The Drake Equation Assumptions & Science A demonstration internal assessment oral for IB Theory of Knowledge [ S.Kern, 2015 ] Assumptions & Science

NOTE: This is a demo!!! With few exceptions, these slides are WAY TOO BUSY! You’ve got all this text so that you have a record of the type and depth of content covered. Generally: This (first) “bullet level” would remain for a real (not a demo) oral. This level would be omitted. The timings listed on slides are approximations to give an idea of relative weighting. A PowerPoint (Prezi, etc.) is not required, and only what you say is assessed. These boxes show the function of each slide in terms of “look for’s” for grading

SETI and the Drake Equation 1 minute The first SETI (Search for ExtraTerrestrial Intelligence) conference in 1961 at the National Radio Astronomy Observatory in West Virginia with Dr. Frank Drake, presiding: “As I planned the meeting, I realized we needed an agenda. So I wrote down all the things you needed to know to predict how hard it’s going to be to detect extraterrestrial life. And looking at them, it became pretty evident that if you multiplied them all together you got a number, N, which is the number of detectable civilizations in our galaxy.” Here is the “Drake Equation:” N = R* fp ne fl fi fc L Describing the RLS

N = R* fp ne fl fi fc L Where N = The number of intelligent, communicative civilizations in the galaxy R* = The rate of formation of suitable stars [5 per year] fp = The fraction of those with planets [50%] ne = The number of Earth-like worlds per system [2] fl = The fraction of those where life develops [100%] fi = The fraction of those where intelligence develops [20%] fc = The fraction of the those that develop communicative technology [100%] L = The "lifetime" in years of those civilizations [10,000] Drake’s original estimate: N = 10,000 intelligent, communicative civilizations in the galaxy 1 minute Describing the RLS

Knowledge Question 30 seconds How do scientists justify the assumptions they use to make estimates? In this context, an assumption is an unproven but plausible speculation. Stating the KQ

Exploring / developing KQ generally – do not refer to RLS here! Assumptions 2 minutes Purpose: Critical to research and unavoidable Start somewhere: like “givens” in math Determine what/how we investigate Fine-tuning & improvement Main ways of justification Extrapolating Constructing models Making arbitrary guesses Limitations Reliability: Data Validity: Models “The problem of induction” Exploring / developing KQ generally – do not refer to RLS here!

How were Drake’s assumptions justified? Extrapolating from known facts (data) R* = rate of suitable star formation [5 per year]: well-justified - based on extensive data through direct observation fp = fraction with planets [50%]: less well-justified - based on some empirical data and indirect observation Use of models (our earth and solar system) ne = Earth-like worlds per system [2]: fl = The fraction of those where life develops [100%] Validity: Are these models representative of other systems? Arbitrary guesses fi = The fraction of those where intelligence develops [20%] fc = The fraction of those that become communicative [100%] L = The "lifetime" of these civilizations [10,000] Little justification: little or no data (deductive not inductive) If N is 10,000, where are all the ET’s? Could some of Drake’s assumptions been faulty? Over the years, other perspectives have offered very different assumptions (and N’s)! 2 minutes Applying KQ to RLS

Other real life situations Other RLS’s in which assumptions play major roles Global warming / climate change Battling epidemics/pandemics of “spillover” diseases Common denominators Extrapolation Projecting trends Building representative models Using computers to simulate complex situations 1 minute Demonstrating significance: other RLS’s

Demonstrating significance: overall Significance: So what? No exaggeration: Improving our assumptions can be a matter of life and death. Well-justified assumptions… Clarify expectations & potential outcomes Inform action Next steps for research Policy decisions i.e., If our assumptions make a dangerous outcome seem unlikely, we are less likely to act. The problem of arbitrary guesses: “Garbage in, garbage out” vs. “but we have to start somewhere.” Therefore, even the most well-justified assumptions need to be explicit, debated, and revised with further research. 1 minute Demonstrating significance: overall

Want to add your own perspective? Check out an interactive version of the Drake Equation with you can adjust the assumptions: http://www.pbs.org/wgbh/nova/space/drake-equation.html http://www.scribd.com/doc/28455374/The-Mathematics-of-Drake-s-Equation-Planets-stars-and-life-elsewhere-ppt-presentation http://www.pbs.org/lifebeyondearth/listening/drake.html