Aliens From Another World? Getting Here From There

Aliens From Another World? Getting Here From There

A rising challenge to Christianity, both within and beyond the borders of America, springs from the popular obsession with UFOs (unidentified flying objects) and ETI (extraterrestrial intelligent life).

Growing numbers of UFO and ETI cults, some overtly religious, others with the pretense of purely scientific endeavor, preach their own message of salvation for the human race, a message that directly contradicts—and overtly targets—the Gospel of Jesus Christ.  These cults deny the existence of a transcendent Creator. They deny that salvation comes only through faith in the redemptive work of Jesus Christ. They preach, rather, that hope lies in receiving “guidance” from advanced extraterrestrial aliens, through a book of solutions to all humanity’s problems. Some call it Urantia and say it has already come; others call it Encyclopedia Galactica and await its coming.

As Christian apologists (including those from Reasons To Believe) address university and community audiences in Africa, Australia, Canada, Japan, Russia, Ukraine, and the United States, questions about UFOs and ETI number among the most frequently asked. These questions make sense in light of surveys indicating that UFO sightings worldwide exceed one million per year.1

 Astronomers readily confirm that the vast majority of supposed UFO sightings can be explained by natural phenomena. Only a small fraction of UFOs truly lack any reasonable explanation from nature or from human activity. In the case of virtually all sightings, however, the immediate response of lay people (and even from some scientists) is that superintelligent aliens traveling in sophisticated spacecraft have arrived from the distant reaches of space. “Flying saucers” and “UFOs” are synonymous terms for the vast majority of the world’s population. Flying saucer clubs (and cults) devote themselves exclusively to studying UFO encounters and to promoting the claim that planet Earth has been and continues to be explored by aliens.

How realistic is the notion of interstellar (between planetary systems) or intergalactic (between galaxies) travel—even if we temporarily suspend questions about the possibility of intelligent physical life beyond Earth? Of all the books available on UFO phenomena, few give adequate attention to the properties of space and to the physical challenges of space travel. Such challenges have been underscored by human endeavors of the past few decades, including Apollo 13 and the biosphere experiments. 

Distance Problems

In this day of almost routine success by the National Aeronautics and Space Administration (NASA) in sending spacecraft to Earth’s neighboring planets (not to mention familiar television and movie depictions of space travel throughout the Milky Way and beyond), people may easily lose sight of two facts: (1) the laws and constants of physics set hard limits on any significant space travel by intelligent physical beings; and (2) no amount of technological capability can overcome such limits.

One obstacle to intergalactic or even planetary-system-to-planetary-system travel arises from the enormous distances separating the stars. Distance, of course, translates to time, and time translates to risk exposure. The more time a living or mechanical body spends in space, the more dangers it encounters—deadly dangers.

The nearest star is 25 trillion miles away. If one were to use a grapefruit to model our roughly million-mile diameter Sun, the distance to the nearest star, on this scale, would be the distance from Los Angeles to Managua, Nicaragua. If a person were to hitch a ride to that star on NASA’s fastest (to date) spacecraft, the trip would take 112,000 years.

The nearest stars, however, fail to meet the basic requirements for life support. Sentient physical beings require an Earth-like habitat—one that orbits a single, middle-aged star closely resembling the Sun. This planet’s orbit must be nearly circular, not too eccentric. The planet must be shielded from asteroid bombardment by a massive companion planet (such as Jupiter) but cannot be bounced around by the gravity of that protector planet. Many more criteria could be listed, but these suffice to make the point.2 No star within about 50 light-years of Earth can meet these requirements. Those with a mass similar to the Sun’s are either too young or too old to burn with sufficient stability.3 They possess partner stars or huge nearby planets that would disrupt the orbit of any Earth-like planet, or they lack large protector planets.4

Even if intelligent beings were to reside a mere 50 light-years distant, they would have to cut a zigzag course through various galactic hazards to reach planet Earth, making their trip considerably longer. Incoming travelers would have to dodge the gravity and deadly radiation of neutron stars, supergiant stars, nova and supernova eruptions, and even the remnants of such eruptions. They would have to avoid the gas, dust, and comets so dense in the spiral arms, as well as the environs of late-born stars (stars formed during the past 5 billion years). But, they would have to stay in the plane of the galaxy. Any departure from the plane would expose the travelers to the deadly radiation that streams from the galactic core. Maneuvering to avoid hazards would extend the minimum distance to an estimated 75 light-years.

