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Nosso universo vai congelar como uma cerveja super-resfriada…

SCIENTIFIC METHOD / SCIENCE & EXPLORATION

Finding the Higgs? Good news. Finding its mass? Not so good.

“Fireballs of doom” from a quantum phase change would wipe out present Universe.

by  – Feb 19 2013, 8:55pm HB

A collision in the LHC’s CMS detector.

Ohio State’s Christopher Hill joked he was showing scenes of an impending i-Product launch, and it was easy to believe him: young people were setting up mats in a hallway, ready to spend the night to secure a space in line for the big reveal. Except the date was July 3 and the location was CERN—where the discovery of the Higgs boson would be announced the next day.

It’s clear the LHC worked as intended and has definitively identified a Higgs-like particle. Hill put the chance of the ATLAS detector having registered a statistical fluke at less than 10-11, and he noted that wasn’t even considering the data generated by its partner, the CMS detector. But is it really the one-and-only Higgs and, if so, what does that mean? Hill was part of a panel that discussed those questions at the meeting of the American Association for the Advancement of Science.

As theorist Joe Lykken of Fermilab pointed out, the answers matter. If current results hold up, they indicate the Universe is currently inhabiting what’s called a false quantum vacuum. If it were ever to reach the real one, its existing structures (including us), would go away in what Lykken called “fireballs of doom.”

We’ll look at the less depressing stuff first, shall we?

Zeroing in on the Higgs

Thanks to the Standard Model, we were able to make some very specific predictions about the Higgs. These include the frequency with which it will decay via different pathways: two gamma-rays, two Z bosons (which further decay to four muons), etc. We can also predict the frequency of similar looking events that would occur if there were no Higgs. We can then scan each of the decay pathways (called channels), looking for energies where there is an excess of events, or bump. Bumps have shown up in several channels in roughly the same place in both CMS and ATLAS, which is why we know there’s a new particle.

But we still don’t know precisely what particle it is. The Standard Model Higgs should have a couple of properties: it should be scalar and should have a spin of zero. According to Hill, the new particle is almost certainly scalar; he showed a graph where the alternative, pseudoscalar, was nearly ruled out. Right now, spin is less clearly defined. It’s likely to be zero, but we haven’t yet ruled out a spin of two. So far, so Higgs-like.

The Higgs is the particle form of a quantum field that pervades our Universe (it’s a single quantum of the field), providing other particles with mass. In order to do that, its interactions with other particles vary—particles are heavier if they have stronger interactions with the Higgs. So, teams at CERN are sifting through the LHC data, checking for the strengths of these interactions. So far, with a few exceptions, the new particle is acting like the Higgs, although the error bars on these measurements are rather large.

As we said above, the Higgs is detected in a number of channels and each of them produces an independent estimate of its mass (along with an estimated error). As of the data Hill showed, not all of these estimates had converged on the same value, although they were all consistent within the given errors. These can also be combined mathematically for a single estimate, with each of the two detectors producing a value. So far, these overall estimates are quite close: CMS has the particle at 125.8GeV, Atlas at 125.2GeV. Again, the error bars on these values overlap.

Oops, there goes the Universe

That specific mass may seem fairly trivial—if it were 130GeV, would you care? Lykken made the argument you probably should. But he took some time to build to that.

Lykken pointed out, as the measurements mentioned above get more precise, we may find the Higgs isn’t decaying at precisely the rates we expect it to. This may be because we have some details of the Standard Model wrong. Or, it could be a sign the Higgs is also decaying into some particles we don’t know about—particles that are dark matter candidates would be a prime choice. The behavior of the Higgs might also provide some indication of why there’s such a large excess of matter in the Universe.

But much of Lykken’s talk focused on the mass. As we mentioned above, the Higgs field pervades the entire Universe; the vacuum of space is filled with it. And, with a value for the Higgs mass, we can start looking into the properties of the Higgs filed and thus the vacuum itself. “When we do this calculation,” Lykken said, “we get a nasty surprise.”

It turns out we’re not living in a stable vacuum. Eventually, the Universe will reach a point where the contents of the vacuum are the lowest energy possible, which means it will reach the most stable state possible. The mass of the Higgs tells us we’re not there yet, but are stuck in a metastable state at a somewhat higher energy. That means the Universe will be looking for an excuse to undergo a phase transition and enter the lower state.

What would that transition look like? In Lykken’s words, again, “fireballs of doom will form spontaneously and destroy the Universe.” Since the change would alter the very fabric of the Universe, anything embedded in that fabric—galaxies, planets, us—would be trashed during the transition. When an audience member asked “Are the fireballs of doom like ice-9?” Lykken replied, “They’re even worse than that.”

Lykken offered a couple of reasons for hope. He noted the outcome of these calculations is extremely sensitive to the values involved. Simply shifting the top quark’s mass by two percent to a value that’s still within the error bars of most measurements, would make for a far more stable Universe.

And then there’s supersymmetry. The news for supersymmetry out of the LHC has generally been negative, as various models with low-mass particles have been ruled out by the existing data (we’ll have more on that shortly). But supersymmetry actually predicts five Higgs particles. (Lykken noted this by showing a slide with five different photos of Higgs taken at various points in his career, in which he was “differing in mass and other properties, as happens to all of us.”) So, when the LHC starts up at higher energies in a couple of years, we’ll actually be looking for additional, heavier versions of the Higgs.

