We are Stardust: Supernovas and the Heavy Elements

530729main_tycho_665 — Expanding globe of debris from the explosion of Tycho's Star. Tycho Brahe observed the star as it went supernova about 540 years ago. The red is the debris, the stardust, created by the explosion. Image from NASA.

We could have been talking about the nuclear meltdowns in Japan, but I’m not sure. Our conversations tend to wander. I remember trying to explain where the carbon atoms, that are so essential for life, came from. It’s been a while since we saw this topic, so I figured it wouldn’t hurt to go it over again. And then I found this wonderful image of the Tycho supernova from the Chandra space telescope. Supernovas are where the heaviest atoms are formed.

In the beginning … the big bang created just the smallest elements, hydrogen and helium. But even these tiny things have gravity, so they pull each other together until there’s so much stuff that the pressure at the center of the clump is enough to fuse hydrogen atoms together.

Now fusion is easy to confuse with chemical bonding that occurs around us every day. After all, the hydrogen in the atmosphere is usually in the form of H₂, which is two hydrogen atoms bonding together by shared electrons.

With fusion, on the other hand, the single protons that make up the nuclei of the hydrogen atoms are pushed together to create a bigger atom, helium. I say pushed together, because it takes a lot of pressure to fuse atomic nuclei. And it also releases a lot of energy. Notice all that heat and radiation that comes from the Sun? All that energy was created by the fusion of hydrogen atoms; the smallest element, hydrogen, fuels the stars.

Fusion-clarified — Fusion of two hydrogen atoms to create helium, compared the chemical bonding of hydrogen atoms to produce hydrogen gas (H₂). The nutrons are left out for clarity.

The huge amounts of energy released by fusion makes fusion power one of the holy grails of nuclear energy research. If we were able to create and control self-sustaining fusion reactions, just like what happens in the Sun, we would have a source of tremendous energy. There is a lot of research in this area. Some people have figured out how to build fusion reactors in their basements, but these use a lot more energy than they produce so they’re not very useful as a power plant (Barth, 2010). The ITER reactor, currently being built in France, aims to be the first to produce more electricity than it uses.

Now back to the stars. Hydrogen atoms fuse to form helium, but it takes a lot more pressure to create larger atoms: carbon has six protons, nitrogen seven, and oxygen eight. These elements are essential for life (as we know it). The only time stellar forces are great enough to produce these are when stars explode; an exploding star is said to have gone nova. Bigger atoms, like iron (26 protons), gold (79 protons), and uranium (92 protons) need even greater forces, forces that only occur when the largest stars go supernova.

So if these elements are only produced in novae and supernovae, how did they get to Earth? How did they get into your DNA?

Well when stars explode, a lot of these newly formed elements are blasted off into space. It’s a sort of cosmic dust. We could even call it stardust. It’s matter, just like the hydrogen and helium from the big bang, only bigger, which means they have more mass, which means they have more gravity.

Nebula_6 — Formation of the solar system (model).

The gravity pulls the stardust together with the hydrogen and helium sill floating around in space (there’s a lot of it), to form new stars, and, now that there are the larger elements to create them, rocks, asteroids, and planets.

So, if you think about it, some stars needed to have been formed, lived their lives (which consists of fusing hydrogen atoms until they run out), and exploded to create the matter that makes up the planets in our solar system and the calcium in our bones, the sodium in our blood, and the carbon in our DNA.

Notes:

1. Lots of information about Tycho’s Star on SolStation.com.

And Women Inherit the Internet

Women are the routers and amplifiers of the social web. And they are the rocket fuel of ecommerce.

–Aileen Lee (2011): Why Women Rule The Internet on TechCrunch.com.

Last month I observed that the girls in my class were blogging a lot more than the boys. It’s still true, and now there’s an informative, if somewhat hyperbolic, article by Aileen Lee that asserts that the blooming of social media websites is driven, primarily, by women.

I’m always a bit leery about articles like this one. There are lots of statistics, a few anecdotes, and a brief reference back to some scientific research (Dunbar numbers), but the overly excited language coming from a venture capitalist is enough to remind me of the irrational exuberance of the dot-com bubble.

The writing is so over-the-top, that I’m truly surprised that there isn’t a single exclamation point in the entire article! Although, based on Ms. Lee’s first words in the comments section, this might be due to the herculean efforts of a good editor.

My antipathy might also be due to my irrational, visceral distaste of the language of business and commerce, which is so geared toward breaking people into faceless demographic groups to be marketed to that it verges on being dehumanizing. I suspect my feelings are truly irrational because I’ve seen scientists do similar parsing of demographic statistics and have had no trouble; although, perhaps, I may have been a little more empathic because the scientists were looking at issues of vulnerability to disease, infant mortality, and the like.

However, since the article’s anecdotes correlate with my own anecdotes, I find it hard to disagree with the underlying premise: women are more inclined than men to make and nurture social connections so they are a key demographic in understanding the future of the internet.

It’s also a reminder that the social atomization typified by the dominance of the nuclear family at the expense of extended family, is now being ameliorated by social networking, which suggests some interesting social and cultural changes in a, possibly, more matrifocal future.

(hat tip The Daily Dish).

