Glaciarios subterrâneos em Marte

Vast Mars glaciers are spotted - Los Angeles Times

Vast Mars glaciers are spotted
Glaciers on Mars

By John Johnson Jr.
November 22, 2008

In a discovery that partly answers the question of where all the water went on Mars, scientists have found vast, debris-covered glaciers much nearer the equatorial region than anyone had expected, according to a report Friday in the journal Science.

The glaciers, estimated to contain at least as much water as Lake Huron and possibly as much as the entire Great Lakes, were found by ground-penetrating radar on NASA's Mars Reconnaissance Orbiter spacecraft.

"We have found a big chunk of the missing water that people have known must be there," said Ali Safaeinili, a member of the radar team at the Jet Propulsion Laboratory in La Cañada Flintridge.

Scientists analyzing Martian topography have seen lots of evidence of water-caused erosion on the planet, but until now the only deposits of ice have been seen at the poles.

One of the glaciers has been estimated as being the size of Los Angeles and as much as half a mile thick.

How did the ice get there? The best guess, said John W. Holt, a researcher for the Institute of Geophysics at the University of Texas, is that climate change was brought on by changes in Mars' rotational axis over time. Because Mars doesn't have a large moon to keep its axis relatively stable, as the Earth does, the planet can tilt dramatically, redistributing the sun's heat and energy and shifting the poles.

These icy deposits may have lain hidden in their current state as long as 200 million years, Holt said.

The discovery wasn't a complete surprise. Scientists had previously noticed rocky debris "aprons" that seemed to flow away from steep hills as if something underground was lubricating their movements. But there was no proof until the Mars Reconnaissance Orbiter's Italian-built radar confirmed the presence of ice.

The discovery could be one of the most significant for those who want to see a manned mission to the Red Planet, a goal that was announced by President Bush in 2004 but has since been quietly de-emphasized by NASA.

Knowing that astronauts could obtain water in the temperate regions would probably make the mission more feasible.

It is still unclear, however, whether the water is accessible from the surface. Holt said the radar measurements indicated that it could be covered by as much as 30 feet of debris.

"If you could get a backhoe in there, you could get at it," said Jeffrey Plaut, a geologist at JPL. "You'd have to figure out how to get a backhoe to Mars."

Johnson is a Times staff writer.

john.johnson@latimes.com

Graffiti e pqnos crimes

Graffiti study bolsters 'broken windows' theory - Los Angeles Times

Dutch researchers find that in the presence of graffiti and trash, people are more likely to commit small crimes.

By Karen Kaplan
November 21, 2008

In a series of real-world experiments, people exposed to graffiti, litter and other cues of lawlessness were more likely to commit small crimes, according to a study published today that bolsters the controversial "broken windows" theory of policing.

The idea is that low-level offenses like vandalism and panhandling create an environment that breeds bigger crimes. According to the theory, authorities can help head off serious violence by keeping minor infractions in check.

Dutch researchers tested the psychological underpinnings of the theory and found that signs of social disorder damped people's impulse to act for the good of the community, allowing selfish and greedy instincts to take over. The results appear in the journal Science.

Community policing strategies based on the "broken windows" theory have taken root in cities across the U.S. and around the world since it was proposed in 1982.

Most famously, New York City saw a 50% reduction in crime in the 1990s after then-Mayor Rudolph W. Giuliani and then-Police Commissioner William J. Bratton -- now head of the Los Angeles Police Department -- cracked down on squeegee-wielding panhandlers and the like. They credited the "broken windows" approach for their success.

An array of social scientists examined the city's crime statistics, and many of them concluded that factors like the booming economy and decline of crack cocaine were actually responsible for the dramatic improvement.

Kees Keizer, a graduate student at the University of Groningen in the Netherlands, thought psychology and sociology could add to the debate. Human behavior is influenced by three competing instincts: to act in a socially appropriate manner, to do what feels good in the moment and to maximize one's resources. Keizer predicted that when there's less motivation to be socially appropriate, the other two impulses would take over.

To test this, he attached fliers for a fake sportswear store to the handlebars of bicycles parked in a shopping area. With no trash can nearby, shoppers returning to their bikes could either take the fliers with them or litter.

A wall near the bicycles had a sign indicating that graffiti was forbidden. When the wall was indeed graffiti-free, 33% of people left the fliers on the ground or attached them to other bikes. After Keizer painted graffiti on the wall, the percentage of litterers rose to 69%.

Keizer said littering jumped because the socially appropriate instinct -- to deposit the flier in a trash can -- was overtaken by the feel-good instinct to let someone else throw it away.

In other experiments, the presence of four shopping carts strewn about a parking lot in violation of posted signs boosted the percentage of people who littered to 58%, from 30%. The sound of illegal fireworks increased the percentage of litterbugs near a busy train station to 80%, from 52%.

To see whether social disorder would induce citizens to steal, Keizer left an envelope containing 5 euros (about $6.26) hanging conspicuously from a mailbox. When the mailbox was clean, 13% of passersby stole the envelope. When the mailbox was surrounded by trash, the percentage jumped to 25%, and when the mailbox was covered in graffiti, it rose to 27%.

"It is quite shocking that the mere presence of litter resulted in a doubling of the number of people stealing," Keizer said.

James Q. Wilson, the political scientist who developed the "broken windows" theory with George L. Kelling, said the Netherlands experiments bolstered his hypothesis.

"If public authorities worry about order, it affects the way people behave," said Wilson, now the Ronald Reagan Professor of Public Policy at Pepperdine University in Malibu.

But Bernard Harcourt, a professor of law and criminology at the University of Chicago who has done studies debunking "broken windows," said Keizer's scenarios were too quaint to take seriously.

"We don't care about those kinds of trivial, manipulated delinquent acts," he said. "What we care about is violence."

Kaplan is a Times staff writer.

karen.kaplan@latimes.com

Mundo tem que abandonar obsessão por crescimento, diz revista - O Globo

        A Ciência e a crise financeira

Plantão | Publicada em 17/10/2008 às 05h51m
BBC


Em plena crise global, com governos e mercados preocupados com uma possível recessão mundial, a revista especializada britânica New Scientist foi às bancas nesta semana com uma capa na qual defende que a busca por crescimento econômico está matando o planeta e precisa ser revista.

Em uma série de entrevistas e artigos de especialistas em desenvolvimento sustentável, a revista pinta um quadro em que todos os esforços para desenvolver combustíveis limpos, reduzir as emissões de carbono e buscar fontes de energia renováveis podem ser inúteis enquanto nosso sistema econômico continuar em busca de crescimento.

"A Ciência nos diz que se for para levarmos a sério as tentativas de salvar o planeta, temos que remodelar nossa economia", afirma a revista.

Segundo analistas consultados pela publicação, o grande problema na equação do crescimento econômico está no fato de que, enquanto a economia busca um crescimento infinito, os recursos naturais da Terra são limitados.

"Os economistas não perceberam um fato simples que para os cientistas é óbvio: o tamanho da Terra é fixo, nem sua massa nem a extensão da superfície variam. O mesmo vale para a energia, água, terra, ar, minerais e outros recursos presentes no planeta. A Terra já não está conseguindo sustentar a economia existente, muito menos uma que continue crescendo", afirma em um artigo o economista Herman Daly, professor da Universidade de Maryland e ex-consultor do departamento para o meio ambiente do Banco Mundial.

Para Daly, o fato de o nosso sistema econômico ser baseado na busca do crescimento acima de tudo, faz com que o mundo esteja caminhando para um desastre ecológico e também econômico, dadas as limitações dos recursos.

"Para evitar este desastre, precisamos mudar nosso foco do crescimento quantitativo para um qualitativo e impor limites nas taxas de consumo dos recursos naturais da Terra", escreve.

"Nesta economia de estado sólido, os valores das mercadorias ainda podem aumentar, por exemplo, por causa de inovações tecnológicas ou melhor distribuição. Mas o tamanho físico dessa economia deve ser mantido em um nível que o planeta consiga sustentar", conclui Daly, que compara a atual economia a um avião em alta velocidade e a sua proposta a um helicóptero, capaz de voar sem se mover.
Reformar o capitalismo

Mas essas mudanças no sistema não serão fáceis. Em uma entrevista à revista, James Gustav Speth, ex-conselheiro do governo Jimmy Carter (1977-1981) e da ONU, afirma que o movimento ambiental nunca conseguirá vencer dentro do atual sistema capitalista.

"A única solução é reformarmos o capitalismo atual. Os Estados Unidos cresceram entre 3% e 3,5% por um bom tempo. Há algum dividendo deste crescimento sendo colocado em melhores condições sociais? Não. Os Estados Unidos têm que focar em indústrias sustentáveis, necessidades sociais, tecnologias e atendimento médico decente, e não sacrificar isso para fazer a economia crescer. Eu não defendo o socialismo, mas uma alternativa não-socialista para o capitalismo atual", diz.

Ele também faz críticas ao atual movimento ambientalista.

"A comunidade ambientalista, pelo menos nos Estados Unidos, é muito fraca quando falamos sobre mudança de estilo de vida, consumo e sobre sua relutância em desafiar o crescimento ou o poder das corporações. Nós precisamos de um novo movimento político nos EUA. Cabe aos cidadãos injetarem valores que reflitam as aspirações humanas, e não apenas fazer mais dinheiro.
Obsessão pelo crescimento

A revista também traz um artigo que discute o argumento de que o crescimento econômico é necessário para erradicar a pobreza e que quanto mais ricos ficam alguns, a vida dos mais pobres também melhora. É a chamada Teoria do Gotejamento.

Segundo Andrew Simms, diretor da New Economics Foundation, em Londres, este argumento, além de "não ser sincero", sob qualquer avaliação, é " impossível".

"Durante os anos 1980, para cada US$ 100 adicionados na economia global, cerca de US$ 2,20 eram repassados para aqueles que estavam abaixo da linha de pobreza. Durante a década de 1990, esse valor passou para US$ 0,60. Essa desigualdade significa que para que os pobres se tornem um pouco menos pobres, os ricos tem que ficar muito mais ricos".

Segundo ele, isto pode até parecer justo para alguns, mas não é sustentável.