If those are found, then the destruction of our Universe would be permanently put on hold. “If you don’t like that fate of the Universe,” Lykken said, “root for supersymmetry”

Planetas extra-solares, Kepler 62 e o Paradoxo de Fermi local

Conforme aumentam o número de planetas extra-solares descobertos, também aumentamos vínculos sobre as previsões do modelo de percolação galática (Paradoxo de Fermi Local).
A previsão é que, se assumirmos que Biosferas Meméticas (Biosferas culturais ou Tecnosferas) são um resultado provável de Biosferas Genéticas, então devemos estar dentro de uma região com pucos planetas habitáveis. Pois se existirem planetas habitados (por seres inteligentes) por perto, com grande probabilidade eles são bem mais avançados do que nós, e já teriam nos colonizado.
Como isso ainda não ocorreu (a menos que se acredite nas teorias de conspiração dos ufólogos e nas teorias de Jesus ET, deuses astronautas etc.), segue que quanto mais os astronomos obtiverem dados, mais ficará evidente que nosso sistema solar é uma anomalia dentro de nossa vizinhança cósmica (1000 anos-luz?), ou seja, não podemos assumir o Princípio Copernicano em relação ao sistema solar: nosso sistema solar não é tipico em nossa vizinhança.  Bom, pelo menos, essa conclusão está batendo com os dados coletados até hoje…
Assim, é possível fazer a previsão de que uma maior análise dos planetas Kepler 62-e e Kepler 62-f revelará que eles não possuem uma atmosfera com oxigênio ou metano, sinais de um planeta com biosfera.

Persistence solves Fermi Paradox but challenges SETI projects

Osame Kinouchi (DFM-FFCLRP-Usp)
(Submitted on 8 Dec 2001)

Persistence phenomena in colonization processes could explain the negative results of SETI search preserving the possibility of a galactic civilization. However, persistence phenomena also indicates that search of technological civilizations in stars in the neighbourhood of Sun is a misdirected SETI strategy. This last conclusion is also suggested by a weaker form of the Fermi paradox. A simple model of a branching colonization which includes emergence, decay and branching of civilizations is proposed. The model could also be used in the context of ant nests diffusion.

03/05/2013 – 03h10

Possibilidade de vida não se resume a planetas similares à Terra, diz estudo

SALVADOR NOGUEIRA
COLABORAÇÃO PARA A FOLHA

Com as diferentes composições, massas e órbitas possíveis para os planetas fora do Sistema Solar, a vida talvez não esteja limitada a mundos similares à Terra em órbitas equivalentes à terrestre.

Editoria de arte/Folhapress

Essa é uma das conclusões apresentada por Sara Seager, do MIT (Instituto de Tecnologia de Massachusetts), nos EUA, em artigo de revisão publicado no periódico “Science“, com base na análise estatística dos cerca de 900 mundos já detectados ao redor de mais de 400 estrelas.

Seager destaca a possível existência de planetas cuja atmosfera seria tão densa a ponto de preservar água líquida na superfície mesmo a temperaturas bem mais baixas que a terrestre. Read more [+]

Espírito Natalino: Doe para o [email protected]

Alguns teóricos da conspiração acham que Jesus era um ET e a estrela de Belém era um UFO. Já outros conspiracionistas creem firmemente que Jesus nunca existiu. OK, também tem aqueles que acham que Jesus era filho de Maria com um soldado romano. E, por que não, ele poderia ser um viajante do tempo também! Bom, eu sei que você tem que escolher entre alguma das teorias (e dizer por que a sua é melhor que a do vizinho), mas em todo caso, com espírito Natalino, doe para o…

SETI@home
 

 


Winter 2012
Dear OsameKinouchi:In 2012, Americans spent more than $6 billion on political campaigns. (That’s 15,000 times the annual [email protected] budget). And during the presidential campaign, none of the candidates mentioned [email protected] even once.

That’s OK. We understand that SETI isn’t a federal priority, and that no flood of federal dollars will be headed our way. But we hope that we’re still one of your priorities. [email protected] and the rest of the Berkeley SETI projects depend on your donations in order to keep going.

If you’ve already donated this fall, we thank you. If you haven’t, or if you liked the process so much you’d do it again, please consider making a donation by going to this link:

http://setiathome.berkeley.edu/sah_donate.php

We promise we won’t spend it on commercials.

– Eric Korpela, [email protected] Project Scientist

 

 

 

 

 

 


The University of California is a nonprofit educational and research organization governed by the provisions of Section 501(c)(3) of the Internal Revenue Code. Donations are tax deductible for residents of the United States and Canada.

Seleção Artificial Cosmológica: primeiras referências

Tive a mesma ideia em 1995, mas não publiquei. Sexta feira passada, achei numa pasta abandonada os escritos que estão digitalizados aqui.  Por um erro de memória, confundi Lee Smolin (em inglês e mais completo aqui) com Sidney Coleman.

Meduso-anthropic principle

The meduso-anthropic principle is a quasi-organic universe theory originally proposed by mathematician and quantum gravity scholar Louis Crane in 1994.

Contents

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Universes and black holes as potential life cycle partners

Crane’s MAP is a variant of the hypothesis of cosmological natural selection (fecund universes), originally proposed by cosmologist Lee Smolin (1992). It is perhaps the first published hypothesis of cosmological natural selection with intelligence (CNS-I), where intelligence plays some proposed functional role in universe reproduction. It is also an interpretation of the anthropic principle (fine-tuning problem). The MAP suggests the development and life cycle of the universe is similar to that of Corals and Jellyfish, in which dynamic Medusa are analogs for universal intelligence, in co-evolution and co-development with sessile Polyp generations, which are analogs for both black-holes and universes. In the proposed life cycle, the Universe develops intelligent life and intelligent life produces new baby universes. Crane further speculates that our universe may also exist as a black hole in a parallel universe, and extraterrestrial life there may have created that black hole.

Crane’s work was published in 1994 as a preprint on arXiv.org. In 1995, in an an article in QJRAS, emeritus cosmologist Edward Harrison (1919-2007) independently proposed that the purpose of intelligent life is to produce successor universes, in a process driven by natural selection at the universal scale. Harrison’s work was apparently the first CNS-I hypothesis to be published in a peer-reviewed journal.

Why future civilizations might create black holes

Crane speculates that successful industrial civilizations will eventually create black holes, perhaps for scientific research, for energy production, or for waste disposal. After the hydrogen of the universe is exhausted civilizations may need to create black holes in order to survive and give their descendants the chance to survive. He proposes that Hawking radiation from very small, carefully engineered black holes would provide the energy enabling civilizations to continue living when other sources are exhausted.

