All I know is that every time a Twister takes out trailer park there's always a brand new shiney Boeing 737
Listen. Creationists. We need to have a frank discussion about your tornado in a junkyard. Because you guys keep repeating it over and over and over again.
Here's the problem: it's not an analogy that remotely resembles the actual process of evolution. The tornado in a junkyard is a scenario in which random pieces (molecules, perhaps) are randomly mixed to randomly create a fully-functional, incredibly complex aircraft (human being, or pick any animal really).
But this isn't how evolution works. In fact, this analogy far better suits
creationism: a scenario in which an incredibly complex living organism springs to life from a jumble of useless molecules. Or from nothing, whichever. A scenario so improbable that it requires the intervention of a supernatural being to become anything other than ludicrous. But, again,
this isn't how evolution works. We need to fix your tornado scenario. So let's do that.
In reality, chemistry is chemistry. Put two hydrogen atoms and an oxygen atom together, you get water. Doesn't require anything fancy, doesn't require any precision. It's chemistry. Mix a puddle of hydrogen with a puddle of oxygen and you'll get water. Yeah, not all of it mixes perfectly so you don't purely get water, but who cares. So, to fix our basic building blocks of the 737 to be more reflective of basic chemistry, your nuts, bolts, rivets, and wires have an affinity for each other. Screws that bonk into screw holes will stick to the hole and twist their way in. Rivets that contact metal skin will rivet in. Wires that contact, I don't know, capacitors, will link up. I'm not an electrician.
Now, spin the tornado through this junkyard and you still don't get anything really useful. Do it a few times and you might get something that vaguely resembles a small section of one of the wings. (a flat piece of metal with some screws in reasonable places) Certainly not a working aircraft. But there's another missing piece here. See, the tornado is still a purely random force. Chaos, as you put it. But evolution is not purely random. It is driven by survival pressures. Small mutations that provide a benefit increase the likelihood of survival. In our junkyard terms, "being more like a 737" is a survival advantage. Any random jumble of parts that happens to more-closely resemble a 737 has to be selected for. So we'll give our junkyard pieces that trait: if pieces happen to collide in a way that matches the 737 blueprint, they stick together.
We're still not getting a 737. Here and there, a piece of metal with some rivets that resemble something on the fuselage of a 737. Over there, some wires that randomly stuck together in a way similar to the Row 37 No Smoking Sign. Look over there on the other side of the junkyard, a roundish piece of rubber stuck to a roundish piece of metal so they look like part of a wheel. Not a plane. Not even close.
There's a last piece of the puzzle. Evolution is a massively iterative process. Each generation passes on genes to the next, along with a few mutations because self-replication can never be perfect. We need to continue the advantageous genes (correctly-stuck part) on to the next generation. So those pieces stay together permanently. If those part clusters happen to strike another part, or another part structure, in the correct way, they are even more like a 737 than they were before. This is yet another advantageous mutation, it survives on to the next generation. Now we've got something. Spin the tornado through the junkyard a few hundred times, and you'll see clusters of parts that have grown much larger and much more complex. Over there, a fully-formed wheel. Back that way, we've got a working piece of avionics. Near the entrance, an aileron has latched itself onto a wing portion.
In this more-correct analogy, the 737 is not only possible, but
inevitable. Spin the tornado enough times, and you're definitely going to get a 737 eventually. It'll take quite a while, right? Well, the universe has been around a very, very, very long time and it is very, very, very big. It's not really just one junkyard, is it? We very, very, very roughly estimate the number of stars in the universe to be literally more numerous than the grains of sand on every beach on Earth. Septillions. And, if the Kepler mission is any indication, planets seem to be freaking everywhere. It's short mission taking a tiny look at the most miniscule fraction of the sky in our own galaxy (let alone the innumerable
galaxies each with trillions of stars) has found hundreds of planets, thousands of planet candidates not yet confirmed. We have an uncountably large number of junkyards, each with tornadoes going for a long, long time.
Of course, reality is more complex than this analogy. Not all mutations are beneficial, and outside factors exist that can threaten the existence of even the best-adapted life forms. Some of our junkyards are at the bottom of the volcano, useless. Everything resembling airplane parts just melts. On the other hand, we're not just working from one blueprint.
Any blueprint is valid, as long as it survives its current environment and current competition. Evolution has no goal. Human beings, as much as we try to pretend otherwise, are not some pinnacle achievement found at the end of a long road. We're another branch on an infinitely-branching tree that has been growing and expanding for billions of years.
But hey, this was your freaking analogy, not mine.