Archive of Writings

Fraser and I got a great letter from someone who listens to Astronomy Cast. This person noted quite correctly that Carl Sagan was strongly criticized for spending so much time popularizing astronomy. This person asked if things have changed significantly for us today....

In the past decade, a few things "real" scientists once poo poo'd as science fiction have been found happily taking place in our universe. For instance, just the other day I heard a colleague discussing how planets aren't found in binary systems. Since he is a...

Fraser and I were interviewed about the search for alien life by Skepticality. The interview is in the second half of this weeks episode. (The first half is all about the iPhone (Mmmmm, iPhones…).) If you’re looking for something new to listen to and haven’t checked Derek and Swoopy’s show recently, give it a listen.

In what is to me the most scientifically important paper of the year, astronomers today announced the discovery of 2 galaxies at redshifts > 10 and 4 galaxies with redshifts >7.7. The most distant of these galaxies was forming stars just 500,000 years after the Big Bang and ~120,000 years after the formation of the cosmic microwave background, and contributed to the re-ionizing the universe after the formation of neutral hydrogen. These galaxies were discovered using the Hubble Space Telescope and Keck II, and by taking advantage of gravitational lensing effects in three galaxy clusters. (Figure shows a selection of Hubble Space Telescope images of the cluster fields with the newly-located sources marked. credit: Stark et. al / STScI / ESA)

That was a lot of exciting information, and now that I’ve gotten some of the excitement out of my system, let me step back and tell you exactly what it means.

As we continue to find extra solar planets around increasing numbers of stars and continue to find liquids (water, ammonia, methane…) in increasing places in our own solar system, one has to wonder when will we find life. Answering this question is a complex dance that requires us to first ask, “What is life?” and follow up with the question, “How can we detect it?” A lot of minds around the globe are focusing on these questions both theoretically and observationally, as scientists work to both find the most extreme life here on Earth, and to guess at what might be waiting to be found on other worlds.

Our search for life can be broadly divided into three different areas:

1. Direct discovery of bacteria/microbes/other life with robot probes in our own solar system. This is the reach out and touch someone with a NASA/ESA rover way of finding life.
2. Discovery of atmospheric components associated with life on another world. For instance, the unique signature of oxygen and smog indicative of the plants and polluters we have in our own atmosphere.
3. Dialing up the radio emissions of alien civilizations using radio dishes (or alternatively optical or microwave beamed signals). This is the ET phones Earth scenario of movies like Contact.

Few science programs have lead to as much public involvement as the Search for Extra-terrestrial Intelligence (SETI) program. With their flag ship “SETI at Home” screen saver, they gave people a tangible way to help find life out there. Despite receiving no public funding, SETI has maintained an active research program, and their scientists have managed to consistently get telescope time and money to search the stars for radio signals.

At a certain level, I think people would endlessly search the heavens with a radio dish in search of a signal no matter how few planets were ever found, and how little liquid was ever discovered. We would keep searching even if we thought the search was futile. We want to know – Are we alone? That single question is one we have asked, at least once, every one of us. As children frightened of the dark we asked, “Are we alone?” as we watched distant planes and more distant satellites criss-cross their way through the pitch black sky. As adults, watching wars on TV, watching celebrity gossip, and watching 1000 small indignities and injustices being played out big on the little screen, we have asked “Are we alone?” We want someone else to be out there among the stars. And we are afraid there is someone else out there among the stars.

And so we search.

And, as scientists, some of us ask, what is the chance we will find that someone out there? If you were the last person on Earth, how would you know? If we were the only civilization in the galaxy, how would we know? Just as the lone survivor of some post apocalypse novel might say to himself, “I wonder if anyone survived in Australia?” and then run calculations based on guessed at wind and radiation and food ration levels and guess at the likelihood anyone else exists, a civilization like our own can look at the stars and calculate, based on guessed values, how likely it is we’ll detect life.

In a new paper by Marko Horvat of the University of Zagreb, calculated the probability of detecting radio signals from an alien civilization is carefully laid out way.

It seems that conferences always come in clusters. This year, back-to-back bookings are becoming a way of life! At the end of July I’ll be the AAPT meeting in Greensboro, NC, followed by the Cosmos in the Classroom meeting in Pomona, CA. Then I come back for a few weeks before taking off to Dragon*Con in Atlanta, GA followed by the ASP’s EPO meeting in Chicago. If you are going to be at any of these meetings and want to meet, please drop me a message.