Some superfast particles arriving at Earth may originate from shock waves in turbulent stellar clusters, a gamma-ray study published in the November 24th issue of Science suggests. The observations are the first firm direct evidence of a longstanding theory for the origin of these particles, called cosmic rays, but they don’t do anything for another, even longer-standing theory in favor of supernova remnants.
Cosmic rays were first discovered in 1912 by Victor Hess, who won a Nobel Prize for his detection of this strange source of radiation entering the atmosphere from space. Until the 1930s scientists thought cosmic rays were some sort of electromagnetic wave — hence their name. But the deceptively dubbed “rays” are actually speedy charged particles whizzing through the universe. They’re mostly protons from hydrogen atoms stripped of their electrons, but they can also be heavier atomic nuclei, electrons, and other subatomic particles.
Gamma rays detected by the Fermi LAT (top image) are emitted by freshly accelerated cosmic rays traveling through the stormy Cygnus X region (in infrared, bottom image). The cosmic ray "cocoon" fills the cavities carved out around and between two star clusters, Cyg OB2 and NGC 6910.
NASA / DOE / Fermi LAT / I. Grenier / L. Tibaldo
Yet even after 99 years, astronomers still don’t know for sure where cosmic rays receive their energy boost. The problem with figuring out where cosmic rays come from is that they appear to come from everywhere. Because they’re charged particles, cosmic rays react to whatever magnetic fields they encounter, and there are a lot of magnetic fields in galaxies, whether from stars or planets or even the galaxy itself. By the time the particles reach Earth, they’re hitting us from all sides.
Gamma rays don’t have this problem. The most energetic photons in the universe, gamma rays basically travel in straight lines from their sources to us. And because cosmic rays are stupendously energetic, they produce gamma rays when they run into stuff.
Astronomers have used gamma rays to probe likely sites of cosmic ray acceleration. For several decades researchers have suspected that our galaxy’s rays come from supernova remnants, and X-ray and gamma-ray observations do indicate that electrons are being accelerated to high energies at remnants’ shock fronts as they slam into surrounding gas and dust, sending the electrons surfing in and out of the blast wave. But there’s no conclusive evidence of proton and nuclei acceleration, and these heavier particles make up 99% of cosmic rays, says Isabelle Grenier (Paris Diderot University and CEA Saclay), a coauthor on the new study. “We have no smoking gun,” she says. “We have very strong hints, but no proof.”
To hunt for cosmic rays’ origin, Grenier and her colleagues turned the Fermi Gamma-ray Space Telescope’s Large Area Telescope to point at the star-forming region Cygnus X, a tumultuous section of space about 4,500 light-years away filled with billows of thousand-mile-per-second stellar winds and strong ultraviolet radiation from young stars. The team detected a diffuse gamma-ray glow from inside a superbubble blown out by the young, massive members of two of the region’s star clusters, Cyg OB2 and NGC 6910. What’s more, the radiation looks like it’s coming from protons, not electrons.
The average energies Grenier’s team observed are much higher than the energies of cosmic rays near Earth. Add that higher energy to the emission’s confinement (meaning, the particles haven’t had a chance to move very far from their energizing source), and the fact that the gamma rays come from protons, and it looks like the team’s caught, as they put it, “freshly accelerated cosmic rays” that haven’t slowed down to near-Earth energy levels yet.
To find the source, the team focused at first on a strong gamma-ray-emitting supernova remnant called γ Cygni that appears in the same part of the sky. The remnant’s distance isn’t pinned down, so it’s not clear if it’s actually associated with Cygnus X. But that it might be there, in the same place as cosmic rays, sparked the researchers’ interest. “We were so excited,” says Grenier. “And I must say that, several months after, I’m not convinced that it’s the best scenario anymore.” The diffuse gamma-ray emission showed no sign of any connection with the remnant.
But the astronomers discovered something else intriguing: the diffuse gamma-rays are completely confined to the superbubble created by the stars’ strong winds, even edged by an infrared-emitting shell of dust grains heated by the intense starlight.
