By Joel Achenbach
Sunday, December 6, 2009
By this point, we've all seen so many pretty Hubble pictures that we're in danger of pretty-Hubble-picture burnout. We've seen exploding stars galore. We've seen majestic pillars of gas that are spawning new solar systems. We've seen galaxies colliding, galaxies getting ripped apart, galaxies becoming mired in their own ennui. We've seen Mars and Jupiter and Saturn in such stark close-ups that we can detect the cosmetic surgery scars.
We've seen quasars, pulsars, brown dwarfs, exoplanets, globular clusters and assorted nebulosities. It feels as if we've seen it all. Literally. The whole cosmos, soup to nuts. It kind of makes you wonder if we'll run out of new things to discover. Here's a real headline on a November news release from Stanford: "High-precision measurements confirm cosmologists' standard view of the universe." All figured out; everyone go home now.
So, you can just imagine the challenge that NASA's Hubble Space Telescope scientists faced earlier this year. In May, astronauts aboard the space shuttle Atlantis flew to the Hubble and, defying a stuck bolt that nearly derailed the mission, removed an old camera and replaced it with a better one. They fixed two other instruments, even though these things were not designed for orbital maintenance. Crew members installed new gyroscopes and batteries. After five spacewalks and much derring-do, Hubble was, in effect, a brand-new space telescope.
But what to look at next? The Hubble people had to pick targets to demonstrate the revamped telescope's abilities. They would call these images the Early Release Observations, or ERO (at NASA, everything has an abbreviation). They wanted to produce pictures with lots of (their term) Wow Factor.
The rollout came in early September at NASA headquarters in Washington. Big shots showed up, such as the new NASA administrator, Charles Bolden, and Sen. Barbara Mikulski of Maryland, the "Godmother of the Hubble," and all seven astronauts from the Atlantis mission. NASA beamed the news conference around the planet. Two huge flat-screens flashed fancy graphics. After much hoo-ha and throat-clearing, the moment came. The ERO! The journalists pounded out their stories, which all said pretty much the same thing: "Wow."
You see the danger here: Wow can turn into Whatever. The whole enterprise can start to feel a little superficial. It's too easy to get blissed out on the eye candy. We can become a little too star-struck.
So here's our challenge: We'll go back and look once again at these new pictures, but this time we'll probe deeper, think harder and search for any messages in the light that careens into Hubble's mirror. We'll do a deep reading of the cosmic text. And we'll ask the hard question: What is space telling us?
Let's start with the Butterfly Nebula, technically known as Planetary Nebula NGC 6302. It's so delicate, so sublime. You can see it fluttering through space. It's such a gorgeous image that we will refrain from dwelling on the extreme color enhancement that NASA uses to make these photographs so seductive.
The Butterfly Nebula is the product of a star in its death throes. It's a star much like the one we see rising in the east every morning. This will happen to us. This is our future. The star is about 3,800 light-years away, in the constellation Scorpius. Those wings are actually hot streams of particles being ejected by the star into interstellar space. As the star starts to run out of hydrogen and helium fuel, its core contracts, and, simultaneously, the intense radiation of the star blows the outer layers into space. It's not an explosion but more of a spewing. Here, the star itself is unseen, obscured by dust. The dust and slower-moving gas form a torus, like a napkin ring, which forces the spew to be conical rather than spherical.
Our knowledge about star mechanics comes largely from models, equations, number-crunching. But this Hubble image of the butterfly lets the models spring to life. Before the rise of scientific astronomy, stars were boring. No one knew that a star and our sun were the same thing. This ancient universe was a two-dimensional backdrop for human actions, like the painted sets in "The Wizard of Oz." And yet the butterfly tells us the truth: The universe is wild. The universe evolves, and change is the norm. There's something of a cosmic ecosystem out there -- the cosmosphere, if you wish. And the death of a star is cosmic fertilizer.
