Are we living in a multiverse? - Anthony Aguirre (SETI Talks) (by setiinstitute)
SETI Talks Archive: http://seti.org/talks
About a decade ago, we completed an epochal transformation in the understanding of our cosmos, unraveling a broad and deep understanding of how the observable universe has evolved from a hot, dense state 13.7 billion years ago. Yet a second, even bigger transformation may now be taking place, because this understanding points to a crucial early epoch of “inflationary” cosmic expansion, during which it expanded at a stupendous rate to create the vast amount of space we can observe. But cosmologists are coming to believe that inflation may do much more: in many versions, inflation goes on forever, generating not just our observable universe but also infinitely many more such regions with similar or different properties, together forming a staggeringly complex and vast “multiverse”. Dr. Aguirre will trace the genesis of this idea, explore some of its implications, and discuss how cosmologists are currently seeking ways to empirically test this idea by actually searching for hints of other “universes”.
Molecular Survival in Extreme Environments - Oana Marcu (SETI Talks) (by setiinstitute)
SETI Talks archive: http://seti.org/talks
A limiting factor for the survival of life in a changing environment is the intracellular production of reactive oxygen species. These can damage the building blocks of life (DNA, proteins, lipids) through oxidation. All organisms, including microbial extremophiles, have developed mechanisms to quench the reactivity of oxygen species or avoid their production. Not surprisingly, these same molecules are drivers for evolution. This talk will discuss the problem of oxygen toxicity, the solutions that life evolved, and will highlight lessons from the synchrotron in understanding the importance of intracellular oxidation for space biology and astrobiology.
Companions to Solar-type Stars - Tristan Guillot (SETI Talks) (by setiinstitute)
SETI Talks Archive: http://seti.org/talks
Although they are relatively frequent as free-floating objects, brown dwarfs are scarcely found as companions to solar-type stars. The paucity of brown dwarfs in close-orbits first noticed by radial velocity surveys has led to the concept of the “brown dwarf desert”.
Dr. Guillot will show that this desert concerns in fact close companions with masses larger than about 3 Jupiter masses orbiting G-type stars. On the other hand, photometric surveys have shown that in fact F-type stars do possess close-in, massive companions. Dr. Guillot will show that this is explained by the loss of an initial population of close-in massive giant planets and brown dwarfs due to tidal interactions: Because stars orbit less rapidly than their close-in companions, the tide raised on the star causes the companion to loose angular momentum and spiral in. The effect is much more pronounced around G-type stars because of a larger magnetic braking and because of increased dissipation, probably by internal gravity waves.
Dr. Guillot will use statistical methods to compare observations and model results and derive constraints on the tidal dissipation in stars as a function of their interior properties. This provides a powerful way to analyze the population of exoplanets and tie present observations with initial conditions at the time of the formation of these systems.
Contact with ET using Math? Not so fast. - Keith Devlin (SETI Talks) (by setiinstitute)
It is often said that mathematics is a universal language that we could use to make contact with another intelligence. But is that really the case? Or is this just a disguised version of anthropocentrism?
Dr Keith Devlin has written 31 mathematics books and over 80 published research articles. He is the recipient of the Pythagoras Prize, the Peano Prize, the Carl Sagan Award, and the Joint Policy Board for Mathematics Communications Award. In 2003, he was recognized by the California State Assembly for his “innovative work and longtime service in the field of mathematics and its relation to logic and linguistics.” He is “the Math Guy” on National Public Radio (For more information see http://profkeithdevlin.com).