(This is an associated webpage, the second part of a talk given on June 9, 2010 to those attending the Summer program of the Senior University Georgetown, a lifelong learning organization.) Re-posted, 6/25/10.)
THE GREAT STORY 2:
THE EPIC OF EVOLUTION FROM THE BIG BANG TO
THE FORMATION OF PLANET EARTH
1st Part: Introduction, Philosophy, Summary, References.
This is Part 2. 3rd Part: The Evolution of Life on Earth. 4th webpage: Further notes not in the lecture.
(Click here to read other papers on philosophy, etc.)
On this webpage, this part of the story, I'll offer a selected history of the Epic of Evolution, illustrated with pictures---describing events from the Big Bang to just before life emerges on Earth. The last part of the talk that "wraps up" the implications of this Great Story is included back on the first webpage.
The Great Radiance (also known as "The Big Bang")
One of the most striking theories that has accumulated increasing evidence that it is valid is that Time and Space "began" about 13.7 billion years ago, starting with a near-infinitely-small and near-infinitely energetic point of whatever, inflating quickly, and going on to generate all the atoms and electrons, all the radiation and other sub-atomic particles that ever were. It's quite fantastic---but what's even weirder is that this theory is corroborated by a variety of sources of evidence. Okay, say it's not entirely true, what is important is that we dare create a creation story that works, that helps people find some positive purpose in life. So this webpage will trace a few highlights of the story as we see it. The webpages by Michael Dowd and Connie Barlow, and others, all support this general story. In turn, this offers yet another way to think about it all.
The Primal ParadoxWell, I find it funny: As I said on the other website, it seems as if the greatest events, events that make the hydrogen bomb or a billion of them, the sun or a billion of them, pale in comparison, is that to understand the vastness and intensity of the biggest cosmic event, the Great Radiance., one must also appreciate that it is an aggregate event, composed of the absolutely tiniest sub-atomic energies and particles-in-formation ---zillions of them. Mythically speaking, I think God is foolin' with us, that it's kind of
funny, juxtaposing the biggest and smallest. (Here on the left is a picture of evidence of these sub-atomic particles taken via a cloud chamber.) Also fun is the growing awareness that we know fairly little about the whole thing. I'm reminded of a book I've recently read by David Bodanis about electricity and how much continued to be learned in the two hundred years after some of the first understandings were reached around 1800.
This first phase took a long time: A billion years---we can say the word, but in truth this is literally inconceivable---the human mind cannot really imagine what that kind of time would be like. It's longer than waiting at the doctor's office! The point, though, is that the first tasks can take more time than we think. It can take months for a baby to learn how to use his hands, while an adult requires only minutes to figure out how how to manipulate a new tool. However, if one imagines mythically that God is trying to figure out how to make a star, and how to make it into a factory for making elements, starting with nothing but the most basic building blocks of single protons and electrons—that is, hydrogen— well, it’s bound to take time. One more thing about the time chart above is that in the middle and to the right, even now, stars are still being born!
We seem to be at the center of the universe, but it's an illusion: The universe is seen as it once was, not as it is today. Far out from us are distant galaxies, mysterious quasars, and beyond that, the cosmic background radiation that is a clue to the way the early universe was more homogenious. Also, closer in, we've become aware that the galaxies are organized in a somewhat filamentous structure, though we don't know what that's about.
This picture to the right reminds us that we are looking outward through telescopes that pick up the light that originated years ago, thousands, millions, even billions of years ago. Also, as we look out from our viewpoint, we see galaxies and note now that they are organized not as homogeneous soup but rather with some structure, with areas of lesser and greater density, an almost filamentous structure. Let me say here that each of these slides could serve as the foundation for a full lecture or a whole series of lectures.
If the Great Story was sort of like a Bible, there might be a thousand chapters and each chapter would have via hypertext thousands of other pages.
For example, below, this picture of the asymmetry of the cosmic background radiation has become more finely grained because over the the last decade our instruments are more able to discern fine differences than they were twenty or even ten years ago.
This is a composite photograph of the cosmic background radiation, with more detail now more than ever because of the increased sensitivity of modern satellite and ground telescopes.
There are innumerable mysteries remaining---a mystery being defined by Huston Smith (a noted scholar of comparitive religion) as one of those things that, the more you learn, the more questions are raised.
Another one of these is the mystery of "dark matter"---what keeps the galaxies coherent. (Current theories of gravity and momentum would predict that they couldn't rotate at the speed they do without the outer stars spinning off.) Another recent finding is that galaxies as you look further out, instead of slowing down their acceleration, actually seem to be speeding up. This data suggests another weird concept---"dark energy"---which again, although we've given a word to it, doesn't mean we know anything more about it. Well, except that if enough energy can be converted to matter according to Einstein's E+MC2, then this would account for a great percentage of the mass of the total universe, which throws everything off.. Saying it another way, familiar matter such as atoms---taking these revised calculations into consideration---accounts then for only about 4% of the mass of the universe---almost an afterthought. Dark energy pervades all of space and accounts for 74% of whatever exists and dark matter then accounts for 22% Mystery continues. (My hypothesis---very possibly mistaken, but maybe---is that dark energy and dark matter are expressions of another dimension---the realm of mind---that underlies the material cosmos.)