Recent findings, however, push that minimum figure even higher. Based on the assumption that any interplanetary craft would likely maintain communication with the home planet (or with other members of the traveling party), a SETI (search for ETI) research group scanned all 202 of the solar-type stars (roughly similar to the Sun) within 155 light-years of Earth. Not one intelligible signal was detected anywhere within the vicinity of each star.5 This finding translates to a minimum alien travel distance of 155 light-years plus hazard-avoidance maneuvers, a total of roughly 230 light-years (or 1.36 quadrillion miles).

Speed Problems

As some readers may remember from their high school science classes, the laws of physics forbid any chunk of matter from traveling faster than the velocity of light. Serious difficulties arise, however, long before an object reaches that speed. At the velocity of light, the energy required to move a specified mass is infinite. At even half the velocity of light, the energy needed to propel an object is several million times greater than NASA’s fastest spacecraft requires.

The energy problem compounds, however, because propellants and engines involve mass. The higher a spacecraft’s speed, the more propellant and the bigger the engines it requires. Therefore, the higher the intended speed of the spacecraft, the (exponentially) higher the mass of the craft.

An additional mass problem arises from the need to move the spacecraft’s payload (the total weight of the passengers, crew, instruments, and life-support supplies). The mass of a craft and its propulsion system rises geometrically relative to the mass of the payload.

The need for speed poses yet another problem: The faster an object travels through space, the greater its likelihood to suffer damage from space debris. Micrometeorites, for example, punched holes the size of silver dollars in the Hubble Space Telescope’s solar panels (while the Hubble was traveling at about 0.04 percent the velocity of light relative to the micrometeorites, and about 0.003 percent the velocity of light relative to Earth). If the telescope had been moving a thousand times faster (relative to the micrometeorites), the damage would have been a million times worse. (I.e., the damage increases with the square of the velocity increase.)

In terms of space debris, micrometeorites may be the least of a space traveler’s worry. A large cloud of comets, estimated to contain 100 billion comets or more, surrounds the solar system. Such clouds very likely surround any star in our galaxy that could possibly harbor planets. Astronomers suspect that the giant molecular clouds scattered throughout the Milky Way galaxy may contain even greater numbers of comets.

To protect against damage from space debris, a spacecraft needs some kind of armor. However, armor means more mass, which means more propellant to move the added mass. More propellant means more propellant to move the extra propellant. Thus, the problem escalates.

While space debris poses a lesser risk at lower velocities, lower velocities also mean greater travel time. The probability of damage from space debris rises in proportion to the amount of time spent in space—and, it rises by the square of the velocity. Therefore, in terms of damage from debris, space travelers face deadly dangers at any velocity, slow or fast. And, slow or fast, a spacecraft will suffer general wear and tear to its component parts.

Exposure to radiation poses yet another serious threat. The faster a craft travels through space, the greater the damage it suffers from radiation. The particles associated with radiation (e.g., protons, neutrons, electrons, heavy nuclei, and even photons) cause erosion to the “skin” and components of the craft. Again, the rate of erosion rises with the square of the velocity. However, a slower velocity means more time in space, and that extra time means more radiation exposure for the aliens on board. (No matter how thick any practical safety shield may be, some radiation inevitably leaks through.)

Very conservatively, any reasonably sized spacecraft transporting intelligent physical beings can travel at velocities no greater than about one percent the velocity of light. At higher velocities the risks from radiation, space debris, leaks, and wear and tear are simply too great to prevent the extinction of the space travelers before they reach their destination. A spacecraft traveling at one percent the velocity of light (nearly 7 million miles per hour) would need 7,500 years to traverse 75 light-years or 23,000 years to travel 230 light-years.

Loopholes Via Wormholes?

Highly imaginative and technically trained UFO and ETI buffs suggest that advanced aliens may have found a way to use space-time “wormholes” to travel to distant locations in the universe in a relatively short time. On closer examination, however, this idea offers no help at all in solving the distance and time problems.

General relativity says that massive objects distort the curvature of space and time in their vicinity. The greater the mass-density of an object, the greater the degree of space-time curvature it produces in its immediate vicinity. General relativity predicts that when matter becomes sufficiently compressed by its own gravity (as in a black hole), a discrete region of space-time will develop where the curvature becomes infinitely sharp (Figure 1). That is, a singularity (region where the mass density and space curvature become infinite) will develop at the center of the mass concentration.

