Intergalactic Space Travel...Meet Physics

Intergalactic Space Travel...Meet Physics ―Klaus Schiessel

WHEN WE PICTURE ALIENS VISITING EARTH, most of us are really picturing Hollywood: zippy saucers, warp drives, and starships dropping by like we’re just off the intergalactic highway.

Since I don’t have the expertise or background to address this, I will summarize an article[1] written by Klaus Schiessel, an engineer with an extensive career in Aerospace Systems and Physics. In his article, he pushes back against the whole Hollywood image, not by talking about conspiracies or cover-ups, but by looking at something much more stubborn: physics.

Schiessel begins with two big claims about life itself. First, he argues that planets like Earth, with the right conditions for life, are incredibly rare—on the order of 1 in 100 million. Second, he says the complexity of DNA is so extreme that, in his view, it couldn’t have arisen by random processes alone. You don’t have to agree with either of those starting points, though, to follow where he’s really going. He then says: even if we assume there are other inhabited planets out there, the challenge isn’t just “Is there life?” but “Could that life ever physically get here?”

To answer that, he starts close to home. If aliens were visiting us, the simplest explanation would be that they come from somewhere else in our solar system. But one by one, our neighboring worlds don’t look promising. Mercury and Venus are roasting, hostile worlds; Venus in particular has a thick, poisonous atmosphere and crushing pressure. Jupiter, Saturn, Uranus, and Neptune are giant balls of gas, with no solid surface to stand on and toxic atmospheres. Their moons are mostly frozen, airless, and desolate. Mars is the least bad option, but still a stretch: it’s cold, has a very thin atmosphere made mostly of carbon dioxide, and so far, we haven’t found any clear sign of life there. If that’s our local neighborhood, it’s hard to imagine that visiting aliens are just popping over from the planet next door.

So, if they’re not from here, they’d have to be from somewhere outside our solar system. That’s where the scale of the universe really kicks in. Once you look beyond the Sun and its planets, distances stop being measured in miles or kilometers and start being measured in light‑years—the distance light travels in a year is about 5.88 trillion miles. Our Milky Way galaxy is roughly 100,000–180,000 light‑years across and contains hundreds of billions of stars. Our own solar system sits about 26,000 light‑years from the galactic center. The nearest star system, Alpha Centauri, is more than 4 light‑years away.

Even if you had a spaceship that could somehow travel at the speed of light (and we’ll get to why that can’t happen), your travel times would still be enormous. It would take over four years just to reach the nearest star. It would take around 26,000 years to come from the center of the galaxy to our location. It would take tens of thousands of years to cross the Milky Way, and tens of millions of years to hop between distant galaxies. This isn’t like flying from New York to Tokyo; it’s more like trying to walk from here to a different universe.

Those huge timescales lead to brutal practical problems. A journey that lasts tens of thousands of years means either hundreds of generations living and dying on the ship, passing on knowledge, culture, and maintenance skills over millennia, or some form of almost perfect suspended animation or cryogenic technology that can keep living beings intact for tens of thousands, maybe millions, of years—without a single catastrophic failure. On top of that, the ship would need staggering amounts of fuel or some other powerful energy source, and life‑support systems for food, water, air, and waste that work flawlessly for longer than human civilization has yet existed. That suggests vast “generation ships” or “mother ships,” more like mobile ecosystems than vehicles, not the small, nimble “flying saucers” people commonly report seeing.

Our own technology helps illustrate just how hard this is, even at low speeds. The Space Shuttle needed five engines and huge fuel tanks to reach about 18,000 mph, fast enough to orbit Earth but only about 0.003% of the speed of light. The Saturn V rocket—the monster that launched astronauts to the Moon—could push a spacecraft to around 25,000 mph, still only about 0.004% of light speed. If you pointed a Saturn V–class ship at Alpha Centauri and just kept going at that speed, it would take over 100,000 years to get there. So with the mightiest rockets we’ve actually built, interstellar travel isn’t just slow; it’s essentially geological in timescale.

