our landscape would look very different.

There’s More Than One Type of Ice

Several years ago, I got around to reading the novel “Cat’s Cradle” by Kurt Vonnegut.  It revolves around the creating of this material known as ice-nine, which is a weapon of mass destruction that can turn all of the liquid water on Earth (and in your body) to ice at a much higher temperature than normal.  It’s a pretty good read, albeit bizarre.

After getting through it, I was looking up ice-nine on the Interwebs to learn about it’s cultural references when I can across this line line at the top of its Wikipedia article which kind of blew my mind:

“This article is about the fictional material in Cat’s Cradle. For the metastable form of solid water, see Ice IX.”

The ice that we all know and love is actually only one possibility.  It’s the form that we experience because the conditions of it’s formation, namely pressure and temperature, are common to Earth.  However, it isn’t the only kind of water ice.  In fact, there are more than a dozen forms of ice; “normal” ice is referred to as Ice 1h since is hexagonal.  There are all sorts of crazy forms…and they have wacky properties.

Ice 1c, for instance, doesn’t have a hexagonal structure. Instead, it has the same cubic structure as diamond and forms in the upper atmosphere in small amounts.

Ice XI is probably the coolest (haha) form.  It is likely the most common form of ice, because it is actually more stable than normal ice.  However, it only forms below 72K, which is colder than liquid nitrogen.  Despite this, we have found some in Antarctica under the right conditions, namely pressure deep below the surface.  Crystalline water in space and on the surface of places like Jupiter and Saturn’s moons is most likely this form.  What’s really interesting is that Ice XI is a type of material known as a ferroelectric.  You’re all familiar with a ferromagnet, it is a material that can hold a permanent magnetic moment, which is responsible for permanent magnets.  A ferroelectric can hold a permanent electric polarization.  This means that the material as a whole would not be electrically neutral.  Crystals of Ice XI floating in space would attach each other electrically, similar to the idea of static electricity, and would be “sticky”.  It is thought that this contributed to holding together enough material to allow the formation of the icy bodies in the solar system, such as comets.

So, ice is pretty awesome.  If it wasn’t for it’s specific properties, life and, perhaps, the entire planet, would not exist.  We wouldn’t have comets and we wouldn’t have snowflakes (at least not the awesome ones we have now).  I am happy, though, that the ice on Earth isn’t more exotic…it would suck even more to shovel out of my driveway.

Big Ba-Da-Boom!!

New Year's Bang

So, as some of you may have heard, the physics building in which I work was shut down for the day due to a frozen helium dewar in one of the basement labs, turning it into a potential explosion hazard.   I felt compelled to tell you (and by “you”, I mean anyone that gives a crap enough to keep reading, especially through this parenthetical statement) why a frozen dewar sucks pretty bad.

First off, what is a dewar?  It’s basically a super Thermos that is used for storing cryogenic liquids, such as liquid nitrogen, oxygen, or helium, for use in low-temperature experiments.  Here’s a helium dewar in my lab; we’re using it to cool down a cryostat so that we can perform superconductivity experiments.

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The basic construction is an inner and outer reservoir, separated by vacuum.  The thing is, even though there is vacuum inside and the reservoirs don’t physically touch, heat can still convect through the gap.  This is why coffee in a Thermos…

…wait, I’m not drinking coffee right now.  BRB…

Ok…crisis abated.  Anyway, this is why coffee in a Thermos doesn’t stay warm forever.  Convection of heat is not nearly as effiecent as conduction of heat (grab some hot metal LOL), but given time, it will transfer the heat from the coffee to the outside world.  In this case, heat is transferred from the outside world into the cryogenic liquid in the dewar.  Of course, when you heat up a liquid beyond the boiling point, it phase changes into a gas.  In your coffee thermos, this isn’t really an issue, because even if you put cold liquid inside, the temperature outside is far below the boiling point of water (hopefully).

The problem with liquid helium is that it has a boiling point of 4.2K.  That’s cold.  Very cold.  4.2K is about -450 °F.  Clouds of gas in interstellar space are 5 times warmer than this.  Saying it’s cold doesn’t really get the point across.  I’ve had the experience of pumping liquid helium into a device (see the above picture and check out the top of the cryostat) and the effect of being near it is basically the opposite of the experience of pre-heating the oven to 400, opening the door, and putting your face in.  This poses several issues.

