Eternity

A conversation with Nikos Prantzos

When trying to convey the feeling of eternity Nikos Prantzos likes to quote an ancient Nordic myth. “In a distant country stands an enormous rock in the shape of a cube, each of its sides measuring one hundred kilometers. Once every ten thousand years a small bird flies over the rock and for a few moments rubs its beak on it. When the rock has disappeared, completely worn away by the rubbing of the beak, one day in eternity will have completed.” Prantzos has calculated how long this will take; 10³⁰ years (1 with 30 zeros following). But as the future of our universe goes, this mind-bending timescale is but a mere moment. Protons, the subatomic particles at the nuclei of every chemical element will disappear in 10³³ years. Black holes, having gulped whatever remaining matter, will evaporate too in 10⁶⁶ years. For an astrophysicist such as Prantzos the cosmological future is eternity raised to the power of eternity many times over.

Born in Volos in 1956 Prantzos is one of the most prominent European astrophysicists. Currently a Director of Research the Astrophysical Institute in Paris and a professor at University Paris VI, he sits on the editorial boards of several significant scientific journals, and consults the European Space Agency. His main scientific interests focus on the evolution of the universe, and he has published pioneering work in the investigation of the natural processes that take place inside stars and galaxies. He is also passionate about communicating his science to the wider public. His popular science book “Voyages in the future” has been awarded the Jean Rostand prize in France, and has been translated in a number of languages, including English and Greek. In it he tackles a major philosophical dilemma that has troubled western thinkers ever since the nineteenth century, when scientists realized that the corollary of thermodynamics was the ultimate “heat death” of the universe. “Twelve years ago”, adds Prantzos, “astronomers discovered that the expansion of the Universe became more rapid in the past few billion years. If this accelerated expansion of the Universe continues in the far future all stars will run out of energy and die. Matter will ultimately decay to elementary particles and radiation, which will be diluted in a vast and cold space.”

So since the universe is destined to end with a pathetic whimper, what could be the meaning of life? If the ultimate future is dark nothingness, why bother with anything? “The vastness of the timescales involved,” says Prantzos, “is such that it leaves plenty of time to us - or to any future civilization - to consider and construct not one but literally millions of interesting futures. Along the way, meaning and purpose will be redefined time and again”.

Of course, in an ever expanding Universe, with temperatures dropping everywhere to nearly absolute zero and matter decaying into elementary particles and diluted radiation, indefinite survival appears impossible. And this is true not only for biological creatures such as us made of flesh and blood, but also of robots made of bolts and nuts. Nevertheless, Prantzos is agnostically optimistic. He contends that one should not forget that our present understanding of the Universe, based on the physics of the 20^th century, is incomplete. “New theories will certainly emerge in the decades and centuries to come, perhaps offering us different and more optimistic perspectives for the far future of intelligence in the Cosmos”.

And if we earthlings don’t manage to figure things out someone else might. Which brings in the centuries-old, and ever-fascinating, question of life and intelligence elsewhere in the Universe.

Science has firmly established that the laws of physics – and therefore chemistry - are the same everywhere in the Universe. However, even if biology is essentially chemistry, biological evolution depends on many unpredictable conditions: it was the disappearance of dinosaurs following an asteroid hitting Earth 65 million years ago that paved the way to mammals and thereof allowed the ascent of humans. Prantzos points out that evolution from bacteria towards high intelligence, and further on to a technological civilization, looks like an extremely improbable event. He is not the first to doubt the existence of ETs. In 1948, the famous Italian physicist Enrico Fermi highlighted the fact that no convincing trace of an extraterrestrial visit to Earth has ever been found, despite the fact that there are billions of stars much older than the Sun in our Galaxy. Pranztos notes that “Fermi interpreted that absence of evidence as evidence that civilizations undergo a nuclear holocaust just before mastering space travel.” He contends that if there were indeed hundreds of civilizations in our Galaxy, it is improbable that all of them blew up or failed to reach us for some reason. “We should therefore get familiar with the idea that we are probably alone in the Galaxy”, he adds. And yet he remains a supporter of SETI (The Search for Extraterrestrial Intelligence) who look for extraterrestrial signals from space. “Despite its small chances of success, the rewards would be enormous if a single such signal is ever detected”, he says.

Aliens may not be in Prantzos mind when he looks at the stars, but space travel is. As a young boy marveling at the night sky over the Pagasitikos Gulf and Mount Pelion, he dreamt of becoming an astronaut. Growing up in the 60s, with the Moon as humanity’s next frontier was inspiring to a whole generation of kids like he, and Prantzos regrets that young people today do not have that same opportunity. Today, although man conquered Moon after travelling 380,000 kilometres from Earth, no astronaut has gone further than 500 kilometres from our planet since 1972. “Progress has been terribly slow both because astronaut security is a more important and funding is considerably less,” he says. “The Cold War and the competition between United States and Soviet Union hastened progress in space matters enormously”.

What appeared an easy feat in the 60s looks much harder today. The harshness of space environment makes problematic all plans for long term exploration of space by humans. The construction of adequate protecting shelters in space will require considerable efforts and resources. Furthermore, access to space is very costly because of the gravitational attraction of our planet. Until today rockets, using chemical propulsion and design principles invented by the Chinese centuries ago, remain humanity’s only means to escape Earth. Prantzos hopes that a new generation of propulsion technologies, such as nuclear, ionic, antimatter, or solar sail pushed by Sun's radiation, will provide alternative and faster ways to visit our nearest worlds, such the Moon and Mars.

Prantzos is particularly fond of manned missions into space and a believer that investing in them is a sound decision for the future of humanity. “The situation of our planet obviously requires all of our attention today”, he says. “We should try to heal the wounds of Mother Earth before embarking to ambitious programs of space travel and colonization of space. However, this does not preclude a reasonable step-by-step, long term program of space exploration. Moon, Mars and the asteroids are the obvious targets of such a program, at least for the 21^st century. All major space agencies have interesting projects for those targets. I don’t think that funding issues are prohibitive. When compared to the cost of the Iraq war, or to the one of the recent financial crisis, the annual cost of a long-term project of human space exploration is substantially smaller”.

Published in the Athens News on May 15th