The next few postings will further review the history, status and future of this challenge. I'll even speculate on what an ET might look like, and it, assuredly, will not take the form to the left.
How rational is it for Humanity to establish colonies on Mars over the next decade, as proposed by Elon Musk? What about flying saucers? One-third of Americans think they are real. Considering all our spending priorities, how much of your tax dollars should be applied to major space projects?
40 light years (LY) away. Remember, though, that the closest star, Proxima Centauri, one of the three in the Alpha Centauri system, is 4.25 LYs away:
- Light takes 4.25 years to get there from here.
- Voyager is tooling along at 38,000 miles/hour, and if headed that way, would take 76,000 years to reach Proxima Centauri.
- 70,000 years ago Humanity almost went extinct, with perhaps 40 breeding pairs left on Earth.
- But we recovered well, for if you weighed all us humans, you would get 750 billion pounds, and that is more than 100 times more biomass than any large animal in the history of this globe.
- How big is our Milky Way Galaxy? Light would take 100,000 years from one end to the other.
- Space is very large, and our technology to survive outer space for any length of time is rudimentary.
Indian astronomer Aryabhata 1500 years ago visualized heliiocentricism (Earth revolves around the Sun), Dominican Monk Giordano Bruno, was burnt at the stake in 1600 for suggesting that there were an infinite number of suns with inhabited planets.
Then, along came Carl Sagan, who was denied tenure at Harvard in 1968 and was at Cal-Berkely when I was attending school at Stanford. Sagan joined Drake at Cornell and remained on the faculty until his death in 1996, already more than two decades ago. I had several interactions with him, including assisting in initial funding for SETI.
- At a distance of ten light years, a Jupiter-size planet cannot be seen revolving around a Sun-size star.
- That is because the star is so much brighter, from 5-10 magnitudes, or, at best, the planet is 1/100,000 as bright.
- However, if the extrasolar planet had an atmosphere, the starlight would cause lasing of the gases, resulting in spikes of discrete frequencies which could be detected and tracked.
- That was the theory suggested by Nobel Laureate Charles Townes, who I went to see at Cal-Berkeley in 1976 when I worked at Ames.
- Knowing the colors of the various monochromatic light sources, you would then be able to determine the atmospheric content.
- The result was the Planetary Abstracting Trinterferometer (or PAT), where my proposal on the cover quoted Miguel de Cervantes:
But SETI is all about detecting signals from outer space, so at least one of those septillion planets had to have evolved into an intelligent civilization. But they have had a 10 billion-year head start, so the chances got to be good.
Part 3 will take a closer look at the wisdom of interplanetary travel.