Wednesday, June 18, 2014

Interstellar Fortresses and Starship Combat

Shields, forcefields, and screens of various kinds adorn much of science fiction that deals with interstellar travel. There's a literary reason why this is so. As per the linked New Scientist Article, while there are on average only 2 hydrogen atoms per cubic centimeter in the vacuum of space (Earth's atmosphere at sea level is 15 billion billion times as dense), a ship going near-light speed would slam into so many hydrogen atoms that the effect would be like standing directly in front of the business end of the Large Hadron Collider. At a high percentage of the speed of light, a human being would receive a lethal dose of radiation in far less than a second.

The way stories have dealt with this phenomenon for the most part is to imagine some future design using a force, unknown to today's physics that conveniently blocks all that pesky radiation. In a future post I'll talk about what I think the best candidate for such a design would be, but for now let's say that any concept of a screen or field or force that could block very high radiation or futuristic weapons fire has no basis in scientific reality. Shields and forcefields just don't work. (Note that not all writers of science fiction have employed them--there has been plenty of realistic writing about space combat, but those stories may not be as well-known to the general public.)

The problem with shields and fields doesn't mean starships could not exist. It might limit their velocity, to say, 10% the speed of light. Using wormholes or "gateways" (yes, also problematic in theoretical physics, but let's ignore that for the moment) could make traveling anything near the speed of light unnecessary anyway.

So humans, assuming the apocalypse doesn't come first, will probably sooner or later design vessels that travel between stars. And before that, in between planets. We can imagine these future humans will have no need for weapons, space fortresses, and space vessels designed for combat. But a brief examination of human history strongly suggests that wherever human beings go, warfare and instruments of war go right along with us.

So, since the standard sci-fi fare of screens and fields won't work, what will? How do you defend a space station or starship against attack? Let me suggest the following seven ways:

1. Dispersion. While space defenses are mostly totally fictional, space weapons are not. Very powerful weapons including lasers, nuclear bombs, and antimatter torpedoes are all solidly either in existence or established as something that would really work. And the best way to survive an atomic or similar blast is not be there when it goes off. Building a vast array of little outposts separated from one another by a healthy distance is the best way to defend against attack. In Star Wars terms, a million TIE fighters is much better for defense than a single Death Star. And may take around the same resources to build (note though that Star Wars blasters and other weapons as they are portrayed are not only weaker than the Hiroshima blast of 1945, they are, with the exception of the Death Star itself, much weaker--likewise with Star Trek weaponry generally--our most popular sci-fi has led the public astray from what's scientifically plausible).

2. Decoys. Related to point 1, sending out as many as possible robotic decoys that employ electronic signatures like the main ship would provide a way to draw off an enemy's devastating ability to attack. The chief difference to this approach from number one is that decoys don't necessarily have any combat power, unlike the dispersion method.

3. Disguise, a.k.a. "cloaking devices" or "invisibility cloaks." The Star Trek universe treats shields like they are standard technology that virtually everyone has, whereas cloaking devices are advanced technology only a few species have mastered. From a scientific viewpoint, they have it backwards. The Pentagon is already experimenting with an invisibility cloak. The thing works, right now, but only for a fraction of a second at a time. You can be sure when spaceships are able to hurl weapons at one another with mega- and gigaton level equivalents of TNT, starships with be protected with cloaking devices. Space warfare will be largely like submarine warfare of our age. The biggest part of the battle will simply be finding the other vessel and successfully firing first. Combat probably would amount to the first on-target torpedo strike and that's it, the battle is over.

4. Mobility. Yes, there is probably an absolute speed a space vessel can practically go, but consider that the position of a craft is known by light coming away from it to a potential attacker. If a vessel is moving at a significant fraction of the speed of light and is far enough away, an attacker can only guess where a starship might be, based on last known location. Not where it actually is. It's challenging to engage a target if you don't know where it is.

