Orphans of the Sky by Robert A. Heinlein

If you can build a huge, indefinitely self-sustaining planetoid of a ship, why would you need to go anywhere with it? I guess there's that little matter of being sent to the converter... Best to stick around the asteroid belt and mine for raw materials.

Off topic, is it an unwritten rule that the cover art of all science fiction books must directly contradict at least one detail of story?

Absolutely true! One of Harry Turtledove's latest books, "Liberating Atlantis" has pictures of dueling ironclad ships (ca. US Civil War) on the cover. Nothing even close to an ironclad appears in the book.

Clive Cussler's latest "Oregon" Novel has a picture of a submerged Chinese junk under water with warm water fish swimming around it. Without giving away the plot, it's a huge contradiction.

In addition to what Art said: any spaceship that could travel faster than light is also a time machine, and that's a no-no.

Alastair Reynolds is a good example of a science fiction author who pushes against the limits of known physics mercilessly but does not cross them. His book House of Suns has a character explaining at length why there can be no faster than light travel: I suspect that Mr. Reynolds got tired of fan mail asking why he didn't just use spaceships with warp drives...

With current technology, pretty much.

The Apollo missions traveled at roughly 3300mph to get to the moon in three days. At that speed, it would take roughly 800,000 years to reach the Centauri system, 4 lightyears away. (A lightyear is approximately 5,800,000,000,000 miles.)

Our fastest space probes ever are the Helios probes, but they are orbiting the sun. The only ones heading out into interstellar space are the Voyager, Pioneer, and eventually the New Horizons probes. The fastest of those is Voyager 1, at about 38,600mph. But even it would still take about 4,500 years to reach Centauri, if it were pointed that way.

There are some promising alternative drives on the drawing boards, but even they don't get an interstellar journey down to a single lifetime.


That's why Science Fiction usually uses one of the various workarounds Art described: FTL ("Faster Than Light") travel, some kind of jump/wormhole shortcut, or "Generation Ships".

or the speed problem could be solved in one of those head slapping "we should have thought of this before!!"moments and we will be fishing for Gerblatzo in the yellow seas of terra 44 in a couple years.Physorg.com is a good place to restore you faith in science,posts like--nano tubes line up in pulses of light--give you the idea that old moon shot science is,well,old science.now if someone could come up with a SPOT that would beam me to an ER------

Rather than travel outside the solar system, maybe it would make more sense to grab another planet in our solar system and insert it into Earth's orbit. Add atmosphere and start planting! ;-)

Sue

Good call on Physorg.com. Lots of good stuff there. Certainly if we ever do colonize another solar system it will be a result of some combination of physics and engineering we don't, or only vaguely, understand presently.

If staying alive when faced with the normal stuff, like hurricanes and earthquakes, is Survival 101 and surviving a nuclear war is Survival 301 living on the moon would be Survival 601. Which makes extra-solar colonization Survival 1201. We have, as a species, barely begun to master our environment enough to prosper. It has only since the 1800s that we haven't been in a constant existential battle with famine and disease. We haven't conquered them. But our booming population shows we are no longer on the edge of extinction.

It seems to me that most of the biggest problems we face in the near future, outside a cosmic boot stomping us, have to do with human behaviors. Can we learn to get along? Can be live together? Can we control our consumption, greed and desire to reproduce enough to avoid being caught in a downward spiral of conflict, violence and destruction over ever scarcer resources?

IMHO the most important results of the space program were the photographs of the earth taken from the moon and Jupiter. The first shows the globe we know suspended in blackness. The second a tiny blue-green speck in a field of stars. We live on a planet-ship, a multi-generational star ship. Until we can build or find a replacement it is all we have to work with. We are living on a space capsule. A lifeboat on a vast empty sea. We either make it work ... or we don't.

One could think of our solar system as the real spaceship as we need most elements in it to survive (ie Jupiter sweeping up cosmic bullets). The system is going places -and pretty fast. Our Galaxy will be meeting up with others in a pretty short time on the cosmic scale.

Unfortunately that's unlikely. One strong argument that current science is correct in saying the problem is fundamentally hard is the question "Where are the tourists?"

If travel between stars were practical we'd expect to be inundated by bug-eyed monsters wearing Hawaiian shirts toting cameras touring the galaxy. Even if some follow an alien Prime Directive it only takes one who doesn't. Yet nothing of the sort is seen outside of Hollywood.

This is all wrapped up in the Fermi Paradox and nobody knows the answer(s). But one implication of the lack of tourists is that such travel really is as hard as it appears and there is no easy solution.

I've always asked myself "Why would beings capable of crossing interstellar space stupidly crash when they get here?"

Then I thought of a possible explanation: The ones that crash are irresponsible alien teenagers out joyriding in Dad's UFO.