"A humanidade está indo além da capacidade da biosfera sustentar nossas atividades anuais desde meados dos anos 1980. Em 2008, nós ultrapassamos essa capacidade anual em 23 de setembro, cinco dias antes do ano anterior".

Ele ainda afirma ser impossível que um dia toda a humanidade tenha o padrão de vida dos países desenvolvidos.

"Seriam necessários pelo menos três planetas Terra para sustentar essas necessidades se todos vivessem nos padrões da Grã-Bretanha. Cinco se vivêssemos como os americanos".

Para Simms, a Terra estaria inabitável há muito tempo antes que o crescimento econômico pudesse erradicar a pobreza.

Para que o mundo possa ter uma economia ecologicamente sustentável, segundo Simms, é preciso acabar com o preconceito de alguns em relação aoo conceito de "redistribuição", que, para ele, é o único modo viável de acabar com a pobreza.

"Só foi preciso alguns dias para que os governos da Grã-Bretanha e dos EUA abandonassem décadas de doutrinas econômicas para tentar resgatar o sistema financeiro de um colapso. Por que tem que demorar mais para introduzirem um plano para deter o colapso do planeta trazido por uma conduta irresponsável e ainda mais perigosa chamada obsessão pelo crescimento?".

Wozniak, entrevista e críticas á Apple

Wozniak prevê 'morte iminente' do iPod e fala sobre futuro da Apple e da indústria - O Globo Online

Publicada em 08/10/2008 às 15h57m
O Globo

RIO - Stephen Wozniak, o descendente de poloneses que fundou a Apple junto com Steve Jobs, deu uma entrevista extremamente franca para o Daily Telegraph sobre o futuro da empresa e da indústria de tecnologia. Entre outras controversas declarações, ele prevê a morte do produto mais popular da Apple, o iPod.

" O iPod já teve uma vida longa para começo de conversa "

- O iPod já teve uma vida longa para começo de conversa. Aparelhos como esse, se você olha para o passado e lembra dos rádios transistores e do Walkman, eles tendem a morrer depois de um tempo. É como se todo mundo tivesse um deles, ou dois ou três. Você chega num ponto em que ele está em todo lugar, pode ser comprado por um preço muito baixo e não vende mais tanto assim - analisa ele.

Wozniak parou de trabalhar na Apple em fevereiro de 1987, doze anos depois de fundá-la. No entanto, ele continua como funcionário da empresa (e recebe por isso) e se relaciona com Steve Jobs, além de possuir ações da companhia.

Na última semana, em meio à crise que afeta a economia global, as ações da Apple despencaram quase 20 pontos percentuais depois que analistas afirmaram que a queda no consumo poderia prejudicar gravemente os lucros da empresa. Qual a opinião de Wozniak sobre o assunto? Para ele, a supervalorização da web 2.0 e das redes sociais pode levar a uma versão menos grave da quebra de empresas pontocom ocorrida entre 2000 e 2002.

- Está na hora de toda a indústria de informática baixar um pouco a bola. Por 20 anos nós estamos nesse mercado de reposição e atualização. É muito fácil postergar isso quando há problemas financeiros - alerta Woz.

" Não é posssível satisfazer completamente os consumidores quando as empresa têm uma atitude muito proprietária e travam seus produtos "

Ele critica também a limitação imposta pela Apple na criação de aplicativos para o iPhone 3G. Qualquer programa criado para o smartphone precisa ser aprovado pela empresa para ficar disponível na App Store. O Google, por outro lado, lançou seu sistema operacional para celulares, o Android, em código aberto e liberou a criação de aplicativos para quaisquer desenvolvedores.

- Não é posssível satisfazer completamente os consumidores quando as empresa têm uma atitude muito proprietária e travam seus produtos. Eu gostaria de poder criar aplicativos mais poderosos do que é permitido - lamenta.

Sobrou até para os apaixonados fãs da Apple, cuja atitude religiosa em relação aos produtos da empresa pode prejudicar o avanço tecnológico, na opinião de Wozniak.

- Eu gostaria que os usuários influenciassem a próxima geração. Numa religião não é permitido contestar nada. Eu quero que nossos consumidores nos desafiem.

Brasileiros ganham o Ig Nobel Prize

2008 Ig Nobel Prizes honor research on stripper fertility and Coca-Cola as spermicide - Los Angeles Times

2008 Ig Nobel Prizes honor research on stripper fertility and Coca-Cola as spermicide.

Studies on armadillo mischief and flea athleticism also garner prizes, which are given for oddball scientific work.

By Mark Pratt, Associated Press
October 4, 2008

BOSTON -- Deborah Anderson had heard the urban legends about the contraceptive effectiveness of Coca-Cola products for years.

So she and her colleagues decided to put the soft drink to the test. In the lab, that is.

For discovering that, yes indeed, Coke is a spermicide, Anderson and her team are among this year's winners of the Ig Nobel Prize, the annual award given by the Annals of Improbable Research magazine to oddball but often surprisingly practical scientific achievements.

Actual Nobel laureates presented the awards Thursday at Harvard University.

Anderson, a professor of obstetrics and gynecology at Boston University's School of Medicine, and her colleagues found that not only is Coca-Cola a spermicide, but that Diet Coke works best.

Their study appeared in the New England Journal of Medicine in 1985.

"We're thrilled to win an Ig Nobel, because the study was somewhat of a parody in the first place," Anderson said, adding she does not recommend using Coke for birth control.

A group of Taiwanese doctors was honored for a similar study that found Coca-Cola and other soft drinks were not effective contraceptives. Anderson said the studies used different methodology.

A Coca-Cola spokeswoman refused to comment on the Ig Nobel awards.

Meanwhile, Geoffrey Miller's award-winning work could affect the earning potential of exotic dancers everywhere.

Miller, an associate professor of psychology at the University of New Mexico, and his colleagues knew of previous studies that found women are more attractive to men when at peak fertility.

So they took the work one step further -- by studying the earnings of exotic dancers.

For the 18 subjects Miller studied, average earnings were $250 for a five-hour shift. That jumped to $350 to $400 when the women were at their most fertile, he said.

"I have heard, anecdotally, that some lap dancers have scheduled shifts based on this research," he said.

Among the other winners:

* Archaeology: Astolfo Gomes de Mello Araujo and Jose Carlos Marcelino of the University of Sao Paulo in Brazil for showing that armadillos can scramble the contents of an archaeological dig.

* Biology: Marie-Christine Cadiergues, Christel Joubert and Michel Franc of the National Veterinary College of Toulouse in France for discovering that fleas that live on a dog can jump higher than fleas that live on a cat.

* Cognitive science: Toshiyuki Nakagaki of Hokkaido University in Japan and colleagues for discovering that slime molds can solve puzzles.

* Medicine: Dan Ariely of Duke University for demonstrating that expensive fake medicine is more effective than cheap fake medicine.

* Peace: The Swiss Federal Ethics Committee on Non-Human Biotechnology and the citizens of Switzerland for adopting the legal principle that plants have dignity.

* Physics: Dorian Raymer of the Scripps Institution of Oceanography in San Diego and Douglas Smith of UC San Diego for proving that heaps of string or hair inevitably tangle.

Quebra fundamental leva Nobel de Física

:: Agência FAPESP :: Notícias - Quebra fundamental leva Nobel de Física

8/10/2008

Agência FAPESP – Dois japoneses e um japonês naturalizado norte-americano são os ganhadores do Prêmio Nobel de Física de 2008, segundo anúncio feito nesta terça-feira (7/10) na Suécia.

Yoichiro Nambu, 87 anos, do Instituto Enrico Fermi da Universidade de Chicago, natural de Tóquio, mas que desde a década de 1950 vive nos Estados Unidos, receberá metade do prêmio, “pela descoberta do mecanismo da quebra espontânea de simetria na física subatômica”, segundo o comunicado do comitê do Nobel.

A outra metade do prêmio de 10 milhões de coroas suecas (cerca de R$ 3 milhões) será dividida entre Makoto Kobayashi, 64 anos, da Organização de Pesquisa de Aceleração em Alta Energia, e Toshihide Maskawa, 68 anos, do Instituto Yukawa de Física Teórica da Universidade de Kyoto, “pela descoberta da origem da quebra de simetria, a qual prevê a existência de pelo menos três famílias de quarks na natureza”.

“Graças à quebra de simetria, nós estamos aqui hoje”, disse Gunnar Öquist, secretário-geral da Academia Real de Ciências da Suécia, durante o anúncio do prêmio.

Há séculos os físicos têm tentado descobrir as leis definitivas da natureza por meio da busca por simetrias, ou propriedades que se manifestam da mesma forma mesmo em circustâncias diferentes. Mas, em 1960, Nambu sugeriu que algumas das simetrias poderiam, na realidade, estar escondidas, ou “quebradas”.

Um lápis em pé sobre uma mesa, por exemplo, representa algo simétrico, mas instável, e acabará caindo e apontando para um lado. O princípio passou a integrar a moderna física de partículas. “Temos que procurar por simetrias mesmo quando não as podemos ver”, disse Michael Turner, professor da Universidade de Chicago, ao The New York Times. Turner descreve o colega como “o homem mais humilde de todos os tempos”.

Em 1972, Kobayashi e Maskawa mostraram que se houvesse três gerações de partículas elementares chamadas quarks (os constituintes de prótons e nêutrons), o princípio da quebra de simetria poderia explicar uma enigmática assimetria conhecida como violação de CP.

Trata-se de um produto de duas simetrias: carga (C) e paridade (P). A descoberta, feita em 1964 pelos norte-americanos James Cronin e Val Fitch, deu aos dois o Nobel de Física de 1980. Até então, os cientistas assumiam que se as cargas positivas e negativas nas equações de partículas elementares fossem trocadas o resultado seria o mesmo.

Mas como a natureza funciona de modo diferente, ou seja, ela não se comporta de forma simétrica, isso explicaria por que o Universo é feito de matéria e não de antimatéria, uma das questões que o LCH, o maior acelerador de partículas do mundo, pretende ajudar a responder.

Também em 1964, o físico inglês Peter Higgs usou os conceitos lançados por Nambu para explicar o que tem sido chamado de origem da massa. Segundo ele, as partículas fundamentais obtêm suas massas de um campo invisível que permeia o espaço desde os primórdios do Universo.