5. Natural body protection. This method is not very compatible with the four methods above, but burying a base deep within a iron-nickel asteroid provides pretty good protection. Yes, an antimatter torpedo does have the blast power to split an asteroid open, but by nature most of the blast power will radiate out into the vacuum of space. As per the movie Armageddon, you'd have to drill into the asteroid to actually crack it. Though of course you could still attack whatever weapons are on the surface of the asteroid, rendering it a worthless rock in space. But I can imagine drilling teams on the surface trying to dig a tunnel, counter-attacked by teams from below the asteroid surface. Space infantry would be the most important element of such a battle (though if it were up to me, I'd send robots to do the drilling).

6. Mass. Yes, while it's also contrary to what's probably better advice of 1-4 above, there is something to be said for making a massively huge body with a smooth outer surface, one naturally resistant to blast damage by its size, one that would be very difficult to drill into, one whose surface could be covered with so many weapons that destroying them all would only come with considerable risk. The problem of course is the bigger you make it, the harder it is for it to move. The easier it is for an enemy to simply bypass it. That means you'd probably only build such a thing in orbit of a home planet. Better build at least 2 or 3, lest an enemy swing around to the opposite side of the planet from your space fortress and attack the home world at will.

7. Composite materials. Whether a future space force adopted the strategy of a massive body that's tough to kill or a plethora of smaller craft that are hard to find, you've got to build the vessel out of something. Our knowledge of modern sailing ships might lead a science fiction writer to assume spaceships would be made out of metal. But of all known materials, carbon has the strongest bonds. It is therefore the most resistant to direct damage and has a very high meting point. It's very difficult to damage by heat alone. Certain plastics are surprisingly good at absorbing radiation and a thin film of gold is good at blocking radiation as well. Make a composite of materials like this and fill it with water in a system designed to vent superheated H2O from the heat produced by a blast and the water will go a long way to protect the surface of the composite material. A design like this may not keep a future space soldier alive for any longer than a single impact of an enemy weapon. But that's better than "one hit and you're dead"...


Friday, June 13, 2014

A Step Toward Replicators

Star Trek series past the original have famously featured "replicators," machines that through technology linked to transporters could create any substance out of pure energy. In my Troubles with Transporters bit on this blog I complained that if transporter technology really were able to work, it would have logical implications that are ignored in Star Trek, like being able to copy people at will. Not to mention there being serious issues with the realism of any transporter technology in the first place due to the Heisenburg Uncertainty Principle--it is impossible under the current understanding of physics to know where all the particles of your body or an object to be assembled really are, which would make it impossible to reassemble them with total accuracy...

But another approach to "replicators" is soon to enter service. A 3d printer is to fly in space on the International Space Station, as referenced in the linked article (by the way, I was steered to the article by Terri Main's publication  Science News for Sci-Fi Writers). For those not familiar with 3d printer technology, what it essentially does is create a 3d object by laying down single layers of a film (typically a plastic), and building layer upon layer until an entire object is created.

Currently, rubber gaskets and seals or even a plastic toy or drinking cup are things well within the reach of a 3d printer. The main limits of this technology come from the materials used, though end-product complexity is also an issue. For an example of material limitations, you can't get a stainless steel wrench out of a 3d printer, because current technology isn't able to lay down layers of stainless steel (doing so would require an ambient heat that's quite high). But it's not inconceivable that advancements in 3d printer technology in the future could allow metal instruments to be fabricated. Though laying down layers of carbon fabric cemented with epoxy would work as well as metal for most items.

The ability to expand the types of materials laid down by an advanced 3d printer--I'll such a device here a "mechanical replicator"--would open up the possibility of creating virtually any inanimate object. Especially if combined with clever robotics technology using manipulator arms. Which would allow the separate creation of, with automatic assembly of, various complex interior parts. This could make mechanical replicators a replacement for virtually every other kind of manufacturing.

