I ran across some interesting news recently proclaiming the design of a Warp Drive Starship as a work in progress by NASA (see here and here). While the graphics look pretty sharp, don’t start studying for your Star Fleet entrance exams just yet. This is merely a public relations teaser; there are some potentially difficult problems to solve before star ships become a reality. For fun let’s assume that we have a warp drive that follows the parameters laid out in the articles – we can attain an apparent velocity of ten times the speed of light. That would give us about a two year trip to the nearest known potentially Earth-like planet (Gliese 682 b).
One big problem that is generally ignored or brushed over as a minor, easily solved issue is the supply of food, water, and air to maintain the crew for the voyages. In SciFi books and movies there is sometimes mention of a biological section of the ship that provides fresh air and food. You must realize that we cannot simply pack up enough food, water, and oxygen to keep the crew alive for an extended trip. Each crew member will consume about a ton of food each year (yes, you do eat that much, don’t deny it). The average person in the world uses about 1,800 cubic meters of water per year; that’s nearly 370,000 gallons or about 1,500 tons (a gallon weighs 8 pounds). We can recycle most of the water (as long as the crew can get over where the recycled water came from) but there will be some loss due to various waste products that simply cannot be recycled. Each crew member will also consume about twenty cubic feet of oxygen per day which weighs around a pound (yes, oxygen has weight too). Most of the oxygen can also be recycled and that’s one of the reasons that plant life is desirable. Plant life can very efficiently process the carbon dioxide exhaled by humans and release oxygen but this process (photosynthesis) requires sunlight. Plants also require oxygen and, as anyone who has ever tried to keep a plant alive will know, they need water as well, adding to that requirement.
That’s a lot of junk we need to haul with us. If we have a crew of ten people and a four year trip (two years out and two years back) that’s forty tons of food, 10,000 tons of water, a few tons of oxygen, and a few tons of the other gases that make the air that we breathe: air is only 20% oxygen and, as was sadly learned the hard way with Apollo I, a pure oxygen environment is very dangerous. One factor on our side is the the theoretical Alcubierre warp drive system is independent of the mass of the ship, only the size of the warp bubble created so we can fill that bubble with as much mass as we can. If we could create a self contained biological environment then we could cut these numbers down quite a bit. As mentioned, the mass is not a factor for the warp drive system but having to haul all of this junk means that we have to build a bigger ship, and that’s expensive.
If we choose the self contained environment route there is another huge problem: this has never been accomplished. Though it may be forgotten there was the Biosphere 2 project that started back in 1991.
This goal of this ambitious project was to enclose eight people in a self contained environment for two years (see). This experiment is widely viewed as a failure because the participants lost massive amounts of body mass and the oxygen levels dropped to dangerous levels. Besides the physical failures, one of the other important findings from this study is that the group separated into two opposing factions who couldn’t agree on how to remedy their situation. It was assumed at the that the participants would spend minimal time maintaining their environment and have lots of free time for environmental experiments but the reality was that they were spending all their time trying to fix the environment.
The second attempt at this experiment was cancelled six months in mostly due to administrative issues. Perhaps if we can find a system that allows the scientists and engineers to do their work without the oversight of administrators and politicians who lack the training to understand the science of what they are administrating we can make some real progress. It has been over twenty years since Biosphere 2 and, as far as I know, it has not be recreated, especially on the same scale. The real result of this experiment was that it showed us how delicate a biological environment is and how little we really know about recreating one. I think we can solve this problem eventually but it will require much funding and research.
Yes, I see you in the red shirt waving your hand in the back row. In Star Trek they have replicators.
One of the basic concepts here comes from our old friend Mr. Einstein:
$latex E = Mc^2$
This states that energy (E) and mass (M) are equivalent so you can convert one into the other. Let’s consider how much energy it would take to create a twelve ounce steak. An ounce is about twenty-eight grams so we need to create 336 grams of mass (or 0.336 kilograms), multiply by c squared and you get approximately thirty million mega joules (c is about 300,000,000 meters per second). If you recall from my article on rail guns (see) that’s a million times the energy required to fire the Navy’s experimental gun just to make one steak with no baked potato or salad (and no beer). I don’t see us using that much energy just to create food, it’s far cheaper to grow and it probably tastes better.
Yes, I am aware that Star Trek replicators are not just energy conversion units but also have the ability to build molecules from base elements. This seems simple enough but the proteins that we need in our food supply are incredibly complex molecules. They are not just basic collections of atoms; the way that the molecule bends and folds as it is created is very important. You can take the same collection of atoms and fold it one way where it is wholesome but fold it wrong and it can be deadly. If you want to help out with that research you can check out Stanford University’s Folding project that uses your computer’s processing power when you aren’t using it (as a screen saver) to solve some of these folding problems.