That made the researchers turn to a second theory for cosmic ray production, one involving exactly this kind of environment. Astronomers have suspected since the 1980s or so that cosmic rays may also come from clusters of massive, young stars called OB associations, where the O and B stand for the two hottest, most massive types of the family of stars that fuse hydrogen in their cores. The suspicion stems from the cosmic rays’ composition. Many of the common heavier elements, such as carbon and silicon, are about as abundant among the particles as they are in the solar system, but there are some elements that are overrepresented. Particularly, a heavy isotope of neon, neon-22, is about five times as abundant in cosmic rays as it is in the solar system. But Ne-22 is seen in the outer layers thrown off by really massive, young, windy stars called Wolf-Rayet stars. Overall, the cosmic rays’ chemical makeup suggests that about 20% are created by WR stars, while the rest are other particles found in the interstellar medium, the stuff between the stars.
A sizable fraction of cosmic rays may be born in WR stars’ massive outflows, but that’s not necessarily where they gain their energy. In 1999 Richard Mewaldt (Caltech) and his colleagues reported the presence in cosmic rays of the cobalt isotope cobalt-59. Co-59 is a daughter isotope, an atom formed by the radioactive decay of nickel-59 when that atom captures an electron and shoves it together with one of its proton to make a neutron. Such a snatch can’t happen when the nickel atom’s nucleus is accelerated to high energies and stripped of its electrons, as cosmic ray particles are. That means that the nuclei that make up cosmic rays aren’t born with their high energies: they hang around a while — about 100,000 years, the team concluded — before being sped up and out into interstellar space.
“This rules out a supernova accelerating its own ejecta,” Mewaldt says, although some of the heavier cosmic ray nuclei probably first formed in supernova explosions. “But [it] is consistent with accelerating cosmic rays from a region where massive stars are born, a region that will be enriched in WR material because of the high-velocity winds of these stars.”
Grenier’s team didn’t measure specific chemical composition, so they don’t know what the cosmic rays are made of. Whatever the ingredients — and they’re probably a combination of interstellar medium, old supernova ejecta, and outflows from an earlier batch of Wolf-Rayet stars — it looks like they’re now being accelerated by the current stellar clusters’ winds.
“This is a very important paper,” says Mewaldt of Grenier’s study, “because it provides the first direct evidence for the distributed acceleration of cosmic rays in OB associations.”
The cosmic rays are still confined in a “cocoon” because they can’t spread out fast in the torrid environment inside the superbubble, Grenier says. The massive stars are only a few million years old, and their powerful winds and ultraviolet radiation create a maelstrom inside the cavity, twisting magnetic fields into tangles that trap the cosmic rays. Over time the particles will escape into quieter regions, but what happens to their energies while inside the cocoon remains a mystery.
It’s a mystery that’s particularly intriguing to Grenier. Low-energy cosmic rays (at least, lower energy than the ones the team observed) “are very, very important for the structure of the clouds of the gas from which we form stars,” she explains. Dense clump of clouds eventually collapse under their own gravity to make stars. While the clouds are pretty opaque to light, cosmic rays can sneak inside, bringing with them heat and catalyzing the formation of molecules. How that heat and chemistry influence star formation isn’t known, and Grenier is pursing the question with her colleagues. What is clear is that “if you radiate those clouds with more cosmic rays or [fewer] cosmic rays, you change the game.”
Fuente...SKY AND TELESCOPE
Posted by Camille Carlisle, November 23, 2011
related content: News Topics, Cosmology news, Milky Way news, Stellar science
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viernes, 25 de noviembre de 2011
martes, 22 de noviembre de 2011
Astrónomos reconstruyen la historia de un agujero negro
Tres equipos de astrónomos han logrado determinar la masa, la rotación y la distancia a la Tierra de un agujero negro especialmente famoso, Cygnus X-1, y con esos parámetros han reconstruido su historia. El objeto tiene casi 14,8 veces la masa del Sol, gira 800 veces por segundo y está a 6.070 años luz de aquí. Fue identificado como candidato a agujero negro hace casi cuatro décadas, pero entonces el gran especialista Stephen Hawking no estaba convencido y, en 1974, apostó con un colega y amigo, el físico teórico estadounidense Kip Thorne, a que no se trataba de tal objeto. Perdió. En 1990, cuando ya se habían hecho más observaciones de Cygnus X-1, el físico británico aceptó la derrota. Fue una de las varias apuestas que Hawking y Thorne han hecho sobre cuestiones científicas.
