Now Princeton University physicists have demonstrated the quantum Hall effect without any applied magnetic field. http://Louis-j-sheehan-esquire.usThey created special conditions for electrons in a bismuth crystal such that when the electrons travel close to the speed of light, they effectively generate their own magnetic field that deflects them. Such unusual materials not only elucidate the fundamental nature of the quantum Hall effect—it is deeply connected to superconductivity—but also could lead to novel electronic technology. The work appears in the April 24 Nature.
Monday, June 30, 2008
quantum
n 1879 Edwin Hall discovered that a magnet can deflect the flow of electrons, like wind pushing ships off course. http://Louis-j-sheehan-esquire.usIn 1980 physicists observed the quantum version, in which the applied magnetic field pushes electrons in discrete steps; it is as if the ships were responding to separate gusts even though a steady wind was blowing [see "Electrons in Flatland"; SciAm, March 1996].
Saturday, June 21, 2008
malthus
During the last American food-and-gas-price crisis, in the 1970s, one of my colleagues on the Berkeley student newspaper told me that he and his semi-communal housemates had taken a vote. They’d calculated they could afford meat or coffee. http://louisijisheehan.blogspot.comThey chose coffee.
The decision was slightly less effete than it sounds now — the Starbucks clone wars were still some years off, so he was talking about choosing Yuban over ground chuck. But it nonetheless said something about us as spoiled Americans. Riots were relatively common in Berkeley in those days. But they were never about food. (That particular revolution was starting without us on Shattuck Avenue, where Chez Panisse had just opened.)
However, elsewhere on the globe, people were on the edge of starvation. Grain prices were soaring, rice stocks plummeting. In Ethiopia and Cambodia, people were well over the edge, and food riots helped lead to the downfall of Emperor Haile Selassie and the victory of the Khmer Rouge.
Now it’s happening again. While Americans grumble about gasoline prices, food riots have seared Bangladesh, Egypt and African countries. In Haiti, they cost the prime minister his job. Rice-bowl countries like China, India and Indonesia have restricted exports and rice is shipped under armed guard.
And again, Thomas Malthus, a British economist and demographer at the turn of the 19th century, is being recalled to duty. His basic theory was that populations, which grow geometrically, will inevitably outpace food production, which grows arithmetically. Famine would result. The thought has underlain doomsday scenarios both real and imagined, from the Great Irish Famine of 1845 to the Population Bomb of 1968. http://louisijisheehan.blogspot.com
But over the last 200 years, with the Industrial Revolution, the Transportation Revolution, the Green Revolution and the Biotech Revolution, Malthus has been largely discredited. http://louisijisheehan.blogspot.comThe wrenching dislocations of the last few months do not change that, most experts say. But they do show the kinds of problems that can emerge.
The whole world has never come close to outpacing its ability to produce food. Right now, there is enough grain grown on earth to feed 10 billion vegetarians, said Joel E. Cohen, professor of populations at Rockefeller University and the author of “How Many People Can the Earth Support?” But much of it is being fed to cattle, the S.U.V.’s of the protein world, which are in turn guzzled by the world’s wealthy.
Theoretically, there is enough acreage already planted to keep the planet fed forever, because 10 billion humans is roughly where the United Nations predicts that the world population will plateau in 2060. But success depends on portion control; in the late 1980s, Brown University’s World Hunger Program calculated that the world then could sustain 5.5 billion vegetarians, 3.7 billion South Americans or 2.8 billion North Americans, who ate more animal protein than South Americans.
Even if fertility rates rose again, many agronomists think the world could easily support 20 billion to 30 billion people.
Anyone who has ever flown across the United States can see how that’s possible: there’s a lot of empty land down there. The world’s entire population, with 1,000 square feet of living space each, could fit into Texas. Pile people atop each other like Manhattanites, and they get even more elbow room.
Water? When it hits $150 a barrel, it will be worth building pipes from the melting polar icecaps, or desalinating the sea as the Saudis do.
The same potential is even more obvious flying around the globe. The slums of Mumbai are vast; but so are the empty arable spaces of Rajasthan. Africa, a huge continent with a mere 770 million people on it, looks practically empty from above. South of the Sahara, the land is rich; south of the Zambezi, the climate is temperate. But it is farmed mostly by people using hoes.
