The Oldest Rocks on Earth

At 200 X 400 micrometres this zircon crystal extends the limits of our understanding of early Earth back to 4.4 billion years ago, a mere 100 million years after the Earth was formed and only 160 million years after the Solar System formed. This discovery pushes back the date for when Earth first had a solid crust and weakens the theory that at this time the Earth was hot and entirely molten. It seems the conditions were much milder much earlier than we thought. There are two methods of dating these minerals, via radioactive dating methods and using atom probe tomography. The research group who dated this sample used atom probe tomography, but I am going to talk about radioactive dating methods.

Zircon crystals are brilliant for radioactive dating because of two reasons. Firstly they're tough, they last a long time and can withstand an amount of tectonic pressures. Secondly, and most importantly, they form with radioactive uranium in their structures AND they do not form with lead in their structures. Why is this significant?  Radioactive uranium degrades into lead. So we can say that any lead present in the crystal is due to the decay of the uranium and nothing else. Zircon crystals are special in another way. They form with two different radioactive isotopes of uranium which both degrade at their own independent rates into two differing isotopes of lead.

Radioactive decay happens with precise timing. We know how radioactive decay works and at what rate it happens at. It's an exponential decay that is as regular as clockwork. Whether this happens over billions of year, hours, minutes or microseconds, all radioactivity follows exponential decay that is given in a simple mathematical expression.

So essentially zircon crystals are like clocks that were set to zero when they solidify from molten rock. Actually more like two individual clocks in each crystal because of the two different radioactive decays. All we need to do is to look at the ratio of uranium to lead to tell what time it is, just like looking at the two hands of an analogue clock. And the beauty is that we have two clocks running simultaneously and confirming each other.

So you start off at time zero with 100% of the parent isotope. This degrades at an exponential rate to a daughter isotope. For example:

We can say how fast each radioactive decay occurs by a concept called 'half-life'. A half-life is defined as the time when half the amount of the parent isotope has decayed into the daughter isotope. So at time zero there is 100% parent isotope and at the half-life there is 50% parent isotope and 50% daughter isotope. And because this decay is exponential, at 2 times the length of the half-life the parent isotope is at 25% and the daughter at 75% and so on.

Each radioactive decay happens at its own rate. For example the half-life of uranium-235 is 704 million years, the half-life of uranium-238 is 4.5 billion years, while ruthenium-106 is 1 year, carbon-11 is 20 minutes and lithium-12 is 10 nanoseconds. So for the two uranium decays in zircon you can see that the decay from uranium-235 happens at a much faster rate than that of uranium-238.

Scientists trying to age a zircon crystal look at how much of uranium-238 versus lead-206 there is and how much uranium -235 versus lead-207.

You can use these ratios to back calculate ages of the crystal. Looking at uranium-238 there is nearly a 50-50 mix of parent to daughter isotopes, so therefore it is just under the age of its half-life of 4.5 billion years. With the uranium-235 you can see that most of it has decayed to lead-207 and there isn't much uranium left at all. It has gone through many half lives. In fact we can calculate it has gone through 6.25 half-lives and 6.25 multiplied by 704 million years is 4.4 billion years. So you can see how the correlation of the ages calculated of these isotopes are a powerful tool with both results pointing to 4.4 billion years or so.

The same method of looking at the ratio of parent to daughter isotopes is used for all radioactive dating. The other type of dating that you may have heard of is radiocarbon dating or carbon-14 dating. This method looks at the amount of carbon-14 in a sample which could be some bones of animals or humans or trees or other living things. Because all living things have a large amount of carbon in them, some of the carbon is naturally occurring carbon-14 (as opposed to the normal carbon-12). When a living thing dies it does not absorb any more carbon into its system and the carbon-14 that remains decays. So the amount of carbon-14 left in a biological sample tells us how long ago it died. The half-life of carbon-14 is 5,730 years and so if we find half the expected carbon-14 in a sample is must be around the age of 5,730 years. This method is limited to around 60,000 years or 10 or so half-lives. After this time there is only 0.1% of the parent isotope left and the error becomes too large to be reliably date a sample.

So you can see how radioactive decay is a useful tool to date objects. You cannot use every type of radioactive decay out there to age objects, it is limited to systems where you know the concentration of one isotope at time zero. But luckily there are several systems where this occurs and knowing this fact gives us a glimpse into the distant past.

Just for the hell of it here is a zircon crystal from my own collection. It's probably nowhere near as old as 4 billion years as it is large and was from a location in the Northern Territory that is not renowned for it's age.