Comprovação em 2001

A descrição matemática da quebra de simetria espontânea, feita originalmente por Nambu, mostrou-se extremamente útil. As idéias permeiam o modelo padrão da física de partículas, que unifica os menores blocos formadores da matéria e três (nuclear forte, nuclear fraca e eletromagnética) das quatro forças fundamentais da natureza (a outra é a gravidade) em uma única teoria.

As quebras de simetria são ocorrências espontâneas que aparentemente existem desde o início do Universo. Apesar de terem sido detalhadas em 1972, por Kobayashi e Maskawa, apenas recentemente experimentos comprovaram as idéias.

Em 2001, dois detectores de partículas, um em Stanford, nos Estados Unidos, e outro em Tsukuba, no Japão, detectaram a quebra de simetria, em resultados exatamente iguais ao previsto pelos físicos japoneses três décadas antes.

A quebra de simetria explica a seqüência do próprio Big Bang, a grande explosão que teria originado o Universo há cerca de 14 bilhões de anos. Se quantidades iguais de matéria e de antimatéria tivessem sido criadas, uma deveria ter aniquilado a outra.

Isso não ocorreu por que teria havido uma pequena variação na forma de uma partícula extra de matéria para cada 10 bilhões de partículas de antimatéria. E é a pequena, mas crucial quebra de simetria que garantiu a sobrevivência do Universo.

O Nobel de Química será anunciado nesta quarta-feira (8/10). Os prêmios – cheques, medalhas de ouro e diplomas – serão entregues em 10 de dezembro, aniversário da morte de Alfred Bernhard Nobel (1833-1896), o inventor da dinamite.

Mais informações: http://nobelprize.org.

Folhas chapeadas

:: Agência FAPESP :: Notícias - Folhas chapeadas

24/9/2008

Por Thiago Romero

Agência FAPESP – Uma chapa produzida com folhas de espécies vegetais da Amazônia que tem múltiplas aplicações, entre as quais a substituição de derivados de madeira, foi desenvolvida por pesquisadores do Instituto Nacional de Pesquisas da Amazônia (Inpa), em Manaus.

A aplicação mais indicada para o novo material, segundo um de seus inventores, Jadir de Souza Rocha, da Coordenação de Pesquisa em Produtos Florestais do Laboratório de Engenharia da Madeira do Inpa, é na confecção de produtos utilizados no acabamento de ambientes internos de construções.

“A chapa de folhas é similar às chapas de aglomerado, compensado e MDF, podendo, portanto, ser utilizada em forros, divisórias, móveis e outros artefatos”, disse Rocha à Agência FAPESP.

“Realizamos uma série de ensaios mecânicos de flexão estática para determinar o módulo de elasticidade, que é a propriedade de resistência mecânica que especifica a rigidez do material, cujos resultados finais se aproximaram das chapas de aglomerado comerciais”, disse.

Segundo ele, no processo de confecção da chapa, que também pode substituir materiais como isopor e gesso, as folhas são trituradas e, posteriormente, secas ao ar livre ou em estufas para que as pequenas partículas vegetais dêem origem a uma plataforma lisa, que recebe outras matérias-primas como resinas e fibras de vidro.

“Esse processo tem início com a seleção das folhas. Devem ser escolhidas as mais espessas e de superfícies lisas, que são bastante resistentes ao rasgo. Um detalhe importante é que as folhas não podem estar infestadas por fungos. Depois de transformadas em pequenas partículas pelas máquinas trituradoras, elas passam pela secagem até atingir umidade final de 8% a 12%”, disse.

Em seguida, o material, que pode ser produzido a partir de folhas de espécies arbóreas e frutíferas, além de palmeiras, ervas daninhas e plantas ornamentais, passa por processo de prensagem a quente.

“Essa é a última etapa, caracterizada pela formação de um colchão de partículas em que as resinas sintéticas e a fibra de vidro são os elementos aglutinadores, que sofrem a ação conjunta de altas temperaturas e pressão”, explica o pesquisador.

Rocha calcula a existência de aproximadamente 180 espécies de palmeiras na Amazônia, distribuídas em 39 gêneros. E, segundo o pesquisador, praticamente todas essas espécies possuem folhas apropriadas para a confecção das chapas.

“Dentre as espécies arbóreas, centenas delas também apresentam folhas com características desejáveis, podendo ser citadas a andiroba, castanheiras, sucupira-amarela, jatobá e ucuúba-punã”, salientou.

Nos grupos das frutíferas, ervas daninhas e plantas ornamentais também podem ser encontradas dezenas com tais aptidões na floresta tropical, com destaque para as espécies do gênero Sansevieria, conhecidas como espada-de-são-jorge. “Essas espécies são extremamente resistentes ao rasgo e apresentam uma reprodução fantástica”, disse Rocha.

A durabilidade do material pode ser exemplificada, segundo o pesquisador, com uma folha gigante do gênero Coccoloba. “Essas folhas medem cerca de 2 metros de comprimento, 1,3 metro de largura e podem permanecer em bom estado de conservação por mais de 15 anos após sua coleta na natureza”, afirmou.

Mistério da calota torta marciana é explicado

:: Agência FAPESP :: Divulgação Científica - Mistério da calota torta marciana é explicado

Com dados enviados pela sonda Mars Express, cientistas conseguem entender os mecanismos que fazem com que a calota de gelo no sul do planeta fique deslocada do pólo (divulgação)


24/9/2008

Agência FAPESP – O mistério acaba de ser devidamente explicado. Cientistas já sabem por que a calota gelada no sul em Marte não está onde deveria – pelo menos onde estaria se estivesse na Terra.

No planeta vermelho, o gelo residual não está simetricamente localizado em torno do pólo do planeta, mas deslocado para o lado. Com a ajuda da sonda Mars Express, da Agência Espacial Européia (ESA), um grupo de pesquisadores conseguiu explicar o motivo do posicionamento inusitado.

A culpa é do clima marciano. Como a Terra, Marte tem calotas congeladas, mas, diferentemente da encontrada no pólo Sul terrestre, a marciana é composta, além de água congelada, por dióxido de carbono. Durante o verão no hemisfério sul, a maior parte da formação é sublimada, em um processo por meio do qual o dióxido de carbono congelado se transforma diretamente em gás, deixando o que é conhecido como calota polar residual.

O problema é que embora a calota do inverno seja simétrica em relação ao pólo sul marciano, a calota residual está bem deslocada, em cerca de 4 graus. O mistério, que confundiu cientistas planetários durante décadas, foi resolvido em 2005, mas agora o novo estudo reúne informações que explicam com exatidão a anomalia.

Marco Giuranna, do Instituto de Física do Espaço Interplanetário em Roma, Itália, e colegas usaram o espectrômetro planetário Fourier, instalado na Mars Express, para medir a temperatura da atmosfera marciana da superfície até 50 quilômetros acima do pólo meridional do planeta.

Os pesquisadores analisaram como a atmosfera muda em relação à temperatura por mais da metade do ano marciano (que equivale a quase dois anos terrestres). Eles também monitoraram como o dióxido de carbono se acumula na calota do outono ao inverno.

“Não é um processo linear. Verificamos que dois sistemas climáticos regionais se desenvolvem a partir de meados do outono e durante o inverno”, disse Giuranna. O estudo será publicado em breve na revista Icarus.

Os sistemas climáticos são derivados dos fortes ventos que caracterizam a circulação atmosférica em latitudes médias. Os ventos sopram diretamente na planície de Hellas, a maior cratera no planeta, com 2,3 mil quilômetros de diâmetro e profundidade que chega aos 7 quilômetros.

A profundidade da cratera e a elevada inclinação de suas paredes desviam os ventos e criam o que na Terra é conhecido como onda de Rossby, movimento ondulatório por meio do qual as regiões de vorticidade ciclônica e anticiclônica se alternam à medida que a onda se propaga.

Essas ondas deslocam os ventos de elevadas altitudes e forçam o sistema climático em direção ao pólo sul. No hemisfério ocidental marciano, essa mudança cria um forte sistema de baixa pressão próximo ao pólo sul. Também cria, próximo ao pólo, um sistema de alta pressão no hemisfério leste.

Os cientistas europeus descobriram que a temperatura no sistema de baixa pressão está freqüentemente abaixo do ponto de condensação do dióxido de carbono, de modo que o gás se condensa e cai na forma de gelo, acumulando-se no solo.

No sistema de alta pressão, as condições não são apropriadas para neve, fazendo com que apenas ocorra a formação de gelo na superfície. A mistura dos dois mecanismos é que leva à formação da calota no sul marciano.

As áreas com extensa cobertura de neve não se sublimam no verão porque refletem mais a luz solar do que as partes com gelo. Essas últimas também são mais rugosas e, por conta disso, acumulam mais luz solar, promovendo a sublimação.

Ou seja, as partes na calota polar marciana compostas de neve e gelo não apenas têm maiores quantidades de dióxido de carbono congelado depositado como também sublimam mais lentamente durante o verão. Enquanto isso, as partes feitas apenas de gelo desaparecem por completo. Isso explica por que a calota residual, que permanece após o verão, não está localizada simetricamente em torno do pólo sul do planeta.

O artigo PFS/MEX observations of the condensing CO2 south polar cap of Mars, de Marco Giuranna e outros, pode ser lido por assinantes da Icarus em www.elsevier.com/locate/icarus.

Água tratada naturalmente

:: Agência FAPESP :: Especiais - Água tratada naturalmente

Especiais
Água tratada naturalmente

14/8/2008
Por Thiago Romero

Agência FAPESP – O engenheiro civil Luciano Zanella desenvolveu um sistema de tratamento de esgoto doméstico que associa a beleza das plantas com o bom desempenho na purificação de efluentes de produtos naturais.

O sistema utiliza espécies ornamentais fixadas em pedra ou bambu colocados sobre uma camada de terra. No recipiente, a água passa pelos espaços entre as pedras (ou anéis de bambu), que, com a ajuda das raízes das plantas, fazem a filtração.