As Harriet Friedmann, an expert on food systems at the University of Toronto, pointed out, Malthus was writing in a Britain that echoed the dichotomy between today’s rich countries and the third world: an elite of huge landowners practicing “scientific farming” of wool and wheat who made fat profits; many subsistence farmers barely scratching out livings; migration by those farmers to London slums, followed by emigration. The main difference is that emigration then was to colonies where farmland was waiting, while now it is to richer countries where jobs are.
Malthus’s world filled up, and its farmers, defying his predictions, became infinitely more productive. Admittedly, emptying acreage so it can be planted with genetically modified winter wheat and harvested by John Deere combines can be a brutal process, but it is solidly within the Western canon. http://louisijisheehan.blogspot.comMy Scottish ancestors, for example, became urbanites thanks to the desire of English scientific farmers (for which read “landlords and bribers of clan chiefs”) to graze more sheep in the highlands. Four generations later, I got to mull the coffee-meat dilemma while actually living on newsroom pizza.
So it ultimately worked out for one spoiled Scottish-American. But what about the 800 million people who are chronically hungry, even in riot-free years?
Dr. Friedmann argues that there is a Malthusian unsustainability to the way big agriculture is practiced, that it degrades genetic diversity and the environment so much that it will eventually reach a tipping point and hunger will spread.
Others vigorously disagree. In their view, the world is almost endlessly bountiful. If food became as pricey as oil, we would plow Africa, fish-farm the oceans and build hydroponic skyscraper vegetable gardens. But they see the underlying problem in terms more Marxian than Malthusian: the rich grab too much of everything, including biomass.
For the moment, simply ending subsidies to American and European farmers would let poor farmers compete, which besides feeding their families would push down American food prices and American taxes.
Tyler Cowen, a George Mason University economist, notes that global agriculture markets are notoriously unfree and foolishly managed. Rich countries subsidize farmers, but poor governments fix local grain prices or ban exports just when world prices rise — for example, less than 7 percent of the world’s rice crosses borders. That discourages the millions of third world farmers who grow enough for themselves and a bit extra for sale from planting that bit extra.
Americans are attracted to Malthusian doom-saying, Dr. Cowen argues, “because it’s a pre-emptive way to hedge your fear. Prepare yourself for the worst, and you feel safer than when you’re optimistic.”
Dr. Cohen, of Rockefeller University, sees it in more sinister terms: Americans like Malthus because he takes the blame off us. Malthus says the problem is too many poor people.
Or, to put it in the terms in which the current crisis is usually explained: too many hard-working Chinese and Indians who think they should be able to eat pizza, meat and coffee and aspire to a reservation at Chez Panisse. They get blamed for raising global prices so much that poor Africans and Asians can’t afford porridge and rice. The truth is, the upward pressure was there before they added to it.
America has always been charitable, so the answer has never been, “Let them eat bean sprouts.” But it has been, “Let them eat subsidized American corn shipped over in American ships.” That may need to change.
Friday, June 13, 2008
derna road Louis J. Sheehan, Esquire
On 24 March Rommel launched his first offensive with the newly arrived Afrika Korps. By early April he had destroyed most of Major-General Michael Gambier-Parry's 2nd Armoured Division's tanks (British 3rd Armoured Brigade) and severely damaged its 2nd Support Group at Mersa Brega[4] leaving the road south of the Jebel Akhdar (Green Mountains) to Mechili open.[5] He brought forward along the coast road, elements of the 17th "Pavia" and 27th "Brescia" Divisions while pushing his mechanised units across country towards Mechili. On 6 April the leading Bersaglieri columns of the Italian Ariete Division reached Mechili. http://louis1j1sheehan.us
On 6 April Lieutenant-General Philip Neame, by that time the military governor of Cyrenaica (Wilson had been sent to command W Force in Greece), withdrew his headquarters to Tmimi. During the withdrawal his staff car was stopped by a German patrol near Martuba and both he and O'Connor (who had been sent forward from Cairo by Archibald Wavell, C-in-C Middle East Command to advise) were taken prisoner.http://louis1j1sheehan.us