Massive Solar Flare

Photo from NASA / Solar Dynamics Observatory

These are a series of images taken of a massive solar flare that occurred on Monday the 24th of February. The images are of the same flare at the same moment but differ in that they are taken at different wavelengths. Kind of like if you took a photo of a butterfly at different wavelengths and one photo displayed all the red on the butterfly, another green, and so on. But these images are of light at smaller wavelengths than we can see, and at a much higher energy.

The wavelengths are given on the images in Angstroms or 10^-10 m, 100 million millionths of a metre. The light we normally see ranges from 3900-7000 Angstroms and these pictures are taken at wavelengths shorter than this. 1600 Angstroms is in the near UV spectrum, while 94 Angstroms is in the extreme UV. The actual colours shown in this photo are false and are just used to help visualise the images better.

While this is the largest recorded flare for this year, the scientists at the Solar Dynamics Observatory state that the effects were minimal here on Earth due to the location of the flare on the surface of the sun being directed away from us. No pretty aurora from this ejection.

Source: The Solar Dynamics Observatory Website.

Ronald E. McNair: Physicist and Astronaut

George Takei just shared this wonderful video on Facebook. It tells a story told by Ronald E. McNair's brother about an incident that happened in their childhood. Ronald E, McNair later became a physicist and astronaut. He was selected for the astronaut program in 1978 and later flew on the Challenger mission STS-41-B in February 1984. He was later selected for the ill-fated Challenger mission STS-51-L of January 1986 in which all crew died 73 seconds after liftoff.

The video is made by a group called 'Storycorps'.

Watching a Demolition

So it's not everyday you get to witness the demolition of a 200 metre tall smoke stack in your hometown. But today I had the privilege and it was quite a spectacle. Everyone who wasn't at work at the time and even those at work flocked to many sites, hilltops and the mountains to watch the stack come down. I watched it from a far off vantage point, up at a look-out on the mountain escarpment.

The stack is what remains of a copper ore processing facility and was built in 1965 which was the height of industrial activity in Port Kembla, mostly dominated by a large steel plant. All throughout it's life the region has dealt with pollution concerns. In fact, in a brilliantly naive decision, the facility was built next to a public school. The solution once awareness was greater to install toxin monitors and alarms. The generation who saw it built and who had a hand in it's construction are still around. While most are proud of the great industrious work they did, it is hard to ignore the 40 year contribution of pollution in the region. As I was growing up in the 80's and 90's there were constantly news articles about pollution and acid rain in the region. The surrounding region would be covered by a film of fine metallic dust high in lead and other toxins.
The plant finally closed in 2003 and the facility has remained dormant since. Application for demoltion was sought in 2010 and demolition was postponed until asbestos could be safely removed before demolition.

It was amazing that everyone was out to see the event. I heard that all the nearby beaches and coastline was full of onlookers. Even my vantage point, a small tucked away look-out, was full of other like-minded people. There were retirees, couples and families all out to see this great event.

The aspect that astounded me most is how long it took to fall. I could have sworn the initial explosion (noticed by sight) happened 4 or 5 seconds before a noticeable lean in the stack. It came down very slowly and only left a small dust plume. I was probably about 10 km away from the tower and the sounds of the explosions had a significant delay which was quite hilarious in it's own right. A little lesson in relativity.

There were several helicopters and planes filming the event and here is footage taken by Channel 7 Sydney:

Braigo: The Braille Printer Made of LEGO

Shubham Banerjee, a 7th grade student from California has made a braille printer from a LEGO Mindstorms kit. If that is not enough, it is a great innovation in that other braille printers can cost $2000 for a basic version and a LEGO Mindstorms kit costs $350. In a world with a large portion of people with seeing impairment being from developing countries, this innovation may open the doors to educating vision-impaired people from those areas. Not only that but if these kits are donated, the communities may also benefit by providing children experience in programming and innovation. It wins on so many levels. While the development is only in the early stages, with only the english alphabet being programmed, Shubham is carrying on his great work expanding into programming numbers into the system. He has also made available to everyone his plans and programming in a gesture of great goodwill. 

It just goes to show how great LEGO and young minds mix. They can change the world.

Book Review: 'An Astronaut's Guide to Life on Earth' by Colonel Chris Hadfield

Most of us nerds got a good idea of who Chris Hadfield is from his youtube videos last year filmed on the International Space Station. For the last few years the Mars rovers have been the sexy at NASA with the demise of the shuttle, the hitchhiking on Russian craft, oh and that psycho cross-country drive diaper caper really doing a number on NASA astronaut public image. But then Chris Hadfield and mustache came along and fixed it all up again. After a gap of 20 or so years I find myself wanting to be an astronaut when I grow up again.

