At a science fiction convention recently, I heard panellists complaining that most spaceships in science fiction, especially in movies and on TV, just aren’t realistic. And it’s true. But there are some creative concepts that might vindicate some of those fiction writers and moviemakers.

One is the thought that we could someday harness gravity to propel our ships. It’s not a new idea—in H.G. Wells’ First Men In The Moon the main character coats a sphere with an antigravity material, causing it to launch into space, and then opens parts of the coating to allow the craft to be pulled to the Moon by gravity. A slow form of travel, to be sure, but maybe we’ll one day learn to manipulate gravity the way we use light energy in lasers. (Comic strip detective Dick Tracy’s Space Coupes of the 1970’s somehow used magnetism to get to the Moon and back, but I’m not buying it.)

Speaking of lasers, last month Russian internet billionaire Yuri Milner announced plans to spend $100 million to send miniature probes pulled by light sails to Alpha Centauri. Mind you the probes would be little bigger than a computer chip with a sail about a meter wide. They’d be propelled by the light from a gigantic laser array pumping out 100 gigawatt laser pulses, which would push them fast enough to travel the four-light-year distance in about twenty years. It’s not impossible that such technology could be scaled up to propel passenger-carrying craft.

The concept of a faster-than-light “warp drive” isn’t pure fantasy, either. In the mid 1990’s mathematician Miguel Alcubierre conceived of a way to get around the light-speed barrier of Einstein’s theories. It would involve warping space: compacting space itself ahead of the spacecraft and expanding it behind, so it would be the bubble of space contained between these areas of altered space that would actually exceed the speed of light, like a surfer riding a wave. Yeah, it makes my head hurt, too. And the Alcubierre Drive would require exotic materials that might not exist. Still, we can hope.

One of the most interesting and controversial proposals of recent times would answer the problem of fictional spaceships not carrying thousands of tons of fuel. In fact, it would be a total game-changer. It’s an electromagnetic drive now often called the EM Drive (shown in the photo) designed by an English scientist named Roger Shawyer about fifteen years ago, but it’s so revolutionary, and contrary to prevailing belief, that most scientists simply won’t accept that it works. The Shawyer engine uses microwaves bounced around in a sealed chamber to produce propulsion. Established wisdom says that in order to go in one direction in space we have to throw something in the opposite direction. So scientists declare that Shawyer’s device can’t work. Except Shawyer showed that it does. And then Chinese researchers got one to work, and an American inventor showed a working model to NASA, and now a respected German professor has made one that works (though he’s still not sure why it produces thrust). The jury’s still out on the EM Drive, but acceptance is growing, and if it turns out to be workable it just might prove that many of the fictional spaceships we’ve read about in books and seen in movies are more realistic than we thought.

Not X-wing fighters, though. They’re still pure fantasy.