There continues to be a lot of talk and concern about intelligent alien life invading planet Earth. This shows up in news reports about the federal government releasing UFO (UAP) files and in recent movies. Is it possible that extraterrestrial life has visited Earth or is presently visiting Earth?
There is no evidence of intelligent alien life anywhere in our solar system. That means any extraterrestrial visitors would have to come from another star system elsewhere in our Milky Way. We don’t have any evidence, either through SETI or by any of our space telescopes, to indicate that intelligent life could be living on a planet or possibly a moon anywhere closer than many light-years from Earth. The closest star to our Sun is Proxima Centauri, which is 4.25 light-years away. So, any intelligent aliens would have to travel for many years, or possibly centuries, to get here. That assumes they could travel at 10% of the speed of light. Light speed is 186,000 miles (300,000,000 meters) per second. Einstein’s equations, which have been verified, indicate that it is not possible to travel anywhere near the speed of light. In fact, most studies suggest that 10% of the speed of light (19,000 miles per second) is the highest realistic speed for traveling through space.
The reason for the speed limitation involves the laws of physics, engineering constraints, and the amount of fuel required to propel a spacecraft. Because space has no air, traveling through it causes less resistance than traveling through our atmosphere. Once the spacecraft achieves its cruising speed, the propulsion system could be shut down. However, it would have to be used again many years later for deceleration at the end of the journey.
Even though there’s no air in space, there are hydrogen atoms and microscopic-sized grains of dust. Traveling at 19,000 miles per second, those dust particles would hit a spacecraft’s hull like speeding bullets, possibly piercing the hull unless it was sufficiently thick. Even striking hydrogen atoms would produce radiation that could erode the hull. Therefore, the hull would have to be thicker, increasing the mass and requiring more fuel. More fuel adds more weight, so you must add more fuel to compensate for the weight of that extra fuel. It’s a vicious cycle.
All of our rockets that propel payloads into space have used chemical reactions for propulsion. The mass of fuel needed for a spacecraft to reach a velocity of 19,000 miles per second would require more chemical fuel than the mass of the entire observable universe. Therefore, chemical propulsion is not feasible. Nuclear fusion is something that NASA has been working on, and it would be a more efficient way to generate propulsion, but getting a spaceship to cruise at 19,000 miles per second would require nuclear fuel equivalent to 150 times the spaceship’s mass. Therefore, that doesn’t seem like a good alternative. Another possibility would be antimatter propulsion, which exists only in theory. So far, scientists have created only 20 billionths of a gram of antimatter, and it lasts only a fraction of a second. Plus, the cost of producing it runs into hundreds of millions of dollars.
If extraterrestrial life has visited Earth, we would expect it to face many physical problems. Beyond that, there is the time required. If they were coming from a star system 50 light-years away and traveling at 10 percent of the speed of light, it would take them 500 years to get here. Unless these intelligent space aliens have extremely long lifespans, it would have to be a multi-generational trip. They would have to be much better than human earthlings at getting along with each other in confined spaces. They would also need a strong desire to visit our planet. If they were that interested in us, they could send electromagnetic radio waves, which travel at the speed of light.
The intelligence, technology, and physical resources required for extraterrestrials to travel to Earth are enormous. In addition, if they came from a civilization so advanced that they could solve all of these problems, why would they waste all those resources to visit the relatively primitive planet Earth?
Considering the facts, the probability that extraterrestrial life has visited Earth seems extremely slim. However, there is very strong evidence that extraterrestrial life has visited Earth. This planet has been visited by its Creator, and He looked like one of us. We have dealt with the evidence of that visitation many times before, and you can read the story of it in the first 14 verses of the Gospel of John in your Bible.
— Roland Earnst © 2026
Reference: theconversation.com
