Archive for December, 2012

h1

Do we get to visit the Tyrant of Sogo?

December 20, 2012

More exoplanet news! A quite a bit nearer than the planet from my previous post, Tau Ceti has been found to have five planets. One of those planets is in the habitable zone, which has excited quite a few people. They shouldn’t be breaking out the champagne quite yet though, as I shall explain.
Tau Ceti has a low metallicity. This means that it is mainly made up of hydrogen and helium, which in turn implies that any planets surrounding it are also made up of the lighter elements, in other words they are likely to be gas giants.

Artists impression of our sun on the left, Tau Ceti on the right. (Picture by R.J. Hall from wikipedia. Licence: Creative Commons Attribution-Share Alike 3.0 Unported)

Artists impression of our sun on the left, Tau Ceti on the right. (Picture by R.J. Hall from wikipedia. Licence: Creative Commons Attribution-Share Alike 3.0 Unported)

The way we can tell that Tau Ceti has such low metallicity is by measuring the light come off it using a technique called emission spectroscopy. In chemistry lessons at school, you held different elements in a Bunsen burner flame and noted the colour of their flames was different for each element. Emission spectroscopy is a continuation of that, in which the light from a star is separated into its constituent electromagnetic frequencies (think a prism separating a white light into its spectrum), and the elements are classified from those frequencies. The easiest ones to measure using visible light are hydrogen and iron, so a star’s metallicity is usually described as the (logarithmic) ratio of iron to hydrogen, or Fe/H.
This doesn’t mean that there can’t be rocky planets around Tau Ceti, but it does make it a lot less likely. Also Tau Ceti is surrounded by a debris disk – a disk of dust and general bits of not-quite-planets – which would mean any planets would be constantly barraged by impacts.
The important thing, however, is the existence of planets in our local neighbourhood, which means that the universe is a lot more familiar that it appeared at our first glances of it.
The paper is here.

Posted in Space | Tagged , , , , , | 1 Comment »

h1

Videos!

December 17, 2012

A couple of videos to keep you going while I recuperate.

Here is a 25 minute long tour of the ISS by its outgoing Commander, Sunita Williams.

And, waiting for the the end of the fad, students at NASA have released a Gangnam Style parody, which does show us around the Johnson Space Center.

Posted in Space | Tagged , , | Leave a Comment »

h1

Now they’re hiding the Markov Chains!

December 13, 2012

This is just a quick entry to explain why I haven’t been blogging recently. The simplest explanation is that I had a chest cold. I have a number of conditions that make this rather more serious than for healthy people, but that’s no excuse for not blogging! The real reason is that I use speech recognition when I can’t use my hands. As you can imagine, given the current state of speech recognition, a chest cold is not a good thing for getting a computer to understand you. In fact:
“It can imagine giving them a better holding more than they are getting your computer to the new room and”
was the output of my computer’s speech recognition to the previous sentence with my cold.
Speech recognition typically uses a form of a mathematical model that I have discussed before – the Markov model. In fact it uses a more complicated version of it called a Hidden Markov Model or HMM. This uses a set of Markov nodes(states that have a probability of linked to other states) that are not connected to the input or output (and so are called hidden) to allow the model to have a form of “memory” that simple Markov chains don’t. Thus, they can be used to recognize what is likely to come next while the input is streaming in, and so recognize speech. The trouble is, if the input is really different to what it’s used to, it messes up the probabilities, and you get a sentence a bit like the one above.
Hopefully normal service will resume shortly when either my voice or my hands are more usable. Without voice recognition, even this short entry took a few sessions to complete

Posted in Mathematics | Tagged , , , , | Leave a Comment »

h1

TED talks in his sleep

December 7, 2012

You may have heard of TED talks. They are a really good platform for scientists and other specialists to put over their research, especially if it’s groundbreaking. It proved so popular that TED branched out to regional talks, put on around the world and hosted by local institutions, who were given the ability to book the best and brightest in their fields from their local area, under the banner of TEDx. This is where things started falling apart.
Once the vetting was out of the primary organizer’s hands, pseudoscience started creeping in, and it became so bad that people started complaining. I would love to give examples, but unfortunately, I live in the UK and our libel laws tend to beggar people, even if they’re proved right. The majority of the talks were still massively informative, such as Sir Roger Penrose’s cosmology talk (and this talk by my old boss) at TEDxWarwick, but the situation became so bad, that the people at TED have had to produce some new guidelines.
“Excellent!” I hear you cry, and I agreed until I got to this line, about things to watch out for: “The neuroscience of [fill in the blank]”, at which point I became filled with righteous indignation, being a neuroscience bod myself(albeit a mathematical one). Then I typed “The neuroscience of” into Google. By a few pages in, I found myself in complete agreement with the new guidelines. Neuroscience explains a lot of things about physiological responses, but the level of extrapolation required for some of those results, along with a truckload of cognitive dissonance, did wonders for worsening my migraine.
Hopefully this will bring a new era for TEDx talks that echoes the joy of discovery that came with the original launch of TED.

Thanks to Ben Goldacre’s Twitter feed for this news.

Posted in Neuroscience | Tagged , , , | Leave a Comment »

h1

Curiouser and curiouser

December 3, 2012

So, we finally had the Curiosity rover talk at the American Geophysical Union Fall Meeting, where they outlined what had been found, as I talked about here, and the update here. There were some interesting insights, not least that Martian soil contains water with a very high percentage of deuterium(“heavy” hydrogen, which with oxygen makes “heavy water”), which is hydrogen with a neutron as well a proton in its nucleus (normal hydrogen just has a proton).

Are those some rocks I see before me?

Curiosity Rover having a look at some rocks.(Artist’s impression – Credit: NASA)

Deuterium is quite useful as a neutron moderator in nuclear fission reactors, but if we can get nuclear fusion off the ground, it would become far more useful, as it can be used as fuel for both deuterium-tritium fusion and deuterium-deuterium fusion (you can make tritium from heavy water too).
The other news from that talk was that some carbon-chlorine compounds(the slide at 21 mins 17 secs in the talk linked above) were found, which are, strictly speaking organic molecules. The reason NASA are not confirming whether the organic molecules are from Mars is because they’re not quite sure where the carbon came from – was it native to Martian soil, did it come from meteorites or some other form of contamination? This is why they were being rather cagey about their find.
As I’ve said before, this is just the beginning of Curiosity’s mission, so hopefully we’ll get a clearer picture in the days to come.

Posted in Space | Tagged , , , , , , | Leave a Comment »