New way to calculate probability of intelligent alien life in universe

By Stephen Beech

Scientists are working on an accurate way of calculating the probability of finding alien life elsewhere in the universe.

Astrophysicists have developed a theoretical model that could be used to estimate how likely it is for intelligent life to emerge on other planets.

American astronomer Dr. Frank Drake came up with an equation in the 1960s to calculate the number of detectable extraterrestrial civilizations in our Milky Way galaxy.

Now, more than 60 years on, researchers led by Durham University’s Institute for Computational Cosmology, have produced a new model based on the conditions created by the acceleration of the universe’s expansion and the amount of stars formed instead.

It is believed that the expansion is being driven by a mysterious form of energy - called "dark energy" - that permeates space and makes up over two-thirds of the universe.

The new research, published in the journal Monthly Notices of the Royal Astronomical Society, has calculated the fraction of ordinary matter converted into stars over the entire history of the universe, for different dark energy densities.

The model predicts that fraction would be around 27% in a universe that is most efficient at forming stars, compared to 23% in our universe.

Scientists say the model could allow them to understand the effects of differing densities of dark energy on the formation of structures in the universe and the conditions for life to develop in the cosmos.

It also takes into account the fact alien lifeforms may develop deep into the future that do not currently exist.

Lead researcher Dr. Daniele Sorini, of the Institute for Computational Cosmology, Durham University, said: “Understanding dark energy and its impact on our universe is one of the biggest challenges in cosmology and fundamental physics.

“The parameters that govern our universe, including the density of dark energy, could explain our own existence.

“Surprisingly, though, we found that even a significantly higher dark energy density would still be compatible with life, suggesting we may not live in the most likely of universes.”

Dr. Sorini says that at present, there is no satisfactory explanation of what dark energy is and of its abundance in the universe.

He explained that dark energy makes the universe expand faster, balancing gravity’s pull and creating a universe where both expansion and structure formation are possible.

However, for life to develop, there would need to be regions where matter can clump together to form stars and planets, and it would need to remain stable for billions of years to allow life to evolve.

Since stars are a precondition for the emergence of life as we know it, Dr Sorini says the new calculation could be used to estimate the probability of generating intelligent life in our universe and in a multiverse scenario of hypothetical different universes.

The study suggests that the astrophysics of star formation and the evolution of the large-scale structure of the universe combine in a "subtle" way to determine the optimal value of the dark energy density needed for the generation of intelligent life.

The new research does not attempt to calculate the absolute number of "observers" - i.e. intelligent life - in the universe, but instead considers the relative probability of a randomly chosen observer inhabiting a universe with particular properties.

It concludes that a typical observer would expect to experience a "substantially larger" density of dark energy than is seen in our own universe – suggesting the ingredients it possesses make it a rare and unusual case in the multiverse.

The research also involved scientists at the University of Edinburgh and the University of Geneva in Switzerland.

Study co-author Professor Lucas Lombriser, of the University of Geneva, said: “It will be exciting to employ the model to explore the emergence of life across different universes and see whether some fundamental questions we ask ourselves about our own universe must be reinterpreted.”

Dr. Sorini added: "I cannot give you a number or a percentage chance of finding intelligent life at this stage as the model is just one step in the process.

"We should be able to give a more accurate figure in the future.

"We are not restricting on when life could emerge past, present or future.

"It could be that many lifeforms could emerge much later in the life of the universe."