O estudo foi feito como trabalho de doutorado, defendido na Faculdade de Engenharia Civil, Arquitetura e Urbanismo da Universidade Estadual de Campinas (Unicamp).

Segundo Zanella, pesquisador do Laboratório de Instalações Prediais e Saneamento, vinculado ao Centro Tecnológico do Ambiente Construído do Instituto de Pesquisas Tecnológicas (IPT), o dispositivo é indicado para o tratamento complementar ao esgoto doméstico, após esse ter passado por uma primeira etapa de purificação para remoção dos resíduos mais pesados.

Em testes realizados na Faculdade de Engenharia Agrícola da Unicamp, o engenheiro utilizou seis tanques de 2 mil litros cada. Os tanques receberam amostras de esgoto que já tinham passado por um primeiro tratamento na faculdade, sendo que em três recipientes foram adicionadas pedras brita nº 1 até a borda e, nos outros três, anéis de bambu.

"A eficiência média de remoção de sólidos em suspensão foi de cerca de 60% para os tanques com brita e de 33% para os tanques com bambu. Os valores médios de matéria orgânica foram de 22 miligramas por litro (mg/l), com 60% de eficiência de remoção, para os tanques de pedra brita, e de 36 mg/l, com 33% de eficiência de remoção, para os construídos com leito de bambu", disse Zanella à Agência FAPESP. O esgoto que saía da estação apresentava valor médio de matéria orgânica de 54 mg/l.

Os resultados médios obtidos para outro parâmetro de qualidade da água, demanda química de oxigênio (DQO), que mede indiretamente a carga de matéria orgânica contida na amostra, foram de 63,9% para os dispositivos com brita e plantas mistas e 55,8% sem o uso de plantas. No caso dos anéis de bambu, os índices foram de 29,7% e 20,4%, respectivamente.

Segundo o pesquisador, o sistema mantém o padrão estético dos jardins, diminuindo os níveis de rejeição da população para os dispositivos de tratamento de efluentes. Podem ser utilizadas diversas espécies de plantas, entre as quais copo-de-leite (Zantedeschia aethiopica), papiro (Cyperus papyrus) e biri (Canna edulis), que colaboram com o tratamento do esgoto ao mesmo tempo em que absorvem nutrientes como fósforo e nitrogênio para crescer com qualidade.

"A planta cresce em cima do esgoto, que serve como uma espécie de adubo natural para as espécies. O sistema lembra o processo de hidroponia acrescido da ação de microrganismos. Outra vantagem é que ele não necessita de nenhum tipo de produto químico ou eletricidade", disse Zanella.

Por ser considerado de baixo custo, o sistema é considerado ideal para pequenas propriedades. A água gerada pode ser utilizada para a irrigação de plantações e as plantas podem servir como uma fonte de renda extra pela exploração comercial das flores e fibras vegetais.

"Em uma população rural, por exemplo, seria possível plantar espécies ornamentais para venda. As fibras do caule do papiro, uma das plantas que melhor se adaptaram ao sistema, também podem ser usadas para artesanato na confecção de produtos como papel ou luminárias", disse.

Brasil em Alta Resolução

:: Agência FAPESP :: Notícias - Brasil em alta resolução

Notícias
Brasil em alta resolução

20/8/2008

Agência FAPESP – O Instituto Nacional de Pesquisas Espaciais (Inpe) disponibilizou na internet uma galeria de imagens em alta resolução do programa CBERS (Satélite Sino-brasileiro de Recursos Terrestres).

O trabalho de geração e tratamento das imagens da galeria foi realizado pela Divisão de Geração de Imagens, da Coordenação Geral de Observação da Terra do Inpe. Os arquivos podem ser utilizados gratuitamente, com menção de crédito para o instituto.

A galeria inclui imagens de todas as capitais brasileiras e de algumas áreas de países da América do Sul.

Também estão disponíveis no site as primeiras imagens produzidas pela HRC – Câmera Pancromática de Alta Resolução, instalada em caráter experimental no CBERS-2B (lançado em setembro de 2007). A HRC produz imagens de uma faixa de 27 quilômetros de largura com resolução espacial de 2,7 metros, em uma região espectral pancromática única.

Desde 2004 está disponível o banco de imagens dos satélites Landsat-1, Landsat-2, Landsat-3, Landsat-5, Landsat-7, CBERS-2 e CBERS-2B. Mas, para visualizar as imagens desse catálogo em resolução plena, é necessário conhecimento e ferramentas de processamento de imagem. Esses arquivos são, portanto, voltados para uso profissional ou acadêmico.

A nova galeria, no entanto, é voltada para meios de comunicação, professores e estudantes de ensino fundamental e médio e as imagens podem ser salvas e utilizadas imediatamente.

Mais informações: www3.dgi.inpe.br/pesquisa2007/galeria/linux_E_galeria/galeriaCD.html

The Joker

Heath Ledger in 'Dark Knight': Bravo! - Los Angeles Times

CRITIC'S NOTEBOOK | THE ART OF PERFORMANCE

Heath Ledger in 'Dark Knight': Bravo!


THE JOKER: Heath Ledger (with Maggie Gyllenhaal) made an already iconic
character his.
Ledger's turn as the Joker shows how rare and fine a talent his was.

By Charles McNulty, Times Theater Critic
August 4, 2008

Great actors, even those who have been blessed with longevity, often bear a tragic mark. It's not just the ups and downs of stardom that can make for a cruel career. Rough inner seas are typically the very reason someone seeks to be among what William Hazlitt, that lyrical witness of the early 19th century British stage, called "the motley representatives of human nature."

Heath Ledger's short legacy as a screen actor offers us enough evidence of the rarity of his talent. "Brokeback Mountain" may be the film that exposed to a wider audience the intensity of his dramatic commitment -- Ledger didn't simply impersonate a closeted cowboy, he showed us the shame and silence that had taken residence in Ennis Del Mar's sinews. But it's his turn as a terrorist clown in a menacing comic-book caper -- the last role he fully completed before his accidental overdose in January at age 28 -- that will seal his place among movie immortals.

Ledger's portrayal of the Joker in "The Dark Knight" is all that it's cracked up to be -- a stunning, frightening, pathological marvel that's deserving of the somber Oscar talk not normally associated with a superhero blockbuster.

Inevitably, the temptation is to scrutinize such a fateful performance for clues into the actor's mental state. We'd all like to catch a glimpse of an explanatory scar. But unlike, say, Judy Garland in "A Star Is Born" or Marlon Brando in "Last Tango in Paris," where the actors were playing characters with sharp biographical parallels, Ledger isn't portraying someone we can easily -- and all too mistakenly -- conflate with his private self.

At least there's some relief that his art won't be trampled by the gossip hounds. Better to celebrate Ledger's performance for the secrets it reveals and harbors about (to borrow from Hazlitt again) "the studied madness" of acting.

Unnaturally natural

Let's take this opportunity to first banish the inane assumption that craft is secondary to inspiration. The two work in tandem, as is obvious from the way Ledger manages to be so chillingly expressive with his face smeared in pancake makeup and lipstick and his hair transformed into a greasy green-tipped tangle. How does Ledger so uniquely personalize this flamboyant arch-villain who's already been colorfully incarnated by Cesar Romero in the 1960s "Batman" TV series and Jack Nicholson in Tim Burton's 1989 film? With his patented good looks concealed, Ledger's forced to be more cunning with his physical resources, and you sense his delight in this freedom from Hollywood vanity.

Ledger's vocal mannerisms constitute a kind of diagnostic manual. Observe, for instance, the way he hits exaggerated Middle American consonants in the beginning, establishing his character not just as a criminal lunatic but a proverbial American one, a heartland offender run amok. And look how his mania affects the rate at which words pour from his scarred lips, slowing down to a normal clip by the end of the Joker's deadly game, even as we can be sure he's still fantasizing about fireballs in city streets.

Ledger isn't just after sick physical comedy with his slouch, jack-in-the-box spring and demonic head roll -- he's jotting down notes in a lengthy psychiatric case file. Quite amazing given the temptation to break loose of all mundane restraints, nothing's overdone -- not even the reptilian tongue, which emerges with the punctuating timeliness of an exclamation mark.

But it's through Ledger's eyes that we can peer into the actor's bottomless conviction and track the scurrying-rodent logic of his character's inexplicable evil. Maniacs who fly planes into buildings don't second-guess their distorted reality, and Ledger ambles around Joker's fun-house mind with an unshockable comfort. The film tosses off cryptic remarks about the Joker's brutal upbringing, but it's Ledger's antic disposition that lets us understand the traumatic past as a slippery myth that can never adequately explain malignant behavior.

The best actors are distinguished by their preternatural capacity to appear natural. They enter dreams and nightmares the way you and I enter our kitchens. An artist's vision is lived, emotionally and physically, so that while a lesser performer will signboard motives and big moments, a subtler talent will experience the not always predictable flux of his character's emotions as the larger dramatic pattern unfolds as though on its own.

That kind of performance requires more than instinct -- it needs an interpretive intelligence to guide it discreetly along. No surprise, then, that the most unforgettable performers are usually the smartest ones -- which is to say the deepest, philosophically and psychologically, as well as the most tactful, aesthetically and dramatically.

But are there unseen costs to this talent for rambling about imaginary places and stumbling over emotional furniture? At a 2001 memorial service for Kim Stanley -- by peer consensus Brando's equal in the '50s and '60s, who prematurely retired from the stage after a series of breakdowns -- Elaine Stritch, her costar in the Broadway premiere of William Inge's "Bus Stop," confided to all who had assembled that, in her view, what happened to Stanley was that "she got too goddamn real."

There's a price

Realness doesn't come cheaply. If you read about the life of Eleonora Duse, the Italian actress who inspired Stanislavsky with her anguished truth, you'll discover that the radiant pain she drew out of Ibsen, Zola and Dumas' "La Dame aux Camélias" was already overstocked in her disappointed heart. The point is that this ability to burst the bounds of artifice and create art that bleeds has to come from somewhere. Imaginations need roots.

