Transcript: In terms of life beyond Earth and life beyond the solar system, what are the prospects? Astronomers have learned that long-lived stars, planets, and carbon chemistry seem to be universal phenomenon. We know that planets exist around many nearby stars. We know that carbon is readily produced by many stars throughout the Milky Way galaxy and in all the hundred billion galaxies beyond the Milky Way. In drawing conclusions from the history of life on Earth, scientists may surmise...

Transcript: In terms of our speculation about life in the universe, what can we conclude with all the information we have learned about the history of life on Earth. We have learned that life formed very early in extreme conditions. We’ve learned that carbon chemistry offers many different pathways for life processes. We’ve learned that the energy sources and chemical natures of life can be varied even though the biological basis of all organisms has a single common ancestor. We’ve...

Transcript: The Multiverse concept seeks to explain the unusual conditions in our universe by hypothesizing a multitude of universes with different physical properties. In only a tiny fraction of those universes are the physical conditions or the laws of nature suitable to the formation of stars and carbon and life, but is this falling into a logical trap? It’s called the inverse gambler’s fallacy. It says that rare or improbable events are more likely to occur somewhere or other in a long...

Transcript: Scientists tend to think in traditional and anthropocentric ways about the possibilities of life in the universe. The Drake equation is a deductive framework, the multiplication sequentially of several probabilities. It works in terms of the possibility of Sun-like stars and Earth-like planets around those stars, under a premise of carbon chemistry, and a strong assumption that intelligence and technology are related to communication through space, but we should think...

Transcript: Chaotic inflation and the concept of the multiverse are an extraordinary potential insight into our role in the universe. These theories say that at the time of quantum genesis, only one space time seed inflated to become the large and old universe that we live in. Many other possible space time fluctuations could have lead to other universes with physical properties utterly different from ours. However, in the huge range of possible physical properties or laws of nature, only...

Transcript: The anthropic principle can be connected to modern cosmological theories in a fascinating way. In current big bang theories, the universe had a quantum genesis. It emerged from a tiny seed of space-time, much smaller than the nucleus of an atom. This was called the Planck era, when the four forces of nature melted together. The birth of the universe was a quantum fluctuation event that led to a rapid expansion and inflation to the universe as large and old as we see now. ...

Transcript: The cosmological anthropic principle connects the existence of life in the universe to the global geometry of the universe. The universe we live in has a spatial geometry very close to flat, and has a matter density within a factor of three of the critical density at which the cosmic expansion is slowly decelerated over cosmic time. The universe could have any value of the mass density. For hypothetical universes with much larger values of the matter density, these universes...

Transcript: The anthropic principle has been and can be criticized on purely logical grounds. Obviously one of the grounds is the fact that it doesn’t necessarily make predictions. It just seeks to retroactively explain why the universe has properties that would allow life to exist. It’s subject to a more fundamental fallacy as well called the observer’s fallacy. The first point, people should not be surprised that they do not observe features of the universe which are incompatible with...

Transcript: The weak form of the anthropic principle in essence states that we can only live in a universe that has the properties such that we can exist. In other words, we can only exist in the universe and should not be surprised that the universe has the properties to allow long-lived stars to exist and carbon to have been created. This sounds like a truism or a tautology, but the anthropic principle elevates it to a level of a scientific theory with hopefully predictive powers. It may...

Transcript: The strong version of the anthropic principle in essence states that the observed values of physical and cosmological quantities are not accidents but are connected somehow with our existence as observers of the universe. The universe was built for us. This sounds like an extraordinary statement, yet at the level of microscopic physics there is a clear tradition in quantum mechanics of a relationship between the observer and the thing being observed. Our best microscopic...

Transcript: When astronomers and physicists are trying to explain coincidences in nature with the anthropic principle they must be aware of a fundamental argument in the field of philosophy. It’s called the argument from design, and it was best put in this quote by Bertrand Russell. “You all know the argument from design. Everything in the world is made just so that we can manage to live in the world, and if the world were ever so little different, we could not manage to live in it. This...

Transcript: Miss Marbles, Agatha Christie’s fictional detective hero once said, “A coincidence is always worth noticing. You can always discard it later if it proves to be only a coincidence.” What are we to make of the coincidences that exist in nature, by which we mean not any coincidence but coincidences of physical constants or fundamental properties of matter that seem to be conducive to the creation of chemistry, biology, and life itself? It’s hard to know what to do with this...

Transcript: The existence of life in the universe also depends fairly sensitively on the ratios of certain fundamental particle masses. If the ratio of the proton to the neutron mass was not approximately one, in the early big bang the fusion processes would have created almost all neutrons or all almost protons, with the result being that there could have been no stable nucleides and no chemistry, and therefore no biology. If the proton to electron ratio were not roughly as large as it is,...