Philosophical implications

According to Crane, Harrison, and other proponents of CNS-I, mind and matter are linked in an organic-like paradigm applied at the universe scale. Natural selection in living systems has given organisms the imperative to survive and reproduce, and directed their intelligence to that purpose. Crane’s MAP proposes a functional purpose for intelligence with respect to universe maintenance and reproduction. Universes of matter produce intelligence, and intelligent entities are ultimately driven to produce new universes.

See also

References

Os deuses de Richard Dawkins

File:NASA child bubble exploration.jpgMy personal theology is described in the Gifford lectures that I gave at Aberdeen in Scotland in 1985, published under the title, Infinite In All Directions. Here is a brief summary of my thinking. The universe shows evidence of the operations of mind on three levels. The first level is elementary physical processes, as we see them when we study atoms in the laboratory. The second level is our direct human experience of our own consciousness. The third level is the universe as a whole. Atoms in the laboratory are weird stuff, behaving like active agents rather than inert substances. They make unpredictable choices between alternative possibilities according to the laws of quantum mechanics. It appears that mind, as manifested by the capacity to make choices, is to some extent inherent in every atom. The universe as a whole is also weird, with laws of nature that make it hospitable to the growth of mind. I do not make any clear distinction between mind and God. God is what mind becomes when it has passed beyond the scale of our comprehension. God may be either a world-soul or a collection of world-souls. So I am thinking that atoms and humans and God may have minds that differ in degree but not in kind. We stand, in a manner of speaking, midway between the unpredictability of atoms and the unpredictability of God. Atoms are small pieces of our mental apparatus, and we are small pieces of God’s mental apparatus. Our minds may receive inputs equally from atoms and from God. This view of our place in the cosmos may not be true, but it is compatible with the active nature of atoms as revealed in the experiments of modern physics. I don’t say that this personal theology is supported or proved by scientific evidence. I only say that it is consistent with scientific evidence.  Freeman Dyson

Parece que Dawkins está rumando para uma posição similar à de Gardner, Clément Vidal e outros da comunidade Evo-Devo Universe.

Human Gods

After two hours of conversation, Professor Dawkins walks far afield. He talks of the possibility that we might co-evolve with computers, a silicon destiny. And he’s intrigued by the playful, even soul-stirring writings of Freeman Dyson, the theoretical physicist.

In one essay, Professor Dyson casts millions of speculative years into the future. Our galaxy is dying and humans have evolved into something like bolts of superpowerful intelligent and moral energy.

Doesn’t that description sound an awful lot like God?

“Certainly,” Professor Dawkins replies. “It’s highly plausible that in the universe there are God-like creatures.”

He raises his hand, just in case a reader thinks he’s gone around a religious bend. “It’s very important to understand that these Gods came into being by an explicable scientific progression of incremental evolution.”

Could they be immortal? The professor shrugs.

“Probably not.” He smiles and adds, “But I wouldn’t want to be too dogmatic about that.”

O melhor livro de divulgação científica que encontrei em quarenta anos de leituras

Depois escrevo minha resenha…

A REALIDADE OCULTA – Universos paralelos e as leis profundas do cosmo
Brian Greene
R$ 59,00 Comprar
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É necessário estar logado para utilizar este recurso. Acompanhe

Meio século atrás, os cientistas encaravam com ironia a possibilidade de existirem outros universos além deste que habitamos. Tal hipótese não passava de um delírio digno de Alice no País das Maravilhas – e que, de todo modo, jamais poderia ser comprovada experimentalmente. Os desafios propostos pela Teoria da Relatividade e pela física quântica para o entendimento de nosso próprio universo já eram suficientemente complexos para ocupar gerações e gerações de pesquisadores. Entretanto, diversos estudos independentes entre si, conduzidos por cientistas respeitados em suas áreas de atuação – teoria das cordas, eletrodinâmica quântica, teoria da informação -, começaram a convergir para o mesmo ponto: a existência de universos paralelos – o multiverso – não só é provável como passou a ser a explicação mais plausível para diversos enigmas cosmológicos.
Em A realidade oculta, Brian Greene – um dos maiores especialistas mundiais em cosmologia e física de partículas – expõe o fantástico desenvolvimento da física do multiverso ao longo das últimas décadas. O autor de O universo elegante passa em revista as diferentes teorias sobre os universos paralelos a partir dos fundamentos da relatividade e da mecânica quântica. Por meio de uma linguagem acessível e valendo-se de numerosas figuras explicativas, Greene orienta o leitor pelos labirintos da realidade mais profunda da matéria e do pensamento.

“Se extraterrestres aparecessem amanhã e pedissem para conhecer as capacidades da mente humana, não poderíamos fazer nada melhor que lhes oferecer um exemplar deste livro.” – Timothy Ferris, New York Times Book Review

Novo artigo sobre automata celulares e Paradoxo de Fermi

Saiu um novo artigo sobre a hipótese de percolação para o Paradoxo de Fermi, onde simulações de automata celulares em três dimensões são usadas.  Dessa vez, a conclusão dos autores é a de que as simulações não suportam a hipótese.

Bom, acho que isso não é o fim da história. Eu já sabia que, para a hipótese dar certo, a difusão deveria ser critica (ou seja, formando um cluster crítico ou levemente supercrítico de planetas ocupados).

Ou seja, a hipótese precisa ser complementada com algum argumento de porque a difusão deveria ser crítica. Bom, como sistemas críticos são abundantes nos processos sociais e biológicos, eu acho que basta encontrar esse fator de criticalidade para justificar o modelo. Minha heurística seria: Read more [+]

Kepler detecta 140 planetas similares à Terra?

Telescópio acha 140 planetas que podem ter vida
22 de julho de 2010 13h48 atualizado às 14h15

comentários
181

Kepler descobre planetas quando eles passam em frente a sua estrela Foto: Nasa/Divulgação

Kepler descobre planetas quando eles passam em frente a sua estrela, assim como registra Vênus ou Mercúrio ao passarem em frente ao Sol
Foto: Nasa/Divulgação

Cientistas anunciaram a descoberta de 140 novos planetas parecidos com a Terra encontrados nas últimas semanas. Com os novos dados, os cientistas acreditam que existam cerca de 100 milhões de planetas parecidos com o nosso e que possam abrigar vida apenas na Via Láctea. As informações são do Daily Mail.