Even for the buttoned-up English, it's not easy to shut the door on that troubled place when the gig is done. On the set of "Marathon Man," Laurence Olivier is said to have advised Dustin Hoffman, who had been putting himself through the ringer for his character, "Dear boy, you look absolutely awful. Why don't you try acting? It's so much easier." It's a good, if over-used, anecdote (apocryphal or not). But not even Lord Olivier, who strode the public scene more and more like an over-complicated Shakespearean king, was always so adept at maintaining a firewall between his life and work, to say nothing of wife Vivien Leigh, whose fragile mental health wasn't exactly shored up by her time as Blanche DuBois.

Roles aren't to blame, of course, for alcoholism, addiction and bipolar disorder. But when they are realized with fierce riptides of feeling, they hint at something peculiarly vulnerable about our icons. What's more, transcendent acting takes a toll in a way that goes beyond painting, poetry or other creative disciplines, because actors must utilize themselves in an inescapably naked way. There's nowhere to run when the camera or audience is before them. And though sophisticated veterans such as Judi Dench or Meryl Streep seem to handle the professional burden without too much wear and tear, it's no wonder they're eager to lighten the load with some lucrative James Bond or brainless "Mamma Mia!"

Let's not pretend there's no difference between Brando in "Tango" and the majority of acting work that earns our aloof respect. The quality that distinguishes the excellent from the extraordinary is danger -- sometimes informally referred to as "going there." It involves enormous freedom as well as discipline, but the genie isn't so easily put back in the bottle.

Ledger had the threatening spark that marks the best, and in "The Dark Knight" it's allowed to erupt into a magnificent flame. The proper response to such a gift, frustratingly short-lived as it was, is gratitude and awe.

charles.mcnulty@latimes.com

Van Gogh esconde Van Gogh

High-tech study reveals early Van Gogh work beneath another painting - Los Angeles Times

University of Antwerp/Deutsches Elektronen-Synchrotron

Researchers
used X-rays from a particle accelerator to reconstruct the portrait of
a woman Vincent van Gogh had painted over before composing his
landscape "Patch of Grass," completed in 1887. Conventional X-rays used
in previous analyses had produced only rough outlines of the portrait.
The image, unveiled in a scientific journal published this week, bears
a striking resemblance to a series of somber portraits the artist
produced in the Dutch town of Nuenen, where he composed “The Potato
Eaters,” completed in 1885 and regarded as his first major work.

High-tech study reveals early Van Gogh work beneath another painting
University of Antwerp/Deutsches Elektronen-Synchrotron
Researchers used X-rays from a particle accelerator to reconstruct the portrait of a woman Vincent van Gogh had painted over before composing his landscape "Patch of Grass," completed in 1887. Conventional X-rays used in previous analyses had produced only rough outlines of the portrait. The image, unveiled in a scientific journal published this week, bears a striking resemblance to a series of somber portraits the artist produced in the Dutch town of Nuenen, where he composed “The Potato Eaters,” completed in 1885 and regarded as his first major work.
X-rays from a particle accelerator help scientists reconstruct a portrait the artist had covered up to paint his 'Patch of Grass' in 1887.
By Karen Kaplan, Los Angeles Times Staff Writer
July 30, 2008
Using a thin beam of synchrotron X-rays generated by a particle accelerator, European scientists have reconstructed a portrait of a peasant woman painted by Vincent van Gogh that had been concealed beneath another painting for 121 years.

The image, unveiled in a scientific journal published today, bears a striking resemblance to a series of somber portraits the artist produced in the Dutch town of Nuenen, where he composed "The Potato Eaters," completed in 1885 and regarded as his first major work.

Conventional X-rays had revealed the rough outlines of the portrait, which Van Gogh covered 2 1/2 years later with a vibrant landscape of a flowering meadow after he moved to Paris and was influenced by Impressionism. But those X-rays weren't good at distinguishing between the many layers of paint on the single canvas, and pigments made from heavy metals obscured colors derived from other elements.

"We get a very partial, fragmentary, color-blind view," said Joris Dik, a materials scientist and art historian at the Technical University of Delft in the Netherlands.

So Dik and his colleagues took the painting, "Patch of Grass," which was completed in 1887, to a particle accelerator in Hamburg, Germany. The intense X-ray beam excited the atoms on the canvas, causing them to emit X-rays of their own that were captured by a florescence detector. It took two days to scan the roughly 7-by-7-inch portion of the meadow that masked the portrait.

Since each element in the painting had its own X-ray signature, the scientists were able to identify the distribution of metals in the various layers of paint and construct a three-dimensional model of the work. Then the team peeled off the layers one by one.

The top layer consisted of paints made with zinc, barium, sulfur and other elements. Behind that they found a uniform distribution of lead, which was used as a primer to hide the portrait and prepare the canvas for a new painting. Once that was removed, they combined the distributions of two more elements -- mercury and antimony -- to produce the outlines of the hidden portrait.

Then, with the help of computer software, the team embarked on an elaborate version of painting by numbers.

"We colorized those two distributions according to the color that the pigment would have had," Dik said.

Chemical analysis revealed that the mercury was an ingredient of vermilion, the red pigment used to color the woman's lips, cheeks and forehead. Antimony was a component of Naples yellow, which was mixed with zinc white paint to highlight certain areas of the woman's face, according to the report in the August issue of Analytical Chemistry.

Van Gogh often recycled his canvases. Art experts estimate that one-third of his early paintings hide others, which may be ripe for new analysis.

karen.kaplan@latimes.com

Dispositivo de Anticitera

:: Agência FAPESP :: Divulgação Científica - Calendário olímpico

Divulgação Científica
Calendário olímpico

31/7/2008

Agência FAPESP – Já se sabia que o Mecanismo de Anticítera, resultado da engenhosidade dos gregos antigos, era mais sofisticado tecnologicamente do que qualquer outro mecanismo inventado pelo menos nos mil anos seguintes. Agora, um novo estudo indica uma complexidade ainda maior.

O grupo liderado por Tony Freeth, do Projeto de Pesquisa do Mecanismo de Anticítera, conseguiu reconstituir inscrições que revelam que o mecanismo, construído por volta do ano 100 a.C., não era usado apenas para operações científicas.

Em estudo publicado na edição de 31 de julho da revista Nature, os pesquisadores usaram imagens feitas em raio X em três dimensões para mostrar que o mecanismo, utilizado principalmente para cálculos astronômicos, também armazenava dados de eventos esportivos, como se fosse um computador portátil.

Segundo eles, um dos discos, até então considerado um calendário de um ciclo de 76 anos, era usado para seguir outro ciclo, o de quatro anos das Olimpíadas e de outros jogos pan-helênicos. Entre as inscrições recuperadas nos fragmentos estão as palavras “olympia” e “nemea”, esta última referente aos Jogos de Neméia.

Os cientistas também identificaram no mecanismo 12 nomes de meses que consideraram de origem coríntia, da Siracusa, e sugerem que o conceito do mecanismo pode ser estendido a Arquimedes (c. 287 a.C. – c. 212 a.C.). Os meses integravam um sofisticado calendário de 19 anos.

O Mecanismo de Anticítera foi descoberto em 1901 por um grupo de mergulhadores que apanhavam esponjas próximo à ilha de Anticítera. As 82 partes hoje disponíveis e que são usadas para os estudos foram retiradas de um naufrágio a 42 metros de profundidade. A data estimada do naufrágio é 65 a.C.

O artigo Calendars with Olympiad display and eclipse prediction on the Antikythera Mechanism, de Tony Freeth e outros, pode ser lido por assinantes da Nature em www.nature.com.

Leonard Susskind

Hawking nemesis Leonard Susskind speaks - Los Angeles Times

Leonard Susskind


Matthew Black / For The Times

Stanford University physicist Leonard Susskind
went from a being a plumber in the South Bronx
to becoming an authority on black holes.


Hawking nemesis Leonard Susskind speaks

In 'The Black Hole War,' Stanford University physicist Susskind recounts his long history of scientific conflict with famed cosmologist Stephen Hawking (whose concession letter he prints).

By John Johnson Jr., Los Angeles Times Staff Writer
July 26, 2008


For two decades, Stanford University physicist Leonard Susskind battled cosmologist Stephen Hawking over the behavior of black holes. Hawking said that when black holes eat their fill, they disappear, taking with them everything they consumed over their billions of years of existence. Susskind found this idea so disturbing that he publicly declared war -- a conflict he describes in his new book, "The Black Hole War." In a conversation before a recent appearance at the Los Angeles Public Library, Susskind recounted his long struggle to "make the world safe for quantum mechanics."


How did this war with Stephen Hawking come about?


I was a particle physicist when I was invited to an event at Werner Erhard's house in 1981. Erhard [founder of the est self-awareness movement] admired scientists and liked to listen to them debate. At one of his events, I met Stephen Hawking. Stephen discovered an amazing fact, which is that black holes evaporate. It's like a puddle of water out in the sun.

OK.

So the question is, What happens to the information trapped in the black hole? Stephen said it was lost forever. Stephen didn't just say it, he proved it. At least he convinced himself and everybody else mathematically that it was true.

And you felt that was wrong.

It violates one of the fundamental principles of physics, which says nothing is ever lost completely. You may say, "How can you say information isn't lost? I can erase information on my computer." But every time a bit of information is erased, we know it doesn't disappear. It goes out into the environment. It may be horribly scrambled and confused, but it never really gets lost. It's just converted into a different form.

In your book, you compare Stephen Hawking to the White Whale and yourself to Ahab.

I obsessed over this. This was never a matter of personal animosity. But he couldn't see how damaging this would be to the rest of physics. And he didn't see what a great resolution might come out of it if thought about in the right way. I love the man, but I wanted to grab him by the neck and shake him a little bit. Stephen would just smile and say, "I'm right and you're wrong."

That's a pretty heady debate for someone who started out as a plumber.

I was from a poor Jewish family in the South Bronx. My father was a plumber, but when I was 16 he got sick and I had to take over. Being a plumber in the South Bronx wasn't fun.

When did physics come along?

I was going to engineering school but fell in love with physics. When I told my father I wanted to be a physicist, he said, "Hell, no, you ain't going to work in a drugstore." I said, No, not a pharmacist. I said, "Like Einstein." He poked me in the chest with a piece of plumbing pipe. "You ain't going to be no engineer," he said. "You're going to be Einstein."

