Imagining Other Earths

Einstein’s theory of General Relativity tells us that mass curves space and deflects light. Thus, observations of light deflection can tell us about the distribution of mass. Microlensing observations use this effect to detect planets around distant stars. We discuss how these observations have shown us that planets are as common as stars and imply the existence of “orphan planets”, planets that were ejected by their Suns and are now wandering the Galaxy.

Stars are remarkably simple objects: their mass and age determine the basic properties. This lecture discusses how we determine the distance and luminosity of stars and how this relates to the Star’s size and temperature.

This lecture introduces the Pauli exclusion principle, which requires that only one electron can be in any state. We use this principle to understand the properties of materials and the atomic lines seen in planetary and stellar structure.

This lecture introduces the basic of optics, explains how lenses and telescopes work, and then discusses the challenges of imaging planets around bright stars.

This lecture discusses the building blocks of life. We focus first on the importance of water as a medium for life and then discuss how amino acids are the building blocks of complex proteins. We then discuss the role of RNA and DNA in reproduction and protein synthesis.

This lecture describes our efforts to understand the origin of life on Earth. While it is relatively easy to synthesize amino acids, we do not yet understand how this building blocks are assembled into complex cells. The lecture ends with an exploration of the speculation that life originated outside Earth.

The basic principles of evolution (selection, mutation, and heritability) do not depend on the details of biochemistry. Thus, we can expect evolutionary principles to apply in extrasolar life. We discuss the role of sex in evolution and discuss how we can use the Tree of Life to study life’s origins.

There have been at least 5 mass extinctions in the Earth’s history. These extinctions were events that wiped out most of life on the planet and drove a large fraction of all life forms into extinction in a very short period of time. The most famous of these extinctions “killed’” the dinosaurs when an asteroid hit the Yucatan. We are in the midst of the sixth extinction due to human induced changes in the environment.

This lecture discusses some of the requirements for habitability. We discuss the faint Sun problem—the ancient Sun was much colder yet the Earth was still habitable and discuss the range of planetary systems that might be able to host life. We conclude by describing plans to use the James Webb Space Telescope, the successor to the Hubble Telescope, to find signs of life.