Features

They float like tiny jewels encased in stone: most are only a few millimetres or centimetres long but full of incredible detail – boasting tiny tentacles, eyes, legs, and forceps-like pincers.

‘Many of them are entirely soft-bodied, they have no right to be preserved over 525 million years. They should really have quickly decomposed on the sea bottom, or have been eaten, or destroyed over millions years of earth history’ explains Derek Siveter of Oxford University’s Museum of Natural History and the Department of Earth Sciences.

These are the Chengjiang fossils from Yunnan, China, on display at the Oxford University Museum of Natural History, in the first major exhibition of these fossils outside China.

The Chengjiang fossils, first unearthed in 1984, are particularly important because they open up a window onto one of the most important events in the history of life: the so-called Cambrian 'explosion' when most of the major animal groups we know today first appeared in the fossil record.

The big question has always been: where did this dazzling variety of animals come from? Did they suddenly develop or were earlier examples of complex animals simply never preserved?

These particular fossils have survived because of an amazing stroke of luck: ‘The preservation of all the soft tissues is a result of the organic materials of these animal bodies being replaced by ‘fool’s gold’ – iron pyrites. It means their forms have been captured for posterity,’ Derek tells me.

At first glance they may not be as impressive as the Museum’s dinosaur skeletons or stuffed dodos but, get your nose close enough to the glass cases, and you’ll enter a different world.  

More than 100 species have been recognised from these golden-coloured fossils:

There are examples of groups that include velvet worms (lobopodians) that Derek describes as ‘worms with legs’, 'lamp-shells' (brachiopods) looking like balloons (the body) on the end of a piece of string (the soft, fleshy, tethering stalk), and ancient arthropods, some of them the ancestors of modern horseshoe crabs with armoured bodies and forceps-like appendages – probably for grabbing on to prey – and others probably representing forms that we would identify as crustaceans (this group today includes crabs, lobsters and shrimps).

‘The collection, significantly, also includes the earliest example from the fossil record of what is generally agreed to be a vertebrate,’ Derek reveals.

But as well as these familiar-looking creatures are others that might go unnoticed but are nevertheless vital scientific finds. One example is the sea gooseberry (ctenophore), which looks like a cross between a soft fruit and a diving bell.

There are some 100 species of sea gooseberry floating in today’s oceans and the Chengjiang fossils show examples of these creatures, some with branched tentacles, which like their modern cousins probably captured their dinner by engulfing it.

Derek comments: ‘Here we have examples of the sea gooseberry. They are exceptionally rare as fossils, numbering just a handful of specimens from just a very few localities anywhere on Earth, and the Chengjiang examples are the oldest.’

‘These miraculously-preserved examples give us rare insights into the very early nature of the sea gooseberry and help determine the timing of the origin of this animal group and its place within the tree of life.’

The exceptional preservation of these fossils (in what researchers call a lagerstatte) makes it possible to examine the remains of soft-bodied animals in intricate detail, and such preservation can often give us a much better idea of how they might have behaved:

The wonderful ‘daisy chain’ fossil creatures, that we reported on back in 2008, are one example of this: shrimp-like animals that have congregated together perhaps for reproduction, or more likely as part of some Cambrian migration through the ancient seas.

If you expect life from 525m years ago to look rather primitive then you’re in for a surprise: these fossils reveal fully-formed, finely-adapted animals that seem as sophisticated as many of their relatives we know today – something we wouldn’t be able to say but for their extraordinary preservation.

‘It’s an amazing treasure, it's the Chinese equivalent of the famous Burgess Shale fossils from North America or, put another way, the material is every bit as wondrous palaeontologically as the Terracotta Warriors are archaeologically,’ adds Derek.

The exhibition, ‘Exceptional Fossils from Chengjiang, China: Early Animal Life’, is on display at the OU Museum of Natural History 18 May-14 November 2010. 

The specimens displayed are from the Key Laboratory for Palaeobiology, Yunnan University.

It seems, early on its life, our Universe was a place of extremes.

That’s the conclusion scientists are drawing from new infrared observations of a very distant, unusually bright and massive elliptical galaxy.

This galaxy [in the white square above] was spotted 10 billion light years away, and gives us a glimpse of what the Universe looked like when it was only about one-quarter of its current age.

Measurements show that the galaxy is as large and equally dense as elliptical galaxies that can be found much closer to us. Coupled with recent observations by a different research team - which found a very compact and extremely dense elliptical galaxy in the early Universe - the findings deepen the puzzle over how ‘fully grown’ galaxies can exist alongside seemingly ‘immature’ compact galaxies in the young Universe.

‘What our observations show is that alongside these compact galaxies were other ellipticals that were anything up to 100 times less dense and between two and five times larger – essentially ‘fully grown’ – and much more like the ellipticals we see in the local Universe around us,’ explains Michele Cappellari of Oxford University’s Department of Physics, an author of a report of the research in The Astrophysical Journal Letters.

‘The mystery is how these two different extremes, ‘grown up’ and seemingly ‘immature’ ellipticals, co-existed so early on in the evolution of the Universe.’