Note though that the main thing that Star Trek uses replicators for is about the last thing you'd want to use a mechanical replicator for--producing food and drink. Well actually, it's easy enough to imagine an automated system like I'm taking about being a whiz at baking and frosting pastries. And it might even do well in creating beverages by adding water, flavoring, CO2 if needed, and mixing it just so. And some other forms of basic cooking, especially cooking soup or something based on stored food items. But trying to make vegetables or something like roast beef from scratch, that would not work well.

Or would it? It is possible that a mechanical system could get so advanced that it would string individual protein molecules one at a time (or lipids or starches) to create food that would taste pretty good. Though it would seem much simpler to me to simply grow food, even on a spaceship, or carry it in stores. So I imagine a machine that advanced would always be expensive, no matter how far in the future you go. And also take more time to operate that Star Trek imagines, so a roast beef would take at least an hour or two to assemble. But for the very rich, owning a food replicator to obtain the flavors of items not available on the local market might become the height of status and prestige.

How does this concept impact science fiction storytelling? Since the idea I'm discussing is based in real science and steps are already being taken to use a precursor to what I'm mentioning in outer space, it's completely realistic for stories set in a technologically advanced future to have replicators of this type. Space explorers would be some of the first to use devices like these, because it isn't economical to carry along in storage every type of tool you could conceivably need. These machines will be larger, heavier, and slower than the whiz gizmos of Star Trek fame, and would require specific material inputs to work correctly. Raw energy will not be enough, you'd at least need stores of atoms of the elements used in the final product--though these could be in cartridges like the printer ink we're familiar with--creating situations where the sodium or boron or carbon cartridge is low and needs to be replaced or refilled.

Just as the ability to create an image on a screen and print it has transformed the world of publishing and art, so would reliable mechanical replicators transform the world of building ordinary objects. Anyone could make anything--limited to the size of the output tray of your replicator-like device...


Friday, June 6, 2014

Breeds of Hypothetical Domesticated Humans

In an earlier post I entitled An Unexpected Artificial Intelligence Revolution- I speculated on the possibility of advanced artificial intelligences keeping human beings around essentially as house pets.

Well, if we're going to speculate along those lines, what if the same artificial intelligences deliberately bred human beings to produce specific traits that especially distinguish them, much like human beings have bred the first wolf-like dogs into creatures as small as teacup chihuahuas to as large as Saint Bernards, in the act of breeding adding spots or stripes or rings, hair of different length and colors, breeding completely different face and body shapes and wildly differing behaviors.

Presume for the sake of this idea that the same thing could be done with human beings--an argument could be made that humans already self-select for certain traits, which is perhaps why "natural" human diversity is quite large. Thinking we've already bred ourselves into a wide set of human varieties would argue against anyone being able to breed us much further, but let's put aside that line of reasoning for the sake of this story idea.

Imagine humans could be bred to be over twice as tall as the current human average and also much smaller, literal hobbit-sized. That patterns of stripes and different tones of hair could be bred into humans. E.g. one breed could have one eye that's blue and another eye that's brown, each individual member of the "breed." Imagine humans bred to have enhanced hearing or sense of scent, or specialized intelligence or other unique skills.

All of these would still be human, of course, but it would be interesting to create a story in which AIs--or aliens perhaps--deliberately pushed the limits of what it meant to be human, creating a future world in which the diversity of sizes and shapes would be so great that races and diversity as we know it would be tiny in comparison, to the extent that all humans of our age would seem basically alike. Larry Niven's Ringworld series does something like this by having his artificial world inhabited by an original progenitor race to humanity, who settled on the ringworld long ago and evolved for ages afterward, adapting to various environments over time. But humans deliberately bred could easily have a much greater diversity than Niven imagined. In a much shorter time--especially if genetic engineering were to be part of the process.

Imagine if this future world of humans bred as pets, with all the vast variety of hairiness and size and shape and color, underwent some sort of collapse. The AIs (or aliens) for some reason self-destruct. Then all these different breeds would have to face one another and build their own place in the world, crafting alliances or perhaps naturally drawn towards war, in a future science fiction story unlike any I have ever known...