Os achados foram feitos pelo telescópio espacial Kepler, que procura novos planetas desde que foi lançado, em janeiro de 2009. Segundo o astrônomo Dimitar Sasselov, os planetas têm tamanho parecido com o da Terra. O cientista descreveu a descoberta como a “realização do sonho de Copérnico”, em referência ao pai da astronomia moderna.

Novos planetas fora do sistema solar são descobertos quando eles passam em frente a sua estrela. O telescópio não capta uma imagem direta, mas registra a minúscula diminuição do brilho do astro quando o planeta passa em frente. Essa passagem causa “piscadas” na luz. Pelo cálculo da diminuição de brilho, do tempo entre as “piscadas” e da massa da estrela, os astrônomos conseguem descobrir o tamanho do planeta.

O Kepler continuará pesquisando o céu dia e noite, sem interrupção, pelos próximos quatro anos, segundo o cientista. Sasselov afirma que nos últimos 15 anos cerca de 500 exoplanetas foram descobertos, mas nenhum foi considerado parecido com a Terra, ou seja, com a possibilidade de abrigar vida.

“Vida é um sistema químico que realmente necessita de um planeta pequeno, água e pedras e uma grande quantidade de complexos químicos para surgir e sobreviver. (…) Tem um monte de trabalho para fazermos com isso, mas os resultados estatísticos são claros e planetas como a nossa Terra estão lá fora. (…) Nossa própria Via Láctea é rica nesse tipo de planetas”, disse o astrônomo durante a apresentação dos resultados do Kepler na conferência TEDGlobal, em Oxford, no Reino Unido.

Redação Terra

Twitter, SETI, ETs e Astrobiologia

Cientistas propõem abordagem ‘Twitter’ para contato com ETs

Farol contínuo seria muito caro para uma civilização avançada manter, especulam cientistas

21 de julho de 2010 | 14h 18

estadao.com.br

A busca por inteligência extraterrestre (SETI) baseada em radiotelescópios depende, para obter sucesso, de haver pelo menos uma raça alienígena transmitindo um sinal contínuo de alta potência para o espaço – o equivalente de um farol cósmico – que pudesse ser detectado na Terra. A manutenção de um farol do tipo consumiria muita energia, no entanto, e vários cientistas questionam se uma civilização qualquer estaria disposta a arcar com esse tipo de custo.

blog O tempo está acabando para a SETI?

Agora, em dois artigos publicados na revista Astrobiology, os irmãos gêmeos Gregory e James Benford – astrofísico e físico – analisam os custos do ponto de vista da espécie emissora e concluem que o meio mais eficiente de sinalizar a própria presença não seria a emissão de um farol contínuo, mas de pulsos intermitentes. “Essa abordagem é mais como o Twitter e menos como Guerra e Paz“, resume James, em nota.

“Qualquer que seja a forma de vida, a evolução favorece economia de recursos”, acrescenta Gregory. “Transmitir é caro, e transmitir sinais por anos-luz iria requerer recursos consideráveis”.

Supondo que a civilização alienígena busque otimizar os gastos, limitar desperdício e aumentar a eficiência da tecnologia, os Benfords propõem que, em vez de um sinal contínuo transmitido em todas as direções, os ETs usariam um sinal pulsado, direcionado e de banda larga na faixa de 1 a 10 Ghz.

Se os Benfords estiverem certos, o programa SETI atual, com seu foco na busca por sinais de banda estreita, pode estar procurando no lugar errado.

Os irmãos também propõem que as antenas sejam apontadas na direção do núcleo da galáxia, onde aglomeram-se 90% das estrelas da Via Láctea.

“As estrelas ali são um bilhão de anos mais velhas que o Sol, o que sugere uma maior possibilidade de contato com uma civilização avançada”, disse Gregory.



Mais um projeto SETI desafiado pelo Paradoxo de Fermi


A Failure of Serendipity: the Square Kilometre Array will struggle to eavesdrop on Human-like ETI

D.H. ForganR.C. Nichol
(Submitted on 6 Jul 2010)

The Square Kilometre Array (SKA) will operate in frequency ranges often used by military radar and other communications technology. It has been shown that if Extraterrestrial Intelligences (ETIs) communicate using similar technology, then the SKA should be able to detect such transmissions up to distances of ~100 pc (~300 light years) from Earth. However, Mankind has greatly improved its communications technology over the last century, dramatically reducing signal leakage and making the Earth “radio quiet”. If ETIs follow the same pattern as the human race, will we be able to detect their signal leakage before they become radio quiet? We investigate this question using Monte Carlo Realisation techniques to simulate the growth and evolution of intelligent life in the Galaxy. We show that if civilisations are “human” in nature (i.e. they are only “radio loud” for ~100 years, and can only detect each other with an SKA-like instrument out to 100 pc, within a maximum communication time of 100 years), then the probability for such civilisations accidentally detecting each other is low (~10^{-7}), much lower than if other, dedicated communication techniques are permissible (e.g. optical SETI or neutrino communication).

Comments: 8 pages, 2 figures, accepted for publication in the International Journal of Astrobiology
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Galaxy Astrophysics (astro-ph.GA)
Cite as: arXiv:1007.0850v1 [astro-ph.EP]

PS: Além do mais, se existissem civilizações tecnológicas (CTs) em um raio de 300 anos-luz, elas já teriam tido tempo de nos colonizar ou colonizar as CTs que estão nesta janela de 100 anos de radio loud (e que portanto, deixariam de ser radio loud). Parece desperdício de dinheiro, acho que outros projetos SETI seriam mais promissores… 
Ver a continuação do “Argumento de Fermi Local” aqui

Equilíbrio puntuado e Astrobiologia


Galactic Punctuated Equilibrium: How to Undermine Carter’s Anthropic Argument in Astrobiology

Milan M. Cirkovic, Branislav Vukotic, Ivana Dragicevic
(Submitted on 30 Dec 2009)