Elliptical galaxies, which are regular in shape, can be over ten times as massive as spiral galaxies such as our own Milky Way and contain stars which formed over 10 billion years ago. One way of checking the density of such galaxies is to use the infrared spectrum they emit to measure the spread of the velocities of their stars, which has to balance the pull of gravity.

Measurements of a distant compact elliptical galaxy have shown that its stars were dispersing at a velocity of about 500 km per second, consistent with its size but unknown in local galaxies.

The new study, using the 8.3-m Japanese Subaru telescope in Hawaii, found a ‘fully grown’ elliptical with stars dispersing at a velocity of lower than 300 km per second, much more like similar galaxies close to us.

‘Our next step is to use the Subaru telescope to find the relative proportion of these two extremes, fully grown and compact ellipticals, and see how they fit in with the timeline of the evolution of the young Universe,’ Michele tells us. ‘Hopefully this will give us new insights into solving this cosmic puzzle.’

Dr Michele Cappellari is based at Oxford’s Department of Physics.

The research was conducted by an international team led by Masato Onodera, CEA/Saclay, France.

What with ash clouds and elections the Large Hadron Collider has been out of the headlines recently.

So I enjoyed this update from Paul Rincon at BBC News online who spoke to Tony Weidberg of Oxford University's Department of Physics about the LHC's ATLAS experiment.

ATLAS is looking for new discoveries in the head-on collisions of protons at very high energy inside the machine. Tony explains that within a few months it could be sensitive enough to probe the 1,000 gigaelectronvolt [GeV] mass scale where particles, such as W prime and Z prime bosons, are thought to exist.

Why do these funny-sounding particles matter?

Well, whilst we already know about their lighter cousins (normal w and z bosons are found at 100 GeV) finding these supersized particles could reveal some strange new physics and help us understand the forces that control our universe.

One possibility is that the 'lighter' bosons, which physicists describe as 'left-handed', could be one of a pair.

Tony tells BBC Online: 'We're into speculation here, but one possibility is that the Universe is really symmetric at high energies and that there are right-handed W bosons as well... For some reason, they happen to be much heavier than the left-handed W bosons we know.'

Of course symmetry is just one thing on the minds of LHC scientists.

As OxSciBlog previously reported Oxford's ATLAS team are exploring a range of phenomena with Caterina Doglioni amongst those looking to 'rediscover' the Standard Model, and assess how it fares in this new high-energy world, and Hugo Beauchemin leading the hunt for early evidence of new physics beyond the Standard Model.

Meanwhile Oxford's Cigdem Issever is planning to use ATLAS to find mysterious (but surprisingly non-threatening) 'mini' black holes.

Exciting stuff. The one downside is that, according to Tony, it's likely to be 2011 at the earliest before researchers can start looking for the biggest piece missing from the physics jigsaw: the Higgs boson.

With new fossil fuel power stations being built every week, and the idea of burying CO2 [carbon sequestration] regarded by many scientists as unproven or even unworkable, coming up with an alternative solution to what to do with CO2 is more pressing than ever.

What chemists dream about is turning CO2 from a dangerous greenhouse gas into a useful fuel. But to make this dream a reality will take more than clever chemistry.

That’s why a team at Oxford University is bringing together expertise in chemistry, materials science, engineering and the social sciences to tackle one of the grand challenges of the 21st Century.

A simple recipe
Peter Edwards of Oxford University’s Department of Chemistry, one of the leaders of this team, starts by telling me about the simplest recipe for turning CO2 into fuel: just add hydrogen, then inject some energy from sunlight and you can produce methanol – a versatile feedstock that can be made into all kinds of fuels.

It’s a nice idea, but there’s a big problem. ‘Where do you get the hydrogen from?’ Peter asks. In fact, he explains, 98 per cent of the world’s hydrogen comes from another fossil fuel, methane: and not only is this a finite resource but turning methane into hydrogen takes additional energy and emits more CO2.

'Back in the 1990s chemists had a thought: what if we could bypass hydrogen and make methane and CO2 react to produce methanol,’ he tells me, an idea given a further green boost by the growing resources of sustainable biomethane, especially in India and China.

The new recipe would see this biomethane added to the CO2 that otherwise would be sent up the power station chimney and would harness the existing heat of this CO2-rich ‘flue gas’ to help make the reaction more energy-efficient.

‘It’s all about the energy balance,’ Peter says, ‘if we can use natural gas or biomethane in this process rather than just burning it we’re winning in terms of the energy we get out and the emissions we eliminate.' Now we’re cooking!

Mix with realism
Yet while this sort of chemical recipe was already shown in the 90s to work with a ‘pure’ gas, the sort of emissions that come from a fossil fuel power station are typically full of impurities.

‘Real flue gas is made up of nitrogen oxide (NOx), nitrogen, and oxygen as well as CO2,’ Peter tells me. Up until now dealing with this sort of realistically ‘dirty’ chemical cocktail of gases has been an almost impossible hurdle – especially as scrubbing out the impurities would use up more energy and generate more CO2 emissions.

And if that wasn’t bad enough NOx is a poisonous pollutant that it takes a lot of effort to remove.

