Updated: July 27, 2009
This notion has been the fascination of science and fiction geeks since the famous Michelson-Morley experiment, which showed that the speed of light is as fast as you can go. Even today, a hundred years later, the zeal for discovering a way of getting past the speed of light barrier is strong in the ultra-geek community.
As a proud member of the geek community, I felt I had to share my own thoughts on the subject ... Can it be really done? Can the speed of light be truly exceeded and the laws of physics sent sniveling into the corner? Or do all geeks, by nature, have an over-developed sense of imagination?
Understand the speed of light
Before we can discuss this magic number (roughly 300,000 km/sec in vacuum), we need to focus on our universe first. Our universe is this crazy 4D thingie, which best can be described as the surface of a transparent, self-inflating balloon. You can see through to the other side, but the information goes round the curvy surface of the balloon. Which is why every object in the universe is getting farther apart from every other object as the balloon continues to grow.
Now, surface implies 2D, which is contrary to our perception of life, where we see and feel things as 3D objects. Similarly, this is how we envision the space. But the direct analogy is misleading. The surface of the balloon is the best human description, but it's too flawed. This is because time is part of the fabric that forms this surface. At any given moment, it's a 2D snapshot, but down the timeline, things start to look logical.
The propagation of information and the way it obeys the different laws of physics is probably the best manifest of the third dimension we're looking for. And this is where speed of light comes into play.
Most people do not realize that speed of light is not a speed per se. It is the characteristic of the medium defining the propagation of electromagnetic radiation inside it. In other words, it's the uppermost limit of how fast the information can travel from one point on the balloon surface to another.
In geek terms, the speed of light is inversely proportional to the square root of electric permittivity (Eo) and magnetic permeability (Uo) of the medium it travels through. In pure vacuum, the speed of light is exactly the magic number we know. In water and other transparent media, the speed changes mainly due to the difference in the electric permittivity factor.
Take a particle and send it hurling through the space. This particle will try to go as fast as it can. In a way, the vacuum will suck the particle into it, lending it speed. The emptier this vacuum is, the higher the pull on the particle - hence its speed.
The particle motion is not linear as we might expect it. The balloon surface is growing, therefore the distance between any two points is growing. The balloon surface is curved, which means that the particle path will not be a straight line as we might envision it. Instead, it will be a straight line, divided by time and space curvature, both of which are highly debatable.
Lastly, there's gravity to take into account. The best way to think of gravity is as of potholes in the road. Each object creates a tension onto the balloon surface, sort of as a rock laid on a rubber sheet. The heavier the object, the bigger the hole the object's mass will exert upon the surface of the balloon.
Thus, a particle going from point A to point B might also have to fight against gravity, which could significantly lengthen its path. And since gravity is also part of the equation, time might also change.
Overall, it's one big mess. Combined, the foul play of vacuum and other forces make sure that the speed of light is the maximal speed a particle may achieve. Even massless particles like photons and docile neutrinos are unable to overcome the intrinsic limitations of our universe. So, what do we do? How can we try to be faster than the speed of light, regardless of the physical limitations?
Going faster than the speed of light
There are several ways to do this. Some are very real, others purely theoretical. I'm going to present all of them. Of course, do remember that the theories I raise are pure speculations, as there is no technology that can achieve what I propose. Still ...
If you're unfamiliar with Quantum Mechanics, the phrase phase means little to you. The thing is, this phase is an important if unreal part of a particle's wave function. The phase can exceed the speed of light, but unto itself, it is meaningless.
To observe a particle, you have to measure one of its eigenvalues. To do that, you have to force it into an eigenstate. The mathematical torture that explain this situation involves multiplying the wavefunction with its conjugate. And when you do that with complex numbers, the imaginary part vanishes. In layman's terms, once you observe a particle, you force its infinite number of momenta and positions into one definite set, determined by probability.
It is difficult to fully understand this, but it's a part of the algebra, so take it or leave it. Physics rules may yet change and then, we might talk about a wholly different set of equations. Still, the fact that changes are not continuous baffles people and defies simple logic. Why should not there be something in between those energy levels, you ask? Well, in four dimensions, this is what it looks like. With a few more, things might get easier to grasp. This is what the String Theory is trying to do, slap an extra half dozen dimensions onto our 4D ball, and Bob's your uncle.
Back to our phase ... it can go faster than the speed of light, definitely. But this does not really help us. To get meaningful, palpable information, we will still have to wait for the information to arrive at its usual speed.
Here's a little experiment that shows you this:
Optics 101: take a lens and project an image through it. Depending on the focal depth and whatnot, there's a certain distance where you will be able to see the projected image clearly, probably inverted and scaled. If you move the object out of focus, it will get blurry. So far, so good.
Now, what you need to do is try to see what the object looks like at the focal point. If you place a screen at the focal point, you will probably see a jumble of shades, nothing that even remotely resembles your real object. Why is this, you may wonder?
Well, any time light (electromagnetic radiation) interacts with a medium, it undergoes a Fourier Transform. In practical terms, it turns from energy into waveforms. In human terms, we are unable to interpret waveforms. We do not think or see in frequencies. We understand energy, or rather, power. The intensity of projected object is meaningful to us. Phase is just gibberish.