Una vez aceptado como tal, el objeto no perdió interés, al contrario. Cygnus X-1 es un agujero negro estelar, es decir, que se ha formado por el colapso de una estrella masiva, y forma un sistema doble con otro astro. Ahora, los tres grupos de astrónomos, que han trabajado con telescopios en tierra y en el espacio, presentan sus conclusiones complementarias en tres artículos publicados en The Astrophysical Journal. "La nueva información nos proporciona pistas sólidas acerca de cómo se formó el agujero negro, su masa y su velocidad de rotación, y es emocionante, porque no se sabe mucho acerca del nacimiento de un agujero negro", señala Mark Reid, líder de uno de los equipos, en un comunicado del Harvard-Smithsonian Center for Astrophysics (EE UU). El horizonte de sucesos (la frontera de no retorno de la materia que cae en un agujero negro) gira en este más de 800 veces por segundo, muy cerca del máximo calculado.
Otro dato importante es la edad: tiene unos seis millones de años, según estudios de la estrella compañera y modelos teóricos. Por tanto, es relativamente joven en términos astronómicos, y no ha tenido mucho tiempo para tragarse suficiente materia de su entorno como para acelerar su rotación, por lo que Cygnus X-1 debió nacer ya girando muy rápido. Además, debió formarse prácticamente con la misma masa que tiene ahora, 14,8 veces la del Sol. "Ahora sabemos que es uno de los agujeros negros estelares más masivos de la galaxia y gira más rápido que cualquier otro que conozcamos", afirma Jerome Orosz (San Diego State University). El telescopio espacial de rayos X Chandra, de la NASA, ha sido clave en esta investigación.
"Como no puede escapar de un agujero negro más información, su masa, rotación y su carga eléctrica supone la descripción completa", dice Reid. "Y la carga de este agujero negro es casi cero".
Un tercer equipo, gracias a los radiotelescopios sincronizados del sistema VLBA, ha logrado precisar la distancia de Cygnus X-1 (dato esencial para determinar la masa y la rotación), así como el desplazamiento del objeto en el espacio. Resulta que el agujero negro se mueve muy despacio respecto a la Vía Láctea, lo que significa que no recibió impulso al formarse. Este dato apoya la hipótesis según la cual este objeto no se formó en una explosión de supernova (cuando una estrella supermasiva ha consumido todo su combustible), que habría dado ese impulso y llevaría mucha más velocidad. Debió ser un colapso estelar, sí, pero sin explosión, lo que dio origen al agujero negro en cuestión. En cuanto a la distancia, antes de estas nuevas medidas que la han fijado en 6.070 años luz, se estimaba entre 5.800 y 7.800 años luz, indican los expertos del National Radio Astronomy Observatory (que opera el VLBA).
Fuente EL PAÍS - Madrid - 21/11/2011
Una vez aceptado como tal, el objeto no perdió interés, al contrario. Cygnus X-1 es un agujero negro estelar, es decir, que se ha formado por el colapso de una estrella masiva, y forma un sistema doble con otro astro. Ahora, los tres grupos de astrónomos, que han trabajado con telescopios en tierra y en el espacio, presentan sus conclusiones complementarias en tres artículos publicados en The Astrophysical Journal. "La nueva información nos proporciona pistas sólidas acerca de cómo se formó el agujero negro, su masa y su velocidad de rotación, y es emocionante, porque no se sabe mucho acerca del nacimiento de un agujero negro", señala Mark Reid, líder de uno de los equipos, en un comunicado del Harvard-Smithsonian Center for Astrophysics (EE UU). El horizonte de sucesos (la frontera de no retorno de la materia que cae en un agujero negro) gira en este más de 800 veces por segundo, muy cerca del máximo calculado.