So I approached this book with some delight, expecting some fun stories from his time in space; how they go to the toilet etc. Which is what you get, to some degree, but you get so much more. The same man who has enough passion to make those videos and promote space exploration so well in that medium can also write a hugely inspiring, humble and insightful work on his life, his philosophies and the universe.

Dotted between the stories of Chris' years working at NASA are wonderful insights into behavior such as how to take criticism, how to learn not to worry and plan instead, how to constructively think negatively, how to keep yourself inspired and set and achieve goals. And most importantly how not to be an asshole while doing it. These lessons meant more to me than other 'life lessons' that you see in the bookstores under self-help or inspiration. This advise made more practical sense than any quote I have seen attributed to the Dalai Lama or some such. But I don't think this type of inspiration is for everyone. I think it will be most applicable to the engineering/scientist type mindset, just like Chris himself.

So this book comes most highly recommended. I felt at times that I was right alongside Chris in parts of his journey and I listened intently to his wisdom on how to be a person with integrity, humility, determination and a sense of humour.

Two fish are in a tank. One turns to the other and says "How do you drive this thing?". Like this.

Book Review: 'The Hobbit' by J.R.R. Tolkien

So after 20 or so years, I finally got around to rereading 'The Hobbit' and it was like reading it anew. I obviously had no previous memories of it, and I'd guess that although I read read it as a precocious child who read beyond their age, I didn't really comprehend that much. Even though this is geared towards a younger audience.

But this time I had so much fun. The prompting to get my finger out was my enjoyment of the movies, especially 'The Desolation of Smaug' (going to re-watch it again in a couple of days). So it was high time I read it.

I guess with the movies being out there and the book being well-read I don't need to talk much about the story. It is a simple story, but for when it was written it was virtually unique. And you can tell that it is written to be read out loud. I'm going to have to purchase an audiobook of this.

So what more can I say? I had a lot of fun reading this and I am ashamed it took me so long to get around to it. Tolkien is the only author that I'll read that can have a dragon on the cover and a map of pointy mountains at the beginning of the book. Have you read it yet? If you haven't why haven't you? Get around to it. You'll have a lot of fun.

Scalzi's 'Redshirts' Coming to Television

It is reported that Scalzi's wonderfully clever book 'Redshirts' is being adapted for television by FX (some US cable company). This is absolutely great news and hopefully it is done faithfully to the book.

The story of 'Redshirts' is a direct satire of Star Trek, where unimportant Redshirts get killed very often, yet senior officers seem invincible. A group of the Redshirts notice this and start plotting and investigating. A great story ensues.

I hope these guys have a great legal team as who knows how Paramount, the company that owns Star Trek, may want to act about it.

Book Review: 'On The Map' by Simon Garfield

Who here loves maps and can pore over a map of an unknown territory, real or fictional, for hours imagining the geography and the adventures to be had? Yeah you are one of those people, a lot of us are. In fact I'd hazard to say that a majority of geeks and nerds are. It's part of who we are and a natural expression of our imagination and deep passion for things.

In the last couple of years there has been a few books about maps starting to be published. It seems that we are all rediscovering our childhoods love of the atlas and also discovering that we weren't the weird outsider we thought we were. The last book on maps I read was a beauty, 'Maphead' by the wonderfully hilarious Ken Jennings (see my review on goodreads.com). Ken takes a look at several applications of mapping in the last few decades and engages with these activities, interviews people involved and just has a lot of fun.

'On the Map' provides a different and more traditional look at maps by presenting a chronological history of cartography via selected maps, or mapping techniques. Simon takes us on a journey from the very first attempts at mapping the known world, the Mappa Mundi, right through to GPS systems and mapping in video games.

It's hard not to compare Simon's work with Jennings' even though they take a different perspective upon the subject and do compliment each other. There were some points where I felt a little let down by Simon, but I'll get to those points after, because despite these, it was a damn good read. Simon has chosen by far some very interesting tales to tell about the history of cartography, and it seems he has done a great deal of research. Each chapter is clear and concise and very entertaining. It is clear that Simon is a great fan of maps and is enthusiastic to share.

