You may be familiar with the “arrow of time,” but did you know there could be a second one?

Dr. Robert Hazen, staff scientist at the Earth and Planets Laboratory of Carnegie Science in Washington, DC, thinks that a single arrow of time may be too limiting. A second arrow, which he dubs “the law of increasing functional information,” takes evolution into account. Specifically, Hazen explains that evolution seems to not only incorporate time, but also function and purpose.

Consider a coffee cup: it works best when holding your coffee, but it could also work as a paperweight, and it would not work well at all as a screwdriver. Hazen explains that it appears the universe uses a similar way of evolving not only biology, but other complex systems throughout the cosmos. 

This idea suggests that while as the universe ages and expands, it is becoming more organized and functional, nearly opposite to theories surrounding increasing cosmological disorder. Hazen suggests that these two “arrows” – one of entropy and one of organized information – could very well run parallel to one another. If true, this theory could be groundbreaking in the way we perceive time, evolution, and the very fabric of reality. 

Robert Hazen: I have to make a confession here. I have to be honest. We could be wrong. We could be spectacularly wrong. But it's also possible that science is missing a profound truth about the cosmos. We have these 10 or so laws of nature, only one of which currently has an arrow of time. That's the second law of thermodynamics, the increase in entropy—it's disorder; it's decay.

We all grow old. We all die. But the second law doesn't explain why things evolve; why life emerges from non-life. You look around, and you see flowers bloom and trees blossom and birds sing. It seems like all of those things are counter to the idea of disorder. In fact, it's a kind of ordering of nature.

So let me tell you what we think: We think there's a missing law, a second arrow of time that describes this increase in order, and we think it has to do with an increase in information. So there are two possibilities. We could just be wrong. We could be terribly wrong, dramatically wrong. But I think, if we're wrong, we're wrong in a very interesting way. And I think, if we're right, it's profoundly important. 

I'm Bob Hazen. I'm a Staff Scientist at the Earth and Planets Laboratory of Carnegie Science in Washington, D.C. I do mineralogy, astrobiology. I love science. We think that, for some reason, there's been a missing second arrow of time. And that arrow has to do with an increase of information, an increase in order, an increase of patterning that goes side by side with the arrow of increasing disorder and increasing chaos, entropy.

The core of everything we've been thinking about, in terms of the missing law, is evolution. When I say the word "evolution," you immediately think of Darwin, but this idea of selection goes much, much beyond Darwin and life. It applies to the evolution of atoms. It applies to the evolution of minerals. It applies to the evolution of planets and atmospheres and oceans. Evolution, which we see as being an increase in diversity, of patterning, in complexity of systems through time.

And so the question is, "Well, what is evolution?" Evolution is simply selection for function. And this applies to every kind of system. Now, in life, you select for organisms that can survive long enough that they can reproduce and have offspring that will pass on their characteristics. That's what Darwin said, and that's one very important example of selection for function. But, in the mineral world, you select for organizations, of assemblies, of structures of atoms that persist, that can last billions of years even in new environments.

They don't break down. They don't dissolve. They don't weather away. It's very analogous to biological evolution, but it's different in detail. We think there's a missing law—it's a law of evolution. And, if there is a law, it has to be quantitative. It has to have a metric. You have to be able to measure something. And what we've zeroed in on is a fascinating concept about information but not just information in general, something called 'functional information.'

Let me see if I can explain this to you 'cause it took me a while to figure it out myself. Imagine a system, an evolving system that has the potential to form vast numbers of different configurations. Let's say they're atoms to make minerals, and you have dozens of different mineral-forming elements, and they can arrange themselves in all different ways. And 99.99999999—I can keep going—percent of those configurations won't work. They will fall apart. They'll never form. A tiny, tiny fraction makes a stable mineral, and you end up with a few stable minerals and lots of rejects.

Now, all you need to do is think about that fraction. If it's one in a hundred trillion, trillion, trillion, trillion possibilities that's stable, then you can represent that fraction as information. And because it's such a tiny, tiny fraction, you need a lot of bits of information to do that—that's functional information. Evolution is simply an increase in functional information because, as you select for better and better outcomes, you select for minerals that are more and more stable. You select for living things that can swim. They can fly. They can see.

You need more information, and each step of the evolutionary ladder leads you to increasing functional information. So, our law, our missing law, the second arrow of time is called the 'Law of increasing functional information.' And that's the parallel arrow of time that we think is out there that we want to understand. The idea of increasing functional information has a really profound implication. Think about the functional information of a coffee cup; you might be holding one right now.

You have a bunch of atoms, and those atoms could be in trillions of trillions of trillions of different configurations, but only a tiny fraction of those configurations will hold a cup of coffee. Now, think about a coffee cup as a paperweight. I know you've used a coffee cup as a paperweight. We all have, and it's pretty good at that, but you can make a better paperweight. And a coffee cup makes a terrible screwdriver. So think about this: We're saying that the coffee cup has value as a coffee cup. It has some value as a paperweight, but it has no value as a screwdriver—that's contextual.

So this is why the second arrow of time is difficult for science because it's saying there's something in the natural world that is not absolute. It's contextual. It depends on what your purpose is. It depends on what your function is. If it's true, what we're saying is there's something in the Universe that is increasing order, it's increasing complexity, and it isn't doing this in a random way. It's selecting for function. And if it is, if you're selecting for function, it means that there almost seems to be—can I use the word "purpose?"

Do minerals have a purpose? Do atmospheres have a purpose? Does life have a purpose? To me, there's something real there, and the old way of thinking of a single arrow of time no longer rings true to me.