Otro dato importante es la edad: tiene unos seis millones de años, según estudios de la estrella compañera y modelos teóricos. Por tanto, es relativamente joven en términos astronómicos, y no ha tenido mucho tiempo para tragarse suficiente materia de su entorno como para acelerar su rotación, por lo que Cygnus X-1 debió nacer ya girando muy rápido. Además, debió formarse prácticamente con la misma masa que tiene ahora, 14,8 veces la del Sol. "Ahora sabemos que es uno de los agujeros negros estelares más masivos de la galaxia y gira más rápido que cualquier otro que conozcamos", afirma Jerome Orosz (San Diego State University). El telescopio espacial de rayos X Chandra, de la NASA, ha sido clave en esta investigación.
"Como no puede escapar de un agujero negro más información, su masa, rotación y su carga eléctrica supone la descripción completa", dice Reid. "Y la carga de este agujero negro es casi cero".
Un tercer equipo, gracias a los radiotelescopios sincronizados del sistema VLBA, ha logrado precisar la distancia de Cygnus X-1 (dato esencial para determinar la masa y la rotación), así como el desplazamiento del objeto en el espacio. Resulta que el agujero negro se mueve muy despacio respecto a la Vía Láctea, lo que significa que no recibió impulso al formarse. Este dato apoya la hipótesis según la cual este objeto no se formó en una explosión de supernova (cuando una estrella supermasiva ha consumido todo su combustible), que habría dado ese impulso y llevaría mucha más velocidad. Debió ser un colapso estelar, sí, pero sin explosión, lo que dio origen al agujero negro en cuestión. En cuanto a la distancia, antes de estas nuevas medidas que la han fijado en 6.070 años luz, se estimaba entre 5.800 y 7.800 años luz, indican los expertos del National Radio Astronomy Observatory (que opera el VLBA).
Fuente EL PAÍS - Madrid - 21/11/2011
Through data, evaluating the potential for life on other worlds
In many fields of science, the imagination is only limited by the language that can explain it.
As we discovered nearly a year ago, forms of life could exist that play by rules beyond our base of knowledge.
Scientists know that it’s likely that they will discover many more planets orbiting distant stars. They also know that researchers are most likely to focus on those that exhibit Earth-like conditions, in an attempt to find life in another part of the universe.
But what if alien life can exist in conditions drastically unlike those of Earth? Will scientists mistakenly overlook them?
Driven by this fear — and the admission that searching for Earth-like conditions as a precondition for life is a basic but incomplete strategy for finding it — an international team of researchers from NASA, SETI and several universities are working to develop a classification system that includes chemical and physical parameters that are theoretically conducive to life, even if they result in decidedly un-Earth-like conditions.
Washington State University astrobiologist Dirk Schulze-Makuch, University of Puerto Rico modeling expert Abel Mendez and seven more colleagues have developed two different indices — an Earth Similarity Index that categorizes a planet’s more Earth-like features, and a Planetary Habitability Index that includes theoretical parameters — that they say can help researchers more easily find patterns in large and complex datasets.
It’s the first attempt by scientists to categorize the potential of exoplanets and exomoons to harbor life, and should prevent Earth-bound researchers from overlooking conditions that are, ahem, alien to them in their search for life.
Their work will be published in the December issue of the journal Astrobiology.
Autor...Andrew Nusca | November 21, 2011, 7:09 AM PST
en la publicacion Smart Planet Daily.
As we discovered nearly a year ago, forms of life could exist that play by rules beyond our base of knowledge.
Scientists know that it’s likely that they will discover many more planets orbiting distant stars. They also know that researchers are most likely to focus on those that exhibit Earth-like conditions, in an attempt to find life in another part of the universe.
