We have recently been flooded with much excitement about the possibility of aliens traveling in UFOs, (now labeled UAPs, unidentified aerial phenomena), that may be visiting us from distant worlds. Much of our attention, however, focuses on how we form beliefs and evaluate possible conspiracies rather than considering the basic physical and biological requirements that may prevent us from believing such events are even possible. And there are good reasons why alien visits from distant worlds are not—and likely never will be—a real possibility. This mythical idea may be mainly designed to titillate us for earth-bound—and not celestial—reasons.

The public has always been enamored by outer space as exemplified by the popularity of science fiction programs such as Star Trek, Star Wars, E.T., Planet of the Apes, etc. The recent unmanned excursions to our moon and nearby planets have further whetted the public’s appetite. That may also explain the recent increased interest in the possibility of aliens from distant worlds traveling in UAPs. Much of our attention, however, focuses on our chasing “weird” aerial phenomena rather than exploring the basic physical and biological limitations that may not allow us or aliens to meet each other or to reach distant planets. And there are good reasons why alien visits from such distances have not—and probably never will—happen. Although we have sought diligently over most of the past century to identify aerial phenomena and link them to distant worlds, all have resulted in abject failure: Either such “discoveries” can be explained by earth-bound phenomena such as mylar balloons, drones, foreign aircraft, space trash, distorted photos of flying insects and other objects such as artillery shells, human failings (hallucinations), etc. Although some of these phenomena remain unexplained, no substantive evidence of alien life or vehicles has been uncovered, and because of facts presented here, I contend that they never will.

Let’s explore this issue from a purely scientific/biologic perspective. We begin by posing two questions: 1) Given our current or probable future technology, what is the possibility that we could reach—either with manned or unmanned spacecrafts—planets in this or other galaxies? 2) What possible circumstances would allow those from other planets to reach us?


As a product of over three billion years of evolution, we have reached a level of intelligence that has enabled us to create machines that can reach beyond our atmosphere into space. A major barrier, however, is that of distance, and according to present information, the distance to the nearest galaxy surrounding the star, Proxima Centauri, is 4.2 light-years from our Sun. The next limitation is the maximum speed of our spacecraft, which currently is approximately 6.5% of the speed of light. Although we cannot predict the maximum velocity of future spacecraft, according to Einstein’s theory, the speed of light is a cosmic speed limit that cannot be surpassed. Radio waves are similarly limited. So, we must accept that faster-than-light travel is impossible, especially for anything with mass such as as a spacecraft. Assuming there are no intelligent occupants on planets in our solar system, given our present rocket technology, NASA estimates it would take approximately 73,000 years for a present spacecraft to reach any planet in the nearest Proxima Centauri galaxy. We could postulate higher velocities, but thus far humans haven’t figured out how to approach such rates, further raising the question whether we, or any other advanced culture, could accomplish this task. Can we hope to overcome these limitations in the future? Possibly, but at present we could conceivably take human beings only to any of the known planets or moons within our Solar System, but not to any destinations beyond this gravitational sphere. Just to reach Neptune, our most distant solar system planet, would require 12 years one-way. Thus, crewed space travel to another galaxy, at least with the technology we have today, is still only a dream. But regardless of future technological advances, we would still be unable to travel faster than—or even approach—the speed of light. If we extend our present laws of physics to their limits, we might be able to travel further in the universe, but given the facts described above, we would be capable of merely making scientific observations, and space travel to allow settlements on distant planets outside our solar system would be unreachable. This would obviously include the nearest planet orbiting Proxima Centauri— Proxima b. That’s a daunting distance, and even an initiative announced earlier this year aims to send super-fast miniature probes to this destination, this journey would require about 20 years. Given our limited lifespans, it would be virtually impossible to send a manned spacecraft to any such destination, let alone to expect any return voyage. Moreover, any encounter with a form of intelligent life would be highly doubtful. Even with a craft that could achieve the unlikely speed of about 50% of the speed of light, this would require at least 9 years one-way, to reach the nearest galaxy, again an impractical feat. Other potentially hospitable planets would likely be far more—and prohibitively—distant. So, from earth, any voyages to distant, habitable planets, is—now or likely in the foreseeable future—is clearly beyond our reach. Thus at present, we could conceivably take human beings only to any of the known planets or moons within our Solar System, but not to any objects beyond this gravitational sphere. If we extend our present laws of physics to their limits, travel might extend further into the universe, but even if we were to reach such unlikely huge distances, our current lifespans would preclude occupied travel, meaning that distant planets outside our solar system would continue to be physically unreachable. This would obviously include the nearest planet orbiting Proxima Centauri. Even an initiative announced earlier this year aims to send super-fast miniature probes to this destination, it’s a one-way journey that would take about 20 years. Sending unmanned craft would also be problematic, since this would require radio waves to control or track them, which would require impractically large time delays.

