Run Multiple Simulations
This tool allows you to run multiple simulations for the current drake equation result, giving you an overview of the likelihood of detecting a civilization.
|1 pixel on screen:||~0 ly
|Age of closest
|Cursor Position:||0 , 0|
|Distance To Sol:||0 ly
|R* = the average rate of star formation per year in our galaxy|
|fp = the fraction of those stars that have planets|
|ne = the average number of planets that can potentially support life per star that has planets|
|fl = the fraction of the above that actually go on to develop life at some point|
|fi = the fraction of the above that actually go on to develop intelligent life|
|fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space|
|L = the length of time for which such civilizations release detectable signals into space|
The Galactic Population Simulator: a way to visualise the galaxy's estimated population
In 1961, a nerd god named Frank Drake came up with the Drake Equation: a mathematical equation to figure out how many detectable civilizations exist in a galaxy. The equation is simple, but involves many factors, most of which are not known accurately or are totally unknown.
This means that we can only put in estimates for several factors, and depending on the estimates you put in, you come up with wildly varying results, ranging from 'zero civilizations (just us!)' to 'hundreds of thousands'. The original figures Drake plugged in ranged from 20 to 50,000. Modern estimates tend to range between 0 and 10,000.
An estimate of 10,000 technological civilizations might sound like a lot, but is it really??
The Galaxy is a big place: current figures indicate that it's about 100,000 light-years across and 1000 light-years thick. It contains more than 100 billion stars, perhaps as many as 400 billion. Recent data from Kepler indicates that the milky way has at least 100 billion planets, and up to 40 billion of them may be earth-like (i.e with liquid water).
The nearest star, Proxima Centauri, is 4.2 light-years away. According to the theory of relativity, the speed of light is a universal speed limit. This means that if we send a message to Centauri, it will take more than four years to arrive. Similarly, it would take tens of thousands of years for any message to reach the every point the galaxy.
One of the terms of the drake equation is "the length of time for which such civilizations release detectable signals into space". Given the size of the galaxy, we need to take this into account when we estimate the probability of extraterrestrial contact: If the nearest civilization is 1000 light-years away, but the average civilization only exists for a few hundred years, then we're not likely to make contact with them.
To this end, the simulator also gives each generated civilization a random age between 0 and the provided L term of the drake equation, and indicates how many civilizations are detectable based on age and distance. Note that 'age' represents the length of time that the civilization has been detectable, not the actual age of the civilization.
There's also an option to show the possible detection ranges for each civilization. This will be represented by a yellow circle surrounding each civilization. Note that Earth's civilization is young, so Sol's circle is invisible even at the highest zoom level.
A galaxy with 10,000 civilizations is not all that densely populated: according to the simulations, the nearest civilization is likely to be anywhere between 100 and 1000 light-years away in this scenario.
The SETI program has been running for a few decades. One of the goals Of the Galactic Population Simulator is to show that this effort is likely going to be a multi-lifetime project which should run for as long as possible and deserves continuing funding despite decades of no results.
To provide a way to visualise the implications of the wildly varying estimates the drake equation provides: it provides a way to see the relative population density of the galaxy given a number of civilizations output by the drake equation.
To provide a way to visualise the size of the galaxy - it's a big place! even at the maximum zoom level, 1 pixel will be more than 20 light-years! Remember that there are hundreds of billions of galaxies in the universe!
TL;DR: The Galactic Population Simulator takes a picture of our galaxy and draws N civilizations (mostly) randomly, with the location of the Sun (Sol) and earth highlighted.
It provides panning and zooming, so you can get a closer look at the simulation. This works somewhat like Google Maps: you can drag with your mouse and use the wheel to zoom. There are also pan/zoom buttons in the control bar to the right of the simulation.
The controls on the right also allow you choose presets or put your own numbers into the drake equation, changing the number of civilizations. You can also see statistics for the simulation and the point in the galaxy your mouse is pointing at.
There is a mode which allows you to run multiple simulations for the current drake equation, and see statistics over many runs. To use this, press the '...' button after choosing your terms for the drake equation, then enter the desired number of simulations and press 'go'.
Important Note: There are no limits in place on the simulator - you can plug in ridiculously large numbers and it will valiantly attempt to generate thirty million civilizations, or do ten billion iterations. If you plug in large numbers, expect it to be slow, and maybe to even crash your browser. Soft-limit numbers: ~100,000 civilizations, ~1000 iterations.
Also note that the Galactic Population Simulator is a work in progress and some things might not work quite right! If you're having trouble, feel free to email me at antisol (at) antisol (dot) org.
Obviously, This isn't a scientific model of a real place: there are several incorrect assumptions being made for the sake of simplicity. This is a toy, not a proper scientific investigation. The idea is that you'll press "simulate" a few times, and compare the 'closest civilization to Sol' figures. In scientific terms, it uses a very simple model, but I have tried to make reasonable and fairly conservative assumptions: