Marcelo Gleiser 'falou e disse' a razão de dizer adeus às teorias do tudo: o Universo é imperfeito!

terça-feira, maio 18, 2010

The imperfect universe: Goodbye, theory of everything

10 May 2010 by Marcelo Gleiser

Magazine issue 2759.
FIFTEEN years ago, I was a physicist hard at work hunting for a theory of nature that would unify the very big and the very small. There was good reason to hope. The great and the good were committed. Even Einstein, who recognised that our understanding of reality is necessarily incomplete, had spent the last 20 years of his life searching for a unified field theory that would describe the two main forces we see acting around us - gravity and electromagnetism - as manifestations of a single force. For him, such a mathematical theory represented the purest and most elegant expression of nature and the highest achievement of the human intellect.

Fifty-five years after Einstein's death, the hunt for this elusive unified field theory continues. To physicist Stephen Hawking and many others, finding the "theory of everything" would be equivalent to knowing the "mind of God". The metaphor is not accidental.

Could an untidy universe have helped complex life emerge? (Image: NASA/ESA)

Modern critics say that Einstein and other giants of 20th-century physics (including Wolfgang Pauli, Erwin Schrödinger and Werner Heisenberg) failed because their models didn't include all particles of matter and their fundamental interactions. Factor them in, they argue, and we stand a much better chance of success. Dreams of a final theory (as a book on the subject, by Nobel laureate Steven Weinberg, was titled) live on, stronger than ever.

But are we really getting any closer? Do we dare ask whether the search is fundamentally misguided? Could belief in a physical theory that unifies the secrets of the material world - a "hidden code" of nature - be the scientific equivalent of the religious belief in oneness held by the billions who go to churches, mosques and synagogues every day?

Even before what we now call physics existed, ancient Greek philosophers pondered whether the diversity of nature could radiate from a single source, a primal substance. Thales, regarded by Aristotle as the first philosopher in the Greek tradition, proposed that everything was made of water, a substance he believed represented nature's dynamic essence. Later, Pythagoras and his followers believed that nature was a mathematical puzzle, constructed through ratios and patterns that combine integers, and that geometry was the key to deciphering it.

The idea of mathematics as a fundamental gateway to nature's secrets re-emerged during the late Renaissance. Galileo Galilei, René Descartes, Johannes Kepler and Isaac Newton made it clear that the mathematical description of nature succeeds only through the painstaking application of the scientific method, where hypotheses are tested by experiments and observations and then accepted or rejected. Physics became the science of the "how", leaving the "why" for philosophy and religion. When Newton was asked why matter attracts matter with a strength that weakens with the square of the distance, he answered that he "feigned no hypotheses"; it was enough to provide a quantitative description of the phenomenon.

That, however, is only half the story. To Newton, God was the supreme mathematician and the mathematical laws of nature were Creation's blueprint. As science advanced, the notion that god interfered explicitly with natural phenomena faded away, but not the idea that nature's hidden code lay in an all-encompassing mathematical theory. Einstein's "God" was far removed from Newton's, as he famously said: "I believe in Spinoza's God who reveals himself in the orderly harmony of what exists." His search for a unified field theory was very much a search for the essence of this natural god.

Modern incarnations of unified field theories come in two flavours. The more traditional version, the so-called Grand Unified Theory (GUT), seeks to describe electromagnetism and the weak and strong nuclear forces as a single force. The first of these theories was proposed in 1974 by Howard Georgi, of Harvard University, and Sheldon Glashow, now at Boston University. The more ambitious version seeks to include gravity in the unification framework. Superstring theory tries to do this by abandoning the age-old paradigm that matter is made of small, indivisible blocks, substituting them with vibrating strings that live in higher-dimensional spaces.

Like all good physical theories, GUTs make predictions. One is that the proton, the particle that inhabits all atomic nuclei, is unstable. For decades, experiments of increasing sensitivity have looked for decaying protons and failed to find them. As a consequence, the models have been tweaked so that protons decay so rarely as to be outside the current reach of detection. Another prediction fared no better: bundled-up interacting fields called magnetic monopoles have never been found.

Read more here/Leia mais aqui: New Scientist



O Mysterium tremendum continua Mysterium tremendum per omnia seculum seculorum!!!

Eu acho que Hashem tem um grande senso de humor, não sei por que, mas parece que tem...

E essa turma torra o nosso dinheirinho suado dos impostos correndo atrás do vento...

Ah, ia me esquecendo, mas é muita arrogância do Marcelo Gleiser 'pontificar' que este universo é imperfeito. Como é que ele sabe disso? Isso não é ciência, e este moço, a cada dia que passa, está mais para metafísico do que cientista. E ainda tem plateia...

Fui, feliz pra cacete, depois desta alfinetada em um ateu que se recusa sair do armário...