Our planet, our sun, our galaxy, are doomed. Our collective fate is sealed by gravity gone mad. A monster approaches. It will engulf us; it is our destiny. Our destructor is relentless, twice the size of our own island of stars, inescapable; there's nothing we can do to stop this cosmic rendevouz. In two-billion years our own Milky Way and the nearby giant Andromeda Galaxy, will merge. The individual stars won't hit each other, space between them is vast. But the clouds of gas in both structures will tear through each other and glow as bright as day. Worse still, lurking deep in the center of both galaxies are truly horrific monsters ripping the fabric of space and time. These two stellar ogres will flirt with each other, distantly at first; then enter into a fatal gravitational embrace. Circling ever closer: waves of heat and deadly x-rays will light up the galaxies from rim to rim for thousands of years. And then, when those two, massive, black galactic hearts finally merge and beat as one, a searing pulse of gamma rays will bathe the galaxy for millennia. It will kill every living thing, within a million light-years.
Our sun is a star. It's one of billions of stars which make up the Milky Way Galaxy. Galaxies are collections of stars, dust, and gas. They come in all kinds of shapes: Globs, blobs, spheres, beautiful pancakes and spirals, bar-shapes, irregular clouds, even rings. Some are huge, containing a hundred trillion stars. Others are just waif-like puffs harboring a paltry few thousand suns. There are
billions of galaxies as large, or larger, than ours in the universe.
Astronomers group galaxies into Elliptical, Spiral, and Irregular. Our own Galaxy, the Milky Way, is of the spiral variety. Our planet is relatively puny as planets go, and our sun is a runt of a star compared to the blue-white powerhouses and red giants scattered about the universe. But our mother galaxy does us proud. The Milky Way, is one big, bad, bitch; and she happens to be a gorgeous one at that.
Two Spiral Galaxies: Left, Our Milky Way (Enlarge) and on the right The
Whirlpool Galaxy (Enlarge)
Left: The giant Elliptical Galaxy M 87 contains perhaps five-trillion stars (Enlarge). On the right two tiny Irregular Galaxies which would appear as pinpricks next to M 87 (Enlarge)
(Enlarge Greatly)
Left: The Barred Spiral Galaxy NGC 1300. Right: the incredible Cartwheel Galaxy
For almost a century, most classical astronomers concerned themselves with how stars form, what powers them, how they change into white dwarfs, form planetary nebula, collapse into neutron stars, and black-holes. But we really didn't know until just a few years ago how galaxies made out of billions of stars might work. Why they form, how they change, why some are balls and others are spiral pancakes, or how they started out in the first place. Why are stars grouped into galaxies at all? Why aren't stars just randomly spread through the universe?
The first clue on that process came from the most distant optical objects we can observe in our cosmos. These things looked like stars in early telescopes, but when our detecting power increased enough to get a spectrum on the critters, the Hubble red-shift revealed they were billions of light-years distant. They were also producing huge amounts of radio waves, microwaves, UV, and X-rays. The amount of energy these objects had to be emitting to be visible in all those bands clear from the other side of the universe was simply staggering. We're talking the energy of a supernovae times a trillion. They were dubbed Quasi-stellar Objects, or Quasars for short.
The weird thing was, there were no Quasars nearby (Thankfully or we'd be fried), they were all extremely distant, and thus seemed to be events that only happened early in the history of the universe, just a couple of billion years after the Big Bang itself. The Quasar light we were detecting was ancient, it had traveled billions of years. The actual Quasar is long gone by the time we see it. And still, no one knew what the hell they were.
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Quasars: Giant Black-holes firing streamers thousands of light-years long into space
With improved telescope and radio astronomy in the 1950s and 60s, long jets arcing out of the center of the Quasars were seen. These streamers were enormous, some over one-hundred-thousand light-years long! Then, as Cygnus X-1 and the stellar mass black-hole physics came to be understood, it became pretty obvious what was going on with the Quasars. It was also sobering as hell to contemplate; A Quasar was a gigantic black-hole with the mass of a billion stars and it was shooting out energetic x-rays and white-hot matter like a cosmic flame thrower for thousands of light-years. If the earth somehow ever got in the path of that kind of power, even for just a split second, our planet would be nothing but a puff of vapor.
