Don't pack your bags: we're staying right here

I'm a normal guy. I like science fiction, but there's a lot more fiction than science in a good deal of it, especially when it comes to space travel.

Now, I'll grant right from the start that there are some loopholes and fig leaves the starry eyed believers can rely on for a glimmer of hope, but the truth is rather glum when it comes to traveling to explore the stars.

I'm not going to throw formulae at you because you probably wouldn't understand them any more than I would. I'm trained in philosophy, not astronomy, physics, or astrophysics. I barely passed algebra before I majored in art in high school.

Even so, I'll tell you some things you should know, and probably would know if you'd spend more time on the Discovery or Science channels and less time watching sitcoms or sports.

The nearest star, Alpha Centauri, is nearly 4.4 light years away. That means that the fastest thing we know of, light, takes more than four years and four months to get here. Nothing other than light travels this fast, and in fact traveling at anything even close to the speed of light is impossible, because the closer you get to the speed of light, the more energy it takes to go that little bit faster, until there simply isn't enough energy available to accelerate any more.

It'd take hundreds, thousands, or millions of years to get anywhere else we might want to go outside our solar system. What are people on Earth supposed to be doing? Waiting for the space travelers to come home and file their report?

But let's imagine that you could go close to the speed of light. Other problems arise. You see, while we think of space as a vacuum, it is not a true vacuum. After all, we and all the stuff in the Universe are in it. Leaving aside gross objects like galaxies, stars, planets, moons, meteors, comets, and so forth, we know that there is space dust out there, and that there are free-floating atoms as well. At 3/4 the speed of light (to take an arbitrary speed), it might be possible to detect and avoid hitting an object the size of a star, planet, or moon, but how about a rock the size of a football? And what would such an object do to a spacecraft that hit it at such a speed? Well, consider hitting a much smaller object...

Astronomer Frank Drake wrote, "At relativistic speeds, even a collision with a particle of a few grams results in something close in energy to a nuclear bomb blast."

It doesn't stop there. Isaac Asimov wrote: "When you begin to approach the speed of light, hydrogen atoms become cosmic-ray particles, and they will fry the crew....So 60,000 kilometers per second may be the practical speed limit for space travel."

While we're talking about cosmic rays, let's talk about gamma rays. They are not so good, either, and together they cause cellular damage, having a very bad effect on the nervous system. Gamma rays are very difficult to shield, requiring at least 10 cm of lead to reliably stop them. A craft of any size with a 10 cm thick lead hull, or lead shielding sufficient to protect a substantial living area, would likely be far too heavy to get us where we want to go.

So, we probably won't go anywhere because of the near impossibility of shielding ourselves from cosmic radiation.

Let's suppose the radiation problem is solved and we're off to Alpha Centauri at a conceivable rate. Some scientists are quoting 40 to 44 years. And that's to reach the closest star system. Stop to think about how impractical such a long trip would be. Cryonics exist in the movies, but hibernating people for 40+ years is a technology that seems far, far off if it's possible at all, which is doubtful.

How about shortcuts? Frank Herbert's navigators in Dune puffed on a magical spice and got so high they could fold space, making travel even from one end of the Universe to the other a momentary thing. Stephen Hawking's postulation, later proven, of black holes in space showed a way to disappear into the opening of a black hole, and while no one knows for sure where matter going into a black hole ends up, one theory is that the black hole is merely the mouth of a so-called "worm hole," which dumps it elsewhere far, far away, perhaps extremely far away.

Science fiction writers have jumped on the black hole/worm hole thing to postulate that given the appropriate information and technology, you could simply surf into a black hole and end up somewhere else in one piece. These guys have obviously not considered what happens when you cross the "event horizon" of a black hole (the point of no return, where it's no longer possible to escape a gravitational pull so strong it can even capture light).

Physical integrity is lost as an object descends into the black hole, and finally the intense gravity tears it apart. Since anything with the information required to reassemble that object would be destroyed, too, there really isn't much hope for coming out someplace else in one piece. Perhaps as a burst of energy, but not as a spacecraft.

No, we are not going anywhere. Not a couple or a few of us, and certainly not all of us! So, we'd better figure out how to make things work here on Earth or being an Earthling will be just a passing fad.