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Contacting other Life in the Universe

by Phil Marks, May 2010


I don’t know if you are convinced by the numbers argument when it comes to intelligent life in the Universe (and I don’t mean homo sapiens), but I certainly am. The numbers argument seems to me to be incontrovertible.

For example, it is generally accepted that there are 100 billion stars in our average galaxy (e.g. Cornell University). It is also generally accepted that there are of the order of 100 billion galaxies (e.g NASA). That means that there are 10,000 x 10^18 stars in the universe. Our sun is one of those stars.

Now, can we believe that we are unique in that vast number? Certainly not!

If only 1 in 10,000 stars had a remotely Earth-like planet in orbit, that would still give us 10^18 Earth-like planets in the universe. And if I was wrong by a factor of a billion, then that still leaves a billion Earth-like planets. And, of course, who is to say that only Earth-like planets can support intelligent life – “It may be life Jim, but not as we know it”?

Our Sun is considered to be an ‘average’ star. In all probability, our level of development as a life form falls within the middle of the range from the most primitive to the most advanced of civilisations. So, there are probably intelligent species in the universe who are trying to contact other such civilisations. Now, I am open minded on the question of so-called UFOs. I believe that it is very possible that we as a race are observed by advanced civilisations, and maybe even visited by them from time to time. That, however, is by-the-by.

Anyway, I occasionally think about the problem of contacting other civilisations. There is of course the SETI project, which is analysing incoming radio noise for coherent signals. Let’s think beyond that though, and consider how, if we were an advanced civilisation in our galaxy, we might want to listen for other such civilisations? I’ve been thinking about this for some time. The other morning, whilst staring at the coffee percolator, an idea occurred to me.

What about a galactic listening post?

Why a listening post? The listening civilisation would have considered the inverse square law problem and come up with the idea of a listening post. If we just sent widebeam signals traffic (e.g. radio) into space then the inverse square law means that its intensity falls off very rapidly. But if we focused that transmission energy at a particular point in space using very narrow beam transmission technology such as lasars then the intensity fall off for a given power of transmission would fall off much more slowly with distance. We could also use infra-red lasars as IR is not attenuated significantly by inter-stellar dust. That particular point in space we aimed at would be a listening post, and would be a collector of signals traffic at a point in our galaxy.

Of course, we are also constrained by c, the speed of light. So how would an advanced civilisation view this problem? We are also currently limited by our signals technology (say infra red lasar). In the future, even on a scale of 100 years, what other technologies will we have? What more will we know about branes and multivereses on the Planck scale, and black holes (for example) on the cosmic scale? On this front we are clearly constrained by our technology.

The listening post location(s) would be chosen to be simple to identify from any point within the galaxy. Now, this isn’t easy, as the galaxy looks different depending where you are located within it. So what would make a good location for a listening post, in general terms?

Well, we do have beacons in the galaxy – they are just like lighthouses, and we call them pulsars. However, many are ‘narrow beam’, and if you are not in the plane of that beam then you do not necessarily see them, unless they illuminate other objects nearby (e.g. gas clouds). NASA have recently discovered 17 so-called millisecond pulsars in our galaxy using the Fermi Gamma Ray Telescope.

Pulsars, as so-called ‘radio loud neutron stars’, have other useful properties in the context of listening posts – their strong gravitational fields would concentrate incoming signals traffic. So, if I was an advanced civilisation setting up a listening post, it would have to be near to and in a stable orbit around a neutron star (and that means very high orbital velocities). Further, there would have to be several of them, to ensure that at least one was visible in the plane of the observer (us) and not obscured say by the galactic nucleus.

One more question. Would the listening post location also be a good point from which to originate transmissions? Our researchers are crawling all over the signals from pulsars, but maybe we should be looking even deeper, for other lower intensity signals traffic from the location of pulsars. Perhaps we could start to move this problem forward if we start to think from the point of view of an advanced civilization?  What are the chances of that, I wonder?

© 2010 Phil Marks