Hello lovely blog-readers,
How are you this sunny (in London anyway) day? To be honest, I am a bit poorly. My body strongly disagreed with something I ate yesterday, and told me so repeatedly all through the night. This has left me a bit wobbly, and also scuppered my plan to visit the Thames Barrier today and blog about – booooo. So, I thought I’d offer a selection of the must-read science news stories from the past week, and ease myself into a day of writing (and rugby-watching). I’ve just picked two, because apparently I am unable to just paste a url and write one sentence to accompany it :) Hope you enjoy them.
1.Water on Mars. If you missed this, I’m guessing you’ve been in a cave somewhere. NASA had been teasing us all with this for weeks, so the announcement needed to be a biggie, and it was. At their press conference on September 28th, NASA told the world that evidence of salt-laden liquid water on the surface of Mars had been found.
I say evidence of water because water wasn’t directly detected – rather, a series of dark streaks on the surface, that have been known to change with the seasons, were finally explained. Using the CRISM instrument on the Mars Reconnaissance Orbiter, these streaks were confirmed to contain minerals called perchlorates, which are only formed in the presence of water. This is huge news, and has certainly reignited the public’s interest in finding life on Mars, but there are limits.
For a start, these streaks are not a flowing river, more like seasonal seepages of water, so any life we do find there will be microbial at best (but still!). And importantly, NASA won’t just be able to drive the Curiosity Rover up there to investigate it – to do so would put the site at a real risk of contamination from the Earth microbes found on the rover – no matter how clean our clean-rooms are, anything coming from Earth is always covered in microbial life. So NASA must operate under the strict planetary protection protocols – see here for an excellent description of the policy. Realistically, the next step for the researcher will be to identify the source of these perchlorate salts, from the safety of Mars orbit.
I’m expecting to see lots more science coming out of this work, and I’m very excited about it. Unlike those who suggested this announcement was a “a technique to advance the leftist agenda” (I shit you not).
The original paper is here.
2.Carbon-nanotube transistors. IBM announced this week that they’ve made a functioning transistor from carbon nanotubes, just 9 nm (nanometres) in size. To put that into context, lined up side-by-side, you’d fit more than 222,000 of them in a space equivalent to the width of a dried peppercorn.
So why do we want tiny transistors? Because we’re tech-greedy, that’s why. Generally, the more transistors you can fit on a chip, the quicker it can process things and the more you can make it do (like having several tills open in a supermarket at once), so making them smaller is a good option. But it’s not without its challenges. Have you heard of Moore’s Law? This was a observation made in the 1960’s that said that computer chip processing speeds, and so, the number of transistors, doubles every 18 months (later revised to every 2 years). While not a “law” in the physical sense (e.g. Newton’s Laws of Motion), it has been used ever since as a metric for chip manufacturers. And until recently, it held. It is now perfectly normal for “billions of transistors (to) be squeezed onto a chip the size of a fingernail” (NY Times) and the cost-per-transistor has plummeted. But our semiconducting material of choice, silicon, appears to be reaching its size limit – it simply can’t conduct electricity any faster.
Part of this is down to scale – shrinking the transistor is one thing, but in order for it to work, it needs to be electrically connected to the rest of the chip. This means we also need tiny, reliable contact materials that allow electrons to flow across the circuit. Semiconducting carbon nanotubes (CNTs) have long been investigated as a replacement for silicon in transistors, because they conduct electricity incredibly well. But the lack of suitable contact materials for them has meant that once the device was smaller than 10 nm, it couldn’t provide the processing speed of its larger brethren. This announcement from IBM suggests that they’ve finally smashed that tiny glass (silicon?) ceiling.
Rather than the breakthrough being down to the nanotubes, it’s really about a new, minuscule welding technique. IBM researchers have found a way to chemically bond a metal (molybdenum) to the ends of carbon nanotubes. Previously, it had only been possible to coat the entire tube, which made it conductive rather than semi-conductive, pretty much ruining it. These metal ends not only make easier to connect the CNT to the contact, but because the electrons can flow without (much) resistance, the final transistor can operate at speeds similar to larger transistors. So we may be one step closer to a new generation of truly nanoscale electronics. We will have to wait and see.
You’ll find the research paper on this here.
And finally, in not-really-news news, it seems the great tradition of making up words to suit common situations (a la The Meaning of Liff) is alive and well. My mate Ben Valsler came up with a word that neatly sums up how I’ve felt on numerous days lately: confutrated – that feeling you get when you can’t understand something, and it’s really beginning to annoy you. It is my new favourite word and I expect I’ll use it a lot :)
Anyway, I think that’s enough from me. I’m off to find some interesting papers for me to write about for Materials Today. Have a lovely Sunday everyone. And please cheer for Ireland tonight – we NEED to come top of our group! #RWC15