We investigate a new strategy which can defeat the (in)famous Carter’s “anthropic” argument against extraterrestrial life and intelligence. In contrast to those already considered by Wilson, Livio, and others, the present approach is based on relaxing hidden uniformitarian assumptions, considering instead a dynamical succession of evolutionary regimes governed by both global (Galaxy-wide) and local (planet- or planetary system-limited) regulation mechanisms. This is in accordance with recent developments in both astrophysics and evolutionary biology. Notably, our increased understanding of the nature of supernovae and gamma-ray bursts, as well as of strong coupling between the Solar System and the Galaxy on one hand, and the theories of “punctuated equilibria” of Eldredge and Gould and “macroevolutionary regimes” of Jablonski, Valentine, et al. on the other, are in full accordance with the regulation- mechanism picture. The application of this particular strategy highlights the limits of application of Carter’s argument, and indicates that in the real universe its applicability conditions are not satisfied. We conclude that drawing far-reaching conclusions about the scarcity of extraterrestrial intelligence and the prospects of our efforts to detect it on the basis of this argument is unwarranted.

Comments: 3 figures, 26 pages
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Journal reference: Published in Astrobiology, 2009, Volume 9, Issue 5, pp. 491-501
DOI: 10.1089/ast.2007.0200
Cite as: arXiv:0912.4980v1 [astro-ph.EP]

Vida no Multiverso


The Drake Equation For The Multiverse

Posted: 09 Feb 2010 09:10 PM PST

The famous Drake equation estimates the number of intelligent civilisations in the Milky Way. Now a new approach asks how many might exist in the entire multiverse

In 1960, the astronomer Frank Drake devised an equation for estimating the number of intelligent civilisations in our galaxy. He did it by breaking down the problem into a hierarchy of various factors.

He suggested that the total number of intelligent civilisations in the Milky Way depends first on the rate of star formation. He culled this number by estimating the fraction of these stars with rocky planets, the fraction of those planets that can and do support life and the fraction of these that go on to support intelligent life capable of communicating with us. The result is this equation:

which is explained in more detail in this Wikipedia entry.

Today, Marcelo Gleiser at Dartmouth College in New Hampshire points out that cosmology has moved on since the 1960s. One of the most provocative new ideas is that the universe we see is one of many, possibly one of an infinite number. One line of thinking is that the laws of physics may be very different in these universes and that carbon-based life could only have arisen in those where conditions were fine-tuned in a particular way. This is the anthropic principle.

Consequently, says Gleiser, the Drake Equation needs updating to take the multiverse and the extra factors it introduces into account.

He begins by considering the total set of universes in the multiverse and defines the subset in which the parameters and fundamental constants are compatible with the anthropic principle. This is the subset {ccosmo}.

He then considers the subset of these universes in which astrophysical conditions are ripe for star and galaxy formation {c-astro}. Next he looks at the subset of these in which planets form that are capable of harbouring life {c-life}. And finally he defines the subset of these in which complex life actually arises {c-complex life}.

Then the conditions for complex life to emerge in a particular universe in the multiverse must satisfy the statement at the top of this post (where the composition symbol denotes ‘together with’).

But there’s a problem: this is not an equation. To form a true Drake-like argument, Gleiser would need to assign probabilities to each of these sets allowing him to write an equation in which the assigned probabilities multiplied together, on one side of the equation, equal the fraction of universes where complex life emerges on the other side.

Here he comes up against one of the great problems of modern cosmology–that without evidence to back up their veracity, many ideas in modern cosmology are little more than philosophy. So assigning a probability to the fraction of universes in the multiverse in which the fundamental constants and laws satisfy the anthropic principle is not just hard, but almost impossible to formulate at all.

Take {c-cosmo} for example. Gleiser points out a few of the obvious parameters that would need to taken into account in deriving a probability. These are the vacuum energy density, matter-antimatter asymmetry, dark matter density, the couplings of the four fundamental forces and the masses of quarks and leptons so that hadrons and then nuclei can form after electroweak symmetry breaking. Try assigning a probability to that lot.

Neither is it much easier for {c-astro}. This needs to take into account the fact that heavy elements seem to be important for the emergence of life which only seem to occur in galaxies above a certain mass and in stars of a certain type and age. Estimating the probability of these conditions occurring is still beyond astronomers.

At first glance, the third set {c-life} ought to be easier to handle. This must take into account the planetary and chemical constraints on the formation of life. The presence of liquid water and various elements such as carbon, oxygen and nitrogen seem to be important as do more complex molecules. How common these conditions are, we don’t yet know.

Finally there is {c-complex life}, which includes all the planetary factors that must coincide for complex life to emerge. These may include long term orbital stability, the presence of a magnetic field to protect delicate biomolecules, plate tectonics, a large moon and so on. That’s not so easy to estimate either.

Many people have tried to put the numbers into Drake’s equation. The estimates for the number of intelligent civilisations in the Milky Way ranges from one (ours) to countless tens of thousands. Drake himself put the number at 10.

Gleiser’s take on the Drake equation for the Multiverse is an interesting approach. What it tells us, however, is that our limited understanding of the universe today does not allow us to make any reasonable estimate of the number of intelligent lifeforms in the multiverse (more than one). And given the limits on what we can ever know about other universes, it’s likely that we’ll never be able to do much better than that.