The bottom line is that will take vast amounts of computing power to properly organize the atoms and make sure that we don’t kill anybody. If we can figure this one out then we can recycle waste into anything we want and we would only need to pack up a supply of basic elements: Carbon, Hydrogen, Oxygen, Nitrogen and a few other trace elements for added flavor.
Let’s assume that we can solve the supply issues, what’s next? Gravity, my friends, we can’t live without it. It’s been known for quite some time that the human body does not react well to extended periods of zero gravity. Your muscles weaken because you don’t use them as much and, even worse, your bones lose density rather quickly (see). Rebuilding muscle mass is easy but recovering bone density is not; it’s best to avoid it happening in the first place. I won’t even bring up what it does to your heart. You can read that for yourself. According to the theory, the ship within the warp bubble will be in zero gravity for the entire trip and I didn’t see any kind of provisioning in the proposed design for creating an accelerated environment such as a rotating ring (the ring in the proposed design is the warp bubble generator). If you are unfamiliar with a rotating ring to generate an accelerated, or artificial gravity, environment then you should watch 2001: A Space Odyssey.
Currently, rotating the ship or part of the ship is the only way that we know to generate artificial gravity. By the way, plants also don’t do very well without gravity.
That’s two down. What’s next? How about radiation shielding? On Earth we are protected from the constant barrage of cosmic radiation by Earth’s magnetic field and the upper atmosphere. I think that we will have some protection because the warp bubble is a distortion of normal space so the cosmic ray paths will curve around the outside of the bubble. The problems will arise with any radiation that is contained within the bubble itself or if we decide to stop somewhere and take a look around. With the warp bubble down the ship will be subjected to massive amounts of radiation so shielding is required. Fortunately for us recent research has shown that it is possible to generate a workable magnetic shield with current technologies (see).
So far we have one of our difficulties that should be solvable in the near future, but it’s still dependent on the generation of the warp bubble itself. Don’t get me wrong, this is exciting stuff but I don’t want to sugar-coat it. If you read Alcubierre’s 1994 paper (see) then you might run across the snag in the system (if the math and deep physics make your eyes glaze over the skip to the end and read the next to last paragraph). The clincher is that the warp drive system requires something called “exotic matter” to make it work. So what is this exotic matter? It’s an oddity that is predicted by Quantum physics: matter with negative energy density. I suppose that doesn’t really tell you much but this is weird stuff; it reacts opposite of normal matter. For example, if you push it it pushes back instead of moving away. The problem is that nobody has ever seen any of this stuff.
There is some good news, it was originally theorized that the amount of exotic matter required for a usable warp drive was on the order of the size of Jupiter but, due to some rethinking of how to apply the field by NASA physicist Harold White, the amount required has been cut down to about 1,600 pounds. Well yes but, since we’ve never found any of this stuff, that’s like saying “We used to think that we needed 10,000 unicorns for this project but now we think we only need five, go find us some unicorns.”
There is another option: it is also theorized that the drive will work just as well with a region of space with negative energy density which is also allowed by Quantum physics, commonly known as the Casimir effect (I’ll let you look it up). This is actually more plausible because this effect has been observed, at least on microscopic scales.
What I find most interesting about Harold White’s research is that he is currently trying to prove that the creation of a warp bubble is possible using a modified Michelson-Morley interferometer.
If you’re not familiar with the history then let me explain. Back in the eighteen hundreds it was assumed that electromagnetic radiation (light, radio waves etc.) propagated through an invisible “luminiferous aether”. Michelson and Morley set out to detect this aether because the Earth would travel through it as well. The assumption was that they should be able to detect a difference in the speed of light in the direction of Earth’s motion as compared to perpendicular to the direction of Earths motion.
This experiment, first performed in 1887, was repeated many times with increasing precision and the result was always the same, there is no difference. It wasn’t until 1905 that this was finally explained by Einstein’s theory of special relativity – the speed of light is the same for all observers. What I find profound is that the same device (though modified heavily to use lasers which weren’t available to Michelson and Morley) that set the groundwork for Einstein’s theories is now being used to find a loophole in them.
So what have we learned today:
- Humans eat a lot of food
- Zero gravity might be fun but it’s not healthy
- Warp drives run on unicorns, but only a few
- A device that once proved that you were right might also prove that you were wrong