What is the great resolution you referred to?

One result is something called Black Hole Complementarity. Let's say Alice falls into a black hole while Bob stays on the outside and watches. Nothing drastic happens to her when she crosses the event horizon [the point of no return around a black hole]. Of course she's eventually going to get it. On the other hand, there is another picture of the black hole, where every bit of information that you throw onto the horizon of a black hole gets sort of stuck on the horizon and builds up a soup of information bits. And this soup is hot, about a 100 billion billion billion degrees.

So Alice would get burned up?

We have a dilemma. One theory, based on general relativity, simply says Alice just floats past the horizon. That would be Alice's view of things. But Bob's view of things, if he believes in quantum mechanics, is that Alice falls into this soup of hot bits and her molecules are ripped apart. So, which one is correct? Alice can't both be killed at the horizon and not killed at the horizon. The answer is they are both correct.

How can that be?

These two ideas are not in conflict because to be in conflict, there has to be a contradiction. Well, nobody can see a contradiction for the simple reason that nobody can send a message from the inside of a black hole. Alice can't send a message saying, "Bob, I'm OK, don't worry about me," because the message can't get out of the black hole. Yet everything Bob sees is consistent with saying that Alice was thermalized.

It's difficult to see how both can be true.

We've had these things before in Einstein's thought experiments. Einstein, in the special theory of relativity, proved that different observers, in different states of motion, see different realities.

There's another strange theory that's come out of this battle, isn't there?

Yes, the Holographic Principle. A hologram is a two-dimensional sheet, such as film, which codes three-dimensional information. A simple way to say it is that the black hole horizon is like a hologram. The horizon of the black hole is like the film, and the image is the stuff that falls into the black hole. It's extremely unintuitive. According to this theory, the exact description of a region of space -- no matter how big -- is like a film on the boundary, where complicated and extremely scrambled versions of that space are going on. So in that sense, the universe is like a hologram.

Stephen now agrees that the information is not lost when a black hole evaporates.

Yes, he's seen the light. When he sees the light, he's very magnanimous.

[Susskind pointed to a page in his book, where a concession letter from Hawking is printed.]

Are there are any evaporating black holes in our region of the universe?

No. They are all accreting [still eating]. Black holes are much, much colder than their surroundings in space. That means heat flows from the surrounding space into the black hole. If we wait for a long, long time, the universe will expand, it'll cool, and eventually empty space will become colder than the black holes. When that happens, they will start to evaporate. But don't hold your breath.

john.johnson@latimes.com

Píon

P:: Agência FAPESP :: Notícias - Professores de física ganham página na internet

Professores de física ganham página na internet

28/7/2008

Agência FAPESP – Os professores de física de todo o país, em especial os do ensino médio, ganharam uma página na internet que fornecerá material instrucional de apoio à atividade docente, visando a melhorar o processo de ensino aprendizagem.

Trata-se do portal Píon, desenvolvido pela Sociedade Brasileira de Física (SBF) com o apoio financeiro do Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), que já está no ar para livre consulta. O site também pretende servir como um meio de divulgação da física para todos os interessados no assunto.

O nome do portal é uma homenagem ao físico brasileiro Cesar Lattes, co-descobridor da partícula elementar conhecida por Méson pi ou Píon. Nele estão disponíveis conteúdos como simulações, aulas prontas, textos, imagens e links.

A página tem uma sessão de artigos que contém adaptações de textos originalmente publicados na revista Física na Escola, da SBF, além de artigos escritos por internautas e colaboradores. Já a sessão “Você sabia” oferecerá uma seleção de desafios em física, elaborados especialmente para professores e estudantes.

Notícias relevantes sobre o ensino de física, um blog com comentários e dicas e uma sessão com informações sobre eventos também estão no portal. Há ainda um fórum de discussões para ampliar o relacionamento e a troca de experiências entre o público, os físicos e os professores.

O idealizador e coordenador do portal é o físico Nelson Studart, professor do Departamento de Física da Universidade Federal de São Carlos (UFSCar).

Mais informações: www.pion.sbfisica.org.br

Entropia e Tempo

Mysteries of time, and the multiverse - Los Angeles Times

Q & A

Mysteries of time, and the multiverse


Gary Friedman / Los Angeles Times

Sean Carroll is a physicist at Caltech in Pasadena. His recent article in Scientific American is called "The Arrow of Time."

In his studies of entropy and the irreversibility of time, Caltech physicist Sean Carroll is exploring the idea that our universe is part of a larger structure.

By John Johnson Jr., Los Angeles Times Staff Writer
June 28, 2008

Caltech physicist Sean M. Carroll has been wrestling with the mystery of time. Most physical laws work equally well going backward or forward, yet time flows only in one direction. Writing in this month’s Scientific American, Carroll suggests that entropy, the tendency of physical systems to become more disordered over time, plays a crucial role. Carroll sat down recently at Caltech to explain his theory.

What's the problem with time?

The irreversibility of time is sort of the most obvious unanswered question in cosmology.

Time has been talked about in cosmology for many years, but we have a toolbox now we didn't used to have.

We have general relativity, string theory, discoveries in particle physics that we can use to help us find the right answer.

What does entropy have to do with all this?

The most obvious fact about the history of the universe is the growth of entropy from the early times to the late times.

The fact that you can turn eggs into omelets but not vice versa is a thing we know from our kitchens.

You don't need to spend millions of dollars on telescopes to discover it.

Can you give me a simple explanation of entropy?

One way of explaining entropy is to say it's the number of ways you can rearrange the constituents of a system so that you don't notice the change macroscopically.

If you mix milk into a cup of coffee, the more mixing that occurs, the more disordered the milk molecules become and the more entropy builds.

If all the milk was somehow separated from the coffee, that would be low entropy.

So what's the problem?

If you really believed the conventional story that the Big Bang was the beginning, that there was nothing before the Big Bang, I think that's a very difficult fact to explain. . . .

There's no law of physics that says it should start at a low-entropy state. But the actual universe did that.

From a layman's standpoint, it seems perfectly rational that things would start small and grow apart. You're saying that's wrong.

Many of my very smart colleagues say exactly the same thing. They say, "Why are you thinking about this? It just makes sense that the early universe was small and low-entropy."

But I think that is just a prejudice: . . . Because it is like that in our universe, we tend to think it is naturally like that.

I don't think there is an explanation for that in terms of our current understanding of physics. I'm just saying it's not a fact that we should take for granted.

So you think the way the universe began is unnatural?

Low-entropy configurations are rare.

If you take a deck of cards and you open it up, it's true that they're in order. But if you randomly chose a configuration of a deck of cards it would be very, very unlikely that they would be in perfect order.

That's exactly low entropy versus high entropy.

The universe is more than what we see?

The reason why you are not surprised when you open a deck of cards and it's in perfect order is not because it's just easy and natural to find it in perfect order, it's because the deck of cards is not a closed system. It came from a bigger system in which there is a card factory somewhere that arranged it. So I think there is a previous universe somewhere that made us and we came out.

We're part of a bigger structure.

Are you saying that our universe came from some other universe?

Right. It came from a bigger space-time that we don't observe. Our universe came from a tiny little bit of a larger high-entropy space.

I'm not saying this is true; I'm saying this is an idea worth thinking about.

You're saying that in some universes there could be a person like you drinking coffee, but out of a blue cup rather than a red one.

If our local, observable universe is embedded in a larger structure, a multiverse, then there's other places in this larger structure that have denizens in them that call their local environs the universe. And conditions in those other places could be very different. Or they could be pretty similar to what we have here.

How many of them are there? The number could well be infinity. So it is possible that somewhere else in this larger structure that we call the multiverse there are people like us, writing for newspapers like the L.A. Times and thinking about similar questions.

So how does the arrow of time fit into this?

Our experience of time depends upon the growth of entropy. You can't imagine a person looking around and saying, "Time is flowing in the wrong direction," because your sense of time is due to entropy increasing. . . . This feeling that we're moving through time has to do with the fact that as we live, we feed on entropy. . . . Time exists without entropy, but entropy is what gives time its special character.

Entropy gives time its appearance of forward motion?

Yeah, its directionality. The distinction between past and future. If you're floating in outer space, in a spacesuit, there would be no difference between one direction and another. However, nowhere in the universe would you confuse yesterday and tomorrow. That's all because of entropy, and that's the arrow of time.

Does God exist in a multiverse?

I don't want to give advice to people about their religious beliefs, but I do think that it's not smart to bet against the power of science to figure out the natural world. It used to be, a thousand years ago, that if you wanted to explain why the moon moved through the sky, you needed to invoke God.

And then Galileo and Newton came along and realized that there was conservation of momentum, so things tend to keep moving.

Nowadays people say, "Well, you certainly can't explain the creation of the universe without invoking God," and I want to say, "Don't bet against it."

Designers Chineses

Computer Arts - China inspired

China inspired

A bold new generation of creative talent is about to burst onto the global scene. Craig Grannell talks to the designers and illustrators who are at the forefront of China’s revolution in graphic design

China is credited with two mainstays of graphic design – paper and movable type – yet the concept of ‘graphic design’ barely existed there 30 years ago. With China’s government beginning to replace the insular thinking of old with a more outward-reaching approach, and the Olympics making the country the focus of global attention, a new generation of Chinese creative talent has emerged, marrying traditional Oriental aesthetics with contemporary methodology and style. An entire nation’s design industry is being forged, and there’s the potential to tap into a massive and lucrative new market. But beware: many Chinese designers are starting to look outwards and thinking exactly the same thing.

Independent thinking
The West’s rich background in design stretches back many decades. So it’s hard to imagine a country where graphic design barely existed a generation ago. But in China, the words for ‘design’ or ‘designer’ only started being used in the early 1990s, and creative graphic design didn’t exist at all before the 1980s. Although the country has a strong history in calligraphy, its long period of being a centrally planned economy meant there was little demand for truly creative design. Output was generally functional, aiming to advertise products in the most basic and brutal sense. Even during periods of great political reform, craftsmanship prevailed over creativity, and only recently has this started to change.

