I’m going to continue the LGM theme. I don’t plan on doing multiple posts on a single subject very often, but there were some things that I want to add to my previous post.
It seems to me that the difficulties of point to point interstellar communication are such that it makes it unlikely that we will be able to find LGM by searching for intentional broadcasting or unicasting of signals, for the reasons that I raised in the previous post. There are other reasons that I haven’t touched too.
One big question is one that occurs to me, probably because I am a computer professional. Why would a civilisation want to be found? If you broadcast something on the Internet, you attract all sorts of undesirables trying to access your systems, your data, your private stuff.
Some of the undesirables might be governments of course, depending on your point of view and political affiliations. On a more personal level, people have told friends on social networking sites of a private party and hundreds of people have read this and gatecrashed. As a consequence the party gets overrun and the house gets trashed, the police get called.
If you broadcast to the Universe the same sort of thing might happen. The LGM might not be friendly and with benign intent. Why would you risk attracting undesirables? Of course, the civilisation sending the signals may not be benign. Such a signal could be a honeypot, designed to attract unwary civilisations.
So, it seems that it might be unwise to respond to alien signals. Murray Leinster’s novelette “First Contact” explores the issues, albeit in a first contact away from the origins of the contactees.
Two technologically equal species are making first contact in deep space. Both desire the technology and trade the other can provide, but neither can risk the fate of the home planet based on unfounded trust.
Another danger would be encountering a more advanced civilisations. In all cases where this has happened on earth, this has always resulted in disaster and absorption of the less advanced civilisation. This usually starts with disease, both sexual and non-sexual, which may be common in the more advanced civilisation but which the less advanced civilisation has no defence against. However, ultimately it is foreign ideas that cause the destruction of the less advanced civilisation and there’s no vaccine against that.
So, maybe we should avoid alien civilisations, at least until we can be sure that contact will not harm us. But how will we know that they are there, so that we can avoid them? Can we detect them before we blunder into something we can’t handle?
One possible way would be to observe the rate of emission of radio waves from a stellar system. If the electromagnetic spectrum emission in the wavelengths that are used for TV and radio is unusually high, it may indicate that a civilisation exists in the stellar system.
So if an otherwise unremarkable star should suddenly (in astronomical terms) start emit radio waves it might indicate that an advanced civilisation might have discovered radio on a planet orbiting the star. Or, rather, that it did discover it, a long time ago. If we did discover such a star (and I’ve no idea if it is remotely possible to detect such an anomalous production of radio waves), it may be thousands of light years away, which means that the waves have been on their way for thousands of years.
If we then send an expedition to a star at, say 20,000 light years, it would take us 20,000 years at least to get there, and probably many, many more. That 40,000 years that would have passed since the wave were generated and no civilisation that we know off has lasted for more than a few hundred. They might have all died out or reverted to savagery or evolved into something that we can’t understand. We might have done similar in the 20,000 years that it would take to get there.
It’s unclear why we would want to contact them anyway. A conversation that takes millennia would be a strange one. About all we could say would be “Hi from Earth. Here are some snaps from our family album”. Of course, when we decode their signals, as XKCD notes, we would most likely find that they are unintentionally broadcasting the alien equivalent of cheesy TV shows like “I Love Lucy” or contrived “reality” shows. After all, that’s what we have been broadcasting.
All of the above is moot as is my previous post if the LGM do not exist. The most famous attempt to estimate the likelihood of there being other civilisations other than ours out there is the Drake Equation. As I mentioned in my previous post, this equation irritates real mathematicians, since it is not derived from anything, but is merely a string of terms strung together to look like an equation. Plausible values for the components of the equation can give answers ranging from almost zero (there are no other civilisations other than ours in our galaxy) to 38 million or more.
The SETI Institute concludes that “The importance of the Drake Equation is not in the solving, but rather in the contemplation”. Certainly the values of most of the terms of the equation are not really known, though estimates can be made. Investigation of one term may throw up information which throws some light on the other terms.
The crucial term is, I feel, “L”, the length of time that a civilisation will be able to and desire to make radio signals. Looking at how we have used radio waves, there seems to be a trend from the low end to the high and very high end of the broadcast spectrum. Early experiments and usage was in the VLF (very low frequency) band, but the frequencies used for most radio broadcasting moved to medium frequencies. TC, both digital and analog use VHF (Very High Frequencies) and UHF (Ultra High Frequencies). Satellite broadcasts use even shorter wavelengths (higher frequencies). So our radio usage has changed over the 100 years or so that we have had radio receivers and transmitters.
All in all I think that it is unlikely that we will contact LGM. We may stumble over some, if we ever manage to go Interstellar, and it may be that some as yet unknown technology might enable us to easily spot advanced civilisations from a distance, so that we can signal or visit, but although I applaude the SETI effort I don’t think that the search will be fruitful.
It may be that we can never visit other stars because no way exists for us to do so. In a story that I once read, but can no longer remember the name of, one character referred to star systems as “God’s test tubes”. I recall that at the end of the story the human race had just found a way to escape its “test tube”.