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Scientists Slow Down the Speed of Light travelling in Free space 


 

Posted on 25/01/2015

Scientists have managed to slow photons in free space for the first time. They have demonstrated that applying a mask to an optical beam to give photons a spatial structure can reduce their speed.

Scientists have long known that the speed of light can be slowed slightly as it travels through materials such as water or glass. However, it was thought almost impossible to do it for particles of light, known as photons, to be slowed as they travel through free space, unimpeded by interactions with any materials.

 

In a new paper published in Science Express today (Friday 23 January), researchers from the University of Glasgow and Heriot-Watt University describe how they have managed to slow photons in free space for the first time. They have demonstrated that applying a mask to an optical beam to give photons a spatial structure can reduce their speed.

The team compare a beam of light, containing many photons, to a team of cyclists who share the work by taking it in turns to cycle at the front. Although the group travels along the road as a unit, the speed of individual cyclists can vary as they swap position.

The group formation can make it difficult to define a single velocity for all cyclists, and the same applies to light. A single pulse of light contains many photons, and scientists know that light pulses are characterised by a number of different velocities.

 

The team's experiment was configured like a time trial race, with two photons released simultaneously across identical distances towards a defined finish line. The researchers found that one photon reached the finish line as predicted, but the structured photon which had been reshaped by the mask arrived later, meaning it was travelling more slowly in free space. Over a distance of one metre, the team measured a slowing of up to 20 wavelengths, many times greater than the measurement precision.

The work demonstrates that, after passing the light beam through a mask, photons move more slowly through space. Crucially, this is very different to the slowing effect of passing light through a medium such as glass or water, where the light is only slowed during the time it is passing through the material -- it returns to the speed of light after it comes out the other side. The effect of passing the light through the mask is to limit the top speed at which the photons can travel.

The work was carried out by a team from the University of Glasgow's Optics Group, led by Professor Miles Padgett, working with theoretical physicists led by Stephen Barnett, and in partnership with Daniele Faccio from Heriot-Watt University.

 

Daniel Giovannini, one of the lead authors of the paper, said: "The delay we've introduced to the structured beam is small, measured at several micrometres over a propagation distance of one metre, but it is significant. We've measured similar effects in two different types of beams known as Bessel beams and Gaussian beams."

Co-lead author Jacquiline Romero said: "We've achieved this slowing effect with some subtle but widely-known optical principles. This finding shows unambiguously that the propagation of light can be slowed below the commonly accepted figure of 299,792,458 metres per second, even when travelling in air or vacuum. Although we measure the effect for a single photon, it applies to bright light beams too. The effect is biggest when the lenses used to create the beam are large and when the distance over which the light is focused is small, meaning the effect only applies at short range."

Professor Padgett added: "It might seem surprising that light can be made to travel more slowly like this, but the effect has a solid theoretical foundation and we're confident that our observations are correct. The results give us a new way to think about the properties of light and we're keen to continue exploring the potential of this discovery in future applications. We expect that the effect will be applicable to any wave theory, so a similar slowing could well be created in sound waves, for example."

The team's paper, titled 'Spatially Structured Photons that Travel in Free Space Slower than the Speed of Light', is published in Science Express. 

 

 

 


 

European science divided on economics


Posted on 11/01/2015

The Horizon 2020 programme may steal away the best scientists from southern Europe.

At the end of 2014, the EU delivered a generous 2015 budget for its science flagship Horizon 2020 funding programme. The scheme, which runs from 2014 to 2020, already on a roll, has already proved immensely popular and welcomed by researchers.

The outcomes of the programme may however be unevenly spread. Horizon 2020 risk to finance countries and regions that are already doing well, at the expense of the other half of Europe, whose research and innovation capacities have been weakening during the crisis, this clashes with the main objectives of the EU Framework programmes.

 

Promoting good research aside, the main mission of H2020 is to develop closer, deeper ties across Europe varied research community. This has turn into a more arduous task with the enlargement of the EU to the east and even more due to the economic crisis affecting mainly the south of Europe.

The principal pillars of Horizon 2020 were already established in 2008 when most European countries were committed to increase science spending. Focused on addressing big challenges, such as climate change and healthy ageing, and on supporting research excellence the scheme was well suited for a time of growth. However the programme got under way only in 2014 with a very different economic scenario with half of Europe under strong austerity measures with heavy cuts on research and innovation budget.

 

 

Financial meltdown has drastically changed the European research’s topography, and after decades of gentle convergence, the system is diverging sharply.

According to the European University Association’s Public Funding Laboratory, public spending in universities has fallen by more than 10% in 10 European countries since 2008. Even more in some countries, such as in Italy where it is down by 20%, and in Greece and Hungary by more than 40%. Meanwhile, funding has been reduced only by one-fifth in Germany, Norway and Sweden, while levels in Austria and Belgium are not far behind.

The European Research Area (ERA), created in 2000, aimed at facilitating a single area within which students, researchers and ideas could freely circulate. Although  some aspects have being improved such as university recruitment, now far more open and international than before, others proof more unsatisfactory such as the one-way flow of talent from the south and east to the north . If this trend continues, this migration of people and ideas can only widening the gap in economic competitiveness that triggered the Eurocrisis in the first place. 

