Saturday, December 31, 2011

The scale of atoms

Saw this on Phil Plait's Bad Astronomy blog and loved it.  Phycisist Brian Cox on a BBC show called "A Night With the Stars" talking about why atoms are mostly empty space.  Watch it!

As Plait says "Post script: can you imagine a show like this running on American TV? No, I can’t either..."   God forbid, with 100+ cable channels, there should be some intelligent program material (which I why I don't even subscribe to cable TV).

In my introductory science classes, I like to explain to students how atoms are really small, mostly empty space, and not at all like they commonly imagine.

Let's look at the size of a typical atom. Nothing is more typical than hydrogen - the most abundant element in the known universe. Hydrogen is simple - it's just one negatively charged electron orbiting a positively charged proton (let's ignore electrically-neutral neutrons for now).

Below left is a simple model of a hydrogen atom. This type of model is called the Bohr model after Danish physicist Niels Bohr. While this is how most people visualize atoms - as hard, little electrons orbiting a nucleus like planets around a star - it's completely incorrect as a physical model. We'll come back to that in a bit.

Above right is an image from Wikipedia showing the diameter of the proton in a hydrogen atom (1.7 x 10-5 Å) and the diameter of the atom itself which is the orbital shell of the electron (1.1 Å).

For those of you unfamiliar with angstroms (Å), one angstrom is equivalent to 10-10 meters.

Why no diameter for the electron?  Well, it's complicated and physicists generally treat it as a point charge.  We can say that the mass of the electron is 1,836 times smaller than the mass of a proton, however.  That's like comparing my weight to something weighing 2 ounces.

Now, let's look at the relative sizes of the nucleus and orbital shell for a hydrogen atom.

     (1.1 Å / 1.7 x 10-5 Å) = 64,706

In other words, in a hydrogen atom, the electron orbital is 64,706 times the diameter of the proton in the nucleus.  Let's make that easier to visualize.  Image we blow up the proton to the size of a golf ball.  Wikipedia gives the minimum diameter of a golf ball as 43 mm or 4.3 x 10-2 m.

     [(1.7 x 10-5 Å) / (4.3 x 10-2m)] = [(1.1 Å) / X]
     X = [(1.1 Å) (4.3 x 10-2m) / (1.7 x 10-5 Å)]
     X = 2,782 m
     Divide diameter by 2 for the radius = 2,782 m / 2 = 1,391 m

That's 1.4 km or 0.9 miles.  In other words, if the proton nucleus of a hydrogen atom were the size of a golf ball, the electron would be orbiting almost a mile away!  That's why we say atoms are mostly empty space!

Atoms are also really, really small.  How small?  Let's compare the size of a hydrogen atom to the size of a penny.  Once again, Wikipedia to the rescue telling us that a U.S. penny is 19.05 mm in diameter (1.9 x 10-2 m).

      (1.9 x 10-2 m / 1.1 x 10-10 m) = 172,727,273

A penny is 173 million times the diameter of a hydrogen atom!  How big is a penny if we blew it up 173 million times?

     1.9 x 10-2 m x 172,727,273 = 3,281,818 m = 3,281 km

For reference, the diameter of the Moon 3,475 km.  Let's suppose a careless astronaut dropped a penny on the surface of the Moon.  The size of that penny compared to the Moon is about the same as the size of a hydrogen atom compared to a penny!

Back now to the Bohr model of the atom.  The image of electrons orbiting a nucleus like the image at left is useful for understanding how atoms bond, it really does give us the wrong idea.

The modern, quantum mechanical model of an atom has variously-shaped electron "clouds" around the nucleus with electrons essentially behaving as waves.  Electrons can only occur in certain orbitals because they're essentially like standing waves as Brian Cox explains in the video.  To really understand this, you have to understand the mathematics of the Schrödinger equation.

Reality gets very strange at the atomic scale!

Friday, December 30, 2011

The 1700 Cascadia Quake

Since I just reviewed Jerry Thompson's Cascadia's Fault book, I thought I'd also say a few words about the massive earthquake which occurred on the Cascadia subduction zone back in 1700.  Before we do that, let me just remind everyone what a magnitude 9.0 earthquake is like when it occurs on a subducting plate under the seafloor.

On March 11 of this year, an earthquake of this magnitude occurred beneath the ocean floor 43 miles east of the Oshika Peninsula of Japan.  The quake and resultant tsunami killed over 15,000 people and resulted in an economic cost of over 200 billion US dollars.

On December 26, 2004, a similar type of earthquake occurred just off the west coast of Sumatra in Indonesia.  The resultant tsunami killed over 200,000 people around the Indian Ocean and caused tens of billions of dollars in damage.