If you go back to the primordial universe, you find only the simplest elements, primarily hydrogen and helium. The heavier stuff, such as carbon and nitrogen, is cooked up inside stars. The Butterfly Nebula is a freeze frame of the seeding of the universe with the material for future stars, planets and life. The universe, to be chemically interesting, and to give rise to life, has to have stars. And stars have to die. Carl Sagan was right: We are star stuff. Life as we know it is constructed around four of the five most common elements in the universe: carbon, hydrogen, oxygen and nitrogen. Only the inert element helium is left out of the recipe (unless you inhale it, which can make you the life of the party). Life is opportunistic and pragmatic: It uses the most mundane materials butterflying through space.
Maybe life could, in theory, be based on exotic, harder-to-get elements. But life throughout the universe probably uses the stuff we use -- because any other strategy would mean going at things the hard way.
Next up, the stellar jet in the Carina Nebula. This is a double image that tells us that there's no single way that the universe "looks." The top image shows a star-forming gas and dust cloud as seen in visible light (the pillar glows from being irradiated by the golden light of out-of-frame stars). The bottom image shows the same structure as seen in infrared light. Visible light is, obviously, the wavelengths we pick up with our eyeballs. Infrared is what you'd see with night-vision goggles; infrared light is given off by any hot object, and it passes through intervening dust. In the infrared photo, the dusty cloud all but vanishes, and we see stars that had been hidden in the upper image. One star is firing jets of material in opposite directions. If Earth were directly in the path of a relatively nearby stellar jet, it would be lights out for all of us. Ditto if we were close to a supernova or to two super-dense neutron stars colliding and emitting a burst of gamma rays. The universe is violent. Almost every galaxy has a black hole at its core. At the center of our galaxy, which we call the Milky Way, there's a black hole with the mass of millions of stars. Fortunately, that's about 26,000 light-years away. We're in Sleepyville.
"We're in a very lucky, quiescent place in the universe," says Matt Mountain, the director of the Space Telescope Science Institute in Baltimore.
A light-year is about 6 trillion miles. The cloud we're looking at in the Carina Nebula is about three light-years from top to bottom. Earth has a diameter of about 8,000 miles, so if Earth were in this picture, it would be imperceptibly tiny. Other than some dust here and there, the universe is fundamentally transparent. This is why astronomy is possible. You can see stuff far away. But it was not always so.
"The early universe was very foggy," says physicist Brian Greene, author of "The Elegant Universe," among other best-sellers. For thousands of years after the origin of our universe in what is known as the big bang, the elementary particles such as protons and electrons sloshed around in a hot, chaotic soup. Light couldn't penetrate the stuff. It was only when the particles finally organized themselves in the form of atoms that light could suddenly zip through space freely. That transition toward transparency -- the cosmic Let There Be Light Moment -- happened about 400,000 years after the big bang. Cosmology, the study of the largest thing we know (the universe), is intimately connected to particle physics, the study of things that are vanishingly small.
Now we come to the globular star cluster Omega Centauri. And gosh, that's a lot of stars. This single image shows a region containing about 100,000 stars, out of roughly 10 million in the globular cluster.
The stars are different colors because they have different masses or are at different stages of their lives, which affect their temperature and brilliance. In a sense, this image of the Omega Centauri cluster is a chart of star life. Until the late 1800s, scientists doubted that Earth had been around for billions of years because they couldn't see how the sun could be on fire for such a long time. But it's not on fire. A star is a fusion reactor. Life on Earth can evolve for a long time because stars are fairly efficient at transforming matter into sunshine.
Size matters. If a star has more than about eight times the mass of our sun, at some point, gravity will overwhelm the dying force of its fusion reaction, and the core will collapse to a point of unfathomable density. When that happens, a shock wave forms, and all the outer layers of the star are exploded into space at 10,000 miles per second. That's your supernova.
When the red supergiant star Betelgeuse blows -- and it will someday, erupting on Orion's shoulder, 640 light-years from Earth -- it'll be so bright, we'll be able to see it in the daytime. All that will be left will be a tiny neutron star. A teaspoon of a neutron star would weigh about a billion tons. Very, very large stars, bigger than Betelgeuse, collapse into something even denser than a neutron star: a black hole. The matter is so dense that nothing, not even light, can escape its gravity.