Luckily for us, on the screen, the light undergoes another Fourier Transform, forcing the waveforms back into energy values and the phases are lost. What happens is, the waveforms combine with their conjugates and the imaginary parts cancel each other out. Even more interestingly, when you're out of focus, due to different travel paths of the light waveforms, they only partially cancel each other out, resulting in some of the energy projected onto parts of the screen that should not contain the image, which causes the blurs that we see.
So, in a way, phase is the indicator to how much of total intensity we ought to see, but of course, it is completely dependent on time and space. This is why getting the phase ahead of the actual information is meaningless.After this lengthy introduction, we now know that phase can't really help us. You can move faster than the speed of light, but the information will be meaningless, because the phase is not a real component. There's a whole bunch of physical phenomena that demonstrates the phase going wild, but I won't go there.
Bending the rules
To move faster than light means beating the medium, which makes it impossible given the physical laws as we know them. Bend the rules and you may go faster than the speed of light. The big, big question is how to achieve this?
Physicists are currently hunting after graviton, the particle responsible for gravity. It has not yet been found, but the hopes are high. In theory, if this particle is found and harnessed, it may be put to good use. Just like photons are used in conventional (optical) lasers, it might be possible to use gravitational laser to focus narrow beams of gravity and create temporary gravity sinkholes in the fabric of the universe.
This may require very powerful sources of energy and possibly some sort of gravitational lenses a la galaxies to focus down the particle beam, but assuming it is possible, gravitational lasers may be used to create black holes in the space. The powerful gravitational pull of black holes may cause time shifts that could be used by travelers to leap frog through the space without paying the full price of time, thus effectively making their travel faster than the speed of light.
An alternative would be to focus gravity pulses into points smaller than the Planck length or shorter than the Planck time, which might help over come the speed limitations, since both these values are calculated using the speed of light.
The gravitational voids could perhaps be dangled like a carrot in front of a donkey, i.e. fired from a spacecraft of some sort directly ahead of it, causing a vacuum/mass cascade that would accelerate the ship to travel in a medium that is even emptier than vacuum, thus easily breaching the speed of light barrier.
Deplete the vacuum
This might be done by matter-anti-matter collisions. In theory, the matter and anti-matter should annul each other completely, possibly releasing energy in the process. There's very little anti-matter in the universe free for grabbing, but assuming it could be distilled from the surroundings on the fly, it might be possible to mix it with matter to create controlled explosions.
If you've ever witnessed an explosion, you will have learned that the epicenter of the explosion remains intact. Furthermore, you may also have heard or seen fireballs collapse back onto themselves. This is caused by the vacuum that is generated in the center of the explosion, by the outward expanding ring of exploded particles.
The same theory may guide a faster-than-c travel. Creating matter-anti-matter explosions around a spacecraft could create expanding energy waves that would suck the vacuum dry, possibly more than its currently emptiness, creating a negative potential that makes anything inside the explosion bubble move faster than the speed of light.
The big problem would be protecting the spacecraft from the backlash of the collapsing explosion, but this could be compensated by additional, more powerful explosions. This means that the matter-anti-matter mechanism would have to continuously throttle up to protect the ship while providing even thinner vacuum and greater speed.
This is kind of like the positive void coefficient in nuclear reactors, and because of the exponential growth, such travel would be short in duration and costly in energy. Emphasis would also have to be placed on focusing the explosions ahead of the traveling spacecraft, as it would tend to gain on the energy front released. This would be another limiting factor, but even the energy could be focused for very short bursts, it could still provide with a substantial increase in speed.
This idea is quite tricky though. Because of the Charge-Parity (CP) violation that probably led to the fact the matter is so much more abundant than anti-matter, at least as we know it, it is possible that some of the ingredients may not be fully transformed into energy, undermining our effort. Furthermore, the explosions would not be environment friendly. There's also the risk of the whole thing spinning out of control, as there's no dampening mechanism to the reaction save for the depletion of energy sources.
Shortcut through the balloon
Today, we are forced to travel around the circumferences of our inflating balloon, even though we can see through. So maybe we could create sort of tunnels that go all the way through to the other end? This is the idea of wormholes.
Creating wormholes sounds tricky, but again, the use of gravitational lasers might help. Very massive distortions might cause tunnels deep enough to reach adjacent areas of universe and allow spacecraft to wriggle through before closing. The big question is how one would survive going through a wormhole, because of the massive gravitational pull.
Possibly, a combination of lasers and matter-anti-matter explosions might work, with explosions protecting the ship against the gravitational forces, while also lending extra speed.
Change the time
This one is really tricky. First, we know almost nothing about time as a dimension. Second, changing the time would force us to account for all sorts of problems like entropy and stuff, which makes this the least likely candidate. Still, it might be worth considering.
There's no reason to go fast; just make sure you travel great distances in a very short time. I have no idea how to do this without getting physical [sic] with all sorts of rules.
That's about it, I think. Some sci-fi food for thought. Going faster than the speed of light is just like jumping higher in a room with a low ceiling; no matter how high you jump, you will always bang your head against it. However, make the ceiling higher ... aha!
One day, we may we able to do it. For now, chlorinating the vacuum or blackholing the universe like a smallpox epidemics is still a wild dream of science geeks. The energy required for the effort would probably make the entire universe go on a strike. Well ... we can keep on dreaming. I hope you enjoyed this nonsense. Have fun.