You might respond that aliens, if they exist, would be far more advanced than we are. Maybe they can get close to the speed of light. This is where Einstein steps in. According to special relativity, as any object with mass speeds up, it takes more and more energy to keep increasing its speed. Near everyday speeds, that’s not a big deal. But as you get closer to the speed of light, the energy required increases dramatically. In the limit, trying to accelerate a massive object all the way to light speed would require infinite energy. “Infinite” here isn’t just a big number—it's literally impossible. That means no spaceship, no matter how advanced, can be pushed to or beyond the speed of light simply by firing engines harder. There is a speed limit for massive objects in our universe, built right into the laws of physics as we understand them.

The numbers get extreme very quickly, even if you aim lower than the speed of light. The author points out that accelerating just a single pound (about half a kilogram) of material to half the speed of light would take about as much energy as detonating roughly a hundred atomic bombs. Now imagine a serious starship, something on the scale of the Star Trek Enterprise, with a mass of hundreds of thousands of tons. To get that up to half the speed of light would require energy comparable to tens of billions of atomic bombs. Getting it up to an ultra‑high fraction of the speed of light would push that into the trillions. And remember, that’s just the energy to speed up. You’d need another similar push to slow the ship down safely when it reaches its destination.

Science fiction often jumps past all of this with concepts like warp drive or hyperspace: faster‑than‑light travel that compresses those ridiculous journey times down to something manageable. But if we’re talking about simply pushing a physical ship with engines faster than light, we’re back to the same brick wall: relativity says a massive object can’t reach light speed at all, much less exceed it, because you run straight into that infinite‑energy barrier.

Even if you bend the rules for the sake of argument and imagine that somehow you could zip around at 10, 100, or even 1,000 times the speed of light, the universe is so big that the travel times are still enormous. Ten times the speed of light might let you cross our galaxy in thousands of years. Even at 100 or 1,000 times light speed, you’d still be talking hundreds or thousands of years to get to a nearby galaxy like Andromeda, which is about 2.5 million light‑years away.

When you put all of this together, the picture that emerges is very different from what we see on screens. In this view, life‑friendly planets are rare, our own solar system looks lifeless aside from Earth, and the cosmos is so unimaginably vast that even light itself takes ages to get around. Building ships that could keep living beings alive and functioning for tens of thousands of years is far beyond anything we know how to do, and perhaps beyond what’s practical for any civilization bound by the same physics. And those same physics say you can’t accelerate a massive object up to the speed of light without infinite energy—and even going at “only” a significant fraction of that speed demands energy on the scale of billions or trillions of nuclear weapons for a single large starship.

From that perspective, given what we currently know about the laws of nature and the size of the universe, the idea that aliens are routinely traveling here in physical spacecraft from distant star systems or galaxies isn’t just unlikely. It’s, for all practical purposes, impossible.

To wrap this up, I [Jay] want to leave you with a thought I often share when I teach from the Book of Revelation.

In Revelation 20:11–14, we’re taken beyond the Millennial Reign to the scene of the Great White Throne. John describes the One seated there—God Himself—and says that from His presence “the earth and the heaven fled away, and there was found no place for them.” In other words, the entire created universe—every star, every galaxy, every solar system—simply ceases to exist at God’s command. That chapter of creation is closed. It’s over.

What remains? Not planets, not galaxies—only people. The souls of all who have ever lived on the earth now stand before their Creator for the final judgment.

Here, all of humanity is judged “according to their works.” This is not the judgment of the saints, but of all who have rejected God throughout history, all the way back to Adam. Their lives are measured against one ultimate standard: whether their names are written in the Book of Life.

Once this judgment is complete, the very next words we read are: “Then I saw a new heaven and a new earth, for the first heaven and the first earth had passed away” (Revelation 21:1). Notice the order: the old universe and the present earth vanish; only the people who lived on the earth remain before God; then God creates a new heaven and a new earth.

So where are the aliens in all of this? When Scripture describes the final judgment and the eternal home of God, it speaks only of humanity—those who have lived on this earth. There is no mention of other sentient beings, no parallel race from distant galaxies entering into this eternal scene. According to the biblical record, they simply are not there.

[1] Klaus Schiessel―The UFO Enigma Exposed: The Physical Impossibility of Intergalactic Space Travel, 2018