Ref: arxiv.org/abs/1002.1651: Drake Equation For the Multiverse: From String Landscape to Complex Life

Astrobiologia na Terra

Microbial Life Found in Hydrocarbon Lake
Posted: 14 Apr 2010 09:10 PM PDT
Scientist find life in a lake of asphalt that is the closest thing on Earth to the hydrocarbon seas on Titan.
Pitch Lake is a poisonous, foul smelling, hell hole on the Caribbean island of Trinidad and Tobago. The lake is filled with hot asphalt and bubbling with noxious hydrocarbon gases and carbon dioxide. Water is scarce here and certainly below the levels normally thought of as a threshold for life.
These alien conditions have made Pitch Lake a place of more than passing interest to astrobiologists. Various scientists have suggested that it is the closest thing on Earth to the kind of hydrocarbon lakes that we can see on Saturn’s moon Titan. Naturally, these scientists would very much like to answer the question of what kind of life these places can support.
Today, Dirk Schulze-Makuch from Washington State University and a few buddies provide an answer. Pitch lake, they say, is teaming with microbial life. They say that, on average, each gram of goo in the lake contains some 10^7 living cells.
These bugs are unlike anything we normally see on Earth. Analysis of gene sequences from these creatures show that they are single celled organisms such as archea and bacteria. They thrive in an oxygen-free environment with very little water, eating hydrocarbons and respiring with metals.
This may be the first time life has cropped up in hydrocarbon lakes on Earth’s surface but these kinds of creepy crawlies have previously reared their heads in hydrocarbon samples from subsea oil wells. Which is another reason they are of interest. Just how microbial organisms can degrade and process of oil reservoirs is poorly understood. A better understanding could lead to a number of advances in techniques for things like microbial remediation.
But the most exciting implication of this discovery is for the possibility of life on Titan. There is a growing sense that Titan may have all the ingredients for life: thermodynamic disequilibrium, abundant carbon-containing molecules and a fluid environment.
And there is also evidence that liquid water may not be as important as everybody has assumed. Schulze-Makuch and co point to recent evidence that some microorganisms can make there own water by chewing on various hydrocarbons. However it is not yet clear how much water the bugs in Pitch Lake require. Although there is very little water here, it’s just possible that the organisms are confined to regions where the water content is higher, as happens with ice-bound colonies in frozen lakes and glaciers. More work needs to be done on this.
Nevertheless, this is an exciting discovery and further study of the extraordinary residents of Pitch Lake will throw new light on all these questions. As Schulze-Makuch and co put it: “Our research is a starting point on investigating what life’s principle constraints are in a hydrocarbon matrix and whether the hydrocarbon lakes on Titan could possibly contain life.”
Ref: arxiv.org/abs/1004.2047: Microbial Life in a Liquid Asphalt Desert

Arqueologia Interestelar

Daqui a dez anos, a Astrobiologia será uma área quente. Comece já o seu mestrado nisso se desejar entrar nessa área no futuro.

Starry Messages: Searching for Signatures of Interstellar Archaeology

Authors: Richard A. Carrigan Jr (Fermi National Accelerator Laboratory)

(Submitted on 29 Jan 2010)

Abstract: Searching for signatures of cosmic-scale archaeological artifacts such as Dyson spheres or Kardashev civilizations is an interesting alternative to conventional SETI. Uncovering such an artifact does not require the intentional transmission of a signal on the part of the original civilization. This type of search is called interstellar archaeology or sometimes cosmic archaeology. The detection of intelligence elsewhere in the Universe with interstellar archaeology or SETI would have broad implications for science. For example, the constraints of the anthropic principle would have to be loosened if a different type of intelligence was discovered elsewhere. A variety of interstellar archaeology signatures are discussed including non-natural planetary atmospheric constituents, stellar doping with isotopes of nuclear wastes, Dyson spheres, as well as signatures of stellar and galactic-scale engineering. The concept of a Fermi bubble due to interstellar migration is introduced in the discussion of galactic signatures. These potential interstellar archaeological signatures are classified using the Kardashev scale. A modified Drake equation is used to evaluate the relative challenges of finding various sources. With few exceptions interstellar archaeological signatures are clouded and beyond current technological capabilities. However SETI for so-called cultural transmissions and planetary atmosphere signatures are within reach.

Comments: 29 pages including 4 figures and 1 table
Subjects: Galaxy Astrophysics (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP)
Report number: FERMILAB-PUB-09-607-AD
Cite as: arXiv:1001.5455v1 [astro-ph.GA]

Laboratório de astrobiologia da USP

A Universidade de São Paulo (USP) abrigará até o final do ano o primeiro Laboratório de Astrobiologia do Hemisfério Sul. O centro de estudos brasileiro está sendo instalado em Valinhos, no Observatório Abrahão de Moraes, ligado ao Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG) da USP.
A previsão é que comece a funcionar em 2010. Orçado em R$ 1 milhão, o laboratório recebeu financiamento federal do recém-criado Instituto Nacional de Ciência e Tecnologia do Espaço.
Será usado pela comunidade científica brasileira e internacional para achar respostas para as três principais questões da Astrobiologia: Como a vida surgiu e evoluiu no nosso planeta? Existe vida fora da Terra? Qual o futuro da vida aqui e nos outros corpos celestes?
De perfil multidisciplinar, a Astrobiologia envolve conceitos de Astronomia, Biologia Molecular, Química, Meteorologia, Geofísica e Geologia. Os estudos são realizados a partir de cálculos teóricos e grande parte dos dados obtidos virá da câmara simuladora de ambientes, o principal equipamento do novo laboratório.
A câmara de simulação planetária do laboratório será revestida de aço inox e é capaz de reproduzir condições e ambientes extraterrestres. O equipamento é projetado para analisar parâmetros de temperatura, pressão, composição gasosa e fluxo de radiação, entre outros. Permite, também, avaliações em tempo real das pesquisas em andamento.
Extraterrestres
Segundo Douglas Galante, pesquisador do IAG, muitos experimentos do laboratório serão feitos com os extremófilos – micro-organismos capazes de sobreviver em condições ambientais extremas, como a ausência de luz solar, exposição a radiação, sal, níveis muito altos e baixos de pressão, temperatura, água e oxigênio. “Essas características fazem deles bons modelos para pesquisas com organismos extraterrestres”, explica.
O pesquisador informa que o laboratório também investigará outros temas, como reações químicas ocorridas em gelos de cometas e a penetração de radiação em diversos tipos de solo.
A instalação do laboratório ocorrerá em duas etapas: na primeira, serão aproveitadas as atuais instalações do observatório. Na seguinte, será erguido o edifício próprio do centro de pesquisa. O prédio será construído numa área de 625 metros quadrados e o projeto prevê incluir soluções para o consumo sustentável de água e de eletricidade.
Quando estiver finalizado, o centro abrigará também laboratórios de apoio de Química e Biologia, ambos com infraestrutura e equipamentos de informática adequados para a pesquisa teórico-experimental.
Para a ciência, vida extraterrestre significa a capacidade de um organismo qualquer, mesmo microscópico, sobreviver em meteoritos, planetas como Marte ou ainda em outros corpos celestes. Essas formas de vida podem ter surgido em processos totalmente independentes dos da Terra, ou ainda possuir origem comum, viajando no espaço e chegando aos planetas, no fenômeno conhecido por panspermia.
Da mesma forma, a vida na Terra pode ser fruto de outro planeta ou pode ter-se originado a partir de precursores formados no ambiente espacial. Moléculas orgânicas como aminoácidos, já encontradas no meio interestelar, em meteoros e cometas, podem ter chegado à Terra, participando do surgimento da vida há bilhões de anos.
Um lugar para ver estrelas
Criado em 1972, em uma área verde e preservada de 450 mil metros quadrados, o Observatório Abrahão de Moraes começou a perder potencial científico duas décadas depois. O motivo foi o crescimento da iluminação e a urbanização de Vinhedo, local por onde se chega ao centro de Valinhos, cidade em que está instalado. Em 1995, um dos telescópios foi automatizado e pesquisas de alto nível puderam voltar a ser realizadas.
Hoje, o observatório possui três equipamentos para observação: o Obelix, o Argus e o Prometeu. A inovação permitiu transformar o local em centro de divulgação científica permanente para grupos de até 40 estudantes do ensino médio e fundamental.
A visita pode ser diurna ou noturna e todas as atividades oferecidas pelo observatório são gratuitas. O agendamento dos grupos é feito pelo telefone (19) 3886-4439.
No ano passado, 1,8 mil alunos conheceram o local. Além da visitação, a escola interessada pode também operar pela internet os telescópios e assim propor atividades ligadas à observação astronômica.
Rogério SilveiraDa Agência Imprensa OficialCrédito fotos: Fernandes Dias Pereira
Reportagem publicada originalmente na página I do Poder Executivo do Diário Oficial do Estado de SP do dia 05/09/2009.
Veja e leia a reportagem original em PDF

