Pretty magnetic monopoles

05/08/2010

Pick of the pics

A pretty magnetic pattern is pretty surprising too

Against the rules, triplets of magnetic north poles (bright points) and south poles (dark points) chum together with amazing regularity on small islands etched in a honeycomb pattern on an iron surface, using an electron beam. Hartmut Zabel at the Ruhr-Universität Bochum calls it a new magnetic order. The polarities are revealed by a magnetic force microscope, and the 20-micrometre scale line tells us that the width of the picture is about the average thickness of a human hair. Credit: RUB

Who’d have thought it? In kindergarten science you learn that like magnetic poles repel each other. Yet here we see energetically unfavourable triplets of poles occurring not just once or twice by mistake but all across a specially prepared iron surface, when subjected to a magnetic field.

The so-called “magnetic monopoles” created in this pattern are not to be confused with hypothetical fundamental particles of that name. And be wary of attempts to explain the phenomenon to you by reference to “spin ice”, and an analogy with water ice. They may be helpful for experts but can baffle non-physicists. All you really need to know is that the exposed north or south poles belong to atoms that can face one way or the other on the lattice surface.

Watch out for novel information-storage devices exploiting this “new magnetic order”. Prof. Zabel points out that “each node point has eight possible dipole constellations – far more than with conventional storage techniques based on two states”. The islands in the experiments were 3 micrometres long, but they might be made ten times smaller.

References

Alexandra Schumann, Björn Sothmann, Philipp Szary and Hartmut Zabel, “Charge ordering of magnetic dipoles in artificial honeycomb lattices,” Applied Physics Letters, Vol. 97, 022509 (2010). doi:10.1063/1.3463482

RUB press release: http://www.alphagalileo.org/ViewItem.aspx?ItemId=82499&CultureCode=en

For a relevant report last year from Helmholtz-Zentrum Berlin für Materialien und Energie see http://www.sciencedaily.com/releases/2009/09/090903163725.htm


Why is science so sloooow 2

05/08/2010

Updating Magic Universe

WHY IS SCIENCE SO SloooOW? — continued

The modest output of major discoveries compared with a century ago, despite the huge increase in the scientific workforce, was the theme of an earlier post on this subject, which you can see here https://calderup.wordpress.com/2010/05/06/why-is-science-so-sloooow/ . A relevant extract  from the Magic Universe story on “Discovery” included this paragraph about the use of peer review to resist the funding and publication of novel research.

As a self-employed, independent researcher, the British chemist James Lovelock was able to speak his mind, and explain how the system discourages creativity. ‘Before a scientist can be funded to do a research, and before he can publish the results of his work, it must be examined and approved by an anonymous group of so-called peers. This inquisition can’t hang or burn heretics yet, but it can deny them the ability to publish their research, or to receive grants to pay for it. It has the full power to destroy the career of any scientist who rebels.’

Lovelock made those remarks in a lecture in 1989, but the situation remains grim. This month the life sciences magazine The Scientist has interesting articles on peer review.

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What Language on Mars?

02/08/2010

Predictions Revisited

What Language Will They Speak on Mars?

The planet Mars in Chinese script. Credit: About.com: Chinese Culture, written by “js”

Chinese, on present showing. Never mind that seven men – Russian (4) European (2) and Chinese (1) – are now two months into a 520-day isolation trial in Moscow, simulating a manned mission to Mars. That’s for show. Political willpower will settle the issue.

In 1964 the rocket engineer Wernher von Braun forecast a human visit to Mars by 1984. That might well have happened had the US not cancelled its proposed Orion rocket in 1965 – the year after von Braun made his prediction. The trouble was that Orion would have had nuclear propulsion, not merely by nuclear motors, but by nuclear bombs. So it had to be abandoned in the aftermath of the nuclear test-ban treaty, much to the annoyance of Freeman J. Dyson and other enthusiasts.

Orion – the gigantic might-have-been

Here’s a diagram from my book Spaceships of the Mind (1978) which accompanied the BBC-OECA series with the same title, produced by Dick Gilling of BBC-TV. Assembled in Earth orbit, Orion would have carried about 2000 10-kiloton nuclear fission bombs, released at a rate of one a second to explode close behind a large spaceship. With a pusher plate absorbing the shocks, the spacecraft would quickly reach a speed that would take about 20 astronauts around Mars and back to Earth in just six months.