Any attempt at prolonged human space travel would create another major problem: Humans are evolutionarily adapted to gravity, which means that prolonged weightlessness is harmful in many ways, among which are atrophy of muscle (including heart) and bone tissue. In short, these, and other unknown factors, render us physically unequipped for prolonged space travel.


Whether we could be reached by occupants from different galaxies is more speculative but would require the presence of intelligent life elsewhere combined with the need to overcome the barriers just depicted for us.


From the thousands of exoplanets in many galaxies, a few possess conditions that are favorable for life as we know it, i.e., moderate temperatures, water, sunlight, etc. However, meeting these and other requirements is extremely daunting, as we discuss:

Pure reason means that intelligence could only stem from evolution on a planet able to support some form of biologic life and then evolving into an advanced culture. From our experience on earth, the progression from the earliest life forms such as microorganisms to the presence of humans (intelligent life?) has required approximately 3-4 billion years, but the effective component has occurred only in the last 100 years. While it is possible that this process has occurred on one or more of the many distant planets, evolution requires multiple and successive life cycles in which mutations or physical changes allow for serial adaptions more favorable for survival. As this dynamic process proceeds, new generations replace prior ones, with the latter dying off. If the prior generations failed to succumb, that would require immortality, while theoretically possible, it is unknown on this planet. Whether other distant planets could produce immortality is doubtful for two reasons: 1. Failure to expire would prevent progressive species adaptation and further evolution. 2. Additional species multiplication, without the expiration of previous generations, would, by virtue of over consumption of planetary resources, ultimately stifle ongoing evolution. Therefore, since virtual immortality would also be required for any prolonged interstellar travel, it is highly unlikely to be attained anywhere. Although our telescopes have identified millions of planets capable of supporting life as we know it, reaching a stage that would reach or exceed intelligence here on earth would represent a quantum leap. After all, we had “intelligent” beings, represented by dinosaurs, here on earth for about 200 million years, but nothing to rival intelligence as we know it until recently.

Let’s assume intelligent aliens did exist and had spacecraft that could achieve a very high velocity. If a foreign entity were to attain even 30-50% of the speed of light, reaching distances as described would still require prohibitively long times, as exemplified by our reaching a neighboring galaxy cited above. Given our state of knowledge, it’s likely that no living forms, however advanced, could reach even a fraction of this speed with an occupied vehicle. But even if we or others could develop superior technology, such efforts would still be limited by the laws of physics. And if Einstein’s theory is correct, this would preclude travel equaling or approaching, the speed of light. If we extend our present laws of physics to equal light speed, travel of any kind might extend further into the universe, but any biologic organisms would be limited by finite lifespans to merely making observations. This also means that any living biologic aliens are likely subject to the similar laws of evolution, and this fact alone would render any such visits virtually impossible.

But could occupants of a distant planet even reach us with an unoccupied spacecraft or one carrying robots? That is a possibility, but that effort would be subject to the same limitations we would encounter in our attempt to reach distant worlds. There is little reason to believe that a distant life-form would correctly identify the presence of life on this planet, and from the huge distances separating us, they would have little incentive to capitalize on this knowledge, other than merely satisfying curiosity, but even informative radio signals would require inordinate return times to provide useful data or even to direct the control of such distant vehicles or robots.

If there were highly intelligent life on distant planets, we might postulate that they might attempt to contact us through radio signals, also sometimes called “Fast Radio Bursts” (FRBs). Thus far, we have received no convincing signals that could be interpreted as such.

Thus, the idea that aliens could reach us—with or without occupied vehicles—is based upon several speculative assumptions, none of which is realistic! Given our current technology, there is no real likelihood that we could reach distant worlds outside the solar system even with unoccupied spacecraft. If we were able to employ highly advanced robots, the time required to reach distant galaxies employing radio controls and responses would be impractically excessive, given our present limited lifespans. Nevertheless, our tendency to explore all available territory seems to be a universal trait of us humans, and we applaud all efforts aimed at discovery, even if just to satisfy our curiosity. Or, analogous to the example of electricity, maybe such knowledge could lead to things of practical value here on earth! In the meantime, I fear that our preoccupation with UFOs, or UAPs, simply represents science fiction! Or are we metaphorically chasing windmills?

To all you SCIFI and Space junkies out there: Please accept my sincere apologies!


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