The problem is energy. We use the concept of energy to understand many useful things, but, when even a familiar concept results in a dead end, or reaches its limits, then it is time to look elsewhere. That is the bad part - it makes us uncomfortable when we venture into new, unexplored territory. So why do I single out energy? Because it acts as a limiting factor, a bottleneck in the quest for FTL communications. Remember, Einstein spelled out how energy operates very precisely. If it is made out of energy, it is limited to the speed of light, maximum. This is the essence of both Einstein's special and general theories of relativity. If you can get rid of energy, you are again left with an unbounded speed limit. Seems simple. But remember when I said earlier that all science is based on phenomena we can observe? The same holds true here. If there exists a way to transfer information without energy, then the universe is already using it somewhere. Well, as it turns out, we do have one ally in this quest for energy-less information transfer. That ally is quantum physics.
In the micro world of subatomic particles, where action is random and chaotic, even in this realm, there are some rules. For example, if a particle is created from energy, it is also accompanied by its anti-particle. A certain balance is maintained. In common particle accelerator experiments conducted today, it is normal for scientists to convert energy into many different kinds of matter. And, for particle creation to be successful, an anti-particle is always created as well. If you were going to make an electron out of pure energy, you would also have to create its anti-particle, the positron, right along with it. If you only have enough energy to make the particle, but not the antiparticle, sorry, you are out of luck. Nothing gets created. This seems to be a dependable rule - particles are always created with their anti-particles. These particles have characteristics exactly opposite to each other.
Matter has its counterpart - antimatter. Everyone knows (thanks to all you science fiction writers) what happens when particles of matter and antimatter meet. They destroy each other, turning themselves back into energy. Like twins linked together by certain characteristics at birth, quantum physics simply says that these characteristics must be exactly opposite at all times, whether the particles are separated in space by an inch, or a light year. If you change the characteristics of one of the particles, the other must instantly compensate for that change, to keep the two-particle system in a sort of balance - and the key word is instantly. For an example, there is a property of electrons, as well as many other particles, called spin. Spin can be measured against any of the three spatial axes, x, y, or z. When a pair of particles are created in an experiment, say an electron - positron pair, the spin of each of those particles are related in a most interesting way. If you measure the electron spin component along the x-axis and find it is spin up, you know the spin along the x-axis of the other particle created in the experiment must be spin down. They must always cancel each other. The physicist will say this is true because spin angular momentum is a conserved quantity. We say these two particles are entangled with each other.
You can easily flip the spin axis of an electron. You can do this just by measuring it, which is how we do it using a Stern - Gerlach apparatus. But the Stern - Gerlach experiment is only large enough to target one particle, say the electron, mainly because the entire apparatus must fit in your lab. What about the other particle generated by your experiment and is now hurtling away from you at almost the speed of light? Well, if you just did the one measurement and got spin-up as the answer for an electron's spin along the x-axis, you also now know that because they are entangled, the spin along the x-axis of the positron is spin-down. Run the experiment again. During the second run, you find the spin of the electron along the x-axis has flipped from up, to down. You also now know the spin of the positron has also, because of entanglement, reversed, from spin-down to spin-up, so spin angular momentum can always be conserved. This means that the spin axis of the second particle must instantly also change to compensate and maintain the balance, no matter how far apart the particles may be from each other. This process must happen instantly, meaning the property we call entanglement is Faster Than Light. Interesting, no?
This is one area where Relativity and Quantum Physics politely disagree. If the two created sister particles are a light year away from each other, and if you flipped the spin axis on one particle, according to the theory of relativity, since nothing can travel faster than light, the information that you flipped the spin on one of the particles would take one year traveling at light speed, to reach the other particle and cause its spin to flip. The quantum physicist would say that during this year interval, electron spin angular momentum would not be conserved, and that isn't allowed. For spin conservation to be maintained, the remote action must be instantaneous or several laws of physics would be violated, and that would lead to other problems. See, that's why particles and anti-particles destroy each other. They are always exact opposites, because their critical properties are conserved at any point in time. If they weren't conserved, there would be no BOOM! because they would not be exact opposites. If this were the kind of universe we were living in, matter and antimatter would behave very differently than they actually do... and the universe would be different enough for us to probably not exist and have this conversation.
This is the main gist of the so called E-P-R paper I talked about earlier. Einstein was in the Relativity camp, opposed to this kind of "spooky action at a distance", as he called it. While in the Quantum camp, physicists like Niels Bohr (1885 - 1963), believed that the only way the universe can avoid a disallowed state, like the non-conservation of a conserved quantity, was for some type of instant information transfer to occur. The debate raged for decades. Finally, in the late 1970's, electronics finally caught up with human imagination. Technology finally became fast enough to actually perform ultra fast E-P-R type experiments. First based on light, then as years rolled on, to also include electrons. Einstein died in 1955, so he was not around to see the results that began to come in from these type experiments. He was wrong. The universe does allow some types of information transfer to occur over vast distances at faster than light speeds. Personally, I think he would have accepted the results with dignity - but only after double and triple checking the results.
We know Einstein as a humanitarian and wise philosopher today, mostly because he is dead. He was one hell of a scientist, and would have instantly began to perform his own experiments to verify the results, like any good scientist would do. This seems to also satisfy one crucial requirement for FTL communication - the fact that nature allows it to happen, and in fact uses it all the time. But, it isn't that easy. The universe doesn't hand out her treasures on a gold platter.
There is one twist to the story. Quantum physics is mainly a theory about true randomness - stochastic randomness. There are rules, like always maintaining conserved quantities. But, when we flip the spin axis on an electron, there are different directions it can go, and we can't control which it will choose. We can make the electron flip its spin, but it confounds us by making random flips. In order to make a FTL communications system based, say, on electron spin flipping, we have to be able to control the flip, so we can imprint information on it - a simple code, for example. If we could make an electron flip its spin axis in a controlled way, then an observer a light year away can simply observe his entangled partner particle, and decode the spin flips into a simple binary coded message - it could be his wife's shopping list: "while in the Andromeda galaxy, get a gallon of milk, a dozen eggs...." OK, not very exciting, but it would be a real faster than light communiqué. We CAN do this kind of experiment today, but because everything about it is random, there is no way we can impress a code on random events... The experimenters must get together at the end of the day, at definitely slower than light speeds (usually over some food - university picks up the tab) to compare the information both sent and received to see the correlation. Shucks.
At best, FTL experiments as they are done today will never lead to a true FTL communications system. It's more complicated than just getting rid of the energy, you also have to be able to control the events in order to create a real communications system -- at best, the results obtained as of now, can only be taken as a sign post. Yes the universe does allow instantaneous translation of information without energy, but we have to be smarter than our forefathers, those crazy radio pioneers, if we want to make something useful out of this fact. Radio, it turns out, was easy in comparison to what we must now do, because, it seems we also now must do the impossible - control the uncontrollable fluctuations of a random nature, and at this quantum physics falls silent. So is it hopeless? Are we doomed to be always slower than light creatures? Or can we once again turn to nature herself for clues...to do the impossible?
Never fear, for once again, nature comes to our rescue. However, this is going to be the painful part because it involves re-thinking some very basic concepts that on their surface seem to work rather well in today's world. In a way, we owe much of our success to the fact that we are such lazy creatures. We expend a lot of creative juice figuring ways around, over, or under, obstacles if we can't just bash our way through them. If you've gotten this far, congratulations. We have been wading in the warm and comfortable shallow end of the pool. It may hurt, but now you're ready for some deep, cold diving. We are going to move into that deep, cold water in the next sections.