The Omega Centauri cluster is hardly representative of the universe as a whole. Much of the universe consists of great gulfs of intergalactic void. We don't see images of the holes, the gaps, the great realms of nothing much. Moreover, if you want to get really technical about it, most of the matter in the universe isn't lighted up in the form of stars. It's dark. We're not sure what it is, exactly, but we can tell it's there from its gravitational effect on galaxies. And even ordinary matter is mostly dispersed in "empty" space. So stars are special features of space. It's a shame that "stars" is already taken as a metaphor, because otherwise we could say that stars are the stars of the universe.
It's hard to look at the Omega Centauri image without thinking, We are not alone. How could we be? The universe is so flamboyantly abundant and huge and awesome. J. William Schopf, a legendary UCLA professor who studies the origin of life, says: "I find it really, really difficult to imagine that the universe is not teeming with life. I don't know about intelligent life, but I think there must be a bunch of that out there, too. Our star is a normal, main-sequence star, so there's nothing special about it. We live on a rocky planet that has a lot of liquid water, but the Earth is 98 percent just like Venus, except Venus is closer to the sun. And I think such planets must be very common. There's nothing special about us, as far as I can tell."
This is a common sentiment among scientists. But there's a counterargument: There are a lot more ways to be dead than to be alive in this universe. In fact, when you look at all those stars in this globular cluster, you're looking at a patch of sky where life may never have taken hold. The stars are so close together that they would create a gravitational maelstrom that would prevent planet formation. Moreover, exploding stars would sterilize everything nearby.
"When you've gone to a globular cluster, you've gone to a not terribly good neighborhood," says Mario Livio, an astrophysicist with the Space Telescope Science Institute.
Earths aren't exactly a dime a dozen. Space all but screams at us: Take care of your planet, because you aren't likely to have a second chance. Our own solar system appears to be chockablock with dead worlds. Schopf's point about Venus can be turned around: This virtual twin of Earth is a furnace with temperatures at the surface of 800 degrees Fahrenheit. Mars may have had life once, but if there's any left, it's hanging by its alien fingernails.
Schopf's recitation of the Copernican Principle -- the realization that the universe doesn't revolve around Earth, that we're not in a special position -- can be extended even further: Not only is the universe not about us, the universe isn't necessarily about the thing we love most, which is life. Sure, the universe is filled with "vital dust" -- complex molecules that prime the pump for the possible emergence of living things. But the universe is also saturated with lethal radiation. Space is a harsh environment, in general. It would be wrong to see the place as preferentially biased toward habitability. There's lots of ice out there. Amazing rocks. It may be that God is a geologist.
The final picture is called Stephan's Quintet. At first glance, it looks like four galaxies, but then you see that the central object is two merging galaxies, with two galactic cores, like a double-yolk egg. The four orange-yellow galaxies will probably merge into a single galaxy; the blue-white galaxy is much closer to us and just happens to be in the line of sight of the other four.
But wait: There aren't just five galaxies here. There are hundreds of them. Only the round objects with X-shaped spikes are stars. Most of the other dots, streaks and smudges are distant galaxies.
This is, in a sense, a four-dimensional scene. With this two-dimensional image, we're looking at three-dimensional structures, but we're also looking back in time -- the fourth dimension. Each layer of the image represents a different epoch of cosmic history. We see the faintest galaxies as they were billions of years ago. "To me, it's like a geologist's core sample," astronomer Eric Chaisson of Tufts University says of the image.
Physicists will argue that we should not give any preferential status to what we call the "present." To a physicist, "now" is a subjective concept that just doesn't show up in the equations of nature. This defies common sense, of course, but no amount of protestation, arm-waving and spluttering will conjure from the physical laws any evidence that any one point in time exists differently than any other.
"The way I'd like to think about it is, there's this big block," Brian Greene says. "Physicists call it the block universe. It's all things in all time. It's a 4-D block."
We perceive ourselves in one thin slice of the block. But other observers -- say, in one of those very distant galaxies in the background of Stephan's Quintet -- will perceive themselves to be in their own slice. No one's slice is more "present" than anyone else's.
