Are we alone?
Read our article "How to find ET with infrared light" in the June 2013 issue of the Astronomy magazine.
Watch the public talk on the Fermi paradox and the Colossus by Dr. Jeff Kuhn on YouTube
The detection of an extraterrestrial civilization (ETC), even without further communication, is important in many gnostic and practical aspects. For instance, one of the current burning issues for our civilization is surviving global climate changes because of increasing power generation. Detecting more advanced civilizations will demonstrate a fundamental possibility that civilization can achieve a phase of sustainable global-scale power consumption.
For a half-century we have sought radio frequency evidence and, more recently, optical communications of ETCs. However, these approaches depend on finding alien transmissions, beam "leakage", or what could be called intentional electromagnetic signals from ETCs that are operating cosmic beacons.
The Colossus will employ a strategy for detecting an unintentional signal caused by alien planetary warming. Thanks to its large aperture and unique coronographic properties, it will be capable of detecting the thermodynamic signal from Earth-like ETC's within an interestingly large cosmic volume. The outcome of such a dual wavelength, visible-IR, search will be largely independent of alien communication modes and will have quantifiable statistical completeness. Even a null result will help us understand the Fermi paradox, "why do we appear to be alone?"
Detecting an ETC signal is possible with current technology but requires a telescope and sensitive detector that can measure the planet's thermal flux and its reflected optical light, while distinguishing these from the star's scattered light and the terrestrial thermal noise background. Glare from the central star comes from the terrestrial atmosphere's distorting effect on the optical wavefront and from diffraction due to telescope optics. Suppressing this noise requires highly accurate adaptive optics (AO) and a coronagraph system. These requirements are implemented in the Colossus design. We will be able to see advanced civilization heat pattern as can be seen in night lights on the Earth from space (Fig. 1.1).
Figure 1.1. The Earth at night seen from space (NASA). The Colossus will be able to detect similar patterns of advance civilization heat islands.