http://youtu.be/HEheh1BH34Q The New Year is upon us, and for many folks it's a time for taking stock. So on this final day of 2014, I thought I'd take a step back, waaay back... My starting point is the video above, which has been making the social media rounds lately. It offers a visually compelling comparison of the sizes of planets and stars, all leading to a central message spelled out in big type at the end: "No, you are not the center of the universe." I also find an implied — and unnecessarily alienating — message in the video: "As a human being, you are an insignificant mote in the unimaginable vastness of the cosmos." This is only true if you make an absolute comparison between your own size and, say, the Milky Way galaxy. But another comparison tells a very different story. And that's the purpose of this post. I can't really say whether the creator of the video, someone with the pseudonym "Morn1415", intended to convey a notion of human insignificance. He or she (I'm guessing the former, since Morn was a Lurian male on Star Trek Deep Space Nine) uploaded it to Youtube in 2009. Since then it has been viewed more than 10.6 million times. And for good reason: It's beautiful, and it effectively conveys a sense of cosmic scale. But it only goes so far. I spotted it for the first time a couple of days ago on a friend's Facebook page. He's a renown environmental scientist who heads a major scientific institution, and he enjoys a wide audience. So I decided to take on that implied message of human insignificance in a reply on his page — and now here: This depressing message about humanity and its place in the cosmos is just plain wrong — and I suspect that it has served to alienate countless ordinary folks from science. With this meme being so common, is it any wonder that so many people cling to nonsense like Creationism? The fact is that there is more to our place in the cosmic scheme of things than, "No, you are not the center of the universe." Much, much more. To tackle this issue, let's first be clear about one salient fact: Saying that we are not at the center of the universe implies that somewhere, some thing is central. But this is false. The universe has no physical center. You can find an excellent explanation of this difficult idea here. Suffice it to say that the Big Bang more than 14 billion years ago wasn't an explosion of stuff in space. It was an explosion of space itself. As a result, since then every point in space has been expanding away from every other point uniformly, with no center to the expansion. So it's true. We are not at the center of the universe. (Yes, I know this contradicts my headline. But stick with me...) Moreover, as the video demonstrates so effectively, we are infinitesimally small when compared to things like red supergiant stars, galaxies, and galaxy clusters. But there are smaller things than us. Much, much smaller. So where humanity fits in the cosmic scheme of things doesn't depend simply on how we measure up to the really, really big things. It also depends on how we compare to the really, really tiny things. To take on this notion, I'll start with a key observation by renown cosmologist Joel Primack of the University of California, Santa Cruz. He is one of the principal originators and developers of the cold dark matter theory, which is the foundation of the modern picture of structure formation in the universe.
The large-scale distribution of dark matter in the universe as simulated by a supercomputer. Without the existence of dark matter, the observed structure of the universe does not make sense. The cold dark matter theory was first worked out by a number of scientists including Joel Primack of U.C. Santa Cruz. (Source: Springel et al. 2005/The Millennium Simulation Project) In "The View From the Center of the Universe," Primack and his co-authore Nancy Ellen Abrams, make this key point:
The size of a human being is at the center of all the possible sizes in the universe. This amazing assertion challenges not only the centuries-old philosophical assumption that humans are insignificantly small compared to the vastness of the universe but also the logical assumption that there is no such thing as a central size. Both assumptions are false, but we have to reconsider the key words of the assertion—center, possible, size, and universe—to reveal the prejudices built into them that constrict and distort our picture of reality. In the modern universe there is a largest and a smallest size, and therefore a middle size.
The largest size is the universe itself. The smallest size is the: the Planck length. And guess what is just about in between those two? You, me. Us. Homo sapiens.
The Cosmic Uroboros represent the varying scales of the universe, from largest (the serpent's head) to the smallest (its tail). In their essays and books, Primack and Abrams use an illustration known as the Cosmic Uroboros to illustrate the vastly different scales of the cosmos — and where we fit in. The serpent's head represents the size of the visible universe. Going clockwise around the serpent from head to tail, you'll find among a number things the size of a supercluster of galaxies (10^25cm), a single galaxy, the solar system (10^16cm), the sun (10^10cm), a mountain (10^5cm), humans, an E. coli bacterium (10^-5cm), DNA, an atom, a nucleus, and on down through tiny scales of particle physics to the Planck length at the tail of the serpent. And as you can see, the size of a human being is near the center of all possible sizes. Primack and Abrams continue:
This turns out to be the only size that conscious beings like us could be. Smaller creatures would not have enough atoms to be sufficiently complex, while larger ones would suffer from slow communication – which would mean that they would effectively be communities rather than individuals, like groups of communicating people, or supercomputers made up of many smaller processors.
These quotes come from chapter 6 of his book, which you can access here.
I even designed the cover. ;-) The idea that we humans are insignificant nothings, that we're not at the center of the universe, etc., is wrong for other reasons as well. Astronomer Sandra Faber, Primack's colleague at U.C. Santa Cruz, and a leading scientist in the field of galaxy formation, had this to say in an interview with me for a book I wrote about the origin and evolution of the universe from the big bang to life (Cosmic Origins—the Quest for Our Cosmic Roots):
One lesson astronomy tells us is that we're a tiny mote in a hostile void, and help is too far away. We're on our own, on spaceship Earth. So we have to solve our own problems. More importantly, we've been given the gift of time. We have at least a billion years in which our home, if we continue to take care of it, will continue to suffice. What a chance, right? And lastly, people like Joel and I are figuring it all out by sitting on this tiny little planet and collecting photons from space. So far from feeling dwarfed by the vast reaches and energy of the cosmos, what we really learn is that we are the most remarkable and complicated product of cosmic evolution, and our potential is unlimited. In little localized pockets, the universe is capable of building some beautiful complexity. I'd really like people to understand that fantastic groundwork has been laid — a cosmic experiment has been running for 14 billion years, and it has gotten to an interesting point. How incredibly tragic it would be if we foolishly pulled our own plug.
The "we're insignificant nothings" meme can easily lead to anguished thinking, and a sense that it does not matter whether we screw things up so badly that we disappear. Yet that meme is is not at all uncommon among scientists. And it is advanced, whether intentionally or not, by videos like the one that got me going on this subject... So here's what I think: Pay attention to cosmologists. They know a thing or two about our true place in the universe.