Quantum Conundrums

I have been absent for the past two weekends, as a few of you may have noticed.  There was a pretty good reason: my internet has been out of order for a while, and getting new internet as a foreigner in Korea leads to several roadblocks, such as the fact that I will only stay six more months, but all the contracts are for two years or more.  So, that's a tidbit from my life.  However, as of now, my internet is back, and I can write and research as before, so look for weekly updates again.

Now, speaking of telecommunication problems, how will communications on Mars work?  Well, I should be more specific: How will communication to and from Mars work?  If you have been paying any attention to the Mars Curiosity rover story, you will know that there was a lot of tension about the landing because of the fact that the landing needed to be fully automated.  This was because of a signal  delay of fourteen minutes between Earth and Mars, which is the problem I will be trying to overcome today.

Now, before we even get started, we should pause a moment and simply consider how very, very far away Mars is.  Mars is so far away that it will take fourteen minutes to reach at light speed!  Actually, since Mars orbits differently from Earth, the real distance varies between about four light minutes to twenty-one light minutes, and fourteen is merely the current figure, roughly 252 million kilometers.  Anyway, we're talking about really, really far.

Okay, now that our minds are done being blown at the distance, let's think about this problem.  First, I want to point out that it isn't really a very big problem.  A Mars colony will have people on the ground, so the issues we are seeing with a fourteen minute delay in problem solving for the Curiosity will not exist; people will be on hand to solve issues that arise immediately.  A mission of the magnitude I am envisioning will include all the experts required to handle any situation that comes up.  Once the colonists arrive, they should be self sufficient, and not rely on Earth for anything, since no matter how fast an SOS gets to Earth, the homeworld won't be able to send help for six months minimum.

Furthermore, even with a fourteen minute delay, we can still communicate with home, send messages that say “I miss you!” or “Mars is awesome, come visit!”  Emails are still easy, just, instead of taking less than one second to be delivered, they will take fourteen minutes.  Humanity survived for thousands of years before lightspeed communications, and slowing down by a few minutes will not hurt anyone.

However, a lot of our conveniences are tied to very fast communications.  The biggest one is the internet; whenever you want to open a web page, a signal goes to the server that hosts it, tells the server to send you information, and then comes back with the information you requested.  On Earth, all of this usually takes less than a second.   On Mars, it would be a half hour back and forth, meaning you click a link, go make a pot of coffee, watch an episode of Arrested Development or some other TV show, and then come back and your page has loaded.  Any interaction with the page would take equally long.  It would be like stepping back into the worst parts of the dial up era.

This would not have bothered us before the 1990's, but now, life without high speed internet seems practically impossible.  As one who has been living with no internet for the last week and a half, I can attest that really, this isn't the case; life goes on.  But, I said in my first post that I plan to spend a trillion US tax dollars building this city on Mars, and at a price tag like that, I would hope that my colonists can at least video chat with their relatives back home.  So how can we do it?

Well, lightspeed is pretty much as fast as it gets in terms of actually moving one thing to another place.   In fact, we believe it is physically impossible for anything to move faster than light, because to do so would violate causality, and make it look like the effect of something happened before the thing even got there.  For example, if a faster than light spaceship hit a planet, we would not see it until after it hit. Then, we would see the light that it had reflected just before it hit, then a little earlier, and so on, so that to an observer on the planet, the ship didn't hit at all; a crater formed, and then a ship shot out of it backwards into space.  The ship would be moving backward in time, but the crater would be moving forward.  Of course, at lightspeed the ship's mass would also be infinite, so really the whole planet would be obliterated by the impact if this sort of thing happened.  Fortunately, we believe that it's impossible.

So where does that leave our communication problem?  Seems like a dead end, but there is actually one way around this rule: Quantum teleportation.   No, this is not like “beam me up, Scotty!” at all.  What happens is this: two tiny quantum particles can be made to interact in such a way that they become “entangled,” which means that they share the same quantum state as one another, even if they are moved apart.  Then, we can move the two particles apart to any distance, it doesn't really matter how far.  So far, the most we've managed is a couple hundred kilometers, for reasons I'll talk about later.  Finally, we can make the particle at one end switch quantum states, and then the other will switch on its own, instantaneously.  This switch can be used to represent a bit of data, a 1 or a 0, and voila, instantaneous digital communication.

This doesn't violate causality, because the entangled particles were moved apart at sub-light speeds, which apparently means that they are causally linked; they share the same light cone.  Now I don't claim to understand why that makes any difference, since it seems that doing this instantaneous communication would break the old causal links, and make a new light cone of its own, but it's been tested experimentally, and it does in fact work.  So, who cares why?  Physicists can figure that out later.

Now there are several ways that this is good.  First, if we can mass produce it, you can play streaming video and multiplayer videogames from Mars on Earth servers with zero latency.  Second, it solves the problem of communicating while Earth and Mars are on opposite sides of the sun (We can't send radio signals through the Sun, because the Sun emits full spectrum  radiation, but quantum communication doesn't rely on sending anything, so the sun won't matter), meaning you don't need to worry about putting long range communication satellites at various Earth and Mars orbital Lagrangian points (although, I would build space stations there anyway, just because, well, why not?).  And best of all, this technology or something like it is a major step toward the next big computer revolution, which is quantum computing.

But, making a machine that actually does this is INCREDIBLY hard.  There are many reasons why, but the most obvious is that once two particles are entangled, they can very easily become disentangled if they touch well, basically anything.  Which is problematic, because we need to move one end of the string to Mars, and how do you move something without touching it?  Very carefully, usually with magnetic fields.  Even then, it doesn't work very well, which is why we've only managed a couple hundred kilometers so far.

Second, quantum particles are really, really small, which makes detecting their state and changes in their state extremely difficult, again, without touching them.  Also, this small size makes them very easy to lose (Where did I put that one quark I had.... Oh, somewhere in this pile of 2,000,000,000,000,000,000,000,000,000 other quarks.... Great...).  Scientists at present can do all of this stuff, but inconsistently and not very well (10% efficiency is something to celebrate).  We don't have the same level of control as we do at the atomic level, because at the quantum level everything is based on probability, which means that we never even really know where the particles we are measuring are, we only know where they PROBABLY are.

So, all told, telecommunications is a problem that has a potential solution, but the solution is waiting for a major breakthrough in quantum control and manipulation before it can become a reality.  How long will that take?  We don't know.  Will it be ready by the time I am president in 2040?  Maybe.  We don't know.  If it's not ready, should we hold off on colonization?  Absolutely not.  If worse comes to worst, we can just download an imprint of the entire internet and put it on the colony ship, and run a local high speed network with updates from Earth streaming continuously once communications are set up.  At least then Mars has internet, just not connected to Earth at high speeds.

All of the internet, in one ship....How many hard drives do you think that would take?  Might be too big.  I'll have to do some research....