But what if alien life can exist in conditions drastically unlike those of Earth? Will scientists mistakenly overlook them?
Driven by this fear — and the admission that searching for Earth-like conditions as a precondition for life is a basic but incomplete strategy for finding it — an international team of researchers from NASA, SETI and several universities are working to develop a classification system that includes chemical and physical parameters that are theoretically conducive to life, even if they result in decidedly un-Earth-like conditions.
Washington State University astrobiologist Dirk Schulze-Makuch, University of Puerto Rico modeling expert Abel Mendez and seven more colleagues have developed two different indices — an Earth Similarity Index that categorizes a planet’s more Earth-like features, and a Planetary Habitability Index that includes theoretical parameters — that they say can help researchers more easily find patterns in large and complex datasets.
It’s the first attempt by scientists to categorize the potential of exoplanets and exomoons to harbor life, and should prevent Earth-bound researchers from overlooking conditions that are, ahem, alien to them in their search for life.
Their work will be published in the December issue of the journal Astrobiology.
Autor...Andrew Nusca | November 21, 2011, 7:09 AM PST
en la publicacion Smart Planet Daily.
jueves, 17 de noviembre de 2011
Neuroscience Challenges Old Ideas about Free Will
Celebrated neuroscientist Michael S. Gazzaniga explains the new science behind an ancient philosophical question
By Gareth Cook | Tuesday, November 15, 2011 | 41
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Do we have free will? It is an age-old question which has attracted the attention of philosophers, theologians, lawyers and political theorists. Now it is attracting the attention of neuroscience, explains Michael S. Gazzaniga, director of the SAGE Center for the Study of the Mind at the University of California, Santa Barbara, and author of the new book, “Who’s In Charge: Free Will and the Science of the Brain.” He spoke with Mind Matters editor Gareth Cook.
Cook: Why did you decide to tackle the question of free will?
Gazzaniga: I think the issue is on every thinking person’s mind. I can remember wondering about it 50 years ago when I was a student at Dartmouth. At that time, the issue was raw and simply stated. Physics and chemistry were king and while all of us were too young to shave, we saw the implications. For me, those were back in the days when I went to Church every Sunday, and sometimes on Monday if I had an exam coming up!
Now, after 50 years of studying the brain, listening to philosophers, and most recently being slowly educated about the law, the issue is back on my front burner. The question of whether we are responsible for our actions -- or robots that respond automatically -- has been around a long time but until recently the great scholars who spoke out on the issue didn’t know modern science with its deep knowledge and implications.
Cook: What makes you think that neuroscience can shed any light on what has long been a philosophical question?
Gazzaniga: Philosophers are the best at articulating the nature of a problem before anybody knows anything empirical. The modern philosophers of mind now seize on neuroscience and cognitive science to help illuminate age old questions and to this day are frequently ahead of the pack. Among other skills, they have time to think! The laboratory scientist is consumed with experimental details, analyzing data, and frequently does not have the time to place a scientific finding into a larger landscape. It is a constant tension.
Having said that, philosophers can’t have all the fun. Faced with the nature of biologic mechanisms morning, noon, and night, neuroscientists can’t help but think about such questions as the nature of “freedom of action in a mechanistic universe” as one great neuroscientist put it years ago. At a minimum, neuroscience directs one’s attention to the question of how does action come about.
Cook: Do you think that neuroscience, as a field, needs to tackle these questions? That is, do you consider free will an important scientific question?
Gazzaniga: We all need to understand more about free will, or more wisely put, the nature of action. Neuroscience is one highly relevant discipline to this issue. Whatever your beliefs about free will, everyone feels like they have it, even those who dispute that it exists. What neuroscience has been showing us, however, is that it all works differently than how we feel it must work. For instance, neuroscientific experiments indicate that human decisions for action are made before the individual is consciously aware of them. Instead of this finding answering the age-old question of whether the brain decides before the mind decides, it makes us wonder if that is even the way to think about how the brain works. Research is focused on many aspects of decision making and actions, such as where in the brain decisions to act are formed and executed, how a bunch of interacting neurons becomes a moral agent, and even how one’s beliefs about whether they have free will affect their actions. The list of issues where neuroscience will weigh in is endless.
