Is There Anybody Out There
An article on the possibilities
and Probabilities of
Is there any intelligent life out there? When the first human looked up in awe into the night sky he asked that question - and we as a species have been asking the same question ever since. It is my belief that the Universe is big, so mind boggling big, that life and in fact Intelligent life, must exist in other locations apart from this one little planet we call Earth. It is just a little conceited for us to presume that we could be the only Intelligent species in our own Galaxy let alone the entire Universe.
Why is it then, that we not heard from, or seen them? The answer to this question is based almost entirely on two factors, time and distance, which within interstellar space are completely interchangeable. As far as we know, from the knowledge we have gained to date; life exists only within certain conditions, those conditions we experience here on our own planet Earth. In the most basic form, these conditions must include the presence of liquid water and a number of important elements most notably Carbon.
For a planet to have access to liquid water it must orbit its own star at particular distance. A distance such that the energy absorbed by the planet from its star is sufficient for water to exist between its frozen (ice) and gaseous (steam) states. In other words the planets mean temperature must be somewhere between 0 and 100 degrees Celsius. To simplify matters we call this orbital distance the stars "Waterhole". In the case of our own planet that "Waterhole" equates to a distance of approximately 150,000,000 kilometres from our own star Sol. If the planet were moved too much closer to the sun the surface temperature would rise to such a point that liquid water no longer existed. If this were the case life as we know it could not exist, for example Venus. In the other direction, water would slowly move towards its solid state, making the formation of life again highly unlikely, the example in this case being Mars.
That looks after the liquid water aspect, but what do we need to ensure that all the necessary elements including the highly important Carbon and oxygen are available. For that we need to look into the evolution of stars themselves.As in all forms of evolution, stars evolve from generation to generation, however concerning stars each generation can last billions of years and the later generation is produced from the exploded remnants of the previous.
The first stars produced after the Big Bang consisted almost entirely of the simplest element Hydrogen. It was not until the final years of these stars existence that heavier elements such as Helium began to be produced. These next heavier elements were actually produced during the stars destructive dying as a Supernova. We call these first generation stars. The stars formed from the debris of the massive explosions of these earlier stars became second generation stars. These stars included within their substance as well as Hydrogen, other more complex and heavier elements that were produced in the Supernova explosion of their predecessors.
As these stars moved through their own life cycle, they too produced during their explosive dying, heavier elements again; these elements then became part of the third generation of stars.Our own star Sol is one of these third generation stars. It was not until this third generation of stars came into being, that sufficient of the heavier elements were produced for rocky-metallic planets like our Earth to come into existence.So, as far as we know today - and I must stress that this could change tomorrow with some incredible new discovery - that life only exists on a rocky-metallic planet orbiting within the "Waterhole" of a third generation "G" class star.
We know that similar "G" class stars exist in our Galaxy (actually many hundreds of thousands of them) and that there is a good chance that some of them would actually have a suitable planet orbiting at the right distance. Some of these planets, through random chance alone, must have produced life and in some cases that life may have evolved to the stage of having a species of intelligent tool users.
So why is it that we have not seen or heard from any other intelligent life forms that live on similar planets orbiting similar types of stars? This is where time and distance come in to it.
Because we are talking about planets orbiting third generation stars, we are talking about stars that were formed, galacticaly speaking, at relatively the same time, give or take a few million years. What this means is that most planets orbiting third generation stars in our galaxy are of approximately the same age. So that in the majority of cases, any life that has evolved, would be at approximately the same state of development as we find ourselves here on Earth. I am not saying that there are not planets out there that started their evolution of life thousands or maybe millions of years earlier than happened here on Earth. However there are a number of factors to be considered regarding the possibility of these species being further advanced than ourselves.
Here on Earth, our planets dominant intelligent species, is at an evolutionary crossroad. It will be within the next few generations that evolution will decide whether we as a species will survive to evolve any further or through action or inaction go the way of the Dinosaurs.The aggressive nature of our species and it's fascination with ever more powerful weapons could result in the untimely demise of our species and possibly even the entire planet. It is hoped that this scenario will not happen but at this stage it could still go either way.
Alternatively, the state of the Earth's ecology is also at a crossroad, through the undisciplined use of natural resources we could find ourselves going out not with a bang but with a whimper. Again, if it is not addressed within the next few generations the Earth may be destroyed by pollution or may fall back into the dark ages through a lack of resources. It is my belief that we will survive this period but this same scenario has no doubt occurred with other intelligent species within our galaxy. How many have reached a similar stage of development only to blow themselves back into the dark ages or to total destruction.OK, so some of these life forms must have survived and evolved further and yet we still have not heard from them. Why not? The answer to this is quite simply distance.