First, the ambient temperature of the room the dewar is in can easily supply enough heat through convection to boil the helium.  So, unlike a Thermos, a dewar requires safety valves that can vent the gas that builds up inside.  The other problem is that helium is so cold it will freeze the air (think about that for a minute) and build up ice in the above mentioned valves, blocking them.

That’s what happened in the physics building yesterday.  A dewar of 100L of helium had been delivered to a lab on Wednesday.  When they went to insert the pumping apparatus into the top of the dewar, ice had completely clogged the intake.  They opened the safety valves to vent the helium gas that was certainly building up, but they were also iced up.  The dewar was basically a giant dry-ice bomb waiting to explode.  If you’ve ever made a dry-ice bomb and seen the devestation created there-by,  imagine doing that with 100L of helium in a giant steel cylinder that is about 3 feet in diameter and 6 feet tall.  It would be bad.  In fact, don’t imagine it, allow me to describe it!

How Bad Could It Be?

There are several things at play here.  We have a gas in a container that is building up pressure.  When that pressure reaches some critical value, the vessel will burst, releasing 100L of liquid helium.  Needless to say, it won’t stay liquid and will immediately expand into gas, releasing energy in the process.  The question is, how much energy?

First, we have to think about latent heat.  Latent heat is the energy it takes to make a substance complete a change of phase.  For instance, if you have a block of ice at, say, -20 °C, you can add energy to warm it up to 0 °C, the melting point of water (under normal conditions).  However, as you add more heat and melt the ice, the water/ice mixture will stay at 0 ºC until you melt all of the ice.  Only then will the water, if you continue to add heat, increase in temperature until you reach the boiling point.  The energy you added served to change the solid ice into liquid water and the amount required to do this is called the latent heat of fusion.  Consequently, you would have to remove that energy to freeze water back into ice; the nifty science word for freezing is fusion, btw.  In similar fashion, and assuming you could contain it, as you boil the water at 100 °C and create steam, the water/steam mixture will remain at that temperature until all of the water has been vaporized; this energy is called the latent heat of vaporization.

As you may imagine, the vaporization energy is much higher than the fusion energy.  The heat of fusion for water is 334 kJ/kg whereas the heat of vaporization is 2260 kJ/kg, almost 8 times more!  This is why steam sucks way more to be burned by; when it hits your skin and condenses, it puts all of that energy into you.  Also, ice “feels” cold because, when you hold it, the energy of fusion is pulled out of your skin to melt the ice.  SCIENCE!!

A bit of a side note…what is a kJ?  The metric unit of energy used in science is the Joule, which has the symbol J.  So, kJ is a kilojoule, or 1000 joules.  But that probably doesn’t help, because most people are familiar with calories.  A calorie is just over 4J.  But (and this is really stupid), the calorie you’re probably familiar with is the one listed on food.  You’ve probably never noticed, but the word “calorie” is always capitolaized.  This is because “food calories” are actually kilocalories, not just calories.  So, our 2000 Cal/day diet is actually 2,000,000 calories/day, which is about 8,200,000 J/day.

Back to the helium dewar.  The latent heat of liquid helium and normal pressure is 20.3 kJ/kg and it turns out that 100L of liquid helium has a mass of about 12.5 kg.  So, the process of turning 100L of liquid helium into gas would require about 254 kJ of energy.  This is about the same as the number of calories in a single Oreo cookie.

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The problem is not the heat, though you have to realize that that energy would be drawn out of the room into the helium; that’s what makes it feel so cold.  The problem is that gaseous helium has a much greater volume than liquid helium.  In fact, it will expand by a factor of 748 times.  So, the 100L, which is 0.1 m³, will expand to fill a volume of about 75 m³ when released.  Over a long period, this doesn’t matter.  However, if the dewar ruptured, the helium would boiled off almost instantly and expand very quickly.  Turns out, the energy released by the gas expanding from 0.1 m³ to 75 m³ is about 7,820,000 J.  This is approximately the amount of energy released when detonating 4 sticks of dynamite.

