SETI Institute Weekly Colloquium - Upcoming Speakers

Dr. Nesbet will describe (in layman's terms) implications of a theory that differs from standard particle physics and cosmology only by imposing a universal symmetry principle. This theory has been found to explain dark energy and dark galactic halos without invoking dark matter. Subgalactic phenomenology (relevant to our solar system) is retained.

The model postulates that strict conformal symmetry (local Weyl scaling covariance), already satisfied by standard fermion and gauge boson theory, can be extended to all elementary massless fields. This modifies Einstein-Hilbert general relativity and the Higgs scalar field model. No new physical fields are introduced.

Dr. Nesbet will show that conformal gravity and a conformal Higgs model fit empirical data on galactic rotational velocities, galactic halos, and Hubble expansion including dark energy. By implication, dark matter is not needed for an isolated galaxy. This model appears to be a promising tool for understanding both cosmology and elementary particle physics.

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The NASA Mars Science Laboratory rover, Curiosity, has safely landed near a 35 km long dark dune field in Gale Crater on Mars. This dune field crosses the landing site from the NE to the SW and lies along Curiosity’s traverse to Aeolis Mons. Dr. Silvestro will present evidence of recent aeolian activity in the form of ripple and dune migration and further estimate wind directions within the dune field through analysis of ripple and dune morphologies and the Mars Regional Atmospheric Modeling System (MRAMS). He will show how constraints on the wind regime provide a unique opportunity to use ground measurements from MSL to test the accuracy of winds predicted from orbital data.

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Directly imaging exoplanets is both scientifically exciting but notoriously challenging. Scientifically, obtaining images of rocky planets in the habitable zones of stars is key to finding if and how life developed outside the solar system. Large-scale biological activity can modify the chemical composition of the planet's atmosphere and its surface properties, both of which can be studied by spectrophotometry. The measurement is however extremely challenging, as the planet light is considerably fainter that the host star's light, and the angular separation between the two objects is about 0.1 arcsecond or less.

Conventional imaging systems cannot overcome the high star to planet contrast, and unusual optics are required for imaging exoplanets. Dr. Guyon will describe such systems (coronagraphs) and the upcoming scientific opportunities associated with their deployment on ground-based telescopes and in space. He will show that ground-based extremely large telescopes (ELTs) will have the ability to directly image and spectroscopically characterize rocky planets in the habitable zones of nearby M-type stars, thus providing scientific evidence for (or against) the presence of life outside our solar system. Space telescopes operating in optical light are well suited to target Earth-like planets around Sun-like stars.

Dr. Guyon will also describe the PANOPTES (Panoptic Astronomical Networked OPtical observatory for Transiting Exoplanet Survey) project, aimed at supporting a world-wide network of small robotic digital cameras built by citizen scientists and schools to identify a large number of transiting exoplanets.

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Convection in the interiors of planetesimals (asteroids), planets, and satellites is driving the thermal and chemical evolution of these bodies including the generation of possible magnetic fields.  The wide size range induces a wide range of time scales from hundreds of thousands of years for small planetesimals to a few tens of Gigayears for massive super-Earths.

Dr Spohn will present a model that includes mantle convection, mantle water vapor degassing at mid-oceanic ridges and regassing through subduction zones, continental crust formation and erosion and water storage and transport in a porous oceanic crust that includes hydrous mineral phases.

Dr. Spohn will show how an abiotic world is predicted to have a much drier mantle than the present Earth but may have a similar surface coverage by continents. The reduced rate of continental crust production on the abiotic world would be balanced by a reduced rate of continent erosion. He will suggest that through the effect of water on the mantle rheology, the biotic world would tend to be tectonically more active and have a more rapid long-term carbon-silicate cycle.

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When Galileo Galilei pointed his telescope toward Jupiter in 1609 and discovered what we now call the Galilean moons, he did not realized that he had just established a new research field in astronomy. In the past four centuries, planetary astronomy, the study of our solar system bodies using telescopes, has increased our knowledge of the environment of Earth, the evolution of the planets, the origin of comets and asteroids and the formation of our solar system. Space exploration accelerated planetary astronomy in the 1960s by allowing planetary scientists to access in-situ and detailed data. In this talk, I will discuss the contributions of telescopic observation over the past 50 years to planetary science, particularly the recent developments like adaptive optics which renewed interest in ground-based observations of planets. I will explore the contribution of all-sky surveys like Pan-STARRS and LSST, which provide several terabytes of data a week, changing radically the way we do astronomy. Looking to the future of space-based astronomy, I will consider whether the James Webb Space Telescope and ATLAST are potential successors to the successful Hubble Space Telescope. Finally I'll explore the way in which specialized low-cost telescopes designed to search and study exoplanets, planets around other stars, constitutes a paradigm shift in our field.

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The past decade has seen an explosion of creativity and progress in radio astronomy telescopes and techniques.  In the coming decade, we will harvest the fruit of these innovations with a powerful new generation of radio telescopes that are coming on line.  These will open avenues for new science, in areas such as the epoch of reionization, synoptic surveys for radio transients, and exquisitely sensitive observations of the most distant objects in the Universe.

Dramatic improvements in digital instrumentation have been and will continue to be central to the advancement of the field.  But there has also been a resurgence of interest in many other areas including receiver technologies, antennas, optimized array configurations, remote site management, software, commensal observing modes, and algorithms. Considerable attention has been paid to manufacturability and array costs in order to address the prospects of optimizing array performance at costs exceeding $1B.  Telescope projects have also bifurcated into general facility instruments and targeted experiments, with significance consequences for their design and operation.

I will review the current state of the art for meter and centimeter wavelength telescopes.  Among the projects of note, I will discuss the SKA Technology Development Project, the Allen Telescope Array, MeerKAT, the Australian SKA Pathfinder (ASKAP), the Precision Array for Probing the Epoch of Reionization (PAPER), the Mileura Widefield Array (MWA), the LongWavelength Array (LWA), the Low Frequency Array (LOFAR), and SKA Phase 1.  I will also explore what telescope parameter space remains unexplored and where  new technical developments are required to make scientific progress. 

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If alien civilizations exist throughout the universe, many have had billions of years to develop technology, expand their population and energy supplies, and travel across their galaxies.  Kardashev classified hypothetical advanced civilizations by the magnitude of their power supply, with Type II civilizations harnessing most of the energy output of their host star, and Type III civilizations using most of the power in their galaxy.  As Dyson pointed out in 1960, the waste heat emitted by a such civilizations would easily overwhelm that of their host star or galaxy, distinguishing them from "normal" astrophysical sources.  This approach to SETI makes few assumptions about the behavior of alien civilizations, primarily: conservation of energy, the laws of thermodynamics, and that given the age of the Universe aliens have had time to develop very large energy supplies.

The WISE all-sky mid-infrared survey has dramatically improved our ability to detect such civilizations and to distinguish them from "natural" astrophysical sources.  I will discuss our team's efforts to identify candidate Type II civilizations in the Milky Way and Type III civilizations throughout the low-redshift universe.   Because the scope and assumptions of this approach are complementary to those of telecommunication SETI, a null result has the potential to rule out broad classes of proposed resolutions to the Fermi-Hart Paradox, particularly those that invoke organization of advanced alien species across the Milky Way.

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