In 1997 Alan Dressler and Douglas Richstone decided to use a recently developed, new method to check for the existence of small massive objects in the center of galaxies. They were just trying to see if they could detect a big black hole in a specific semi-regular spiral galaxy. This particular spiral was nowhere near Quasar levels of energy, but it was unusually active in various wavelengths and the massive black-hole model had worked so well for Quasars these gentlemen were curious if it could explain other galactic anomalies. To act as a control, they also used the same observational method on the nearby Andromeda Galaxy ... To the utter amazement of everyone involved, not only did the distant active spiral have a super massive black-hole in the center, the Andromeda Galaxy did also! Curiosity and speculation now peaked that super massive black-holes might lurk in the heart of all galaxies. Quickly others were checked, and sure enough, they all had super massive black-holes in their centers!
Milky Way Center as seen from earth, with the position of our own local super massive black-hole marked (Enlarge)
So ... you can guess where the next place we looked for one was; our own Milky Way. And again, sure enough, tucked into the center of our own galaxy, a mere thirty-thousand light-years from our solar system, there is a super massive black-hole. The mass is about 3.5 million times that of our sun! And that's a small one as super massive black-holes go. Thanks to the Hubble Space Telescope and new technology for earthbound platforms, astronomers can watch stars orbit this thing so fast they literally move in the frame from night to night. Some of them are traveling at half the speed of light!
Most every galaxy it turns out has a super massive black-hole in the center. And here's the catch: In every case that black-hole is exactly 5% of the mass of the galaxy. That tight a correlation between masses of the central black-hole and the entire galaxy repeated thousands of times in every kind of galaxy cannot be a coincidence. That ratio and the early active objects called Quasars were trying to tell us something very important about how galaxies are made.
Here's a plausible process: A giant black-hole forms early in the history of the universe. It has the mass of a million to a billion stars, it sucks in matter (Mainly hydrogen) all around growing larger and larger. An accretion ring forms encircling the black-hole, much of the hot gas is ionized and gets channeled up to the poles shooting out instead of being sucked in. This material forms the great jets observed streaming out of the Quasar. The ejected material hangs around the general vicinity, usually distributed in a roughly spherical manner. That gas then begins collapsing into clouds, then Bak Globules form from the larger clouds, and we have the formation of stars underway inside the Bak Globules. The size of the galaxy, the number of stars, depends on how much material the super massive hole shot into the space around it. The bigger the hole, the more stuff it attracted from nearby space and thus the more it fires out. The more stuff shot out, the more stars will be able to form from that material giving the ratio between the mass of the resulting galaxy and the original super massive hole. Sometimes for relatively small super massive holes, that's only a few thousand stars. For the largest super massive black-holes, it could be trillions of stars. And there's the start of your elliptical galaxy. Sooner or later all the really easy, nearby gas is sucked up or spat out in the jets, and the whole shebang quiets down--unless a new source of material suddenly becomes available in which case the Quasar will briefly fire up again. But what usually happens is the galaxy becomes less and less active, until it's just a regular old elliptical galaxy with a big black-hole in the center. Pretty slick, huh?
Two elliptical galaxies approach one another, distort, and merge. The collision produces rotation and the beginning of the spiral pattern. Two spiral galaxies are born which will soon merge again forming a final single spiral
And spiral galaxies like our own Milky Way? Well, one way those can form from elliptical galaxies is via collision. This idea came easy enough. Galaxies bump into each other. We can see them in all stages of collision throughout the universe. Ellipticals can form into spirals and spirals can congregate into ellipticals. When this happens, it's like a swarm of bees passing through each other, the individual stars rarely collide, but the collective gravity of each swarm radically distorts the other as they interact. They can end up orbiting their common center of mass, drawing out streamers of stars from each other, usually introducing rotation forming a flat pancake of stars. Eventually they merge completely, the rotation is retained. The central black-holes quickly seek each other out and merge as well; and that event is probably quite energetic to put it mildly. Some types of collisions would probably produce ring-like compression patterns radiating out from the center in concentric circles. Stars would form in these denser bands of gas and dust, making those concentric circles glow with new starlight. The pattern would be twisted and warped by galactic rotation until they were trailing spiral arms. And presto, that's one way to make a spiral galaxy. They might also come straight out of the supermassive black-hole accretion disk; they may form in more than one way. Bar-galaxies and ring galaxies are probably just variations on the collision scenario.
Our own Milky Way may have originated in this fashion not so long ago in cosmic time. It suffered at least one major collision, probably about 5 to 6 billion-years in the past. Hanging past the outskirts of the Milky Way, high above the southern pole of our galaxy, is the telltale signs of that ancient catastrophe; two wispy patches of stars called the Magellanic Clouds. These are probably streamers which haven't yet been absorbed. For all we know, prior to that event, our galaxy might have been an elliptical, and our sun could have been merely one of countless stars produced in the dynamics from that primeval collision!