If a black hole connected to one sheet of space-time in the universe happens to make contact with another black hole connected to a different sheet of space-time, that point of contact may (hypothetically) offer a travel corridor. The point of contact, however, must be singularity to singularity (Figure 2) so that a traveler funneling into the center of one black hole can come into contact with the center of another black hole.

While these so-called wormholes connecting one black hole to another black hole are mathematically possible, one must question the physical practicality (not to mention plausibility) of their use by alien travelers. According to the best-established models for the universe, regions of space that could be connected via wormholes are already close to one another. In other words, the use of a wormhole would offer little time advantage. One cosmic model in which a ten-dimensional space-time sheet bends to make a U (Figure 3) offers the possibility of a significant shortcut through space, but ongoing research has yet to verify the viability of such a model.

Social Considerations

At 7,500 years (minimum) for a one-way trip from their home to Earth, space aliens would no doubt face some daunting social challenges. Longevity anywhere within the confines of the universe must be finite, not infinite, according to the laws of physics. Moreover, life spans inevitably decrease with exposure to radiation such as space travel yields. The complexities of carbon-based biochemistry (the only possible chemistry for physical life)6, 7 set life’s limit at about a thousand years—even if traveling aliens were to hibernate for long periods.

A journey across more than 75 light-years would extend through multiple generations. A multi-generational journey presents another set of difficulties. Whether or not the original voyagers volunteered for the mission, their progeny would receive the mission by inheritance, not by choice. Like it or not, the mission is theirs. If space travelers were to resemble humans in any way, one can easily imagine that dedication to the original goals might be difficult to maintain. Changed or confused priorities would likely add to the trip’s duration, among other difficulties. They might even lead to aborting the journey. 

A multi-generational strategy for space travel requires a sufficiently large and diverse base population for the initial passengers. Otherwise the aliens would probably become extinct before their craft reached its intended destination. And, a population of any size, from 2 to 20,000, requires various resources and systems for sustenance. At a minimum, these resources and systems must include food and respiration products and waste recycling, and all must be maintained at sufficient levels to minimize the risk of ecological disaster. 

Survival Problems

A one-way trip that takes 7,500 years or more raises serious doubts about the alien travelers’ survivability. The extinction risk, given the limited population and all the contingencies of space travel, seems overwhelming. As humanity has discovered during the past fifty years, a civilization advanced enough to launch a trip through space may not survive long enough to even build a transport and get it off the ground. High technology carries a terrible price: reduced survivability.

High technology and resultant high living standards mean individuals carrying deleterious mutations typically survive long enough to reproduce. High technology and high living standards strongly encourage both men and women to delay reproduction. In a high-tech world, an individual needs more time to be educated and trained for self-sufficiency, even more for making a contribution to ongoing technological advance.

Delayed reproduction, particularly for males, results in transmission of increased numbers of deleterious mutations.8 According to one research study, the human population at the close of the twentieth century suffered an accumulation of deleterious mutations measuring three per person per generation.9 This rate significantly accelerates humanity’s movement toward extinction.

To make matters worse, wealth and technology inversely correlate with the birth rate. In other words, the greater a society’s wealth and the greater its use of technology, the fewer offspring it produces. Today, not a single nation with a per capita income exceeding $20,000 has a birthrate high enough to prevent eventual extinction. In Europe and Japan, for example, the birthrate is less than 75 percent of that needed to maintain the population at a constant level.10

For space travelers all these problems are compounded by limits on the size of their traveling party. Whereas six billion people living on a large planet can tolerate epidemics, natural disasters, ecological crises, and wars, a few (or few thousand) individuals on board a space ship or cluster of space ships would likely be wiped out by such catastrophes. Humanity holds the added advantage of having a large habitat with a wide variety of refuges where one can find temporary escape from a given problem or disaster.

These extinction risks suggest that for distant stars and planets, technology sufficient for space travel is much more likely to doom a society’s destiny than to fulfill it. Intelligence would tell such aliens to stay at home or to limit their colonization efforts to their own planetary system.