Similarly large earthquakes have occurred along offshore subduction zones in 1985 in Mexico, 1964 in Alaska, and 1960 in Chile.  They're not especially uncommon.

Queule, Chile, before and after the 1960 earthquake and tsunami

In the late 1980s and through the 1990s, researchers like USGS geologist Brian Atwater started noticing evidence for a very large earthquake along the Pacific Northwest coast.  Groves of trees were found submerged into salt water and killed when the land suddenly subsided.  Radiocarbon dating and studies of growth rings in the trees narrowed the time of the earthquake to around 1700. 

Submerged cedar forest - Willapa Bay, Washington

A connection was then made to historical records of a tsunami striking numerous villages in Japan on January 27, 1700 (leading to a date of the earthquake of January 26).

Painting of 1854 Hiro Village, Japan tsunami

Pacific Northwest native peoples also had legends of a large earthquake and tsunami (although not specifying a date).  Many of the stories are wrapped in stories of battles between mythological creatures like Thunderbird and Whale. 

Here's one matter-of-fact account from at 1864 diary entry by James Swan, the first schoolteacher on the Makah reservation at Neah Bay near the Straits of Juan de Fuca...

Billy also related an interesting tradition. He says that "ankarty" but not "Irias ankarty" that is at not a very remote period the water flowed from Neah Bay through the Waatch prairie, and Cape Flattery was an Island. That the water receded and left Neah Bay dry for four days and became very warm. It then rose again without any swell or waves and submerged the whole of the cape and in fact the whole country except the mountains back of Clyoquot. As the water rose those who had canoes put their effects into them and floated off with the current which set strong to the north. Some drifted one way and some another and when the waters again resumed their accustomed level a portion of the tribe found themselves beyond Noothu where their descendants now reside and are known by the same name as the Makah or Quinaitchechat. Many canoes came down in the trees and were destroyed and numerous lives were lost. The same thing happened at Quillehuyte and a portion of that tribe went off either in canoes or by land and found the Chimahcum tribe at Port Townsend.

Now let's review the following image from my previous post.

See that red dot labeled "Subduction zone earthquake (1700)"?  Can a magnitude 9+ earthquake and resultant tsunami happen again along this subduction zone?  Absolutely!  Large sections of this megathrust fault have been basically locked for 300 years or so and there is a chance that it will let go in our lifetimes.

A piece of advice... If you're on a Pacific Northwestern beach or live in a low-lying area, and you feel a large quake with prolonged shaking, run, don't walk, to higher ground!

Wednesday, December 28, 2011

Cascadia's Fault - Part 2

Finishing my review of Cascadia's Fault by Jerry Thompson.  Read yesterday's post if you haven't already and then come back here...

My last post illustrates the biggest problem with the book - not one diagram of the Cascadia subductions zone.  Not one map.  Not one cross-section.  The purpose of the book is to make the public “sit up, pay attention, and get ready” yet non-geologists will simply not understand the geological explanations Thompson provides.  It would have been trivially easy to include these illustrations, and Thompson does provide a few pictures of historical earthquakes, like the 1964 Good Friday quake in Alaska, so it's puzzling why he didn't do so.

One strength of the book is the historical background but even this comes with a caveat.  Geologists began recognizing the danger of the Cascadia subduction zone around the time the modern theory of plate tectonics was being developed.  It was an exciting, and sometimes acrimonious, time in geology.  Thompson covers this historical development in detail, almost too much detail at times, yet fails to capture this excitement.  I honestly found much of the central part of this book to be tedious reading and started skimming even though I should have been interested.

Finally, the book was a bit sensationalistic (Thompson was trained as a journalist and he wants to sell documentaries).  The subtitle "the coming earthquake and tsunami that could devastate North America" is a bit overblown and the last part of the book is an absolute worst-case scenario of what could happen if a major earthqauke occurred along this fault zone.

So, bottom line, I can't recommend this book that much but it is an important issue and an interesting geologic feature which could cause great devastation when it lets go some day.  If you're still interested in reading it, borrow the book from the library like I did.

Tuesday, December 27, 2011

Cascadia's Fault

I recently read Cascadia's Fault: The Coming Earthquake and Tsunami that Could Devastate North America by Jerry Thompson (Counterpoint, 2012).

Thompson is a documentary filmmaker living outside of Vancouver in British Columbia who's produced and narrated several television documentaries on the Cascadia fault for the CBC.  Thompson's interest in the Cascadia subduction zone was due, in large part, to his home being located in an area that might be directly affected by a large earthquake along that fault zone.

