Stephen Hawking – His Life And Work

THERE IS A SINGULARITY IN OUR PAST

Penrose’s discovery that a star of great enough mass undergoing gravitational collapse must form a singularity set fire to Hawking. With Robert Geroch and Penrose, he began to extend ideas about singularities to other physical and mathematical cases. He was certain the discovery had significant implications for the beginning of the universe. This was exhilarating work, with the ‘glorious feeling of having a whole field virtually to ourselves’. Hawking realized that if he reversed the direction of time so that the collapse became an expansion, everything in Penrose’s theory would still hold. If general relativity tells us that any star that collapses beyond a certain point must end in a singularity, then it also tells us that any expanding universe must have begun as a singularity. For this to be true the universe must be like what scientists call a Friedmann model.

Click on the imagem below and catch a glimpse of the Friedmann models of the universe:

Credits: NASA / Chandra X-Ray Observatory

Which model fits our universe?Will the universe collapse some day or go on expanding forever? It depends on how much mass there is in the universe […]. It will take much more mass than we presently observe to close the universe. […]

Penrose’s theory about stars collapsing and becoming singularities only worked with a universe infinite in space that will go on expanding forever, not collapse. Hawking first set out to prove that a universe infinite in space not only would have singularities in black holes but also must have begun as a singularity. He was confident enough by the time he finished his thesis to write: ‘There is a singularity in our past.’

© Kitty Ferguson – Stephen Hawking – His Life and Work (excerto, com comentário) – Bantam Books

Stephen Hawking – His Life and Work

PREDICTING THE DETAILS OF THE UNIVERSE WE LIVE IN, THE THEORY OF EVERYTHING

The calculations necessary to study all the data in the universe are ludicrously far beyond the capacity of any imaginable computer. Hawking points out that although we can solve the equations for the movement of two bodies in Newton’s theory of gravity, we can’t solve them exactly for three bodies, not because Newton’s theory doesn’t work for three bodies but because the maths is too complicated. The real universe, needless to say, has more than three bodies in it.

No começo eu não entendia muito bem como não se é possível tirar conclusões exatas sobre situações e coisas tão recorrentes, tão práticas, cotidianas… tão físicas. Na verdade tinha plena certeza de que era possível: só era preciso tempo e capacidade.
Eu até estava certo, só não sabia que o tempo e a capacidade necessários podem, de repente, ser infinitos.

Nor can we predict our health, although we understand the principles that underlie medicine, the principles of chemistry and biology, extremely well. The problem again is that there are too many billions upon billions of details in a real-life system, even when that system is just one human body.
Even with the Theory of Everything in our hands we’d still be a staggeringly long way from predicting everything. Even if the underlying principles are simple and well understood, the way they work out is enormously complicated. ‘A minute to learn, the lifetime of the universe to master’, to paraphrase an advertising slogan. ‘Lifetime of the universe to master’ is a gross understatement.

© Kitty Ferguson – Stephen Hawking – His Life and Work (excerto, com comentário) – Bantam Books