It may seem daft now but Orion was a recognition, at the very start of the Space Age, that if human beings are ever to become serious about space travel, they’ll have to think nuclear. That’s still the case, although nuclear fusion will be preferable, of course, with ignition as far from the Earth as possible.

When von Braun contributed to the New Scientist’s 1964 series on “The World in 1984” he remained mute about Orion although he glanced the nuclear option. At the time he was director of NASA’s Marshall Space Flight Center in Huntsville, Alabama, with the Apollo missions to the Moon at the top of his agenda. Here, for a start, are two early extracts from his article entitled “Exploration to the Farthest Planets”:

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Monsoon 2010

01/08/2010

Climate change: News and Comments

Floods in Pakistan, Relief in India

Harrowing news of lives lost in unusual monsoon floods in NW Pakistan, close to the Afghan border, doesn’t mean that this year’s rains have been exceptional across the subcontinent. On the contrary, the Indians were worried by a shortfall in early July.Their rains have now perked up.

Strong La Niña conditions (the opposite of El Niño) now showing in the Pacific are historically favourable for the Asian monsoon, and the India Meteorological Department seems to be sticking to an earlier forecast that this season’s total rains will be close to normal. See this Reuters interview with D. Sivananda Pai, director of the National Climate Center in Pune. http://in.reuters.com/article/idINSGE66K0IL20100721?loomia_ow=t0:s0:a54:g12:r3:c0.638402:b36099434:z3

For earlier posts here about the Asian monsoons, see https://calderup.wordpress.com/2010/05/01/monsoons-and-the-sun/ and https://calderup.wordpress.com/2010/05/05/maps-of-monsoon-history/


Wishful thinking Czech style

23/07/2010

Predictions Revisited

Wishful thinking, Czech style

Every since Thomas More invented the term, utopias have cast futures in a “normative” manner, saying here’s how the world ought to be. Such wishful thinking is political. The Marxist vision of a better world of true Communism, “from each according to his ability, to each according to his needs,” led huge sections of the human species into the long dark tunnels of Stalinism and Maoism, where utopia was deferred indefinitely.

A memorable episode more than 40 years ago was an attempt in Czechoslovakia to outwit the thought police and modernize Communism by highly organized speculations about the future. Unusually for a science writer I found myself on the inside track of political news, when routeing myself home from Moscow via Prague. It was Christmastime in Wenceslas Square – just three weeks before Alexander Dubček came to power and began trying to throw off Soviet shackles in the “Prague Spring”.

The mathematician Jaroslav Kozešnik, vice-president of the Academy of Sciences, briefed me about what was in the wind. And in August 1968, when the Soviet bloc was closing in on its dissident member, I wrote about it in the London magazine New Statesman, as follows.

Czech Crisis: The Czechnocrats’ Key Role

If the writers were the shock troops of the movement that overthrew the residual Stalinists in Czechoslovakia, the heavy armour was provided by the Academy of Sciences. Ideas emanating from years of officially-sponsored reformist studies are much less stoppable than Soviet tanks. Even if they were to be extinguished or compromised by present events, they would reappear elsewhere. Nor do I mean only in Moscow or Warsaw; in London and Paris, New York and New Delhi, we all have a lot to learn from the Czechs. Starting from a higher political level they have thought more deeply than any other nation about the impact of current science and technology on everyday life. They have sought to re-invent democracy in modern form.

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Silly season for melting ice

22/07/2010

Climate Change: News and Comments

The Silly Season Again for Melting Ice

At this time of year, while the Arctic sea ice dwindles under the midnight sun and the wind pushes it around, silly stories are needed to fill the pages of summer newspapers. So it’s party time for the global warming alarmists and their editorial cronies. For example, Nature magazine today laments:

Arctic melting: The Arctic has set another record for losing sea ice. Last month saw the lowest extent of sea ice in the Arctic for any June since satellite records started in 1979.”

[Note added 25 July: The day after I posted this, CNSNews reported Sen. John Kerry (D-Mass.) as saying,  “Instead of waiting until 2030 or whenever it was to have an ice-free Arctic, we’re going to have one in five or 10 years.”]