Two irregular galaxies nearest our own Milky Way, the Large and Small Magellanic Galaxies. These wisps are likely remnants from an ancient collision which occurred before our sun was formed
The Andromeda Galaxy as it may fill our night sky in 1.5 billion years.
It will happen again. The Andromeda Galaxy is barreling on in to smash us up. In two-billion years it will fill the night sky from one horizon to the other. Glorious yes, but it will tear into the Milky Way, the interstellar gas in each galaxy will heat up until it glows white-hot. Hordes of stars will go nova, our galaxy and Andromeda will twist and distort, making several passes spraying out stars like a firework fountain. Eventually the two masses will form one big galaxy, the two black holes will go into a tighter and tighter orbit around one another until they also merge. And the violence that will ensue from this inevitable super massive consummation will sterilize everything for millions of light-years around; at least in my version here. No really knows.
If some form of human descendant still exists at this future date, we'd better damn well be totally out of the galaxy if we/they hope to survive the apocalypse. Anyway, it is two billion years away, we don't have to start packing just yet.
Back to our Quasars and theories of galactic formation; all we need to be able to do is explain how these titanic black-holes formed in the early universe and we'd have one hell of a sweet theory explaining a lot. Unfortunately, we only know one sure-fire way to form a black-hole, and that's the stellar evolution model reviewed in the previous article. That will get you a black-hole all right, but it will be puny compared to these galactic sized monsters. No where near the mass needed to make a Quasar and a galaxy. It's possible that early stars called VEMOs (Very Early Massive Objects) formed a bunch of black holes quickly and they merged to make big ones.
But it doesn't really seem like there was enough time for a bunch of stellar mass black-holes to form and merge to make giants with a million to a billion solar masses. And keep in mind that billions of these giant black-holes have to be created to account for all the galaxies we can observe. It may be that during the period called Inflation, in which the very, very early universe underwent a sort of second Big Bang and expanded greatly in a short interval of time, that a few 'strings' as in string theory were also blown up to colossal sizes and masses that spanned the cosmos. In this scenario enormous black-holes would then condense on the cosmic strings like dew drops on a spider web.
Note that galaxies are not scattered randomly about the cosmos, here and there. They form clusters arranged in sheets, arcs, and filaments, with enormous voids, bubbles of empty space, between them. The cosmic string hypothesis might explain why galactic super-clusters are arranged in this manner; these are the pathways swept out by the cosmic strings and therefore this is where the super massive black-holes condensed and formed the galaxies they inhabit.
Or these early massive black-holes could have developed by a process we currently know nothing about. Perhaps dark matter or dark energy played a role; the origin of these objects remains one of the great galactic mysteries. One waiting to be solved.
The large scale structure of our universe. Each pixel represents a cluster of galaxies. Each of those galaxies in turn contains on average, billions of individual stars.
However they were made, like so many occupants in our universe, super massive black-holes have the power to both create and destroy; they just happened to do both on the grandest scales we can conceive; these things forged our familiar, starry cosmos! They are the Architects of the Universe.
The Quasars lit up early on, just a billion or so years after the Big Bang and crafted the very galaxies themselves out of dust and gas, with a power and energy that makes a super nova look like a fire-cracker.
The calcium in your bones, the iron in your blood, the carbon in your DNA; all of it started out as hydrogen gas whizzing around a super massive black-hole billions of light-years away at near the speed of light. That material was shot into intergalactic space by a giant natural particle beam accelerator courtesy of a Quasar and eventually condensed into stars around the behemoth black-hole. There it was cooked into heavier elements inside stellar furnaces at millions of degrees and recycled back into space to be reformed into stars again and again.
Finally, one of those super massive denizens at the center of a galaxy came crashing through another elliptical collection of stars, transforming both with ineffable violence into a glowing multicolored spiral, painted in every color of starlight and glowing gas. One sun in particular formed as a result of that collision, one planet formed around that small yellow star. Through a series of events we're only beginning to understand, some of those elements formed self-replicating molecules, unleashing the powerful engine of evolution and natural selection. And, over four billion years, one of those evolutionary lineage's out of zillions become us: Humans.