I have to confess that I wanted to like this book, but I'm afraid I didn't.  First a little background...

I don't believe regular readers of this blog need much of an introduction to plate tectonics. The Earth's rigid outer shell, called the lithosphere, is split into a number of tectonic plates which all move relative to one another.  Virtually all of the continental United States and Canada, with the exception of a small sliver of southern California, is sitting on the North American Plate.

Just offshore of the Pacific Northwest (Northern California, Oregon, and Washington) is a small plate of oceanic crust called the Juan de Fuca Plate.

Since I love tangential stories, I'll share the following.  Juan de Fuca was a Greek navigator (Ioánnis Fokás) who sailed for Spain to look for the fabled Strait of Anián, a supposed Northwest Passage across the top of North America, and claimed to have discovered it in 1592.  The English captain, Charles William Barkley named the Juan de Fuca Strait in 1787 in his honor believing that's what Juan de Fuca described from his voyage almost 200 years earlier.

Anyway, here's a closer view of the region.  The north-south purple barbed line just off the coast of the Pacific Northwest is the Cascadia Subduction Zone - the trench down which the Juan de Fuca plate subducts as it pushes eastward, away from newly-forming ocean crust at the Juan de Fuca and Gorda Ridges, and as the North American Plate moves westward away from the distant mid-Atlantic Ridge on the opposite side of the continent.

Here's an oblique-view of the region showing the subduction of the Juan de Fuca Plate down the Cascadia Subduction Zone beneath North America.

Melting of the subducting plate provides magma for the Pacific Northwest chain of volcanoes comprising the Cascades Range.  Mount Lassen, Mount Shasta, Crater Lake, Mount Hood, Mount St Helens, Mount Rainier, and others have all erupted in historic times and will all erupt again (many people living in the shadows of these beautiful mountains are in a state of deep denial about that fact).

Subduction zones are also the locations of some of the largest and most destructive earthquakes on Earth.  So, while the San Andreas Fault is the one in the public's consciousness, the Cascadia Fault is potentially just as deadly (if not more so).

Let me just add that if Thompson, the author of Cascadia's Fault, had given a background like I did above, with drawings of the plates and subduction zone, I would have reviewed his book much higher than I will tomorrow, when I finish this discussion!

Monday, December 26, 2011

Gastroenteritis for Christmas

One of the downsides of being the parent of young children is that they occassionally get sick.  Then they make you sick.  My 10-year-old son picked up a stomach virus last week and gave it to me just in time to have a low-grade fever all day on Christmas Eve and unable to enjoy all the good food and beverages on Christmas Day (a turkey dinner with all the fixings at my house).

On the positive side, The worst of it is only 24 hours and it's mostly gone after a couple of days.  I also lost a couple of pounds over Christmas weekend rather than gaining weight as I normally would have done!

I've been feeling bad about not keeping the blog active lately but really stressed over the last few weeks of the semester.  Hopefully, things will be back to normal (relatively, at least) soon.  I've been reading some interesting books lately on geology and hope to share some of that this week.

Monday, December 19, 2011

Ding, dong, the evil little dwarf is dead

Kim Jong-il, the evil little dwarf that has enslaved North Koreans for several decades has assumed room temperature.  The only sad part is that it wasn't the result of a bullet to the head.

The late Christopher Hitchens had an interesting article in Slate a while ago titled A Nation of Racist Dwarfs which is worth a read.

And here's the famous image from space of the Korean Peninsula at night.  See South Korea all lit up (especially Seoul).  North Korea is pretty much all as dark as the Gobi Desert (the one bright light in Pyongyang).

What I am completely unable to understand are the brainwashed North Koreans weeping and wailing because "Dear Leader" is dead.

Boys and girls, no one on this Earth ever deserves to be worshiped as a god.  No one.  Ever.  Anyone who wants this is an egomaniac asshole.  You'd think no one would have to say this.  Evidently not.  People are just naturally stupid and easily led, I suppose.

Saturday, December 10, 2011

Japan tsunami dash cam footage

Just saw this dash cam footage from a guy who survived the Japanese Tohoku earthquake and tsunami last March 11 in his car.  Check out how quickly the water rose and the cars bobbing like corks...

Never underestimate the power of mother nature!

Tuesday, December 6, 2011

Selling science

A colleague brought the following New Scientist article, Science in America: Selling the Truth, to my attention recently (unfortunately, you need to register to read this article).