It’s a replay of the polar stories of 2007, mentioned in a 2008 talk on the Tradecraft of Propaganda that I posted earlier: https://calderup.wordpress.com/2010/06/07/tradecraft-of-propaganda/

Here’s the relevant extract from that talk: Last year [2007] you were told – shock, horror! — that Arctic sea ice was at its lowest extent since satellite measurements began. How that news was trumpeted on television and radio and in all the newspapers! What went completely unreported was that simultaneously, at the other end of the world, Antarctic sea ice was at a record high. Although the big freeze in Antarctica was again plainly announced in a press release from the US weather bureau, NOAA, not a single newspaper in North America or Europe carried this news unfavourable to the global warming brigade.

Let’s check what’s going on this year, around the southern end of the Earth’s axis.

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Tarantula’s Superstar

21/07/2010

Pick of the Pics

The Tarantula’s Superstar

The star at the very centre of this picture, called R136a, turns out to be nearly ten million times brighter than the Sun. It’s now revealed to be by far the most massive star ever discovered. Its current mass is 265 times that of the Sun and it probably had 320 solar masses at birth. The superstar lies 165,000 light-years away in a neighbouring galaxy, the Large Magellanic Cloud, at the very heart of a huge nebula aptly called the Tarantula. The European Southern Observatory (ESO) obtained this infra-red image with the MAD adaptive optics instrument on the Very Large Telescope in Chile. Credit: ESO/P. Crowther/C.J. Evans

The report by Paul Crowther of Sheffield and his colleagues, released today, is in press in the Monthly Notices of the Royal Astronomical Society, under the title “The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 Mstellar mass limit.”.

The Tarantula Nebula in a mosaic of images from ESO's 2.2-metre telescope. Credit: M. Schirmer, T. Erben, M. Lombardi, IAEF Bonn, ESO

What fascinates me is to picture the young superstar R136a, and her obese sisters b and c, hurling off gas equivalent to dozens of suns. Combined with the pressure of their intense radiation, the resulting winds have shaped the Tarantula Nebula with its spidery arms that stretch 500 light-years from the stormy centre.

The theorists will now have a merry time explaining how such a massive star could form from a gas cloud without breaking up into a swarm of normal objects. The discovery also lends credence to an idea that very massive stars can explode as supernovae, scattering chemical elements into space, without leaving any relic like a neutron star or black hole.


Amazon rainforest

19/07/2010

Predictions Revisited and Climate Change: News and Comments

Will the Amazon rainforest survive?

A flurry of stories about the rainforests confirms that the proper concern about tropical deforestation has been thoroughly confused by improper attempts to invoke man-made global warming. Before turning to thunderstorms felling trees,  let’s start with the big picture of expectations, past and present, for the Amazon rainforest. For more than 30 years, large-scale assessments have been based on satellite imagery, despite the problem that much of the forest is covered with clouds at any one time. Brazil’s own Instituto Nacional de Pesquisas Espaciais, INPE, has played a leading part.

In a forecast that proved wrong even more rapidly than The Population Bomb (see the previous post) an ecologist Philip Fearnside declared in 1982 that the Amazon forest was vanishing at an accelerating rate, with more than 40% to be gone by 1988. I told the tale in my 1991 book about remote sensing, Spaceship Earth, after visiting INPE in São Paulo.

During the 1980s Brazil found itself at war on two fronts. At home, the government tried to moderate the rate of clearances in the Amazonian forest, and police a frontier region as gun-happy as the old Wild West of the USA. Internationally, they had to deal with a rising chorus of criticism about the rate at which the forest was disappearing. In 1982, on the basis of INPE’s figures, predictions by an American scientist P.M. Fearnside amounted to a forecast that 44 per cent of the Amazonian forest would be lost by 1988.

The Brazilians greeted such estimates with frank disbelief. There then followed a contest between calculation and remote sensing to try to establish the true facts. …

In 1989, the World Bank published estimates indicating that 12 per cent of Legal Amazonia was already deforested by 1988. This was based on calculations from the state of affairs in 1980. By this time the Brazilians were growing very angry. Although the figure was far less than the Fearnside estimate, the fact that it came from the World Bank secured it a place in international environmental folklore. The Brazilians appealed again to the umpires in space: the unblinking instruments of the remote-sensing satellites.