Cook: Please explain what you mean by the idea of an "emergent mind," and the distinction you draw between this and the brain?
Gazzaniga: Leibnitz raised the question almost 300 years ago with his analogy of the mill. Imagine that you can blow the mill up in size such that all components are magnified and you can walk among them. All you find are individual mechanical components, a wheel here, a spindle there. By looking at the parts of the mill you cannot deduce its function. The physical brain can also be broken into parts and their interactions examined. We now understand neurons and how they fire and a bit about neurotransmitters and so forth. But somehow the mental properties are indivisible and can’t be described in terms of neuronal firings. They need to be understood in another vocabulary.
This is sometimes called the emergent mind. Emergence as a concept in general is widely accepted in physics, chemistry, biology, sociology, you name it. Neuroscientists, however, have a hard time with it because they are suspicious that this concept is sneaking a ghost into the machine. That is not it at all. The motivation for this suggestion is to conceptualize the actual architecture of the layered brain/mind interaction so it can be properly studied. It is lazy to stay locked into one layer of analysis and to dismiss the other.
Cook: How does the mind constrain the brain?
Gazzaniga: No one said this is going to be easy and here is where the going gets tough. Picking up on the last thought the idea: we are dealing with a layered system, and each layer has its own laws and protocols, just like in physics where Newton’s Laws apply to one layer of physics and quantum mechanics to another. Think of hardware-software layers. Hardware is useless without software and software is useless without hardware.
How are we to capture an understanding how the two layers interact? For now, no one really captures that reality and certainly no one has yet captured how mental states interact with the neurons that produce them. Yet we know the top mental layers and the layers beneath it, which produce it, interact. Patients suffering from depression can be aided by talk therapy (top-down). They can also be aided by pharmacological drugs (bottom up). When these two therapies are combined the therapy is even better. That is an example of the mind constraining the brain.
Cook: And how does this idea of the mind and brain interacting bring you to your position on free will?
Gazzaniga: For me, it captures the fact that we are trying to understand a layered system. One becomes cognizant there is a system on top of the personal mind/brain layers which is yet another layer--the social world. It interacts massively with our mental processes and vice versa. In many ways we humans, in achieving our robustness, have uploaded many of our critical needs to the social system around us so that the stuff we invent can survive our own fragile and vulnerable lives.
Cook: You talk about “abandoning” the idea of free will. Can you explain what you mean by this, and how you came to this conclusion?
Gazzaniga: As I see it, this is the way to think about it: If you were a Martian landing on Earth today and were gathering information how humans work, the idea of free will as commonly understood in folk psychology would not come up. The Martian would learn humans had learned about physics and chemistry and causation in the standard sense. They would be astonished to see the amount of information that has accumulated about how cells work, how brains work and would conclude, “OK, they are getting it. Just like cells are complex wonderful machines, so are brains. They work in cool ways even though there is this strong tug on them to think there is some little guy in their head calling the shots. There is not.”
The world is not flat. Before this truth was realized, people use to wonder what happened when you got to the end of the earth-- did you fall off? Once we knew the earth was round, the new perspective, made us see how the old questions were silly. New questions also seem silly many times until a new perspective is accepted. I think we will get over the idea of free will and and accept we are a special kind of machine, one with a moral agency which comes from living in social groups. This perspective will make us ask new kinds of questions.
Cook: Are there particular experiments which you think have shed important light on the question of free will?
Gazzaniga: All of neuroscience in one way or another is shining light on how the brain works. That is the reality of it and it is that knowledge, slowly accumulating that will drive us to think more deeply. One way to get going on this is to try and answer the simple question. Free from what? What does anybody want to be free from? I surely do not want to be free from the laws of nature.