Technology Problems

Obviously, the problems of damage by space debris, radiation, leaks, ecological breakdown, and wear and tear are much worse for intelligent physical beings on board spacecraft than for mechanical instruments. If gathering (or giving) knowledge is the goal, men typically have the advantage over machines in that they can adapt more quickly and successfully to changing circumstances and unexpected contingencies. However, as the travel distance increases, the advantage shifts: the greater the difficulty of transporting people relative to machines, the less adaptable the people become.

Even for exploration of our own solar system, machines hold a huge advantage. For visiting the moons of Jupiter (less than 0.0001 light-years away), at least ten thousand instrument missions can be sent for the cost of one manned mission. If something goes wrong with an instrument on such a mission, no one dies (though someone may lose a job). If the instruments detect something they were not designed to probe, another set of instruments can be designed and sent out. If circumstances warrant a longer stay, it can be accomplished with little redesign or extra provisioning, in most cases. A few men on a month-long mission are likely to learn much less about a planet or a moon than would ten thousand space instruments operating over many years.

This kind of analysis would not be lost on aliens more advanced than humans. If aliens exist on distant planetary systems and have some interest in planet Earth, they would more likely send machines than members of their own species.

Call for Further Research

This brief analysis of the feasibility of long-distance space travel may not account for all the significant factors, and time will tell whether its calculations and estimates are too optimistic or too pessimistic. It does demonstrate, however, that a little time in the library with a calculator can bring some realistic considerations to questions about UFOs and ETI. Taxpayers’ money would be more wisely spent on this relatively inexpensive research than on costly probes for alien signals or ships.

Programs designed to systematically discover and explore the characteristics of distant planets would be most helpful. Astronomers have determined the masses and orbits for over sixty planets outside Earth’s solar system.11 Moreover, NASA has been promised funding to send an array of telescopes into space that will have the capacity, not only to measure the masses and orbits of Earth-sized planets orbiting distant stars, but also to determine their rotation rates and the composition of their atmospheres.12

Consider the Motive

The compelling interest in UFOs and ETI seems rooted more deeply in spiritual concerns than in scientific ones. Origin-of-life researchers now acknowledge the virtual impossibility of any natural explanation for life’s origin on Earth, on Mars, on any solar system body, or anywhere among the comets or interstellar clouds.13 The additional finding that microorganisms could not have been transported across interstellar space (radiation pressure from stars would inevitably have killed them) effectively seals the case.14

The ironies seem too great to ignore. An obviously spiritual quest accounts for huge research expenditures of both government and private funds. As long as that quest opposes, rather than supports, Christian doctrines, no outcry arises from the separation-of-church-and-state camp. The greater irony is that humanity already holds in its hands all the information and instructions needed for the best possible life on this planet, as well as for life beyond. This “extra-cosmic encyclopedia” was delivered to humans by God’s Spirit and corroborated with tangible evidences. To ensure humans understood and received it, the Creator Himself personally visited this planet two millennia ago, in human, not alien, form. He revealed—in Himself—the source of answers to life’s greatest questions and challenges.

  1. Jacques Vallee, Dimensions (New York: Ballantine, 1988), 230-31.
  2. Hugh Ross, The Creator and the Cosmos, 3d ed. (Colorado Springs: NavPress, 2001), 176-87.
  3. NASA catalog of the 2613 known stars within 81 light-years of Earth, Web site address:
  4. Jean Schneider, Extra-solar Planets Catalog, a frequently updated Web site catalog at
  5. Christopher F. Chyba, “Life Beyond Mars,” Nature 382 (1996), 577.
  6. Robert Dicke, “Dirac’s Cosmology and Mach’s Principle,” Nature 192 (1961), 440.
  7. Ross, Creator, 178.
  8. James F. Crow, “The Odds of Losing at Genetic Roulette,” Nature 397 (1999), 293-94.
  9. Adam Eyre-Walker and Peter D. Keightley, “High Genomic Deleterious Mutation Rates in Hominids,” Nature 397 (1999), 344-47.
  10. John W. Wright, ed. The New York Times 2000 Almanac (New York: Penguin Reference, 1999), 487.
  11. Schneider.
  12. Bijan Nemati, “The Search for Life on Other Planets,” Facts for Faith 4 (Q4 2000), 22-31.
  13. Fazale Rana and Hugh Ross, “Life from the Heavens? Not This Way . . .” Facts for Faith 1 (Q1 2000), 11-15.
  14. Paul Parsons, “Dusting Off Panspermia,” Nature 383(1996), 221-22.