Steven Pinker – Toward A Consilient Study Of Literature

THE EVOLUTION OF THE ART

[…]
I sense that most people involved with the arts want them to be an adaptation because they feel it would somehow validate or ennoble the arts — perhaps even protect them against budget-conscious politicians seeking to cut them from school curricula. Part of the problem is an ambiguity in the word itself. In the common vernacular, “adaptive” is a good thing; it means “healthy, clever, well-adjusted.” In the biologist’s technical sense, though, it refers only to a trait that evolved because, compared to alternative versions of the traits, it increased the rate of reproduction of an organism’s ancestors. Biological adaptations need not be praiseworthy by human standards. Quite the contrary. As symons has pointed out, a willingness to commit genocide may very well be an adaptation, whereas the ability to read almost certainly is not. The arts could be evolutionary by-products, and be among the most valuable human activities for all that.
To demonstrate that X is an adaptation, one can’t simply show that people like doing X, or that good things happen when people do X. This is circular; a restatement of the fact that people tend to do X. Instead, one has to show — independently of anything we know about the human behavior in question — that X, by its intrinsic design, is capable of causing a reproduction-enhancing outcome in an environment like the one in which humans evolved. This analysis can’t be a kind of psychology; it must be a kind of engineering—an attempt to lay down the design specs of a system that can accomplish a goal (specifically, a subgoal of reproduction) in a particular world (specifically, the ancestral environment). with these design specs in hand, one can then compare the specs against the facts of the human drive or talent we are trying to explain. The closer the design specs match the empirical facts about human beings, the more confidence we have that the trait in question is an adaptation.
[…]
What about the arts? We can immediately see that any supposed function that appeals only to the effects we observe post hoc in people won’t cut it. Perhaps singing lullabies soothes babies; perhaps dancing relieves tension; perhaps shared stories bond the community. The question is, why would anyone have predicted, a priori, that people would be constituted in such a way that these things would happen? What exactly is it about a sequence of tones in certain rhythmic and harmonic relations that would lead a baby to ease up on its demands for parental attention (compared to any other signal), and what’s in it for the baby? In the case of fiction, why should communally recounted falsehoods about characters and events that never occurred make people any more attached to one another than they would otherwise find it in their interests to be? it’s not that these questions are necessarily unanswerable, but they do need answers, and the answers cannot simply repeat what we already know about people’s tendency to produce and consume works of art.
Appealing to this logic, i proposed that many of the arts may have no adaptive function at all. They may be by-products of two other traits: motivational systems that give us pleasure when we experience signals that correlate with adaptive outcomes (safety, sex, esteem, information-rich environments), and the technological know-how to create purified and concentrated doses of these signals (such as landscape paintings, erotica, or hero stories). fiction may be, at least in part, a pleasure technology, a co-opting of language and imagery as a virtual reality device which allows a reader to enjoy pleasant hallucinations like exploring interesting territories, conquering enemies, hobnobbing with powerful people, and winning attractive mates. Fiction, moreover, can tickle people’s fancies without even having to project them into a thrilling vicarious experience. There are good reasons for people (or any competitive social agent) to crave gossip, which is a kind of due diligence on possible allies and enemies. fiction, with its omniscient narrator disclosing the foibles of interesting virtual people, can be a form of simulated gossip.
[…]
The literary scholar and nabokov expert Brian Boyd presents an incisive overview and critique of evolutionary theories of art (including mine) and a defense of his own favorite: that art is no by-product, but has the dual function of fostering social cohesion (an idea he credits to the scholar Ellen Dissanayake) and of engaging attention. Boyd rightly criticizes an alternative theory of the function of arts from the psychologist Geoffrey Miller in which art is a costly signal of the neural fitness of the artist, a kind of cognitive peacock’s tale. Boyd points out that this theory falsely predicts that art should be produced and consumed primarily in the context of courtship. I agree with the criticism, though it must be said that Miller’s theory at least passes the test of being a logically coherent, noncircular adaptationist hypothesis. The same cannot be said for the social-cohesion theory, because we have been given no a priori reason to predict that the sharing of imaginary events would be an efficacious way for the members of a social species to stay together (compared to drawing circles in the air, reciting prime numbers, banging elbows, and so on) — other than that we know that our species seems to do it that way. (To say nothing of the issues papered over by the assumption that “social cohesion” is an evolutionary desideratum, a problem i will return to.) a similar problem faces the suggestion that shared attention is the evolutionary function of fiction. It begs the question of what’s so adaptive about sharing attention, particularly attention to events that never happened, other than that people like to do it.
[…]

© Steven Pinker
Excerto. Artigo na íntegra em: Pinker, S. (2007) Toward a consilient study of literature (review of J. Gottschall & D. Sloan Wilson, “The Literary Animal: Evolution and the Nature of Narrative”). Philosophy and Literature, 31, 161-177.