Astrobiologia Computacional


Numerical Testing of The Rare Earth Hypothesis using Monte Carlo Realisation Techniques

Duncan H. Forgan (1), Ken Rice (1) ((1) SUPA, Institute for Astronomy, University of Edinburgh)
(Submitted on 11 Jan 2010)

The Search for Extraterrestrial Intelligence (SETI) has thus far failed to provide a convincing detection of intelligent life. In the wake of this null signal, many “contact pessimistic” hypotheses have been formulated, the most famous of which is the Rare Earth Hypothesis. It postulates that although terrestrial planets may be common, the exact environmental conditions that Earth enjoys are rare, perhaps unique. As a result, simple microbial life may be common, but complex metazoans (and hence intelligence) will be rare. This paper uses Monte Carlo Realisation Techniques to investigate the Rare Earth Hypothesis, in particular the environmental criteria considered imperative to the existence of intelligence on Earth.
By comparing with a less restrictive, more optimistic hypothesis, the data indicates that if the Rare Earth hypothesis is correct, intelligent civilisation will indeed be relatively rare. Studying the separations of pairs of civilisations shows that most intelligent civilisation pairs (ICPs) are unconnected: that is, they will not be able to exchange signals at lightspeed in the limited time that both are extant. However, the few ICPs that are connected are strongly connected, being able to participate in numerous exchanges of signals. This may provide encouragement for SETI researchers: although the Rare Earth Hypothesis is in general a contact-pessimistic hypothesis, it may be a “soft” or “exclusive” hypothesis, i.e. it may contain facets that are latently contact-optimistic.

Comments: 13 pages, 10 figures, accepted for publication in the International Journal of Astrobiology
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Galaxy Astrophysics (astro-ph.GA)
Cite as: arXiv:1001.1680v1 [astro-ph.EP]

Terra a vista

A menos que a Hipótese da Terra Rara esteja correta (ou seja, de que a evolução de seres multicelulares e explosões Cambrianas sejam muito raras), não vejo como escapar o Paradoxo de Fermi Local: se existem planetas habitados num raio de 1000 anos-luz daqui, por que eles ainda não nos colonizaram?

Descoberta de planeta habitável é iminente, dizem astrônomos

Dentro de quatro ou cinco anos, estimam especialistas, um planeta capaz de abrigar vida deve ser encontrado

Associated Press

Tamanho do texto? A A A A

WASHINGTON – Astrônomos afirmam que estão à beira de encontrar planetas semelhantes à Terra em órbita de outras estrelas, um passo essencial para determinar se estamos sozinhos no Universo.

Planeta semelhante à Terra pode ser inferno vulcânico

Nasa descobre planetas gigantes fora do Sistema Solar

Cerca de 15% dos sistemas solares são como o da Terra

Moléculas orgânicas descobertas em mais um planeta distante

Um alto funcionário da Nasa e outros importantes cientistas dizem que, dentro de quatro ou cinco anos, o primeiro planeta semelhante à Terra e capaz de abrigar vida deve ser encontrado, ou talvez até já tenha sido. Um planeta com o tamanho aproximado da Terra pode até mesmo ser anunciado ainda este ano, se certas pistas detectadas por um telescópio espacial se confirmarem.

Na reunião anual da Associação de Astronomia dos Estados Unidos, cada uma das descobertas a respeito de “exoplanetas” – os localizados fora do Sistema Solar – aponta para a mesma conclusão: planetas onde a vida pode surgir provavelmente abundam, a despeito da violência do ambiente espacial, repleto de explosões, buracos negros e colisões.

Vida e morte nas marés galácticas

Este artigo me parece relevante também para a teoria de extinções periódicas devido às marés galácticas.
Friday, December 18, 2009

Galactic Tide May Have Influenced Life on Earth

The galactic tide is strong enough to influence Oort Cloud comets, which means it may also have helped shape our planet.

The Moon’s tides have been an ever-present force in Earth’s history, shaping the landscape and the lives of the creatures that inhabit it. Now there’s a tantalising hint that the galactic tide may have played a significant role in Earth’s past.