Yet the Oxford team - Peter, Tiancun Xiao and Zheng Jiang (the first-ever John Houghton Fellow at Oxford) and colleagues - believe the key to making their CO2-into-fuel dreams a reality lies in new catalyst technology and a different way of thinking.

Instead of getting rid of the NOx the team believe they can use it as a catalyst to help power the reaction. They also cite the fact that the latest technology makes it possible to work with the sort of ‘dirty’ nitrogen-rich gas mix produced in a power station.

To be able to turn the CO2 in this mixed gas and methane into methanol in a power station without an accumulation of carbon causing everything to grind to a halt will take a new generation of nanoscale-structured magnetic catalysts.

Because such catalysts, based on metallic compounds like cobalt oxide, are magnetic they can be moved around by strong magnetic fields, agitating or ‘stirring’ them to ensure that the reaction is more efficient and doesn’t snuff itself out. It’s a novel approach that will require new research in materials science, chemistry and physics to work.

A good result
In the end though, even overcoming these challenges will come to nothing if the new approach isn’t economically viable and environmentally beneficial.

‘There are a lot of broader questions we need answers to: such as, how much natural gas or biomethane is there in the world? And can our solution have a real impact on overall carbon emissions?’ Peter tells me.

But, the team feel, this is where Oxford has an advantage calling on the expertise of the Department of Engineering Science, Begbroke Science Park, the Smith School of Enterprise and the Environment, and Rutherford Appleton Laboratory, as well as partners in the UK and China.

The Oxford team believe that by working on the whole challenge – not just the scientific or technological aspects – they can help to crack one of the world’s biggest and most intractable problems: how to make the CO2 we produce work for us and the planet.

A field in Chilbolton, Hampshire, could help unlock the secrets of peculiar rotating neutron stars known as pulsars.

It's here that an international team, including Oxford University scientists, are building an array that, linked up with stations in the Netherlands, Germany, and France will form LOFAR, one of the world's most powerful radio telescopes.

I asked LOFAR scientist Aris Karastergiou of Oxford's Department of Physics about the new telescope, the search for pulsars, and how games console hardware could help decode their enigmatic signals...

OxSciBlog: What makes pulsars so challenging to study?
Aris Karastergiou: In a sense it is amazing that we can study pulsars at all, as they are compact objects around 10-20 km in diameter. However, they emit very bright beams of light (in the radio frequencies) from their two magnetic poles, which sweep through space as the pulsar rotates.

If Earth happens to be in the path of these sweeping beams of a pulsar, we can point a radio telescope towards it and collect this light. Even then, however, the fact that the most scientifically interesting pulsars rotate over 100 times a second means that observations require not only high sensitivity but also very fast recorders, capable of sampling the incoming light at extremely short intervals.

The fact that pulsar light travels through the Galaxy before reaching us adds further challenges to pulsar studies, as radio waves interact with electrons in the medium between the stars.

OSB: What is LOFAR and how can it help with these studies?
AK: LOFAR (the Low Frequency Array) is a brand new telescope, made up of a large number of receiving elements organised in so-called stations. The core of this telescope is located in the Netherlands, while outer stations are located in Germany, France, the UK and elsewhere. Unlike other radio telescopes, LOFAR is not made up of parabolic reflectors (like satellite dishes), but of little radio antennas.

To point the telescope at a star in the sky, we electronically combine the signals from these antennas with a certain set of time delays LOFAR is a very sensitive telescope and we expect to discover a large number of new pulsars by surveying the northern sky. Compared to the existing giant radio telescopes, pulsars are brighter at LOFAR radio frequencies.

Observing at low frequencies will give us better understanding of the radio emission mechanism, and also shed light on the physical processes associated with the propagation of pulsar light through our Galaxy.

OSB: What difference will the new Chilbolton facility make?
AK: Each of the international LOFAR stations, including Chilbolton, contributes to LOFAR by increasing the capability to tell apart objects in the sky that appear very near to each other. If we imagine that LOFAR can take photographs of the sky, the most distant stations are necessary to reduce the pixel size and make images of greater detail.

On the other hand, the international LOFAR stations are very sensitive telescopes in their own right and can be used independently from LOFAR. They can observe large fields in the sky with large sensitivity and very fast sampling of the incoming radiation, making them very useful instruments for searches of bursty signals like giant radio pulses from pulsars.

We are enhancing the LOFAR station at Chilbolton to take full advantage of these capabilities, and we aim to transform it into a fantastic instrument of discovery.

OSB: How does the sort of hardware found in games consoles help you analyse signals?
AK: Modern games consoles use very powerful graphics processors to deliver stunning images and animation. The secret behind this lies in the enormous computing power of these processors at performing certain simple calculations in parallel. When searching for bright, short duration radio pulses of astronomical origin, we need to counter the effects of propagation of light through the Galaxy. This process involves a simple, repetitive algorithm that can be easily run in parallel on graphics processors.

We are currently building a computer cluster based on graphics processing units, which will be capable of performing a real-time search for bright, short duration astrophysical radio pulses in the data from the Chilbolton station.

Dr Aris Karastergiou is based at Oxford University's Department of Physics where he is a Leverhulme Early Career Fellow.