IIRC, if you create matter out of pure energy, anti matter will appear, since they're like twins of each other, evil one that is.

Nuclear fission produces a tiny amount of anti-matter too but it's so little that, bgeh's mentioned 'nanogram' sounds like a few megatons in perspective

Space exploration is possible if we can achieve a self-sustained ecosystem on the ship or so. Energy will be important as everything solid can be recycled into their original state with the proper amount of energy. Can't rely on solar, no sun no juice. Fusion is good but there aren't proper working generator and it also require fuel.

You will also need to have enough material in cycle to sustain life. If say an entire ship will depend on grain as food, you'll need to have enough of grain to feed the human while newer grain grow and so on.

After all that, you have to handle the ravage human instinct. Munity is just too stupid if you're on a mission to save human race.

Headache

There are several advantage building in space.

Building in space meaning the ship do not have to cope with gravity, only the force of the ship's acceleration/deceleration, thus saving material.

Modular configuration, the world's most expensive lego set. Like the ISS

Design doesn't need to be aerodynamic since there aren't air resistance, sure there's space dust but that's a small amount unless you're zooming across space really fast.

Traveling through wormhole is still a theory. We are having difficulty proving wormhole's existence let alone manipulate it to travel through

Even such technology exist, you still need to physically travel to your destination to build the 'gate', so it's still back to the good old rocket riding.

This post has been edited by SeaGates: Jul 4 2009, 08:08 PM

Natural wormholes that have been theorized with eccentric characteristic. They appear and disappear at their own will, having random exits, and maybe it even takes you to nowhere. It's like playing Russian roulette with a semi automatic weapon.

So the best way to travel is probably through one that is being artificially sustained/created.