At least that's what scientists say now.
Each of these four images shows a universe that is obeying laws of physics that can be expressed mathematically. The gravitational attraction that is making our galaxy head toward a possible collision with the Andromeda galaxy is governed by the same equation that describes an egg falling and splattering on the kitchen floor. This is Newton's great achievement. Physicists will profess humility about what they don't know, but theirs is an audacious science, one that presumes that we can discover truths that are universal. If we make contact with aliens, physicists will leap in as the initial translators -- because in this cosmos, everyone speaks physics.
So why do these laws exist? Who wrote them? Why are they just so? The universe appears to be finely tuned to foster the rise of complex structures such as stars, galaxies, planets, living things and, eventually, theoretical physicists. Change, even fractionally, a few of the basic constants of nature -- the ratio of the gravitational force to the binding force within the atom, for example -- and no star would ever ignite.
There are those who say this is an argument for intelligent design. But that's not a testable idea. Ours could be just one of a multitude of universes that have different laws, different constants and where life never evolves. That's not a testable idea, either. But inferring anything about a creator from the array of circumstances that line up in life's favor is a stretch: Intelligent observers can exist only in universes with physical laws that allow their existence.
We've wandered deep into the territory of faith. For many religious people, the idea of multiple universes, with only some of them giving rise to life, is never going to be as satisfactory as the idea of a universe governed by an all-powerful and loving creator. But even the creator explanation doesn't really explain the origin of the cosmos. Because where does the creator come from? These are different ways of asking the very basic question: "Why is there something rather than nothing?" Greene, who spends his life trying to discover a single theory that explains and unifies the forces and particles of nature, says, "I don't think in the history of human thought we've really made any progress on that question."
But he does offer a head-scratcher of an idea. Nothingness, he says, doesn't look like a stable form of nature. Modern physics says that, at its essence, reality is unpredictable, shot through with uncertainty. So maybe Nothing just kind of ... toggled ... morphed ... twitched ... into Something. Says Greene: "You have it in your mind that Nothing is stable. But it could be that Nothing is a very unstable state. Nothing could be just always on the verge of falling apart into Something."
Which, let's face it, isn't a very satisfying explanation, either. The universe just kind of happens. It seems a mismatch of ambition and outcome, like some punk kid who can't get out of bed suddenly directing a movie starring Angelina Jolie.
So what does it all mean? That we're small, is one very obvious message.
This has been humbling, this investigation of space. The Copernican Principle keeps hammering flat our presumptions of specialness. Even the matter we're made of, the ordinary protons and neutrons and electrons, is trivial, compared with the much more abundant dark matter that we've yet to detect directly but are certain is out there.
But wait: Perhaps we're just getting started. We'll star-trek across the cosmos! We'll seed the universe with human intelligence and meet fascinating alien races and, occasionally, you know, mate with the ones with nice tentacles. The problem with this scenario is that NASA has put the Buck Rogers stuff on hold for the moment. Costs too much. Nowhere to go that's worth the trip. We could fly to the moon, but we already did that (they say). We could head to a near-Earth asteroid, but that would be exciting only if NASA promised to blow it up on live TV. Mars is enticing, but a Mars mission is almost as much of a budget buster as the Wall Street bailout. So, it doesn't look as if we're going to be visiting Stephan's Quintet anytime soon.
Where does that leave us with regard to outer space? It leaves us with a job: to gaze. It is our duty to look at the universe.
Let Eric Chaisson explain it: "If we weren't here, the galaxies would twirl, the stars would shine, and the universe would go on being its magnificent self. It's almost like we're animated conduits for the universe's self-reflection. If life did not occur in the universe, then the universe in all its awesomeness and magnificent beauty would not be appreciated. The universe would not come to know itself."
So, keep looking at those pretty Hubble pictures. Or, better yet, go outside on a clear night. Get away from the city. Look up and stare into the firmament.
And then say: "Wow."
Post staff writer Joel Achenbach blogs at washingtonpost.com/achenblog and can be reached at firstname.lastname@example.org.