Study reveals life in the universe could be common, but not in our neighborhood

To help answer one of the great existential questions - how did life begin? - a new study combines biological and cosmological supercomputer models. Professor Tomonori Totani from the Department of Astronomy looked at how life's building blocks could spontaneously form in the universe - a process known as abiogenesis. 

If there's one thing in the universe that is certain, it's that life exists. It must have begun at some point in time, somewhere. But despite all we know from biology and physics, the exact details about how and when life began, and also whether it began elsewhere, are largely speculative. This enticing omission from our collective knowledge has set many curious scientists on a journey to uncover some new detail which might shed light on existence itself. 

{module INSIDE STORY} As the only life we know of is based on Earth, studies on life's origins are limited to the specific conditions we find here. Therefore, most research in this area looks at the most basic components common to all known living things: ribonucleic acid, or RNA. This is a far simpler and more essential molecule than the more famous deoxyribonucleic acid, or DNA, that defines how we are put together. But RNA is still orders of magnitude more complex than the kinds of chemicals one tends to find floating around in space or stuck to the face of a lifeless planet.

RNA is a polymer, meaning it is made of chemical chains, in this case known as nucleotides. Researchers in this field have reason to believe that RNA no less than 40 to 100 nucleotides long is necessary for the self-replicating behavior required for life to exist. Given sufficient time, nucleotides can spontaneously connect to form RNA given the right chemical conditions. But current estimates suggest that magic number of 40 to 100 nucleotides should not have been possible in the volume of space we consider the observable universe.

"However, there is more to the universe than the observable," said Totani. "In contemporary cosmology, it is agreed the universe underwent a period of rapid inflation producing a vast region of expansion beyond the horizon of what we can directly observe. Factoring this greater volume into models of abiogenesis hugely increases the chances of life occuring."

Indeed, the observable universe contains about 10 sextillion (10^22) stars. Statistically speaking, the matter in such a volume should only be able to produce RNA of about 20 nucleotides. But it's calculated that, thanks to rapid inflation, the universe may contain more than 1 googol (10^100) stars, and if this is the case then more complex, life-sustaining RNA structures are more than just probable, they're practically inevitable.

"Like many in this field of research, I am driven by curiosity and by big questions," said Totani. "Combining my recent investigation into RNA chemistry with my long history of cosmology leads me to realize there is a plausible way the universe must have gone from an abiotic (lifeless) state to a biotic one. It's an exciting thought and I hope research can build on this to uncover the origins of life."

U.S. Army game-theory research using artificial intelligence may help treat cancer and other diseases, improve cybersecurity, deploy Soldiers and assets more efficiently and even win a poker game.

New research, published in Science, and conducted by scientists at Carnegie Mellon University, developed an artificial intelligence program called Pluribus that defeated leading professionals in six-player no-limit Texas hold'em poker.

The Army and National Science Foundation funded the mathematics modeling portion of the research, while funding from Facebook was specific to the poker. {module In-article}

"It's all about strategy," said Dr. Purush Iyer, division chief, network sciences at the Army Research Office, an element of the U.S. Army Combat Capabilities Development Command's Army Research Laboratory. "A limiting factor in game theory has always been scalability (i.e., ability to deal with exponentially increasing state space). Poker is an accessible example to show how these mathematical models can be used to devise strategies for situations where a person doesn't have complete information - they don't know what the adversaries will do, and what their capabilities are."

This research is extremely relevant to many real-world and military challenges that involve multiple parties such as cybersecurity and defense posturing, he said.

Poker has been an AI challenge because it is an incomplete information game, where players cannot be certain which cards are in play and opponents can, and will, bluff, much like military strategy.

"Thus far, superhuman AI milestones in strategic reasoning have been limited to two-party competition," said Dr. Tuomas Sandholm, Angel Jordan Professor of Computer Science, who developed Pluribus with Noam Brown, who is finishing his doctorate in Carnegie Mellon's Computer Science Department as a research scientist at Facebook AI. "The ability to beat five other players in such a complicated game opens up new opportunities to use AI to solve a wide variety of real-world problems."

"Playing a six-player game rather than head-to-head requires fundamental changes in how the AI develops its playing strategy," said Brown, who joined Facebook AI last year.

Pluribus dispenses with theoretical guarantees of success and nevertheless develops strategies that enable it to consistently outplay opponents. Pluribus first computes a blueprint strategy by playing six copies of itself, which is sufficient for the first round of betting. From that point on, Pluribus does a more detailed search of possible moves in a finer-grained abstraction of game. It looks ahead several moves as it does so, but not requiring looking ahead all the way to the end of the game, which would be computationally prohibitive. Limited-lookahead search is a standard approach in perfect-information games, but is extremely challenging in imperfect-information games. A new limited-lookahead search algorithm is the main breakthrough that enabled Pluribus to achieve superhuman multi-player poker.

The software also seeks to be unpredictable. For instance, betting would make sense if the AI held the best possible hand, but if the AI bets only when it has the best hand, opponents will quickly catch on. So Pluribus calculates how it would act with every possible hand it could hold and then computes a strategy that is balanced across all of those possibilities.

With Army funding, Sandholm and some of his other students are developing related techniques for bio-steering, where the researchers are computing optimal treatment plans that steer a patient's immune system to better fight cancers, autoimmune diseases, infections, etc.

Previous Army-funded game theory research is now being used by the Transportation Security Administration, the U.S. Coast Guard and the Los Angeles Metro Rail to schedule resources in a manner that decreases cost for the those organizations ensuring safety while increasing the costs for an adversary, thus reducing the chances for attacks.

Furthermore, Army-funded foundational research in algorithmic game theory has been used in civil society to reduce poaching of elephants in Queen Elizabeth Forest, Uganda, and tigers in Southeast Asia, as well as in addressing homelessness and implementing HIV-prevention campaigns in Los Angeles.

"The research work of Dr. Sandholm and others will be used in a variety of ways in the not-too-distant future to address societal problems in a cost-effective manner," Iyer said. "Dr. Sandholm's work is an exciting advance in game-theory; the applications are enormous."

The CCDC Army Research Laboratory (ARL) is an element of the U.S. Army Combat Capabilities Development Command. As the Army's corporate research laboratory, ARL discovers, innovates and transitions science and technology to ensure dominant strategic land power. Through collaboration across the command's core technical competencies, CCDC leads in the discovery, development and delivery of the technology-based capabilities required to make Soldiers more lethal to win our Nation's wars and come home safely. CCDC is a major subordinate command of the U.S. Army Futures Command.