Now, armed with an ape's brain and primate digits to count on, we've invented writing, mathematics, and built devices that peer into the heart of distant galaxies and subatomic structures. And through that, using a knot of neural tissue at the end of a pogo stick spine, we've started to unravel just a tiny bit of all that has gone into making us and everything else we can observe. That to me is a pretty damn powerful story: A barebones outline of The Greatest True Story Ever Told. It's the 13 billion year saga of how inanimate matter came to life in our Cosmos, evolved sentience, and through us, became aware of itself. And the best part is, it gets to be our story; A Progressive's story. For the GOP has gone batshit crazy and turned their backs on science.
Prologue
There's another anomaly possibly related to massive black-holes and gravitational monsters. All of the nearby galaxies including our own are blazing along at over 1,000 miles per second to a point about 150 million light-years away. That region seems to be drawing in matter from all over, from hundreds of millions of light-years in all directions. It is therefore called, for lack of a more precise name, the Great Attractor. This beast would need to have the mass of a hundred-thousand galaxies the size of our Milky Way to account for the effects we observe. But we can't see anything in telescopes or detect anything in other wavelengths to account for it. Could a giant black hole, free of a galaxy be lurking there? Or is it something else, some kind of dark matter object; the non bayronic analogue of a super massive black-hole or giant galaxy? Something new, exotic, maybe even dare I say it, something artificial (That would be a scary race of beings, to have that kind of power ... maybe we'd call them, Xeelee?)? Right now, no one has a clue what it might be.
So, fact is, there are real mysteries out there in the cosmos, giant black-holes, gravitational monstrosities, mysterious attractors, bizarre forms of exotic matter, dark energy, and things we haven't even dreamed of yet, waiting to be found and explained. There's plenty to learn, we haven't even scratched the surface. We need lots of young scientists to take up the good fight and push our knowledge one more notch, one more iota, one more datum. There's a whole dark sea full of unknowns, it's every where we look, in the large and the small, the subtle and the obvious; just waiting to be seen, examined, understood, appreciated, and passed on to the next generation to build upon.
That's not to say we should ignore what we do know or what is plausible in favor of utter lunacy. The Theory of how super massive black-holes form galaxies is speculative, it's only a few years old. There's probably going to be a lot of tweaking and adjusting and that's assuming it holds up down the road. But, it's not quite in the same league as the idea that a large mythical female goat crapped black-holes out of her cosmic uterus and sprayed stars onto them with her divine teats. All ideas and explanations are not equal, and not all deserve to be taught as such. EG: Creationism. If those clowns were still in charge of science like they once were, we wouldn't know any of this stuff I'm writing about right now.
Yet, sometimes non-scientists get the idea that we science geeks think we have it down, we know everything, we have it all sewn up, the rest of the world is just too stupid to bother trying to educate. But that's not the case at all. (In fact I'd say that the idea of scientists as elitest snobs is a carefully manufactured, devious piece of winger propaganda, designed to implant the idea in the collective psyche that science really can't be trusted because scientists can't be trusted. That makes it all the more easy to dismiss science when scientific fact inconveniences political ideology and the endless pursuit of gold Latinam by the Ferengi Repugs). Those of us who study the universe and nature are in awe of mysteries unsolved, phenomena unexplained, and discoveries that await: And I'd wager that most of us, scientists, science buffs, and folks who don't particularly care for science at all, enjoy a good mystery. And that's what science is really all about; solving the mysteries of nature.
We're all pretty proud of what past generations have managed to wrangle out of the natural world, but we hunger for ever more information, we peer over the edge to see what we can see, we take shots in the dark: Scientists and science buffs and just everyday folks are driven to know, to understand, for the sheer delight of it. From quark to Quasar, we science geeks do realize, perhaps more than most folks, just how ignorant we walking apes really are about this amazing structure we call the cosmos. Even the greatest scientific luminaries are humbled by it.
Case in point: Isaac Newton was arguably the greatest scientific genius who ever lived. From his brain came The Calculus, The Theory of Gravity, The Laws of Motion, even a theory of light-all before age 30. His orbital mechanics are used virtually unaltered to put payloads into space, to set sail for distant worlds. The Calculus alone is the basis of every field of engineering and physics on earth. If anyone has ever earned the right to be an arrogant know it all, Newton was that person. And he was by all accounts smugly inclined to do exactly that. Yet this greatest of scientific intellects insisted that his headstone be engraved with modest words that still ring true today, perhaps they always will:
"I don't know what I may seem to the world, but, as to myself, I seem to have been only like a boy playing on the sea shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.' --Isaac Newton