That would be very bad.  To make things worse, this doesn’t really take into account the energy released in actually rupturing the dewar, which would increase the above energy by about a factor of 10.  If that dewar exploded in the basement, it would be akin to detonating 40 sticks of dynamite.  That makes for a very bad day for all parties involved, particular the poor bastards in the room with it.  Even if they managed to survive the blast, all of the air would be replaced with helium and they would asphyxiate.  That’s why hazmat was called and the building was evacuated…and we were happy to leave.  Not to mention the damage to the lab; if you need liquid helium, you can assume that what you’re putting into probably cost at least a million dollars.

That’s why cryogen dewars are kind of a big deal when they freeze up.  As an added bonus, you now know that the energy intake you need everyday to run your body is equivalent to detonating 4 sticks of dynamite.  Science rules!

“Gigantic multiplied by colossal multiplied by staggeringly huge…”

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I have been watching a brilliant show produced by the BBC called “Wonders of Life”, a 5-part series about the origins and functionality of life, narrated by Dr. Brian Cox, whose mouth my wife takes issue with.  As you can imagine, the program starts with a description, using the current scientific wisdom, of the beginning of life on Earth and, indeed, anywhere.  I have no intention (at this point, anyway), to descend into a discussion on the origin of life.  To quote Neal Stephenson’s Cryptonomicon, “let’s set the existence-of-God issue aside for a later volume, and just stipulate that in some way, self-replicating organisms came into existence on this planet and immediately began trying to get rid of each other, either by spamming their environments with rough copies of themselves, or by more direct means which hardly need be belabored.”  But, there is a point that is made in debates about the origin of life that I would like to address, as it is frequently on my mind.

A common argument against life “just happening” seems to be that the complexity that exists today simply could not have randomly occurred, presumably over the given timescale. It’s like digging up a naturally occurring pocket watch or monkeys with typewriters creating a Shakespeare sonnet.  As I see it, a core issue here is the human mind’s lack of ability to comprehend large amounts of anything: time, money, number of things, etc.  As a scientist, I have to deal with quantities that are completely beyond everyday experience all the time…so ridiculous, in fact, that we had to invent scientific notation to express the numbers because words just fail.  Archimedes, the Greek badass that brought us things like the screw and the lever, pondered huge numbers in his work title The Sand Reckoner, where he conjectured that the grains of sand on the beaches of Sicily were infinite.  The Hitchhikers Guide to the Galaxy has this to say about infinity: “Bigger than the biggest thing ever and then some. Much bigger than that in fact, really amazingly immense, a totally stunning size, real ‘wow, that’s big’, time. Infinity is just so big that by comparison, bigness itself looks really titchy. Gigantic multiplied by colossal multiplied by staggeringly huge is the sort of concept we’re trying to get across here.”  Are they really infinite?  Well, no…but the number is so ridiculously huge that they are uncountable.  We have words and concepts, but we can’t really connect them to reality without really digging in and calculating something or generating a sequence of “things” to put it in perspective.

Take, for example, the chemical quantity known as the mole.  All matter is made up of atoms, but the number of atoms in “stuff” is incomprehensibly large.  The mole was created to scale that huge number down to something manageable.  One mole of “things” is equal to 6.02e23 items.  The “e23” just tells you how many times you multiply by 10.  So, 6.02e23 is equivalent to  602,000,000,000,000,000,000,000 things.  That’s a stupid amount of things.  How stupid?  Here’s an exercise to help put it in perspective.

I went into my wife’s office an snagged a random romance novel…“Slightly Sinful” by New York Times best-selling author Mary Balogh.  Not my thing, but anything for science!  Busting out my ruler, which I have since placed in a more accessible location since the last time I measured something, I find that the average area covered by a single letter on any given page is about 2 mm².  The page itself has dimensions 10.5 cm wide by 17.5 cm high, which gives an area of 183.75 cm².  If the page was completely packed with letters, each page would contain 6589 letters; more realistically, given indentation, spacing, margins, and empty space, 1500 letters per page is a reasonable estimate.  Now, the book has 355 pages, which means there are approximately 532,500 letters in this book.  So far so good…

This book is 2.5 cm thick.  Given that a mole is stupid huge, we need a large distance to work with…like the distance from the Earth to the Moon!  This distance, from surface to surface, is 376,292 km.  Thus, if you were to stack up copies of “Slightly Sinful” from the surface of the Earth to the surface of the Moon, you would have 15,100,000,000 books in the stack, that’s 15.1 billion books.  Side note: if you bought these books for the list price of $6.78, the national debt ($16.7 trillion) would buy you 163 of these Earth-Moon stacks…New York Times best-selling author indeed.