At INPE, Roberto Pereira da Cunha decided to make a ‘wall-to-wall’ assessrnent of the deforestation in Legal Amazonia. As he remarked, ‘No one wants to do the dirty work of gathering the data. It is a very trivial task for scientists.’ Trivial, but not unlaborious. Pereira’s team assembled 234 Landsat scenes and selected for close interpretation 101 images that showed evidence of deforestation. From colour composites of three wavelength bands the scientists outlined the deforested patches, and used a grid to measure their areas. Images for different years established rates of deforestation.

The most important conclusion was that there was no acceleration: deforestation was proceeding at a more or less steady rate. As for the total recent deforestation up till the end of 1988, INPE’S answer was 5 per cent of the area of Legal Amazonia. Meanwhile, Fearnside had changed his forecast. His new figures indicated 7 per cent deforestation of Legal Amazonia by 1989 – a far cry from his 44 per cent figure of just 7 years earlier, and almost in line with INPE’s figure. In 1990 Jim Tucker and Chris Justice of NASA broadly confirmed the Brazilian result by a similar large-scale use of Landsat imagery, but with a different technique, using only a single infra-red channel.

So what do the umpires in space say now, two decades later?

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The Population Bomb

12/07/2010

Predictions revisited

The Population Bomb

On World Population Day (today, if you didn’t know it) the Royal Society of London announces a new working group on human population growth, led by the geneticist Sir John Sulston. But this is no exercise in professional demography. Political overtones are evident in the working group’s inclusion of “experts on the environment, agriculture, economics, law and theology drawn from a mix of rich and poor countries including the UK, China, Brazil and the US,” as the BBC tells us. So when the working group reports in 2012 we can expect technocrats once again to be wanting to tell other people how to live.

Of course the population scare goes way back to Thomas Malthus (1798), but in its modern guise it has underpinned militant environmentalism for more than 40 years since a butterfly expert, Paul Ehrlich of Stanford, published The Population Bomb in 1968. Never mind that what he predicted turned out to be wrong. That sort of mishap doesn’t matter once you’ve been sanctified by true believers.

Ever been stuck in traffic on a hot night in Delhi? I once was in the 1960s, before I first read The Population Bomb, so I recognised the scene described by Ehrlich:

The streets seemed alive with people. People eating, people washing, people sleeping. People visiting, arguing, screaming. People thrusting their hands through the taxi window, begging. People defecating and urinating. People clinging to buses. People herding animals. People, people, people, people.”

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Milankovitch back to 1974

10/07/2010

Climate Change: News and Comments

Milankovitch and the ice ages – welcome back to 1974

Why am I chuckling? After he’d had misgivings about the Milankovitch theory of the comings and goings of the ice sheets, Luboš Motl now says in The Reference Frame:

… the Milankovitch orbital cycles do describe the glaciation cycles in the recent 1 million years very well and nothing else – CO2 or random internal variations – is needed to account for the bulk of the data.”

You can read Motl’s story in full at http://motls.blogspot.com/2010/07/in-defense-of-milankovitch-by-gerard.html#more

— and download from there a 2006 paper that wins Motl over, by Gerard Roe of the University of Washington in Seattle.

The abstract of that paper reads (with my emphasis added):

The Milankovitch hypothesis is widely held to be one of the cornerstones of climate science. Surprisingly, the hypothesis remains not clearly defined despite an extensive body of research on the link between global ice volume and insolation changes arising from variations in the Earth’s orbit. In this paper, a specific hypothesis is formulated. Basic physical arguments are used to show that, rather than focusing on the absolute global ice volume, it is much more informative to consider the time rate of change of global ice volume. This simple and dynamically-logical change in perspective is used to show that the available records support a direct, zero-lag, antiphased relationship between the rate of change of global ice volume and summertime insolation in the northern high latitudes. Furthermore, variations in atmospheric CO2 appear to lag the rate of change of global ice volume. This implies only a secondary role for CO2 – variations in which produce a weaker radiative forcing than the orbitally-induced changes in summertime insolation – in driving changes in global ice volume.

Roe, G. (2006), In defense of Milankovitch, Geophys. Res. Lett., 33, L24703, doi:10.1029/2006GL027

The reason for my chuckles is that the “change in perspective” that Roe adopts was available more than 30 years earlier in the first formal verification of Milankovitch, which I published in Nature in 1974. Using a pocket calculator, I simply assumed that the rate of change in global ice volume per thousand years was proportional to the difference between the summer sunshine at a high-ish northerly latitude and a level of sunshine at which the ice neither advances or retreats.

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