Transcript: The existence of life in the universe is also very sensitive to the electromagnetic force and its absolute strength. If the electromagnetic force were slightly stronger than it is now, stellar luminosities would be sharply lower then they are in the present day universe. Stars would be too cold to have any kind of extensive habitable zones, and no elements beyond iron would have been created in the history of the universe. If the electromagnetic force were much weaker than it...

Transcript: As examples of fine tuning in nature, consider the strength of the nuclear forces that hold the atom and the nucleus together. If the weak nuclear force were much stronger than it is, the big bang would have cooked all the hydrogen into helium rather than just a fraction of it with the result that in the present day universe there could be no water and no long-lived stable stars. If the weak nuclear force had been much weaker, early neutrons would not decay into protons and...

Transcript: Nature exhibits certain coincidences that physical scientists have to take note of. Even if the physical laws of nature are described by an as yet unknown fundamental physical theory, we have to be able to understand why the forces of nature are the way they are, why they masses of fundamental particles are the way they are. Normally, this would not be a cause for interest when considering life in the universe, but it turns out that many of the physical properties of the...

Transcript: The anthropic principle is an extraordinary idea that is somewhat controversial even amongst scientists. It’s possible that the existence of life in the universe is not an accident, that the role of life in the universe is more central than we might imagine. The anthropic principle postulates that the presence of life in the universe is intimately connected with the properties and structure of the universe itself. There are several forms of the principle. The weak form of the...

Transcript: Why do people so strongly believe in aliens despite no evidence for their existence? When Orson Wells’ radio War of the Worlds episode was broadcast, it caused widespread panic on the east coast because people were ready to believe that Martians could attack us. When Star Wars and Star Trek and the X-Files moved from the status of simple movies or TV shows to widespread cultural phenomena, it’s because the idea of aliens resonates with something deep in our psyche. The idea of...

Transcript: It may or may not be reassuring to know that SETI researchers have protocols in place for what to do if we finally detect evidence of intelligent aliens in space. Protocols have been set up to contact the United Nations and the world leaders and to avoid the widespread panic that might ensue. The truth is, we have no idea of the likelihood of SETI experiments being successful. We are compelled to do such experiments, and almost all that we know is that the idea and the reality...

Transcript: While scientists conduct, on a modest scale, the search for extraterrestrial intelligence, a significant number of people think we already know the answer. The majority of the American public believes that UFOs exist, that contact has already been made with aliens, that perhaps the government is hiding such information from us. Also, many people believe that there are biblical references to aliens or that alien visitations are encoded in many ancient human cultural artifacts...

Transcript: The issue of what message to send if we want to communicate with extraterrestrial intelligences is a very interesting one. If the message is too simple, it may be understood but will convey little information. If it’s too complex, it can carry more information, but it’s unlikely to be able to be decoded. So we must avoid anthropocentric thinking. Most of the previous experiments, the Pioneer plaque, the Voyager record, even the Arecibo message, are highly anthropocentric...

Transcript: As a follow up to the Pioneer Plaque, the Voyager 1 and 2 spacecraft, which have also left the solar system, carried a phonograph record, a twelve-inch gold disc containing samples of the world’s music, spoken greetings in many of the world’s languages, and images of various kinds digitized and placed on the record. The arbitrary selection of musical choices was of course the selection of a small set of people. Some people might argue. For instance, the record was made before...

Transcript: The first message to leave the solar system from humans towards aliens was attached to the leg of the Pioneer 10 spacecraft. It was a plaque designed, amongst others, by Carl Sagan and Frank Drake. This gold plaque contained graphics indicating aspects of human culture and indicating their intelligence. There were two naked human silhouettes, a map of the solar system showing the path of the Pioneer spacecraft, a schematic of the hydrogen molecule, a silhouette of the...

Transcript: Rather than simply theorize or speculate, astronomers have been conducting modest experiments in interstellar communication. One of the first and most famous was done in 1974 using the Arecibo Radio Telescope, a thousand-foot radio dish in Puerto Rico. A pulsed set of messages was sent out sequentially to the M13 globular cluster. The sequence of signals consisted of one thousand six hundred and seventy-nine bits of information, that is on-off radio pulses. An intelligent...

Transcript: If we want to communicate through interstellar space with intelligent civilizations, we’ll have to decide on what message we want to send and how to code it. This is highly complex. How do we turn a subtle and complicated idea into a simple set of signals or bits of information? We have to reduce complexity to simple form, ones and zeroes, on and off, light and dark. This is a difficult process. We presume that a successful SETI signal will have to be pulsed to distinguish it...