The work comes from Jozef Klacka at Comenius University in the Slovak Republic. He has calculated the strength of the galactic tide and its effect on the Solar System. His conclusion is that the tide is strong enough to significantly effect the orbital evolution of Oort Cloud comets.

That’s a fascinating result. We’ve long known that the Moon’s tides must have been crucial for the evolution of life on Earth. The constant ebb and flow of the oceans would have left sea life stranded on beaches, forcing adaptations that allowed these creatures to cope with conditions on land.

Astrobiologists also believe that comets played an important part in the development of life on Earth because the atmosphere and oceans were seeded, at least in part, by comets. By that way of thinking, the forces and processes that have shaped evolution stretch to the edge of the Solar System.

But if the galactic tide plays a role in sending these comets our way, then it looks as if we’re part of a much larger web. Could it be that Earth and the life that has evolved here, is crucially dependent, not just on our planet, our star and our local interplanetary environment, but on the Milky Way galaxy itself?

Klacka has a lot more work to do to prove that the galactic tide plays such a role. But it might just be that the field of astrobiology has become a whole lot bigger.

Ref: arxiv.org/abs/0912.3112: Galactic Tide

Luas habitáveis

The Hunt for Habitable Exomoons

Posted: 30 Nov 2009 09:10 PM PST

Forget exoplanets, the first habitable body to be discovered beyond our solar system could turn out to be an exomoon in a habitable zone

The discovery of habitable planets around other stars is one of the great goals of modern astronomy. But it’s not just planets that can host life. Astronomers have long believed that moons orbiting Jupiter-like planets in the habitable zone could have Earth-like qualities. The problem is how to detect them.


One of the best ways to spot exoplanets is to look for changes in a parent star’s brightness as the they pass in front of its disc. So why not look for exomoons in the same way? A planet-moon system orbits a common centre of mass which itself orbits the star. Consequently, the planet’s position can be shifted by a small amount as it moves in front of the disc, leading to a small change in the time that a transit begins and ends. This transit timing variation (TTV) is a signal that could be used to spot an exomoon.


In theory, at least. The trouble is that that up to 98 per cent of promising exoplanet signals turn out to be false alarms caused by other effects. It turns out there is no way of teasing the exomoon signal out of this mess.


And there the field of exomoon hunting would have remained were it no for the work of David Kipping at the Harvard-Smithsonian Center for Astrophysics in Cambridge and a few buddies. Earlier this year, these guys showed that exomoons produce another signal. They pointed out that not only does an exomoon change the start time of a transit, it should also change the duration of the transit and that together, these signals can uniquely identify an exomoon.


Today, Kippling and co say this method is possible now. Earlier this year, NASA launched the Keppler Space Telescope to stare continuously at a fixed region of the sky and measure the changes in brightness of some 100,000 stars.


After crunching a few numbers, Kippling and co say that Keppler should be able to see exomoons smaller than Earth around Saturn-like exoplanets if they are orbiting any of 25,000 stars in the Keppler’s field of view.


That’s exciting news. Keppler is already sending back data. If habitable exomoons are out there, we’ll see them soon.

Ref: arxiv.org/abs/0911.5170: Pathways Towards Habitable Moons

Água é um pre-requisito para Gaia II


Mariana, minha filha, eu tô falando pra você que Atrobioologia é a carreira quente do mmomento!
Takata, eu sei que a água não é um pre-requisito necessário para a vida. Mas é um pre-requisito necessário para a nossa vida, e para uma Gaia tecnoverde criar uma filhote lá!
Na próxima década

Busca de vida em outro planeta será a grande pesquisa mundial

Além disso, outro foco das pesquisas deve ser a busca pela água
04/08/09 às 10:21 | Agência Brasil
A Assembleia Geral da União Astronômica Internacional (IAU), realizada a cada três anos, foi aberta oficialmente no Rio de Janeiro. Para o astrofísico Carlos Henrique Veiga, do Observatório Nacional, a procura de vida fora do sistema solar e a presença de água serão a grande pesquisa nos próximos dez anos.

“A grande pesquisa será a busca por planetas como a Terra em outras estrelas. Acho que a grande discussão vai ser em torno de água fora do sistema solar, ou mesmo dentro do sistema solar”, disse Veiga. O observatório é uma das entidades coordenadoras do simpósio Impacto da Variabilidade Estelar e Solar na Terra e Planetas, que ocorre até o próximo dia 7 como parte do encontro da IAU.

Carlos Veiga destacou que a assembleia é importante pelas consequências e conceitos que pode gerar. Na última edição do evento, realizada em Praga, na República Tcheca, por exemplo, foi decidido que Plutão seria excluído da família dos grandes planetas e passaria a integrar um grupo de menor porte.

A pesquisa em busca de vida e água em outros planetas tem especial interesse para a Terra no momento em que ela sofre os efeitos do aquecimento global. “A gente está percebendo que o planeta está esgotando suas fontes de sobrevivência. A água não vai durar muito. O ar é altamente poluído. E tudo isso pode acabar em uma catástrofe daqui a 200, 300 anos”.

A idéia, disse Veiga, é programar para que se possa enviar pessoas a outro lugar em que existam condições de vida, como satélites numa lua de Saturno. Esse é um dos principais assuntos que serão tratados na IAU por cerca de 2 mil representantes de todo o mundo. No Observatório Nacional, 80% dos pesquisadores do Departamento de Astronomia estão envolvidos com a meta de encontrar água em outros sistemas solares.

Coordenador da Divisão de Atividades Educacionais do observatório, Carlos Henrique Veiga explicou que um dos objetivos é atrair a juventude brasileira para as ciências exatas, de modo que ela comece a pensar nesses problemas.

“Passar o conhecimento para eles, informar o que está acontecendo de uma forma correta e precisa, de maneira que esses estudantes novos sejam atraídos para todas as áreas do conhecimento científico, de modo que a gente possa pensar cada vez mais sobre a questão da sobrevivência do ser humano em outro planeta, em outra estrela. Esse é um pensamento para daqui a 100, 200 anos. Mas, se a gente não começar a pensar agora, vai ser muito tarde”, afirmou.