But onto those niggling negatives, and there are only two. Firstly, there is a chapter on mapping in video games that is quite well-researched and he admits that the maps and geography in these games are intricate and the effort that goes into these works is astounding. Yet he writes derisively about these games being time wasters and infers that people who play these games are on the fringe of society. Surely he has heard of leisure activities and that normal people play these games not just unemployed stoners. Anyway, being a bit of a gamer, especially a fan of sandbox games, where mapping and geography get expressed in the most beautiful ways, I felt disappointed  that Simon did not express a greater understanding and appreciation of these points.

Secondly, there were instances when Simon interviewed  a person about a subject that he was writing about and mentions going to meet this person etc. But sometimes there was no more information about this meeting or person for more than a paragraph. I am supposing that most of what he talked to the person about made it into the text as pure information, but it seemed like that in a few instances I would have liked to have heard more from that person and about that person. I know I have written a lot about these negatives, but they are very small.

I purchased this book without looking at a single review and it was a great surprise that it was so good. I don't often purchase books blindly these days. Part of the motivation was that a few weeks previously I had visited a great exhibition of maps in Canberra (National Library for all the Australians. Go see it!). It was a great surprise to have a major part of a chapter about one of the highlights of that exhibition, the Fra Mauro world map, an imposing approx 3m X 3m intricately detailed 15th century map.

So Simon has produced a wonderful work that expresses deep love for the subject. It is both a fun and informative read that is also well-written. I'd recommend this book for anyone who loves maps. Yes you!

Book Review: 'The Knowledge: How to Rebuild Our World From Scratch' by Lewis Dartnell

Thank you to both Netgalley and Random House UK for an advance reader copy in exchange for an honest review. 

If someone came up to me and said "Hi, here is an instruction manual to rebuild civilisation after collapse. You're welcome!" guess how I'd react. There would be sarcasm and the little wizened skeptic that lives in my head would be having a field day. And I did approach this volume with an amount of skepticism. How can you boil down all of civilisation into one 250 page volume?

Being a fan of post-apocalyptic fiction I am no stranger to the thought experiment. The first 'grown-up' book I ever read was John Wyndham's 'Day of the Triffids'. My older sister was assigned this novel to read in high school and complained about a stupid novel in which stupid plants come to life and kill everyone. Not ideal for a thirteen year old girl, ideal for a eleven year old boy. Ever since then I have had a soft spot for apocalyptic fiction with stand-out favourites being 'Earth Abides', 'The Walking Dead' comics and the other works of Wyndham. So I have been part of this thought experiment for a while now.

And as my education has furthered into the sciences and gone into research, my environmentalism has increased and the knowledge of human activity with respect to the stability of the climate has caused these thought experiments to become more of a possible future reality. I believe it is within the realm of possibility that civilisation as we know it could collapse during my lifetime. The more I learn, the more I realise it would not take much at all to tip the scales into a decline in drastic decline in living standards.

It's obvious that Lewis has thought extensively on this also. But he is infinitely more talented and had set himself the task to write an instruction manual to reboot civilisation. And despite approaching this work with complete skepticism, I come out the other side amazed and completely humbled by this work and it's author. Lewis has achieved exactly what he has set out to do. This is a work that I would want in my hands in an apocalypse. The irony being that I have read this reviewer copy as an e-book, the most inaccessible method of transmission of data in a coming apocalypse. A part of me even feels that paper might not be robust enough nor last long enough to hold this wisdom.  I'd sleep better at night knowing that this was reproduced in stone buried in a sealed crypt somewhere far from any cities.

What Lewis offers isn't a complete set of instructions (but some methods are described in great detail), but rather an overview of differing technologies such as agriculture, food preservation, basic and advanced chemistry, communications and more with specific methods and examples of the history of certain technologies and how to reboot these technologies from scratch. And Lewis admits that reproducing the historical progression of science and technology is not the most efficient reboot scenario, and that just having certain knowledge can hopefully leapfrog past certain stages and methods. He even suggests that several technologies that were adopted were inferior to abandoned competitors in hindsight and that a new civilisation should take advantage of this hindsight.

Lewis' writing is succinct,accurate and informative. His ability to refine a concept down to one or two sentences that manages to convey exactly how a thing works and why it does what it does is astounding. This is what all educators and science communicators strive for and it seems like he as a great talent. When he was explaining concepts that I have previously learnt I was amazed at the clarity of which he would convey the ideas. How easily can you explain how refrigerators work using the laws if thermodynamics?

What Lewis presents is truly an astounding work that actually does have the potential to achieve what it set out to do. I'd recommend this book for not only any post-apocalyptic fan, but anyone interested in science, technology and any curious person who likes to know why things work. I am now an instant fan of Lewis' and I look forward to the publication of this book in April 2014. I'll at least be buying a paper copy.