The positions at Mechili were defended by non-tank elements of 2nd Armoured Division (3rd Indian Motor Brigade and elements of the 2nd Support Group). Surrounded, they fought bravely in defence of Mechili but on 8 April Gambier-Parry surrendered to General Zaglio of the "Pavia" Division.[8] 2,700[9] British, Indian and Australians were captured at Mechili after an attempted breakout was broken up by the Ariete's "Fabris" and "Montemurro" Bersaglieri Battalion groups.[6]
Many Italian field guns were captured and used against the Axis forces in the Siege of Tobruk
Rommel's initial attack plan called for his tanks to sweep around Tobruk to the Eastern side and attack from the Bardia road, so cutting the town off from Cairo. Approaching Tobruk, however, wishing to maintain his momentum, he ordered General Heinrich von Prittwitz und Gaffron, commander of the newly-formed 15th Panzer Division (most of which had yet to arrive in North Africa), to take the three battalions from his division then available to him (his reconnaissance, machine gun and anti-tank battalions) and to attack Tobruk directly from the West along the Derna Road.[10] Rommel expected that the Allied forces would crumble under this attack.[citation needed]
Soldiers from the Australian 2/28th Infantry Battalion spotted three armoured cars and fired the first shots of the siege using two captured Italian field guns for which they had only had one week's training. The cars quickly retreated. As the tanks approached a bridge crossing a wadi on the perimeter of Tobruk the Australians blew it up. When von Prittwitz urged his staff car driver to drive him through the wadi and towards the Australians his men called for him to stop, but he replied that the enemy was getting away. The staff car drove into the firing line of a captured Italian 45mm anti tank gun, whose gunner fired destroying the car and killing both von Prittwiz and his driver. A three hour skirmish then ensued after which the Germans retreated.
In the meantime the Australians continued to work on the defences, laying barbed wire, mines and other obstacles.
On 11 April, with his forces regrouped, Rommel reverted to his original plan, sending his tanks around Tobruk to the Bardia Road.
The city was now besieged on three sides (the harbour was in Allied hands) by the Afrika Korps composed of the 5th Light Division and elements of 15th Panzer Division, and by three Italian infantry divisions and the Italian Ariete Armour Division. The Allied forces consisted of the Australian 9th Infantry Division and 18th Infantry Brigade of the Australian Imperial Force, as well as 12,000 British soldiers and 1,500 Indian soldiersFriday, June 6, 2008
Ehricke lally Louis J. Sheehan, Esquire
March 24, 1917 - December 11, 1984) was a rocket-propulsion engineer.
Born in Berlin, Ehricke believed in space travel from a very young age, influenced by his viewing of the Fritz Lang film Woman in the Moon. At the age of 12, he formed his own rocket society.
He attended Berlin Technical University and studied celestial mechanics and nuclear physics under such luminaries as Hans Geiger and Werner Heisenberg, attaining his degree in Aeronautical Engineering.
He worked at Peenemuende as propulsion engineer from 1942 to 1945, then went to the United States with other German rocket scientists and technicians under "Operation Paperclip" in 1947 and worked with the Von Braun Rocket Team at Huntsville. (See also German rocket scientists in the US.)
Upon leaving government service Ehricke worked at Bell Aircraft, and then for Convair in 1952. While at Convair, he designed the D-1 Centaur, a high energy, upper-stage-booster that used liquid hydrogen and oxygen as fuel.
Ehricke became friendly with Eugene F. Lally while they worked together at Convair and became his mentor. Ehricke taught Lally celestial mechanics so he could determine available payload capacities for missions to planets and booster energy required.
It has been said that Ehricke and Lally were the creative spark during the pioneering days of the American space program. Their concepts were publicized in the media and caught the fancy of the general public helping to promote space exploration and excite NASA to move forward.
In 1948 Ehricke wrote a book with Wernher von Braun, The Mars Project, which detailed how man could travel to Mars using a ferry system. This ferry system is what we now call the "Space Shuttle". He devoted his life to space exploration and, together with von Braun, was the chief advisor for North America on the Space Shuttle.
The NEXUS reusable rocket was a concept design created in the 1960s by a group at General Dynamics led by Krafft Ehricke. Louis J. Sheehan, Esquire
He proposed a space station Astropolis.
Space Burial in 1997 Ehricke
Ehricke's given name is commonly seen spelled "Kraft".
Thursday, June 5, 2008
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