Yes! Love The Thought Out Behind Space Travel Here.

Yes! Love the thought out behind space travel here.

Thought on science fictional hyperspaces:

So, like a lot of science fiction writers, in a couple of my science fiction settings I explain “fast” interstellar communication and travel by saying it involves sending messages and spacecraft through “hyperspace.” Hyperspace is a sort of “basement” of our universe that messages and ships can pass through; it is more compact than our space, and there is a correspondence between locations in hyperspace and locations in our space. So, a ship can enter hyperspace, travel a few hundred or thousand AU or a light year or something, go back to our space, and be in the Alpha Centauri system. This is possible because hyperspace offers a possible path where e.g. the distance between our solar system and Alpha Centauri is less than 4 light years; hyperspace is a cosmic short-cut. You can send radio messages through the same short-cut, if you stick the right parts of the transmitter and receiver into hyperspace.

So far, so I good, but like a lot of science fiction writers I also prefer to limit hyperspace travel so it’s more-or-less useless for relatively short journeys, e.g. between planets of our solar system within the orbit of Uranus. This is mostly because I like that hard SF stuff where space travel within a solar system is treated relatively realistically and a solar system still feels big. I’m OK with hyperspace for letting my characters get to Tau Ceti in less than twelve years, but when it comes to asteroid mining, space battles, etc., I want that stuff to work more-or-less like it would in real life. Larry Niven had a nice approach for this: just say you can’t enter or exit hyperspace close to a large mass, so e.g. you can’t enter or exit hyperspace within 20 AU of our sun. To travel to Alpha Centauri through hyperspace you have to travel out beyond Sol’s hyper-limit, then go into hyperspace and take the hyperspace short-cut, then exit hyperspace outside Alpha Centauri’s hyper-limit, then travel the rest of the way in our space. A hyper-limit limitation on hyperspace travel works well for me. I’m less satisfied with it as a limitation on hyperspace communication though, and a few days ago I had an idea for that which I like.

It came to me as I was thinking about how hyperspace travel is kind of analogous to being able to travel through the interior of a sphere instead of being limited to travelling on its outer surface. If you have a sphere the size of Earth and you want to get to a point on the exact opposite side of it, if you have to travel along the outer circumference that’s a journey of 40,000 kilometers, but if you could travel in a straight line through the center of the sphere that’s only 12,750 kilometers. Travelling from Sol to Alpha Centauri in our space is analogous to being limited to travelling along the outer circumference of a sphere, making the same journey through hyperspace is analogous to taking a short-cut through the interior of the sphere.

And it occurred to me to mentally pull on one feature of this analogy: a short-cut through the interior of a sphere would be much more useful for long journeys than for short ones. Again, let’s say the sphere is the size of Earth. If you only want to travel one meter, the difference between a path along the outer circumference of the sphere and a short-cut through its interior is very small. A 1 meter path along flat ground is pretty close to being a straight line. On the other hand, if you want to get to the other side of the sphere, the path along the sphere’s outer circumference is more than three times as long as the path through the center of the sphere.

And I had the idea: what if hyperspace works in a way that’s analogous to that? Maybe the distance between, say, Earth and Jupiter is analogous to a 1 meter distance on the surface of the Earth; so small that the shortest possible path through hyperspace is almost as long as the shortest possible path through our space. Then the distance to Alpha Centauri might be more analogous to a journey across a large fraction of Earth’s circumference; it’s big enough that the shortest possible path through our space is orders of magnitude longer than the shortest possible path through hyperspace. The geometry involved is probably a lot less straightforward than spherical geometry to humans, so for short distances the relationship between our space distances and hyperspace distances might even invert; you might have a set-up where 100 light years in our space is 5 light years in hyperspace, 4 light years in our space is 1 light year in hyperspace, and 1 AU in our space is 4 AU in hyperspace.

This might get you a set-up where you can have relatively fast interstellar communication and travel, but within the orbit of Neptune (or equivalent distance) you’re stuck dealing with light lag.

It would also have the interesting effect that hyperspace travel gets faster for longer journeys. A 1 year voyage might take you to Alpha Centauri, a 5 year voyage might take you 100 light years, a 20 year voyage might take you to the other side of the galaxy, a 100 year voyage might take you to a distant galaxy billions of light years away.