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Tuesday 30 September 2014

TWDK makes two "Your Life" pledges

Your life STEM campaign logo
Helping young people to discover a passion for science that takes them to university and beyond is an important part of our mission here at TWDK.

So I'm very happy to announce that Things We Don't Know is one of 200 British businesses that are pledging their support for the Your Life campaign, with the purpose of inspiring young people to study maths and physics as a gateway to exciting and wide-ranging careers.

Specifically, TWDK is making the following two pledges:

Tuesday 23 September 2014

Ten Things We Don’t Know about Tyrannosaurs

Tyrannosaurus rex and its closest relatives, the tyrannosaurs, are among the best known and most popular dinosaurs - and yet there is still plenty we don’t know about these fascinating creatures...

Photograph of "Sue", a Tyrannosaurus Rex at the Field Museum of Natural History in Chicago, IL.
Despite its name, we don't know if the T-rex we know as "Sue" was male or female. Dinosaurs aren’t sexually dimorphic, including T. rex; their skeletons provide no clue as to their gender. The only evidence we have of a particular specimen's sex comes from either finding eggs inside of a skeleton, or finding medullary bone in long bones. Medullary bone has been found in only one T. rex so far. Image credit: Heather Paul (CC-BY-ND)

1. What age could T. rex live to?

It's possible to work out how old a tyrannosaur was when it died, by looking at growth rings inside its bones - just like counting the rings of a tree. The oldest T. rex yet examined in this way has been nicknamed Sue, and is on display at the Field Museum. It’s thought that Sue was 28 years old[1] when it died. Only about a dozen skeletons have been cut up to determine their age, and there are other T. rex’s that look like they might be older than Sue, but haven't had their growth rings counted. This means that we really don’t exactly know the maximum age of T. rex; it's possible that it will turn out to be much more than 28 years once the sample of adults has increased.

2. How were tyrannosaurs related?

Evolutionary trees are diagrams that can be drawn to show how animals are related to each other. Researchers gather data and use this to try to reconstruct the evolutionary history of a group of species - but it isn’t always simple. At the moment there are two versions of the evolutionary tree of tyrannosaurs[2][3] which differ in which species they include, and where they appear on the tree. As more data is collected, trees produced by different groups of researchers usually become more similar. It is likely that with more time and research we will, eventually, find a history that all of the available data supports. Until then though, how tyrannosaurs evolved remains something we don’t know.

3. What did their eggs, embryos, & hatchlings look like?

Despite the popularity of tyrannosaurs, we don’t know anything about the earliest growth stages of any tyrannosaur species. Currently, there are no skulls or skeletons of embryos or juveniles up to a year old. We don’t even know what a tyrannosaur eggshell looks like - very few embryos have been discovered inside fossilised eggs, which is the only way we could be certain of the species the egg belonged to, so the number of dinosaur species identified in this way is very low. It could be that tyrannosaur eggs have already been collected (among those that currently lack embryonic bones) but we just haven’t realised it yet! Hopefully this situation, at least for eggs and embryos, will change very soon as dinosaur eggs are being discovered all the time in places such as China.

Monday 15 September 2014

Wondering about water

One day back in the last century (literally) while I was working on my PhD, I went on an expedition into the University’s library archive. I remember it as a dusty cavern with rows of metal shelves creaking under the weight of volumes that smelled of old paper. You had to get a special key to get in, and I remember nervously looking over my shoulder just in case the lights flickered out and my life turned into a cheesy horror movie. I can’t remember what I was actually looking for now, but what I do remember is that I got diverted. In an ancient, dusty volume I found a paper which had been written about a hundred years ago, at the start of the 20th century.

It concerned the structure of water, its bonding and the shape of the molecules. It was a bit of a revelation at the time. I had been drawing the classic ‘Mickey Mouse’ water molecule diagram for years and I’d just never thought about the fact that there was a time when the structure of water was an unknown. Something that people argued over and, indeed, published papers about.

Now, fast forward a few years, and Things We Don’t Know have asked me to write about water clusters, something which is currently at the edges of chemistry. It almost seems meant to be.

Diagram of water molecule H20 showing pairing of electrons, electron sharing between atoms or covalent bonding, and the effective dipole moment of the molecule. Image copyright Things We Don't Know (CC BY 3.0).
Scientists use the "delta" symbol δ to mean “a little bit”. Oxygen is very electronegative, which means it draws the electrons it's sharing with hydrogen (in a covalent bond) towards itself. This leaves the hydrogens slightly positive and the oxygen slightly negative. You might also think it resembles a famous cartoon character, but we couldn't possibly comment. Image ©Things We Don't Know (CC BY 3.0)

Water is important stuff. Without it, life wouldn’t have evolved on this planet. It’s made up of one atom of oxygen and two atoms of hydrogen, joined together with the oxygen in the middle as H-O-H. One of these elements, oxygen, is the second most electronegative element (topped only by its periodic table neighbour fluorine). Electronegativity is a much-abused term in the world of pseudoscience; all it actually means is the ability of an atom to attract electrons in a covalent bond. Hydrogen is far from the least electronegative, but it’s pretty wimpy by comparison. So basically, examine a water molecule and you find that oxygen has greedily dragged the bonding electrons around itself, like a child refusing to share her sweets with the poor, deprived hydrogen atoms.