Now aiming to become a major player in the global economy, China is beginning to understand the value of independent thinking when it comes to design and branding, particularly relating to products for export. “However, despite rapid development, China needs to catch up with the world in the field of design,” says designer Han Jiaying, whose classic poster series ‘Mouth’ and ‘Beauty’ for Frontier effortlessly blended the old and new in Chinese design. A good starting point, he thinks, would be for China’s design world to fully integrate with the international community: “We must broaden our vision to an international scale, with our thousands of years of historical and cultural background as a foundation.”

It’s clear that some Chinese designers already think along those lines. The Victoria & Albert’s China Design Now exhibition (open until 13 July) showcases contemporary Chinese design works, including those by relatively old hands Han, Chen Shaohua and Wang Xu. What’s interesting is how many of the posters on show were intended for international exhibitions. It’s through these international forums that many Chinese designers discovered an audience interested in Chinese characters and imagery, and became informed by outside interest.

A new generation of Chinese designers is keen to capitalise on pioneering work by the likes of Chen and Han, and one notable success is Ji Ji. Arguably a superstar of Chinese design, he’s graced TIME, been interviewed by numerous publications, and his iconic Hi Panda figures are conspicuous throughout much of the V&A show.

Despite fronting Poledesign, Ji Ji is almost becoming a brand himself – a marketing machine with a desire to take on the world, selling toys, T-shirts and more. Crucially, while his work appeals to China’s new urban youth, it also strikes a chord worldwide.

Design by type
While Ji Ji’s most celebrated current project embraces China’s most popular animal, the panda, it’s Chinese lettering that most resonates with Western audiences, albeit often in stereotypical fashion. Chinese characters are popular with designers aiming towards the exotic, and the tattoo industry seems to thrive on them.

Within China, too, traditional elements remain fairly popular. Chinese calligraphy continues to inform contemporary art and design, partly because those heading government organisations and large companies are slow to adapt and embrace design reform, and partly because of historical reasons. Designer and illustrator Zhang Jing notes that calligraphy was once considered a very important skill. She adds: “Although it’s no longer necessary, it’s still valued because it reveals one’s personality.”

Zhang notes that other elements of Chinese culture remain apparent in some modern work: “Chinese art was mainly influenced by Buddhism and nature, with elements being similar across many paintings. There’s more emphasis on curves and lines, rather than colour, which sets the Chinese aesthetic apart from that of the West.” Illustrator Xi He also considers a sense of underlying harmony intrinsic to the Chinese aesthetic: “The thinking of Taoism combines opposites to form balance, and this still influences Chinese creative output. As per Taoism’s yin-yang symbol, objects represented in Chinese design are often carefully combined and harmonised.”

Other designers argue that ancient concerns no longer fully apply to contemporary work. New York-based art director Qian Qian uses modern design methods to reinterpret traditional aesthetics, or as he describes it, “revisiting traditional culture from the ruins”. In a sense, the China of old is considered little more than a toy box, akin to a musician’s bank of samples, rather than offering methodology to be revered and adhered to.

This home-made spirit almost mirrors the UK’s punk movement during the late 1970s, and perhaps points to a time when the old will be trashed entirely. “I don’t really think there’s a particular ‘Chineseness’ that makes Chinese art unique,” reveals designer Gary Chen, founder of webzine Pigstyle.net and head of creative group Design By Guangzhou. “I can already see the ‘exotic’ elements fading from the Chinese design scene, and much outstanding Chinese design today has no apparent Oriental features.”

Imports and exports
Chen argues that several factors instigated a shift from traditional imagery, most of which are grounded in a desire to experiment and evolve. “The Chinese are becoming more concerned about the world we live in, and the prevailing ideologies in society,” he says. “Perhaps this awareness and consciousness now build our identity.” Han Jiaying reckons this is merely a symptom of the country’s late entry to the world of graphic design. It’s only natural that many modern Chinese designers are heavily influenced by the West – not just in terms of design, but also its values and culture.

However, there are pros and cons to this. Tommy Yen, a commercial graphic designer and instigator of his own T&Y brand, says: “On the one hand, this is a good thing because it enables Chinese designers to think in a more liberated way, and to find the means to go beyond what they already have. But from another perspective, there’s the danger of Chinese art and design becoming Westernised.” However, he adds that new graduates are more aware of originality as well as the importance of traditional culture.

The constant desire to make something new and unique means trends come and go with alarming speed, removing any doubts that Chinese design is stifled by a desire to be functional rather than creative. Shanghai-based illustrator Chun Guan thinks that Chinese design is transitioning away from its roots towards a more creative and unique conclusion.

The struggle ahead
Passion and rampant creativity are fantastic for design, but China is still plagued by output, industry and political issues. John Millichap’s 3030 Press imprint is dedicated to profiling the new generation of Chinese creatives, and he’s discovered that although young designers take risks, their brands and projects rarely impact on the international scene. “Large domestic companies remain cautious about how they present their products, and as a result often imitate successful foreign brands, rather than ask a designer to come up with something new,” he explains.

Additionally, there are rights issues, with plagiarism and theft still rife. There’s also a language barrier that stops Westerners truly appreciating Chinese output and hampers many Chinese when communicating with the outside world. “The infrastructure is weak,” says Zhang Hongxing, curator of China Design Now. “There’s little living space for young people, and a huge volume of graphic designers graduating. Many are forced to work in advertising, with little space for creativity, and competition is increasingly fierce, which reduces the value of work.”

Without the government undergoing a major shift in attitude, Zhang reckons most Chinese designers will continue to struggle: “Until the whole platform, including education, infrastructure and manufacturing, becomes more supportive of independently minded people and the value of independent design, I think the language and style of Chinese design won’t be very distinct, dominate or even be on a par with Japan.”

Despite this negative prediction, it’s clear that changes are happening, and only relatively small adjustments are required for China to become a design powerhouse. Its designers have the impetus, the skills, the desire and the drive. Even with his misgivings, Zhang concedes that within the next ten years Chinese graphic design will likely be a part of global design culture, even if it’s not entirely distinct.

But once a number of shifts occur – the Chinese government investing in infrastructure, more Chinese designers becoming conversant in English, the gradual replacement of today’s cautious generation – there’s a good chance the design landscape could change forever. While China’s creative explosion inspires Western designers with its brashness, stark colours and recycled propaganda, a future China might pose stiff competition when countless hungry, educated, skilled designers start looking outwards, rather than in.

Massa de Buracos Negros Supermassivos

:: Agência FAPESP :: Divulgação Científica - Como pesar buracos negros

Divulgação Científica
Como pesar buracos negros

24/7/2008

Agência FAPESP – Como pesar os maiores buracos negros do Universo? Certamente não dá para usar uma balança, mas uma nova resposta foi conseguida por um grupo de pesquisadores com ajuda de dados obtidos pelo Chandra, o observatório de raio X da Nasa, agência espacial norte-americana.

Ao medir a elevação de temperatura do gás no centro da galáxia elíptica NGC 4649, os cientistas foram capazes de determinar a massa do buraco negro supermassivo da galáxia. O método, usado pela primeira vez, trouxe resultados consistentes com técnicas tradicionais.

A nova técnica aproveita a influência gravitacional que um buraco negro tem no gás quente no centro da galáxia. À medida que o gás de desloca lentamente em direção ao buraco negro, ele se torna mais comprimido e ainda mais quente. O resultado é um pico na temperatura, que é detectado pelo Chandra. Quanto mais massivo o buraco negro, maior o pico.

O efeito foi preciso por Fabrizio Brighenti, da Universidade de Bolonha, na Itália, e por William Mathews, da Universidade da Califórnia em Santa Cruz, há quase dez anos, mas nunca havia sido observado.

Há tempos os astrônomos têm buscado novas formas de medir com precisão os buracos negros supermassivos, cujas massas são milhões de vezes a do Sol. Até agora tem sido usados métodos baseados nas observações dos movimentos de estrelas ou de gases em discos próximos a tais formações.

“O novo trabalho é muito importante, uma vez que buracos negros podem ser elusivos e quanto mais formas de medir suas massas, melhor”, disse Philip Humphrey, da Universidade da Califórnia em Irvine, nos Estados Unidos, que coordenou o estudo. Os resultados serão publicados em breve em artigo na revista The Astrophysical Journal.

A NGC 4649 é agora uma das únicas que teve a massa de um buraco negro supermassivo medida por dois métodos diferentes. Segundo a pesquisa, a formação tem cerca de 3,4 bilhões de vezes a massa do Sol e mil vezes a massa do buraco negro no centro da Via Láctea.

The Black Hole War

'The Black Hole War' by Leonard Susskind - Los Angeles Times

BOOK REVIEW

'The Black Hole War' by Leonard Susskind

Stephen Hawking and Susskind, two titans of theoretical physics, slug it out over whether or not information is lost forever once it enters a black hole.

By Jesse Cohen
July 13, 2008

The Black Hole War

My Battle With Stephen Hawking to Make the World Safe for Quantum Mechanics

Leonard Susskind

Little, Brown: 480 pp., $27.99

In a packed lecture hall at Columbia University in 1958 -- or so the story goes -- the eminent physicist Wolfgang Pauli was presenting a radical new theory. In the audience was Niels Bohr, another eminent physicist, who, at lecture's end, stood up and announced: "We are all agreed that your theory is crazy. The question that divides us is whether it is crazy enough to have a chance of being correct."

"Crazy enough" is no doubt a thought that occurred to Stanford theoretical physicist Leonard Susskind when he came up with his holographic principle -- an idea that has recently gained traction in the physics community. The principle, which states that our universe is a three-dimensional projection of information stored in two dimensions at the boundary of space, certainly ranks as crazy. But is it crazy enough?

After reading Susskind's entertaining new book, "The Black Hole War," you may decide that, yes, the holographic principle may well be on the good side of crazy. But before he gets to the holographic principle, Susskind gives an explanation, both lucid and enjoyable, of why black holes are so crucial to the future of physics and to any eventual reconciliation of relativity and quantum mechanics.

Einstein's general theory of relativity describes the world of the very large: planets, stars, galaxies, black holes, the warped curvature of space. Quantum mechanics describes the world of the very small, the bizarre precincts of subatomic particles, where gravity is trivial. General relativity is "classical," in that it can be used to make definite predictions about reality. Quantum mechanics is not: One can predict outcomes only in terms of their probability. The dream of many physicists is to find a way to unify these two seemingly antagonistic conceptions of reality.