Cook: Do you think this science is going to force philosophers to change how they think about free will? And how about the rest of us?
Gazzaniga: Human knowledge can’t help itself in the long run. Things slowly, gradually become more clear. As humans continue on their journey they will come to believe certain things about the nature of things and those abstractions will then be reflected in the rules that are set up to allow people to live together. Beliefs have consequences and we will see them reflected in all kinds of ways. Certainly how we come to think and understand human responsibility in the context of modern knowledge of biologic mechanisms will dictate how we choose our laws and our punishments. What could be more important?
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Fuente... http://www.scientificamerican.com/article.cfm?id=free-will-and-the-brain-michael-gazzaniga-interview
By Gareth Cook | Tuesday, November 15, 2011 | 41
'''''''''''''''''''''''''''''''''''''''''''''''''''
Do we have free will? It is an age-old question which has attracted the attention of philosophers, theologians, lawyers and political theorists. Now it is attracting the attention of neuroscience, explains Michael S. Gazzaniga, director of the SAGE Center for the Study of the Mind at the University of California, Santa Barbara, and author of the new book, “Who’s In Charge: Free Will and the Science of the Brain.” He spoke with Mind Matters editor Gareth Cook.
Cook: Why did you decide to tackle the question of free will?
Gazzaniga: I think the issue is on every thinking person’s mind. I can remember wondering about it 50 years ago when I was a student at Dartmouth. At that time, the issue was raw and simply stated. Physics and chemistry were king and while all of us were too young to shave, we saw the implications. For me, those were back in the days when I went to Church every Sunday, and sometimes on Monday if I had an exam coming up!
Now, after 50 years of studying the brain, listening to philosophers, and most recently being slowly educated about the law, the issue is back on my front burner. The question of whether we are responsible for our actions -- or robots that respond automatically -- has been around a long time but until recently the great scholars who spoke out on the issue didn’t know modern science with its deep knowledge and implications.
Cook: What makes you think that neuroscience can shed any light on what has long been a philosophical question?
Gazzaniga: Philosophers are the best at articulating the nature of a problem before anybody knows anything empirical. The modern philosophers of mind now seize on neuroscience and cognitive science to help illuminate age old questions and to this day are frequently ahead of the pack. Among other skills, they have time to think! The laboratory scientist is consumed with experimental details, analyzing data, and frequently does not have the time to place a scientific finding into a larger landscape. It is a constant tension.
Having said that, philosophers can’t have all the fun. Faced with the nature of biologic mechanisms morning, noon, and night, neuroscientists can’t help but think about such questions as the nature of “freedom of action in a mechanistic universe” as one great neuroscientist put it years ago. At a minimum, neuroscience directs one’s attention to the question of how does action come about.
Cook: Do you think that neuroscience, as a field, needs to tackle these questions? That is, do you consider free will an important scientific question?
Gazzaniga: We all need to understand more about free will, or more wisely put, the nature of action. Neuroscience is one highly relevant discipline to this issue. Whatever your beliefs about free will, everyone feels like they have it, even those who dispute that it exists. What neuroscience has been showing us, however, is that it all works differently than how we feel it must work. For instance, neuroscientific experiments indicate that human decisions for action are made before the individual is consciously aware of them. Instead of this finding answering the age-old question of whether the brain decides before the mind decides, it makes us wonder if that is even the way to think about how the brain works. Research is focused on many aspects of decision making and actions, such as where in the brain decisions to act are formed and executed, how a bunch of interacting neurons becomes a moral agent, and even how one’s beliefs about whether they have free will affect their actions. The list of issues where neuroscience will weigh in is endless.
Cook: Please explain what you mean by the idea of an "emergent mind," and the distinction you draw between this and the brain?
Gazzaniga: Leibnitz raised the question almost 300 years ago with his analogy of the mill. Imagine that you can blow the mill up in size such that all components are magnified and you can walk among them. All you find are individual mechanical components, a wheel here, a spindle there. By looking at the parts of the mill you cannot deduce its function. The physical brain can also be broken into parts and their interactions examined. We now understand neurons and how they fire and a bit about neurotransmitters and so forth. But somehow the mental properties are indivisible and can’t be described in terms of neuronal firings. They need to be understood in another vocabulary.
