The four principal arguments offered in support of the skeptical view of the ETH are described as follows:
“We Are Alone.” This debate has gone on for centuries, and while there are “good scientific reasons to think that intelligent life does not exist elsewhere,” with the recent and continuing discovery of numerous planets orbiting stars of the not too hot or cold variety, it does now seem that there are also “equally good scientific reasons to think that it does.”
“They Can’t Get Here.” It has been argued that if intelligent life does exist somewhere else in the universe, it would simply be too far away to get to Earth. However, further research and “computer simulations suggest that even at speeds well below light, any expanding advanced civilizations should have reached Earth long ago.” Beyond the benefit of great lengths of time, theoretically utilized by an advanced civilization traveling through our galaxy, other possibilities aiding in long-distance, inter-stellar travel might include the use of wormholes – tunnels through space-time that would greatly reduce the distances to be travelled – and the possible use of something akin to a “warp drive,” which would engineer a vacuum around a spacecraft enabling it to “skip over space without time dilation.”
These techniques, and the possibility of the development and existence of sufficient technology to reliably master them, are, of course, highly speculative. It is literally the stuff of science fiction, though a science fiction supported by physics as currently understood. However far out such concepts may sound, we should note that we’ve come up with them “just 300 years [after] our scientific revolution, imagine how far another civilization might have advanced 3000 years (much less 3,000,000) after theirs.” Of course, put this way, alien visitors should be here now. So, where are they!? This is the famous “Fermi Paradox” and leads to the next skeptical argument.
“They Would Land on the White House Lawn.” So: “If visitors from other planets have come all this way to see us, why don’t they land on the White House lawn and introduce themselves? After all, that’s ‘what we would do.’ ” Since this hasn’t happened it is seen as further evidence that UFOs do not exist. But, really, how strong is this evidence?
“On what scientific basis,” do we really presume to fathom the intentions of alien beings upon encountering Earth? Beings “whose nature and agenda might be utterly unimaginable to us.” In short, “there is none, and as such one cannot rule out the possibility that extraterrestrials might have reasons for avoiding contact.”
“We Would Know If They Were Here.” Because of our sophisticated surveillance capacities, we would know if ETs were here. This argument has the added benefit of appealing to our technological vanity. But, again, how decisive is this argument? Do we really know what a UFO looks like? And, taking a page from military stealth technology deployed on Earth, isn’t it plausible that occupants of alien craft would have the “technology to limit knowledge of their presence?” Also, “the authorities have not actually looked for UFOs, and what is not looked for or expected is often not seen.” And, “in view of pervasive official secrecy about UFOs, more is probably known about them than is publicly acknowledged.”
The authors stress that the point of fleshing out these arguments a bit is not to prove they are wrong, “but that reasonable people can disagree about whether they are wrong.” What they all have in common is that they rely on unproven assumptions “rather than established scientific facts.”
“Indeed, the very fact that it is so easy to raise reasonable objections to UFO skepticism is further evidence that, scientifically speaking, human beings can’t rule out the extraterrestrial hypothesis.” Some may look at the evidence and say the probability of the ETH is zero, while others may feel it holds promise – “but who really knows?”
“No one knows, because we do not have the scientific knowledge to make such probabilities meaningful. As former secretary of defense Donald Rumsfeld might put it, we are dealing here not with ‘known unknowns’ but ‘unknown unknowns,’ where objective likelihoods are anyone’s guess. Far from proving that UFOs are not extraterrestrial, in short, current science proves only its ignorance.”
(Part 3 of 6)