Submit Essay

Once you submit your essay, you can no longer edit it.

# Drake's Equation 4th parameter f_l

### Question

This is the fourth question in a series estimating input parameters for Drake's equation, inspired by a recent paper, on the Fermi paradox.

The first question in the series, with more explanation, is here

The model in question uses probability distributions over the following parameters:

• $R_∗$ log-uniform from 1 to 100.
• $f_p$ log-uniform from 0.1 to 1.
• $n_e$ log-uniform from 0.1 to 1.
• $f_l$ log-normal rate, $1 − e^{−λVt}$ (giving $f_l$ mean 0.5 and median - 0.63).
• $f_i$ log-uniform from 0.001 to 1.
• $f_c$ log-uniform from 0.01 to 1.
• $L$ log-uniform from 100 to 10,000,000,000.

In this case we will be addressing the fourth parameter in the Drake's Equation, $f_l$. It is the fraction of suitable planets (see some discussion at the relevant question) on which life actually appears. Predictors should use the sliders to best approximate their estimate and uncertainties in this parameter.

Most estimates assume abiogenesis to be the mechanism by which life appears on a suitable planet, but panspermia and other means merit considering. Again the possibility of alternative biochemistries should be weighed in your answer.

The lower bound because there is no clear source of a lower limit on this number.

The resolution to this question will be the scientific consensus 100 years from now, regardless of any remaining uncertainty.

### Prediction

Note: this question resolved before its original close time. All of your predictions came after the resolution, so you did not gain (or lose) any points for it.

Note: this question resolved before its original close time. You earned points up until the question resolution, but not afterwards.

Current points depend on your prediction, the community's prediction, and the result. Your total earned points are averaged over the lifetime of the question, so predict early to get as many points as possible! See the FAQ.