It turns out, though, that black holes may have just the right ingredients for a unification recipe. A black hole is a region of space at whose center is the remnant of a collapsed star. But "remnant" isn't really the right word: Because of intense gravitational pressure, that star has become what physicists call a singularity -- an infinitesimal point of infinite density. Black holes suck up everything in their vicinity; gravity in a black hole's interior is so strong that nothing can escape, not even light.

In the 1970s, Cambridge theoretical physicist Stephen Hawking made the brilliant deduction that black holes dissipate their energy the way everything else in the universe does, through the radiation of heat -- a process known now as Hawking radiation. Gradually, that is, black holes evaporate. In 1983, Hawking also claimed that, along with everything else a black hole has gobbled up, "information is lost in black hole evaporation." ("Information" means the same thing as it does in computer science: data that can be measured in bits -- 0's or 1's. The "information" is what the bits encode.)

For Susskind, this was a declaration of war. Susskind is a quantum theorist, and a central principle of quantum mechanics is that information is conserved; it can never be annihilated. If Hawking was right, "the foundations of [quantum mechanics] were destroyed."

"War" may seem an overblown word to describe the debate between Susskind and Hawking, especially since the two are friends and Susskind's admiration for Hawking is boundless -- he considers him a "truly heroic figure" and "the first to enter a remote country and bring back gold." At Hawking's 60th birthday celebration, Susskind declared that "of all the physicists I have known he has had the strongest influence on me and my thinking." But perhaps "war" has the right emotional tone to convey his near-panic about Hawking's conjecture.

So how did Susskind -- and several others -- save quantum mechanics? It has to do with the peculiar nature of singularities at the heart of black holes. Infinitesimally small, infinitely dense, they are macroworld objects that behave with the quantum weirdness of the microworld.

In the quantum world, particles behave like particles or like waves, depending on what experiment is being performed; it's as though there were two separate realities. Within black holes, there's a similar duality. Susskind asks us to imagine two space travelers: Alice, who drifts toward a black hole, and Bob, who stays behind on the space station: "To Bob . . . it takes an eternity for Alice to reach the point of no return, but to Alice it may take no more than the blink of an eye." As Alice reaches that point -- the black hole's invisible, spherical "horizon" -- she appears to Bob to be frozen in time. From Alice's point of view, though, she passes through the horizon "without any sense of slowing down or speeding up." Her reality is completely different from Bob's.

Alice's fate isn't kind. The tidal forces of the black hole will tear her apart. According to the Hawking version, that's the end of her and her bits -- the information she's made up of. But, as Susskind and his colleagues discovered, that's not the case. The black hole's heat is a shredded and scrambled version of the information Hawking thought was lost, and "[i]nformation leaks out in the Hawking radiation in the same way that it escapes from an evaporating pot of water."

It gets weirder. That heat -- comprising the information that fell into the black hole -- exists as a thin layer coating the black hole's horizon. It's as though the black hole were a three-dimensional projection of that two-dimensional layer of information -- in short, a hologram.

As black holes go, so goes the universe: "The most notable inhabitants of the universe -- the galaxies -- are built around giant black holes that are continually gobbling up stars and planets. Out of every 10,000,000,000 bits of information in the universe, 9,999,999,999 are associated with the horizons of black holes." And consider this: As the universe's expansion accelerates, the light from faraway galaxies, the most distant of which are receding at light speed, will cease to reach us. Yet, to our eyes, nothing will look any different; this "cosmic horizon" will simply seem frozen, much as Alice appears to Bob when she enters a black hole. "It is as if we all live in our own private inside-out black hole," says Susskind. Could that ultimate, visible layer of the universe contain the information we experience as our three-dimensional reality?

This necessarily skeletal account may suggest the flavor of Susskind's bold thinking but does little justice to his book. Unlike his first book for a general audience, "The Cosmic Landscape," which was more didactic in tone, "The Black Hole War" is a gregarious narrative of intellectual brinkmanship. Although the narrative has a tendency to meander -- a chapter in which Susskind fails to meet Hawking in Cambridge is unnecessary -- it glows with the warmth of conversation. It's as though he has joined us for dinner, regaling us with tales of genius. Hawking and Richard Feynman make appearances, living up to their legends. There are also loving portraits of Susskind's fellow physicists, colorful characters who meticulously draw fanciful menageries or fight South American dictators or even profess evangelical Christianity. Susskind celebrates them all.

Like the best teachers, Susskind makes it fun to learn. With a deft use of analogy and a flair for language, he tames the most ferocious concepts. In his hands, a D-brane in anti de Sitter space seems like the most natural thing in the world. He has also come up with the best visual metaphor for the multidimensionality of string theory that I've yet come across, one that alone is worth the price of the book.

The holographic principle is dependent on string theory, and string theory is still controversial: It makes big claims that are unconfirmable by experiment. Susskind, one of the founders of string theory, is aware of its limitations and doesn't expect a solution anytime soon. But he does leave us with a glimmer of hope. It turns out that particles in the atomic nucleus act in ways that are similar to the behavior predicted for higher-dimensional strings. It's as if the 10-dimensional world of string theory were a -- dare one say it? -- holographic projection of the information contained in three-dimensional atoms. It's nothing less than the holographic principle, crazy like a fox. *

Jesse Cohen is the series editor of "The Best American Science Writing."

Sistema Solar é amassado

:: Agência FAPESP - Divulgando a cultura científica ::

Divulgação Científica

Sistema Solar é amassado


03/07/2008

Agência FAPESP – O Sistema Solar não é arredondado como se achava. Ele tem uma forma assimétrica, pois é amassado pelo campo magnético interestelar. A comprovação vem de um estudo feito a partir de dados enviados pela sonda Voyager 2, que está na fronteira final do Sistema Solar.

A Voyager 2 foi lançada em 20 de agosto de 1977, seguida alguns dias depois por sua nave irmã, a Voyager 1. Percorrendo mais de 1,6 milhão de quilômetros por dia, ambas estão em uma região turbulenta que começa a cerca de 14 bilhões de quilômetros do Sol e na qual o vento solar é reduzido ao encontrar o meio interestelar, o fino gás que preenche o espaço entre as estrelas.

Entretanto, a Voyager 2 tomou um rumo diferente ao cruzar, em agosto do ano passado, a fronteira da região conhecida como heliosheath, região da heliosfera que fica entre a heliopausa e o choque de terminação do vento solar.

Em artigo publicado na edição de 3 de julho da revista Nature, ao lado de outros quatro sobre resultados de observações recentes a respeito dos limites do Sistema Solar, Linghua Wang, da Universidade da Califórnia em Berkeley, nos Estados Unidos, e colegas confirmam o formato “amassado”, ou seja, que a bolha formada no espaço interestelar pelo vento solar não é redonda.

O motivo é que a bolha é empurrada de volta em direção ao Sol pelo campo magnético interestelar, o que faz com que se deforme. A sonda cruzou a heliosheath em um ponto mais próximo do Sol do que seria esperado se a bolha fosse arredondada, indicando um “dente” irregular no local.

O vento solar, formado por partículas carregadas eletricamente, é soprado pelo Sol em todas as direções, formando uma bolha que se estende pelo espaço além da órbita de Plutão. Essa bolha é a heliosfera, e teve sua camada externa explorada pela primeira vez em 2004, com a Voyager 1, quando então a nave encontrou a onda de choque que envolve o Sistema Solar.

Embora a Voyager 1 tenha cruzado antes a zona de choque de terminação, seu instrumento de ciência de plasma, capaz de medir diretamente a velocidade, densidade e temperatura do vento solar, não estava mais funcionando.

O instrumento similar a bordo da sua nave irmã está operando perfeitamente, o que permitiu os novos estudos. Outra diferença é que a Voyager 1 cruzou essa fronteira uma vez, quando dados não foram enviados, enquanto a outra o fez por diversas vezes.

O resultado das medições feitas pela Voyager 2 também apontam uma onda de choque incomum. Em uma onda normal, o material que se move rapidamente diminui a velocidade e forma uma região densa, mais quente, à medida que encontra um obstáculo.

Entretanto, a sonda encontrou uma temperatura além da zona de terminação cinco vezes inferior à esperada. Segundo os cientistas, isso indica que a energia está sendo transferida para partículas de raios cósmicos que se aceleram a altas velocidades com o choque.


Companhia após décadas

Por muitos anos as duas Voyager serão a única fonte de observação local da fronteira final do Sistema Solar, mas a Nasa, agência espacial norte-americana, pretende lançar ainda este ano uma missão com o objetivo específico de estudar a região. O Explorador da Fronteira Interestelar (Ibex) usará átomos energéticos neutros para produzir mapas da interação da heliosfera com o espaço interestelar.

As Voyager estão longe demais do Sol para poder usar energia solar. Elas empregam geradores termelétricos radioisotópicos para garantir o funcionamento de seus instrumentos que, em cada uma, tem consumo menor de 300 watts. A Nasa estima que a energia interna seja suficiente para que as sondas continuem operando até por volta de 2020.

As duas se comunicam com os cientistas da Nasa por meio da rede Deep Space, um sistema de antenas instalado em diversos países. Elas estão tão distantes que comandos enviados da Terra precisam de 12 horas para chegar à Voyager 1 e 14 horas para serem recebidos pela outra nave.

As espaçonaves carregam mensagens, para o caso de serem encontradas por alguma outra forma de vida. Um disco de cobre e ouro de 12 polegadas contém dados selecionados para mostrar a diversidade da vida, da sociedade e da cultura da Terra.

O conteúdo do disco foi selecionado por um comitê então liderado pelo astrônomo e escritor Carl Sagan (1934-1996). Estão gravadas 117 imagens e diversos sons obtidos na natureza, além de seleções musicais de diferentes culturas e períodos e saudações em 54 línguas.

O artigo Domination of heliosheath pressure by shock accelerated pickup ions from observations of neutral atoms, de Linghua Wang e colegas, e os demais a respeito dos dados enviados pela Voyager 2 podem ser lido por assinantes da Nature em www.nature.com.