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Huachuca Astronomy Club—Speakers
Kim Rogalski
Kim Rogalski gave a presentation to the Huachuca Astronomy Club on Friday, May 8, 2009, at Cochise College, Sierra Vista, Arizona. Photo by Del Gordon
Are We Still Alone? A Growing Consensus in Astrobiology
At the public meeting of the Huachuca Astronomy Club on Friday, May 8, 2009, at Cochise College, Sierra Vista Campus, the speaker was Kim Rogalski, math and astronomy instructor from Cochise College. The topic was "Are We Still Alone? A Growing Consensus in Astrobiology."
Kim presented the argument popularized in a recent book called Rare Earth, that complex, intelligent life as we know it, such as our technological human civilization, could have a low probability of developing elsewhere in our galaxy and throughout the universe. Kim discussed the many factors that influence the improbability of our existence, such as planetary geometries, distribution and types of suns, habitable zones in the solar system and galaxy, and how chemistry and physics constrains the equation. All of these factors, and more, conspire against the commonality of complex life.
The famous Drake Equation was discussed. Given values that can vary widley, depending on your philosophy as much as science, this equation yields the current number of intelligent civilizations capable of radio transmission.
What is the current number of intelligent civilizations in the universe capable of radio transmission?
A.) 1
B.) 1 to 10
C.) > 10
D.) > 1,000
E.) > 1,000,000
In 1961, Drake and his colleagues at the original meeting in Green Bank, West Virginia, came up with the value of 10.
Here are some computations of the Drake Equation, given different assumptions:
- 50 (so fifty civilizations exist in our galaxy at any given time, on the average).
- A "pessimist" might equally well believe that life seldom becomes intelligent, and intelligent
civilizations do not last very long: 0.05 (we are probably alone.)
- Alternatively, making some more "optimistic" assumptions, and assuming that 10% of civilizations
become willing and able to communicate, and then spread through their local star systems for 100,000 years
(a very short period in geologic time): 5,000
- The best current estimate, as listed in the Wikipedia: 2.31
- Carl Sagan: "billions and billions" (actually, he estimated 1,000,000 for the Milky Way Galaxy)
The May 2009 talk at Cochise College was about the possibility of the abundance of complex (metazoan) life in the universe.
Mr. Rogalski argued that we are alone. He has been doing this for years in astronomy classes, but recently scientists in disparate fields have come together to examine the issue. See the April 2009 Astronomy article "Is Earth One of a Kind?" and the excellent book by Ward & Brownlee Rare Earth. The growing consensus is that complex life is probably quite rare in the universe due in large part to ample "dead zones" in both space and time—a cosmological argument, but there are many astronomical reasons to feel lonely as well. He spoke about several of these reasons (while
admitting that simple unicellular life is presumed to be common).
The talk was organized as follows:
1) A brief history of the question and a mention of the Drake Equation.
2) What the talk is not about: extremophiles contrasted with metazoan life forms
3) Reasons we are unusual in the contexts of...
a) Cosmology
b) Galactic astronomy
c) Stellar astronomy
d) Planetary astronomy
4) The issue of timing
5) Conclusion
Kim Rogalski at Cochise College, May 8, 2009. Photo by Del Gordon
Bio
Kim Rogalski has been teaching at Cochise College since 1988. Not long
after he arrived there he was astonished to discover there was no
astronomy course taught at the school. He mentioned his surprise, and then was commanded to teach the subject! He has a BS and a MS (1984 and 1986) in Mathematics from NAU and has taken too many Physics courses over the years to be very happy about that.
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