Related papers: An Objective Bayesian Analysis of Life's Early Sta…
The early start to life naively suggests that abiogenesis is a rapid process on Earth-like planets. However, if evolution typically takes ~4Gyr to produce intelligent life-forms like us, then the limited lifespan of Earth's biosphere…
Life arose on Earth sometime in the first few hundred million years after the young planet had cooled to the point that it could support water-based organisms on its surface. The early emergence of life on Earth has been taken as evidence…
Life appears to have emerged relatively quickly on the Earth, a fact sometimes used to justify a high rate of spontaneous abiogenesis ($\lambda$) among Earth-like worlds. Conditioned upon a single datum - the time of earliest evidence for…
The probability that life spontaneously emerges in a suitable environment (abiogenesis) is one of the major unknowns in astrobiology. Assessing its value is impeded by the lack of an accepted theory for the origin of life, and is further…
One of the most interesting unsolved questions in science today is the question of life on other planets. At the present time it is safe to say that we do not have much of an idea as to whether life is common or exceedingly rare in the…
Estimates of the time at which life arose on Earth make use of two types of evidence. First, astrophysical and geophysical studies provide a timescale for the formation of Earth and the Moon, for large impact events on early Earth, and for…
An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a…
According to the "hard-steps" model, the origin of humanity required "successful passage through a number of intermediate steps" (so-called "hard" or "critical" steps) that were intrinsically improbable with respect to the total time…
If two physical timescales are independent, i.e. they depend on different physics, then (statistically) there is no reason to believe that their values should be equal, even to an order of magnitude. The timescale for abiogenesis…
It is sometimes assumed that the rapidity of biogenesis on Earth suggests that life is common in the Universe. Here we critically examine the assumptions inherent in this if-life-evolved-rapidly-life-must-be-common argument. We use the…
A simple stochastic model for evolution, based upon the need to pass a sequence of n critical steps (Carter 1983, Watson 2008) is applied to both terrestrial and extraterrestrial origins of life. In the former case, the time at which humans…
It is unclear how frequently life and intelligence arise on planets. I consider a Bayesian prior for the probability P(ETI) that intelligence evolves at a suitable site, with weight distributed evenly over ln(1 - ln P(ETI)). This log log…
Why did the emergence of our species require a timescale similar to the entire habitable period of our planet? Our late appearance has previously been interpreted by Carter (2008) as evidence that observers typically require a very long…
It is shown that, contrary to an existing claim, the near equality between the lifetime of the sun and the timescale of biological evolution on earth does not necessarily imply that extraterrestrial civilizations are exceedingly rare.…
It is sometimes asserted that the rapidity of biogenesis on Earth suggests that life is common in the Universe. We critically examine the assumptions inherent in this argument. Using a lottery model for biogenesis in the Universe, we…
In a recent paper [1] Lineweaver and Davis performed a statistical analysis to claim that the rapidity of biogenesis on Earth indicates high probability of biogenesis on terrestrial- type planets. We argue that the rapid appearance of life…
The prediction that (due to the limited amount of hydrogen available as fuel in the Sun) the future duration of our favourable terrestrial environment will be short (compared with the present age of the Earth) has been interpreted as…
Creep under a sustained load can persist for long times yet culminate in abrupt yielding or rupture, implying a finite lifetime even when the material appears solid. Here, we formulate lifetime prediction as Bayesian inference over an…
The origin of life on Earth via the spontaneous emergence of a protocell prior to Darwinian evolution remains a fundamental open question in physics and chemistry. Here, we develop a conceptual framework based on information theory and…
First contact with another civilization, or simply another intelligence of some kind, will likely be quite different depending on whether that intelligence is more or less advanced than ourselves. If we assume that the lifetime distribution…