This is sometimes called the emergent mind. Emergence as a concept in general is widely accepted in physics, chemistry, biology, sociology, you name it. Neuroscientists, however, have a hard time with it because they are suspicious that this concept is sneaking a ghost into the machine. That is not it at all. The motivation for this suggestion is to conceptualize the actual architecture of the layered brain/mind interaction so it can be properly studied. It is lazy to stay locked into one layer of analysis and to dismiss the other.
Cook: How does the mind constrain the brain?
Gazzaniga: No one said this is going to be easy and here is where the going gets tough. Picking up on the last thought the idea: we are dealing with a layered system, and each layer has its own laws and protocols, just like in physics where Newton’s Laws apply to one layer of physics and quantum mechanics to another. Think of hardware-software layers. Hardware is useless without software and software is useless without hardware.
How are we to capture an understanding how the two layers interact? For now, no one really captures that reality and certainly no one has yet captured how mental states interact with the neurons that produce them. Yet we know the top mental layers and the layers beneath it, which produce it, interact. Patients suffering from depression can be aided by talk therapy (top-down). They can also be aided by pharmacological drugs (bottom up). When these two therapies are combined the therapy is even better. That is an example of the mind constraining the brain.
Cook: And how does this idea of the mind and brain interacting bring you to your position on free will?
Gazzaniga: For me, it captures the fact that we are trying to understand a layered system. One becomes cognizant there is a system on top of the personal mind/brain layers which is yet another layer--the social world. It interacts massively with our mental processes and vice versa. In many ways we humans, in achieving our robustness, have uploaded many of our critical needs to the social system around us so that the stuff we invent can survive our own fragile and vulnerable lives.
Cook: You talk about “abandoning” the idea of free will. Can you explain what you mean by this, and how you came to this conclusion?
Gazzaniga: As I see it, this is the way to think about it: If you were a Martian landing on Earth today and were gathering information how humans work, the idea of free will as commonly understood in folk psychology would not come up. The Martian would learn humans had learned about physics and chemistry and causation in the standard sense. They would be astonished to see the amount of information that has accumulated about how cells work, how brains work and would conclude, “OK, they are getting it. Just like cells are complex wonderful machines, so are brains. They work in cool ways even though there is this strong tug on them to think there is some little guy in their head calling the shots. There is not.”
The world is not flat. Before this truth was realized, people use to wonder what happened when you got to the end of the earth-- did you fall off? Once we knew the earth was round, the new perspective, made us see how the old questions were silly. New questions also seem silly many times until a new perspective is accepted. I think we will get over the idea of free will and and accept we are a special kind of machine, one with a moral agency which comes from living in social groups. This perspective will make us ask new kinds of questions.
Cook: Are there particular experiments which you think have shed important light on the question of free will?
Gazzaniga: All of neuroscience in one way or another is shining light on how the brain works. That is the reality of it and it is that knowledge, slowly accumulating that will drive us to think more deeply. One way to get going on this is to try and answer the simple question. Free from what? What does anybody want to be free from? I surely do not want to be free from the laws of nature.
Cook: Do you think this science is going to force philosophers to change how they think about free will? And how about the rest of us?
Gazzaniga: Human knowledge can’t help itself in the long run. Things slowly, gradually become more clear. As humans continue on their journey they will come to believe certain things about the nature of things and those abstractions will then be reflected in the rules that are set up to allow people to live together. Beliefs have consequences and we will see them reflected in all kinds of ways. Certainly how we come to think and understand human responsibility in the context of modern knowledge of biologic mechanisms will dictate how we choose our laws and our punishments. What could be more important?
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Fuente... http://www.scientificamerican.com/article.cfm?id=free-will-and-the-brain-michael-gazzaniga-interview
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