Anybody out there?

Ken Tapping, August 19th, 2015

In the sky this week…

  • Venus and Jupiter are now close to being in line with the Sun, and lost in the glare.
  • Mars lies low in the dawn twilight.
  • Saturn lies in the southwest during the evening. Look for a moderately bright, amber starlike object, shining steadily.
  • The Moon will reach First Quarter on the 22nd.

Scientists agree pretty unanimously that there are living creatures out there on other worlds. We just have to find the evidence. However, what about intelligent life out there? Are there creatures on other worlds looking at the sky and wondering if they are alone in the universe? As a number of scientists have pointed out, in a universe comprising countless billions of galaxies, each containing billions of stars and planets, there have to be some intelligent beings out there, even if the probability of life appearing on a planet is minute. How can we find out for sure if we are not alone?

About a hundred years ago we started transmitting a lot of strong radio signals. Today there must be millions of radio stations around the world broadcasting radio and TV entertainment. In addition there are numerous high-power radars and other transmitters in operation. These signals are radiating outwards into space from the Earth and have so far reached a distance of about 100 light years. A light year is the distance light waves (or radio waves) travel in a year: just under 10 million million kilometres. This expanding sphere of radio transmissions now encloses thousands of stars. If any beings on planets orbiting those stars are operating radio telescopes, which are tuned to the right frequencies and pointing in our direction, they could be detecting our signals. Of course what they make of our TV shows is anyone’s guess. Maybe that is why they don’t visit us.

Back in the 1960’s American radio astronomer Frank Drake used a radio telescope to do a limited search for radio signals from some of the nearest stars. Nothing conclusive was detected, however, when you consider all the conditions that have to be met, that failure is not surprising. Do those stars have planets orbiting around them? Are any of those planets suitable for life? Are there intelligent beings on those planets? Are they technologically at the point where they use radio? Are they transmitting? Are they transmitting in our direction? Are they doing it now? What radio frequencies are they using? Are their transmissions something we would recognize as artificial? Frank Drake combined all these questions into an equation, which is now known as the “Drake Equation”. You can put in the numbers and the result will be the number of civilizations out there who could be sending us their radio transmissions. Back in the days Frank Drake put his equation together most of the numbers needed to use the equation were unknown. We did not even know whether other stars might have planets.

We are in a far better situation now. We know that planets are common and are even finding planets that resemble ours. This means we can narrow the search a lot and concentrate on them. This still leaves the question as to whether there are beings there who are transmitting signals, now, and in our direction. Finally, what are their signals like?

Luckily, we are technologically well ahead of what Frank Drake had to work with. We can now capture huge chunks of radio spectrum in one go and process it in many ways, searching for different kinds of artificial signals. The number crunchers Canada developed as part of its contribution to some major international radio telescope projects are an indicator of what we can now do with radio signal analysis. Moreover, our radio telescopes are orders of magnitude more sensitive and becoming more sensitive still.

Knowing whether we are alone in a really huge universe is the ultimate big question. It has been pondered by theologians and philosophers for centuries, and it is highly likely that it won’t be too long before science can give us an answer.

Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory, Penticton, BC, V2A 6J9.

Telephone: 250-497-2300
Fax: 250-497-2355

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