[Cdude]

Ik vond direkt niet wat ik bedoel maar er zijn uiteraard al iets "slimmere" mensen die er over nadachten. Dit komt in de buurt :

Further obstacles to find other civilizations

A further complication can be demonstrated by the following consideration - let's call it the eggshell theory.

The thickness of an expanding eggshell in this theory would represent the space-timespan within which a scientific civilization would be able to broadcast its signals to other worlds before its own civilization expired.

Let's assume some distant planet had developed an advanced scientific civilization. It would be extremely unlikely that such a civilzation would have developed exactly at the same time as our own here on earth. It could have occured - let's say - two million years ago. ( If we take into account that the formation of our own solar sytem occured around 5,000 million years ago a 2 million year difference would be miniscule ).

Let's further assume that the lifespan of a scientific civilization would be 100 000 years - a very generous assumption. We only have to look at the fragile state of human affairs here on earth. Is it very likely that mankind will survive for more than a few thousand years after the onset of the nuclear age? ( If we consider the risks of nuclear war, the long term effects of global warming and a myriad of other problems it seems problematic that our scientific civilization will survive for more than 100 000 years).

That would not neccessarily be different on an another planet. If such an alien civilization had broadcast its existence for all of 100 000 years, but starting two million years ago, the timespan - or the thickness of the eggshell - would have radiated out from the originating planet at the speed of light. It would mean this electronic wave (the eggshell) would have hit our earth two million years ago but it would have lasted for only 100 000 years. So we would have missed it since at that time only primitive hominids roamed the African continent, barely having invented primitive stone tools.

Similarly, our own electronic projection - starting less than one hundred years ago - would hit another planet millions of years after its civilization had expired, or alternatively, long before it evolved. In that case no communication would be possible because we would attempt to communicate with each other millions of years apart. The probability that an expanding eggshell from one civilization would intersect another civilzation exactly at the right time when the receiving civilization would be able to detect such signals would certainly be 'astronomically' small, that is, almost non-existent.

On the other hand, if we assume a much more optimistic estimate - let's say a potential civilization would have evolved - 'progressed' - over several million years, then another possibility arises. The late Dr. Carl Sagan pointed out that such an extremely advanced civilization might have no interest whatsoever in our primitive human species. The gap would be too immense and such aliens would conceivably look at us, as we look at lower forms of life, such as insects for example. Or they might just ignore us as so underdeveloped that communication with us would be a waste of their time.

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