Figures illustrate this divergence, in 2013, for example, Germany and the United Kingdom were the top two recipients of Framework funding, receiving € 1.1 billion each. The Netherlands was granted with € 560 million, much the same as Italy, which has almost four times the population, while Poland received € 67 million and Romania just € 17 million.

Beside Horizon 2020, the EU counts with the so called “structural funds” for infrastructure projects in poorer regions, aimed at lime the disparities between eastern European countries and speeding up their development to western standards. Currently, they are increasingly needed in southern European countries.

For the 2014–20 period, the EU will made available around € 50 billion in structural funds for research and innovation-related projects, such as new laboratory buildings. However the use of structural funds for research purposes has not being satisfactory, with toured glass palaces, constructed in improbable locations, with no researchers budgeted for and scant prospect of them ever arriving. Such projects are often backed by local political leaders, often with an electoral agenda, who have weak understanding of what breeds innovation, wrongly believing that fancy buildings with Wi-Fi will do the job.

Structural funds in cohesion with the total Horizon 2020 budget of € 70 billion could in theory achieve a lot. Nevertheless, in practice structural-fund projects are selected locally, with less EU oversight, need political backing in their own regions and take years to accomplish. Even when such infrastructure is finished, local researchers may be as unlikely as before to win fiercely competitive Horizon 2020 grants.

The EU has set up a small project, called Stairways to Excellence, to help applicants marry the two approaches. But a more fundamental reform is needed: a comprehensive re-alignment that would use structural funds to build up research teams that are already almost good enough to partner in Horizon 2020 projects, together with a touch of ‘positive discrimination’ to favour these partners within Horizon 2020. Under the current structure this is unlikely to happen, and stores up problems for the future.

As some other instruments created for European integration, Horizon 2020 may not be as successful as intended if forces pulling the continent apart exceed the ones holding it together. The EU research policy has always shine for its focus on “excellence”, however under current economic circumstances a cohesive approach is fundamental for reaching its main objectives.

 


We may have discovered most Earth-like planet beyond our solar system


Posted on 11/01/2015

A team of astronomers announced on Tuesday that they may have discovered the most Earth-like planet ever found outside our solar system.

The futuristic movies of the past painted 2015 and beyond as a time of flying cars, hovercrafts and alien contact. While we may not be zooming down sky highways just yet, discovering life beyond Earth may not be outside our reach in the coming years. In fact, 2015 had barely begun when scientists at the Harvard-Smithsonian Center for Astrophysics announced that they had discovered what they believe to be the most Earth-like planet ever found outside the solar system.

The Guardian reports that the planet, Kepler 438b, which orbits a distant star in the constellation of Lyra, may be slightly larger than the Earth. It circles an orange dwarf star that bathes it in 40 % more heat than we receive from our sun. The small size of Kepler 438b makes it likely to be a rocky world, while its proximity to its star puts it in the so-called ‘Goldilocks’ or habitable zone where the temperature is just right for liquid water to flow, according to the Guardian.

The newly-discovered world, which is 470 light years away, completes an orbit around its star every 35 days, making a year pass 10 times as fast as on Earth. And Kepler 438b is not alone. It is one among eight new potentially habitable planets, including some close to Earth in size and situation, which were announced at the recent meeting of meeting of the American Astronomical Society. Speaking of the announcement, Douglas Caldwell of the SETI Institute in Mountain View, California noted to Science magazine, ‘We’ve significantly increased the list of verified small planets in the habitable zone’.

One of the other planets on the new list also looks promising. Kepler 442b lies in the same constellation 1 100 light years away. The Guardian reports that it is about a third larger than Earth, receives about two thirds as much starlight, and has a 60 % chance of being rocky. According to Scientific American, both Kepler 438b and Kepler 442b may be somewhat warmer than Kepler's two previous premier rocky worlds, Kepler 186 f and Kepler 62 f, each of which gets significantly less starlight—similar to that received by Mars.

The research team used a statistical technique known as Blender to confirm that the planets originally spotted by NASA’s ‘planet hunting’ Kepler space telescope were real. Science magazine elaborates, calculates what various false-positive objects would look like and then compares them with the brightness curves of the Kepler candidates, also incorporating any follow up data from other observations. Starting with 12 Kepler candidates believed to be small rocky worlds, the Blender analysis whittled them down to eight new exoplanets with radiuses smaller than 2.7 times Earth’s, all believed to be in the habitable zone.’

Although the newly-discovered planets show positive indicators for habitability, study co-author David Kipping, an astronomer at the Harvard–Smithsonian Center for Astrophysics, sounded a word of caution in Scientific Amercian: ‘We can't say for sure whether these planets are truly habitable—only that they are promising candidates for habitability.’ He also noted to the Guardian that Kepler 438b and 442b were ‘as close to Earth analogues as we’re going to find in the Kepler data’.

So what’s next in the quest to find life beyond our world? The Guardian believes that planet hunters’ hopes are now likely pinned on the next generation of telescopes, including Hubble’s replacement, the James Webb Space Telescope, and the European Extremely Large Telescope. Scientific American meanwhile looks stateside to NASA's upcoming Transiting Exoplanet Survey Satellite, or TESS, expected to launch in 2017. TESS would perform an all-sky survey focused on finding transiting rocky planets around nearby stars.