Each stack of books gives us 8.04e15 letters.  Now, create that stack 74, 875,622 times (!!!), and you will have one mole of letters.  If you were to count the books, not the letters, just the books, at a rate of 1 per second, it would take roughly 36 billions years, almost three times the age of the universe.  If you were to stack them up in a single stack, that stack would extend 28 trillion miles.  Voyager 1, of which there has been much hoopla as of late, wouldn’t even be halfway up stack by now.

Damn…

When you look on the Periodic Table, you see stuff like this:

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In the top-right of the square is the atomic mass of iron, 55.847.  This is the number of grams of iron you need to collect to have one mole of iron atoms.  Now, this…

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…is a cool nail that I inherited from my dad’s garage a few months ago.  It has a mass of just over 40g.  So, there are as many atoms of iron in this nail as there are letters in 54 million stacks of “Slightly Sinful” that reach from here to the Moon.

Again I say, damn…

To carry on the ridiculousness, consider that the Earth’s core is about 0.5% the total mass of the Earth itself and is comprised almost entirely of iron.  The mass of the Earth is about 6e24 kg, therefore the core is a lump of iron with a mass of about 3e22 kg.  Divide that by the mass of my bitchin’ nail, an you get 7.5e23.  So, there is about 1 mole of nails in the Earth’s core.  Which means there is a mole of mole’s worth of iron atoms!!!

Continuing on, ask yourself where does all of the iron come from?  Supernovae!!  It is formed in the cores of superheavy stars and then blown out into the Universe, where it accretes due to gravity and eventually forms planets like ours.  There is a debate, but the average amount of iron ejected into space in a supernova is projected to be near 0.2 solar masses, that is 20% the mass of the Sun.  The mass of the Sun is a whopping 2e30 kg!!  That’s 4e29 kg of iron per supernova…13 million moles of nails!!

Current estimates place the number of stars in the observable Universe at about 1e24…there’s 10 moles of stars!!!  Only about 3% of stars will be massive enough to die in a supernova.  Consider that the Universe is estimated to be about 13.7 billions years old and stars that are massive enough to supernova have a lifespan, say, of around a billion years (a high estimate).  So, it is estimated that there have been at least 2 generations of stars in the universe before the current crop, given the amount of time it takes to accrete enough mass to make a star in the first place.  So, 3% of the current number of stars is about 3e21 stars.  If each generation had the same number of stars supernova, then 6e21 stars have blown up, each injecting 4e29 kg of iron into the Universe.  That is 2.4e51 kg of iron…that is almost 1 million moles of moles of nails!!!!!!

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This exercise got really, really stupid a long time ago.  The point is that people have such difficulty understanding ridiculously large numbers that it is hard to trust yourself when you start working with them.  When you start writing down numbers that have 51 zeroes on the end, you are obviously well beyond common experience.  When science starts talking about things that involve such large quantities, it is really difficult for people who aren’t comfortable with them to understand.  It’s hard to imagine the amount of water in the ocean (1,386,000,000 cubic km), the distance to the nearest star (39,900,000,000,000 km), the number of neurons in the human brain (100,000,000,000 cells), or the amount of carbon dioxide humans put into the atmosphere each year (26,000,000,000 kg).  And yet, we have conversations about these types of things all the time.

Back to my original inspiration, when one talks about the origin of life as having randomly occurred because one cosmic ray hit one molecule in the ocean just right so that it formed the amino acid need to self-replicate, that seems completely impossible.  But, consider the fact that you had an entire ocean’s worth of chemicals “steeping” for a billion years being bombarded by cosmic rays in an era well before there was any kind of atmospheric shielding to protect the surface.  One mole of reactions could have easily have occurred…maybe, nigh probably, more.

My ultimate point here is not about the origin of life.  What I want to convey is the simple fact that our everyday notions of number an probability just don’t cut it when we talk about things on geologic timescales and in quantities that defy language.  Am I an expert on such existential things as how life began?  No.  But, I am comfortable with ridiculous quantities that one encounters when discusses it.

The question, then, is this: did “God” have to create life on Earth?  Maybe he just put the pot in the oven and let the soufflé rise on it’s own…