The Odds of Contacting ET Are Nil, Despite That They Are Already Watching (cont.)
By Jim Elvidge
They Are Already Aware of Our Existence
That is not to say that I don't believe they are out there; on the contrary. Let's use the Drake equation again to make an estimate. Billions of stars in each of 125 billion galaxies gives an estimate of 9•1021 (9 billion trillion) stars in the observable universe. Using the figures above, that would give 4.5•1018 (4.5 billion billion) intelligent civilizations that either currently exist or have existed at some point in our past. Why do I consider the whole universe and not just our galaxy? Because the distance to the nearest galaxy is only 20 times further than the distance across the Milky Way. If Moore's law holds for space travel, then a civilization can figure out how to fly to a nearby galaxy only a few years later than they figure out how to traverse their own. Let's assume that our level of technology is about average compared to the other civilizations; it is as good an estimate as any. Then there must have been 2.25 billion billion civilizations who achieved technology well beyond our own.
What do I mean by "well beyond our own?" Let’s take a closer look at Moore’s Law.
Moore's Law was originally applied to the trend of transistor density on a chip doubling every two years. Since then it has been applied to many other technology trends. For example, the following technology metrics tend to grow exponentially, doubling in the number of years given2,3:
 Transistor density  2 years
 Hard Disk density  2 years
 Pixels/Dollar (Digital Camera)  2.2 years
 Processor speed  2.8 years
 Energies achieved in particle accelerators  3.3 years
 Screen resolutions  4 years
 Internet  5.2 years
Note that it doesn't matter what the doubling period is. The mere fact that the trend doubles regularly over any interval makes it exponential. In fact, some trends may be so slowly exponential as to be not noticeable without close scrutiny. Or, they may follow a more jagged trajectory, with growth spurts and pullbacks, due to funding sentiments and technological hurdles. Yet, over the long term, the growth could still be exponential. For example, the state of the art in rocket engine technology in 1958 was the Pratt & Whitney J58, which could generate .052 kN of thrust per kg (which is a reasonable measure of rocket efficiency given that rocket and fuel weight is a critical factor to getting into space). Nine years later the Rocketdyne F1 rocket engine (used in the Saturn V) generated .922 kN/kg, which is equivalent to a doubling every two years. The progression slowed a bit with the Kuznetsov NK33 in 1971 (1.34 kN/kg)4. But then the trend stopped, as public sentiment for space research waned and funding dried up. However, while chemical rockets may have neared the limits of their technology, other technologies will fill the void and pick up the pace, such as beam power, nuclear power, and antimatter. And, as Moore's law has been shown to describe advancement rates in physics as well (see particle accelerators above), it is likely that it will also describe the rate of growth of the efficiency of advanced propulsion systems as well; those systems that are required to move a civilization through the Kardashev types.