Our own Galaxy comprises of over 100,000 million stars spread out through a spiral shaped cluster that is some 100,000 light years in diameter and some 18,900 light years in breadth (at it's maximum).The reason these distances are measured in light years is so that we can write what would be unwieldy numbers, if we were to use Kilometres or Miles, into a form of shorthand. One light year is approximately equal to 9,460,000,000,000,000,000 Kilometres (9.46 million, million, million). That makes the dimensions of our own Galaxy a staggering 946 thousand million, million, million Kilometres in diameter by some 189 thousand million, million, million Kilometres thick; the mind boggles.
With 100,000 million stars spread out through such enormous distances and only a small percentage of being the type we are most interested in, it is therefore quite likely that we are quite a long way from our nearest intelligent neighbour. To make things that little bit more difficult, our own star Sol is situated out towards the outer edge of the Galaxy some 33,000 light years from the Galactic centre.As we have already determined, in interstellar space, distance equates to time.
So a planet orbiting a star 100 light years away from us in distance (some 946 million, million, million Kilometres) is also 100 years away from us in time. This time factor is only relevant to the electromagnetic spectrum, which includes visible light and not to any form of physical matter. Any physical matter would take enormously more time to travel the distance.For instance if a spacecraft could be instantly accelerated up to as little as 10% of the speed of light and could be instantly decelerated at the other end, it would still take 1000 years for it to make travel to our hypothetical planet 100 light years away. In reality however that time would be greatly increased by both the acceleration and deceleration times.
So at this stage, there is no point of trying to send a spacecraft between the stars, so why don't we or our counterpoints at the other end use radio signals? Radio signals do travel at the speed of light and would only take 100 years for the message to get there or back as the case may be. The main problem with this is, exactly where do you direct that radio signal? To send a radio message to a planet 100 light years away and have it clearly understood at the other end would require an extremely high powered narrow beam transmitter aimed directly at the receiver. This type of equipment does not come cheap, either initially, or in operating costs. So unless you knew exactly where to aim it, all you would achieve is a great waste of money.
For any intelligent species to send out a message to every possible location where other life might conceivably exist would be an incredible drain on the planets' resources for little or no return. So the next best thing to do is to listen and hope that maybe you will hear something transmitted by another intelligent species such as our own SETI (Search for Extra Terrestrial Intelligence) program.
The only problem with this is as was previously explained; no species is likely to spend the resources necessary to directly beam a message to another star if there is little likelihood of any return. If you did manage to make a lucky guess as to a likely location and a message was received it would be decades or even centuries before you got any reply. This being the case the only signals that the SETI project are likely to pick up (if any at all) would be the spill from any local planetary radio broadcasts.
If we were to take a hypothetical planet orbiting a "G" class star some 100 light years from Earth with their own version of the SETI program set up conducting a search of likely stars in their search for other intelligent life. What would be the chance that they would discover us? Well, believe it or not, almost none.Transmission of radio waves have been occurring here on the Earth a little more than 100 years; as Marconi's first wireless radio transmission did not happen until May 14, 1897. Since the time of that first radio transmission, the use of radio waves has increased at an exponential rate. Slowly but surely, a sphere of man made electromagnetic radiation has been expanding outwards from the Earth's surface. The leading edge of this nearly 100 light year sphere of electromagnetic radiation would now have reached our hypothetical planet 100 light years away.
So would they hear us? The simple answer, no. Even if they happened to have their radio telescopes trained on our part of the sky, it would still be unlikely that they would hear those faint early transmissions through the background noise of the Galaxy. It might be anywhere up to fifty years before the electromagnetic radiation escaping from the Earth would be strong enough to be detected over those sort of distances.So what does this say about the possible success of our own SETI project? Well, bearing in mind that it is unlikely that any one would be beaming us direct, our only chance is that we might pick up another planets' electromagnetic radiation spill. Now depending on just how close the nearest other intelligent species is to us in light years, they would have had to been making radio transmissions for approximately fifty years plus the time or distance from us in light years.
For example if our nearest neighbour was only a mere twenty light years away, their equivalent of our Marconi would have had to have made his first broadcast a minimum of seventy years ago for us to have much chance of us picking up anything of interest. Even then all we would be likely to receive is their equivalent of our 1940's radio programs and just possibly some early television broadcasts, interesting stuff! So if our nearest neighbours were much further away, the start of their first transmissions would have to be further and further back in time for us to have any chance of picking them up. On our hypothetical planet 100 light years away they would have to have started their transmissions over 150 years ago for us to be able to pick them up today.
If the closest intelligent species was over 1000 light years away it starts to get less and less likely that we will here from them for a couple of centuries or more. For planets that are 10,000+ light years away and in a Galaxy 100,000 light years across that is a distinct possibility; the likelihood of us hearing them at all is so remote that it is almost non existent.
Of course none of this takes into account, Hyperspace, Warp Drive and Wormholes in space but unfortunately some of these are still only available in theoretical mathematics and Science Fiction and not here in the real world. Although I personally have no doubt that we are not alone, I doubt we will hear from our neighbours anytime in the near future.
I do believe however that SETI is a good idea and that we should continue to listen. It's a bit like a Galactic Lotto; the prize would be well worth it - if it ever came up.In regard to meeting up with them well.....