Biosignatures and the Search for Life on Earth

Vázquez, M.; Πάλλη, Ε.; Rodriguez, P. Montanes

doi:10.1007/978-1-4419-1684-6_5

Cited by 2 publications

(1 citation statement)

References 116 publications

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“…While any of these explanations might turn out to be true, given our current knowledge, it is reasonable to assume that intelligent life can exist on other star systems, and interstellar travel does not violate the laws of physics and can be assumed to be practicable [16]. One additional important consideration is that the Earth has distinguishing biosignatures of life (e.g., atmospheric oxygen, water and methane in extreme thermodynamic disequilibrium) that are detectable across large distances [17]. As such, even if star travel is expensive and dangerous, and even if there are many systems to explore, the Earth has had a unique biosignature for >2 billion years [18].…”

Section: Fermi's Paradox and Setimentioning

confidence: 99%

A direct communication proposal to test the Zoo Hypothesis

Magalhães

2016

Space Policy

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Whether we are alone in the universe is one of the greatest mysteries facing humankind. Given the >100 billion stars in our galaxy, many have argued that it is statistically unlikely that life, including intelligent life, has not emerged anywhere else. The lack of any sign of extraterrestrial intelligence, even though on a cosmic timescale extraterrestrial civilizations would have enough time to cross the galaxy, is known as Fermi's Paradox. One possible explanation for Fermi's Paradox is the Zoo Hypothesis which states that one or more extraterrestrial civilizations know of our existence and can reach us, but have chosen not to disturb us or even make their existence known to us. I propose here a proactive test of the Zoo Hypothesis. Specifically, I propose to send a message using television and radio channels to any extraterrestrial civilization(s) that might be listening and inviting them to respond. Even though I accept this is unlikely to be successful in the sense of resulting in a response from extraterrestrial intelligences, the possibility that extraterrestrial civilizations are monitoring us cannot be dismissed and my proposal is consistent with current scientific knowledge. Besides, issuing an invitation is technically feasible, cheap and safe, and few would deny the profound importance of establishing contact with one or more extraterrestrial intelligences. A website has been set up (http://active-seti.info) to encourage discussion of this proposal and for drafting the invitation message.Comment: 16 page

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Section: Fermi's Paradox and Setimentioning

confidence: 99%

A direct communication proposal to test the Zoo Hypothesis

Magalhães

2016

Space Policy

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The Habitability of Our Earth and Other Earths: Astrophysical, Geochemical, Geophysical, and Biological Limits on Planet Habitability

Lineweaver

Chopra

2012

Annu. Rev. Earth Planet. Sci.

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For life-forms like us, the most important feature of Earth is its habitability. Understanding habitability and using that knowledge to locate the nearest habitable planet may be crucial for our survival as a species. During the past decade, expectations that the universe could be filled with habitable planets have been bolstered by the increasingly large overlap between terrestrial environments known to harbor life and the variety of environments on newly detected rocky exoplanets. The inhabited and uninhabited regions on Earth tell us that temperature and the presence of water are the main constraints that can be used in a habitability classification scheme for rocky planets. Our compilation and review of recent exoplanet detections suggests that the fraction of stars with planets is ∼100%, and that the fraction with rocky planets may be comparably large. We review extensions to the circumstellar habitable zone (HZ), including an abiogenesis habitable zone and the galactic habitable zone.

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Biosignatures and the Search for Life on Earth

Cited by 2 publications

References 116 publications

A direct communication proposal to test the Zoo Hypothesis

A direct communication proposal to test the Zoo Hypothesis

The Habitability of Our Earth and Other Earths: Astrophysical, Geochemical, Geophysical, and Biological Limits on Planet Habitability

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