St. Mary’s Physics professor and department chair Charles Adler used the physical laws of nature to predict the future of Earth and humanity in his talk The World of the Future: Physics as the Art of the Possible. The lecture was the fourth Natural Science and Mathematics Colloquium of the semester.
Adler presented the colloquium, also the 2010 Steven Muller Lecture, to an audience-packed Daugherty-Palmer Commons at 7 p.m. on Feb. 24, following an introduction by College professor and Chemistry department chair Andrew Koch. “The first NS&M lecture [of the semester] pointed out that what I am doing is very foolish,” said Adler, “[but] the laws of physics do allow us to speculate about big-picture things.”
Adler introduced the lecture by discussing the idea of Sagan problems, named after astrophysicist and author Carl Sagan by theoretical physicist Kip Thorne. Sagan problems are “speculations about what the laws of physics ultimately allow,” said Adler. The lecture focused on three Sagan-like ideas that attempt to predict the future of humanity and the world using the laws of physics.
The first idea, titled “RUR or RU Ain’t Smart,” focused on the next twenty years of world’s history, when computers will be able to out-process the human mind. Computers “think” using a system of semiconductors known as transistor gates, which switch electrical signals and work as a system of logical operations. While computers can only conduct one logical operation at a time, they can do so very quickly, reaching a rate of roughly one to 10 billion times per second.
The human brain also processes the equivalent of logical operations in its 100 billion-neuron system. Human minds can process multiple logical operations at once (parallel processing), but only at a rate of 10-100 operations per second. The multiple integrations of these neurons, however, leads to an overall computing power of 20,000 trillion operations per second. “Brains are not much like computers,” said Adler.
Computers are beginning to reach a similar processing speed, and based on the 1,000-trillion operations/second processing speed of the 100,000-processor network in the Large Hadran Collider, it may be only ten years before computers surpass the human brain. This may, however, be limited by transistor gate thickness, or enhanced by atomic processing units and the Margolus-Levitin theorem, which sets the limit of processing units to 6 x 10^33 operations per second per Joule of energy.
“[Computers] are going to out-compute us in the near future based on the relative processing speeds of human brains versus supercomputer clusters,” said Adler.
Adler’s second idea, “ET Phones Home?” is a prediction for 2,000-one million years from today, the human race will find life on other planets, or that other life forms will contact humans. Currently, technology is limited to only being able to detect potential carbon-based life-supporting planets within the solar system. “If current trends keep going, we will be able to detect Earth-like planets circling other stars within the next 20 years or so,” said Adler.
One of the biggest obstacles, however, is the distance from other stars that may support life. The closest star to Earth, Alpha-Centauri, is four light years away, a distance that would require an amount of energy equivalent to how much the United States uses in ten years and would take eight years or more to traverse. While radio signals would be less expensive and a more efficient means of communication, it could take years for the signals to travel from Earth to that planet, which would need a means of radio wave communication. For now, technology does not permit the detection of life that may still take thousands and thousands of years to develop and advance to a level of communication.
“The end of the world” marked Adler’s final prediction of the future, in which the world and humanity would reach the finish line. With the threats of global warming, nuclear war, and energy crises, the human race may see its end within a few centuries. If not, however, the return of ice glaciers and the loss of agriculture could cause humanity to become extinct within 10,000-20,000 years. Even later, humanity would experience a fatal loss of plant life and sunlight within 100 million years if a meteor crashes into the planet, creating a dust storm in the stratosphere similar to what killed the dinosaurs.
“If we survive that,” said Adler, “in five billion years, the hydrogen in the Sun’s core is going to get used up. When it does that, the Sun is going to swell up, get redder, and emit more heat…and at that point, Earth will no longer be in an inhabitable zone around its star.”
However, if humanity survives the Sun burning out, all of the stars will die in one trillion years, removing a major heat source from the universe. Once this point is reached, if the human race is still alive, black holes are the only remaining energy source. Massive ones could be used for about 10^94 years before the universe’s black holes would evaporate, at which point life would be predictably impossible.
Adler encouraged his audience to think about these predictions when he concluded the lecture. “It’s fun thinking about these sorts of things,” he said. “Think big, but obey the laws of physics, too.”
“I am a biology major, but what’s nice about the colloquia is that they cover a wide range of science topics and therefore can appeal to all kinds of interests,” said Gabrielle Cantor, a sophomore who attended the lecture. “Dr. Adler’s breakdown of the likelihood of contacting other planets was extremely interesting.”
“Dr Adler has a wonderful way of addressing some of the most profound questions with simple logic and ordinary observations,” said Koch. “I think it is fantastic that he has the ability to share his understanding of physics in such a broad manner that reaches both nonscientists and scientists alike.”
The next lecture of the NS&M Colloquium Series, Developmentally Regulated Alternative Splicing and its Disruption in Neuromuscular Disease, will be presented by Baylor College of Medicine professor Thomas Cooper, and will be held on Mar. 10 at 4:40 p.m. in Schaefer Hall.