From the start of the article:
JOHN HOLDREN, science adviser to President Barack Obama, is a clever man. But when it comes to the science of communication, he can say some dumb things. In January, Holdren welcomed the prospect of climatologists being called to testify before Congress: "I think we'll probably move the opinions of some of the members of Congress who currently call themselves sceptics, because I think a lot of good scientists are going to come in and explain very clearly what we know and how we know it and what it means, and it's a very persuasive case."
The article explains that this is the "deficit model" of science communication, which assumes that opposition to issues like climate change result from a lack of knowledge about the subject.  In other words, we just need to "educate them" and the opposition will be convinced.

Well, of course it's not that simple.  The article claims, and I concur, that all of us "filter and interpret knowledge through our cultural perspectives, and these perspectives are often more powerful than the facts."  Obvious examples of this are the opposition to the concept of biological evolution from many Evangelical Christians and the misguided belief that vaccines cause autism by many on the other side of the political spectrum.  There's even evidence that education may strengthen our cultural biases, not weaken them as you might expect.

The proposed solution?  If you want to change someone's mind on a controversial issue, find someone they identify with to make the argument.  In other words, don't expect Al Gore to change a Conservative's mind on climate change.  An Inconvenient Truth, with its not-so-subtle digs at George Bush, would be rightly viewed as having an ideological bias (even if the overall message was scientifically-based).  Don't expect an atheist will be able to convince Evangelical Christians that young-Earth creationism is not science.  Of course they don't believe God created man, they would think, the don't even believe in God.

To convince political conservatives that climate change is real, one needs to first repect their ideological beliefs, even if you don't share them and find conservative scientists to discuss the issue (they do exist).  Similary, Christian scientists (not the Mary Baker Eddy type!) are the ones best able to convince other Christians that young-Earth creationism is nonsense.

While I understand the necessity of talking about "selling science", it also makes me somewhat uncomfortable.  Many people in this country already hold to a type of postmodernism that claims scientific ideas are purely human constructs with no objective reality.  I mostly reject that idea as, I think, do most practicing scientists.  Scientific "truth" does not belong to the person making the cleverest argument as you might see on a Fox News type scenario of two talking heads arguing climate change as if all opinions on the issue are equally valid.  They're not.  The opinion of an atmospheric scientist with 30 years of research experience and peer-reviewed publications does not have the same weight as that of a state senator with a degree in business when it comes to climate change.

Monday, December 5, 2011

I'm back (I think)

I haven't posted anything for two weeks but needed a break.  Thanksgiving was a busy time and we're now in the home stretch for the fall semester (today starts the last week of classes and final exams are next week).

I've also has a staff member abruptly resign and I have a lot of work to deal with that (forensic recreation of what the person was working on at the time, hiring and working with a temporary replacement, writing a new job ad, etc).  We're also in the process of rewriting all department syllabi to make sure we have assessible student learning outcomes and assessment plans. Political bullshit - don't get me started on that topic.

I've been so stressed lately I've been having lots of dreams at night about working.  Nothing interesting or exciting in the dreams - just me working.  It sucks.  I wake up exhausted. Also working on losing some weight and cutting back on some of life's pleasures - good food and good beer.  Easy rule of thumb, if I like it and it gives me pleasure, it's bad for me.  If there is a god - he's cruel that way.

To top it all off, it's the "Holiday Season." One of my wife's nicknames for me (she has many, few flattering) is Scrooge. Yes, I hate Christmas.  Not Christmas Eve and Christmas Day, those are fine, it's nice to see the kids all excited about getting presents and the warm feelings associated with all of that (I'm not a monster).  What I hate is the lead up.  The raw, naked greed exhibited by retailers (and some people) in the weeks leading up to Christmas.  Let's celebrate the birth of Christianity's Messiah by buying shit we can't afford (and often the gift recipients don't really want or need) on credit.  If it was up to me, we would just celebrate the solstice at my house.

I totally avoid retail stores and malls in December (online shopping works just fine, thank you) but sometimes can't avoid the big increase in traffic (and holidays seem to bring out the worst drivers).  I also DESPISE having to hear "Christmas music" EVERYWHERE!!!  Do I really need to hear Jingle Bell Rock in fucking Starbucks or Dunkin Donuts or Panera when I want a cup of coffee?  Really?  It doesn't put me in the holiday spirit, it makes me even more grouchy than I already am since I'm usually in line behind people who appear to have all the time in the world (yes, I'm impatient too).  Is "Fuck you!" an appropriate response to "Happy holidays!" from some cheery cashier.  Probably not, but that's what I'm thinking.  I'm a very, very bad man.

So, anyway, I'll try to start posting more regularly again.  I'll even try to make the posts about science!  Just needed to vent a bit.