Tag Archives: simulations

A SETI simulation

In a former life, back when computers were powered by steam and the Web was only a twinkle in Tim Berners-Lee’s eye, I helped develop simulations for teaching and learning physics. Years have gone by since I last coded a physics simulation, but I still find enjoy using them and I’m convinced that the best ones can really improve a student’s understanding of physical theory. I’m not alone in that belief. For example the Nobel laureate Carl Wieman, who has long argued that metrics for assessing the quality of an academic’s teaching should sit alongside metrics for assessing the quality of an academic’s research, founded PhET Interactive Simulations to improve the way physics is taught and learned. (PhET stands for “Physics Education Technology”, but since Wieman founded it in 2002 the project has expanded to include biology, chemistry and earth sciences.) The simulations that PhET release allow students to see in real time the effect of changing the value of a physical variable; these software-based experiments allow students to play safely, quickly and cheaply with systems, and can help inculcate a deeper understanding of the underlying physics. The simulations don’t have to be particularly complicated to be of value. A basic simulation of a wave on a string, for example, will allow students to change the values for frequency, wavelength and amplitude – and the students will immediately be able to visualise and understand what those terms mean. Simulations don’t necessarily replace textual descriptions – there has to be a pedagogic scaffold surrounding the simulations – but they certainly bring texts to life.

In writing Where is Everybody? I toyed with the idea of developing simulations to illustrate some of the points I wanted to make. When discussing the challenges faced by SETI scientists I couldn’t help but think that readers would get the point more readily if they were able to visualise the search space. What is the effect on likely detection if we double the range over which we believe radio signals from an extraterrestrial civilisation can be detected? What happens if we treble the range, or half it? What is the effect on likely detection if we increase the lifespan over which a civilisation is likely to transmit, or decrease the time over which a civilisation is motivated to listen? How important to the SETI endeavour is the rate at which radio civilisations come into existence? A reader could of course answer these questions by working through the mathematics. But not all readers have a mathematical background. A simulation would handle the mathematics for the reader, and allow everyone – even the math-phobic – to explore these questions.

I no longer have the time to devote to coding simulations. However I recently discovered that Roger Guay has already produced a gorgeous-looking simulation, called Alien Civilization Detection, that allows us all to play with various factors associated with SETI.

ACD introductory screen

The introductory screen from Roger Guay’s app Alien Civilization Detection (Credit: Roger Guay)

Roger’s simulation features a concise introduction that first outlines the problem of detection and then explains why his simulation is of only a “small” (10000 x 8000 light year) region of the Galaxy. Interactive tabs at the bottom of the simulation present useful information on the Drake equation, a slider that illustrates timescales, and example analyses. Screen tools at the side of the simulation allow you to change its appearance (and toggle some “fun facts”; did you know, for example, that firelight from the last of the Stone Age people is now just a quarter of the way to the centre of the Galaxy?).

Instructions for ACD

Some of the features in the Alien Civilization Detection simulation. (Credit: Roger Guay)

The simulation itself presents the viewer with a number of dials. We can set the typical maximum distance for radio detection, from 600 light years to 2000 light years. We can set the timespan over which a civilization will broadcast, from 160 years up to 2000 years; similarly, we can set the timespan over which a civilisation will be actively listening. The view can be either “Earth-centric” or “Galaxy-centric”. Press the green “Start” button, or the space bar, and watch as this small part of the Galaxy fills with radio signals. We see civilizations appear; we see civilisations that are currently both listening and transmitting; we see civilisations that are listening but no longer transmitting; and we see the ever-weakening signals from civilisations that are no longer listening, no longer transmitting. A counter keeps track of the elapsed time along with the number of potential detections that could have been made during that time.

ACD-typical run showing detection potential

Screenshot of a typical run of the Alien Civilization Detection app. Note the detection potential! (Credit: Roger Guay)

It’s rather hypnotic to watch civilisations pop into existence, transmit radio waves into the cosmos, and then cease transmitting or listening (perhaps they die?) before those waves cross the path of another civilisation. Occasionally, though, there is the chance for detection. Those rare events are what SETI scientists hope to see.

I viewed the simulation on a Mac, but I believe that a Windows version is in the pipeline. If you would like to contact Roger to discuss the simulation, his email address is irog@icloud.com. And if you would like to download the app, you can do so via this Dropbox link.

Enjoy!