Trail of Tears State Park in Missouri

trail-of-tears-outlook-panorama_b — View over the Mississippi River from the scenic outlook in the Trail of Tears State Park. The outlook juts out over rocky bluffs, which allows you to see the flood plain across the river.

Driving through Missouri last week, I stopped at the Trail of Tears State Park, which may be an excellent place to study the post-colonial history of Native Americans (perhaps as part of our civil rights discussions), and observed the Mississippi River and its flood plain before it becomes engorged at its confluence with the Ohio River.

In 1830, President Andrew Jackson passed the Indian Removal Act, which called for the removal of American Indians living east of the Mississippi River to relocate west of the Mississippi River. …

While some of the Cherokees left on their own, more than 16,000 were forced out against their will. In winter 1838-39, an endless procession of wagons, horsemen and people on foot traveled 800 miles west to Indian Territory. Others traveled by boat along river routes. Most of the Cherokee detachments made their way through Cape Girardeau County, home of Trail of Tears State Park. While there, the Indians endured brutal conditions; they dealt with rain, snow, freezing cold, hunger and disease. Floating ice stopped the attempted Mississippi River crossing, so the detachments had to set up camps on both sides of the river. It is estimated that over 4,000 Cherokees lost their lives on the march, nearly a fifth of the population.

–Missouri Department of Natural Resources: Remembering an American Tragedy

The small museum at the main park building does a very good job of trying to dispassionately tell the tragic story.

View Trail of Tears State Park, MO in a larger map

trail-of-tears-nature-walk — Taking a break on the Nature Walk behind the park's museum.

There’s a short, 1 km nature walk behind the building that was nice on a beautiful, sunny day in early spring. Warm, with the trees just barely beginning to bud you can get a feel for the ridge-and-valley topography of the park, which is in stark contrast to the flat floodplain of the Mississippi on the other side of the river. The park’s roads weave up and down the ridges, and I wished I’d had my bike with me.

riverside-campground-barge — Barge going downstream on the Mississippi River, past the river-side campground.

This early in the year (mid-March) most of the campgrounds in the interior of the park seem to be closed, but there is one down on a beach of the Mississippi River that was empty but open. This one has electrical hookups which is not a bad thing if you have the place all to yourself.

The scenic outlook is a wooden platform that juts out through the trees so you can see across the Mississippi to the flat floodplain and farmland beyond. Sitting on a cliff of sedimentary rock (it looked like limestone from a distance), the outlook is high enough that you can just make out the shapes of old meander bends and ox-bow lakes.

It’s a small park, probably worth a visit for the museum, and the outlook is nice, but probably not somewhere you’ll want to spend the night unless some of the upland campgrounds are open.

The museum’s focus on the relocation of the Cherokee would be a nice followup to the pre-Columbian focus of the Chucalissa Museum in Memphis.

cape_giradeau-river-wall — Cape Girardeau River Wall.

If you’re looking at river processes, you’ll probably also want to stop in Cape Giradeau, which boasts a fromidable wall to protect the downtown from the Mississippi River’s spring floods.

Panyee F.C.: Soccer on the Lake

This cute, little, true story of how a bunch of kids (they look like adolescents) living on rafts in a lake built their own soccer field (on rafts), and eventually created the Panyee Football Club, is actually an advertisement for the Thai Military Bank (TMB), but it’s quite inspirational nonetheless. The setting and videography are also superb.

Editing and Reviewing

Even if seven editors and seven reviewers, marked it up for half a year, I doubt they’d be able to completely clean up the mess I post to this blog every day (and they’d be full of bitter tears). However, in case they were willing to try, I thought it would be useful to be clear about what I mean by editing and reviewing.

Editing is catching all the grammatical errors, loose spelling, punctuation and so on that the author is liable to miss. Usually it is because he or she is reading what they thought they wrote, not what they actually typed. It might also involve checking citations to make sure they are right. In this case, it does not involve extensive fact checking, though at a real newspaper it would. Partly that’s because facts can be so malleable, but mostly it’s because I believe that making sure the facts are right are the responsibility of the author.

Reviewing is a lot harder, largely because, since it primarily deals with style, it is extremely subjective. I will admit that an awful lot of people are likely to consider my writing boring and atrocious, but I will often disagree. Good review is a process of negotiation. The reviewer tells the author what they like, and why, and what they don’t like, and why. Then, instead of yelling, the author carefully considers the comments and adjusts their piece accordingly. The reviewer then looks it over again and gives the same type of feedback as before. Ultimately, what’s published remains the responsibility of the author; they make the final choice about which comments to accommodate and which to ignore, but good reviewers are invaluable if used well.

So, if you see a tag at the bottom of a post saying “Reviewed by So and So”, or “Edited by So and So”, or even, “Reviewed and edited by So and So”, please spare them a moment’s thought because they’re not an easy or trivial jobs. This is especially true for a blog where the author sets themself the task of posting something every day, and finds it hard to stop writing once they’ve started. Even when they know they should. Like now.

Peat Pellets

We just planted seeds using peat pellets. The students are always impressed by just how much they expand when you add water, so one student decided to record it on video. Since they recently acquired a new iPhone app that reverses the video, they posted the video played backwards.