In 1977 the Lick Observatory took hundreds or perhaps thousands of photos of the heavens and put together this composite picture of not the stars, but just the galaxies. There are around a million of them shown here. But what boggles my mind is that what we've found since then is that the number of galaxies may well number as many as a trillion---that is, a million millions! That is, imagine this picture and each tiny dot is the whole picture of a million galaxies!
Another thing to note: galaxies are not distributed evenly, but rather clump as a filamentous network, along lines, with other areas that are relatively less dense. We don't know what that is yet. It arouses in me what a friend called "astonishmentality."
The Hubble deep field. In 1994 they pointed the Hubble space telescope at a seemingly "empty" patch of sky---i.e., no visible stars there---the size of a what might be covered by your fingernail held at arm’s length. They collected photons, evidence of light, for a week, then developed the film, and discovered countless galaxies beyond the stars.
In 2005 or so they did it again with the refurbished Hubble space telescope, aimed at another patch of seeming darkness and again found even more! They worked out a way to portray these in apparent 3-D (three dimensions) and posted the video at http://www.flixxy.com/hubble-ultra-deep-field-3d.htm
The point is that the cosmos is prolific, far more than any animal in the production of sperm cells, any seed or even forest in the production of seeds. 26 webpage deep field So the Cosmos is, shall we say, prolific, far more than the sperm of squids or the seeds of whole forests.
The Galaxy, the Sun, and Star FormationOur Milky Way galaxy is a spiral type and the sun is about 2/3 out on the periphery, located around 6 o'clock in this picture on the right. Looked at from the side, the sun is shown again "in the suburbs"---which is probably perfect for protecting its planets from too much radiation.
Here's a diagram of the electromagnetic spectrum. You could study this for a year and not mine all the knowledge here, nor the mysteries remaining. Note that radio, microwaves, x-rays, and cosmic "gamma" rays or the type that can cause radiation sickness---all are the same as light, but with either slower or faster frequencies. Slower frequencies are still as fast as the speed of light, but they are less intense. They glow with infra-red heat or even more subtle non-visible energy---i.e., microwaves, etc. On the other hand, faster waves are more bluish, and beyond blue, in the ultra-violet, or again invisible. Because they're so energetic, unlike radio waves, they can be destructive to living tissues. Their energy breaks up molecular structures. The diagram portrays a logarithmic scale, so you don't see it clearly: what we can actually see is only a tiny fraction---a billionth!---of all the possible ranges. As for stars, let's say that blue stars are hotter, like white hot is hotter than red hot. Such stars are more massive and their extra gravity causes extra pressure which in turn causes faster burning, so their lifetimes are much shorter. When they give out, they explode as supernovae and spew out heavier elements into outer space. Big red stars are yellow stars that have reached near the end of their life cycle, which our Sun will do after three or four billion years in the future. (Don't worry, be happy.)
Considering the "Color" of Stars
To appreciate the next few slides, let’s notice a few things that have been discovered in the last century or so: First, light is but one tiny fraction of other types of less-than and more-than light. Radio and TV are slower kinds of light, and X-rays and cosmic rays are faster kinds of light. The faster kinds of light are more energetic, look bluer, or even ultra-violet; while the slower kinds of light are less energetic, infra-red and microwave and radio.
Now we have telescopes that pick up these other wave lengths, just as we have microscopes—electron microscopes—that pick up all sorts of stuff that ordinary light microscopes or telescopes can’t see. In other words, our tools are becoming more sensitive.
Also, in understanding stars, bluer is hotter, and hotter burns faster; while yellow and orange and red are relatively cooler—though still very hot— and burn slower.
The Different Kinds of StarsHere's a chart of the different kinds of stars: Our sun is a yellow star sort of a little to the right of the middle. Old stars of this type turn into "red giants" noted at the upper right, while the bright, more massive, faster-burning stars that turn into supernovae are at the upper left. The more to the right a star is placed, the slower it burns---by many orders of magnitude.
30. This will happen to our sun in 4 billion years or so. Then they’ll blow off some of their outer shell and shrink to a white dwarf.
As for the faster-burning bluer stars, they are our sun's "grandmother," that sprinkled material that we have been able to incorporate into our bodies, like iron for our red blood cells.
And the other stars that finished their lives, our sun's "mama," also sprinkled the surrounding regions of space with elements that, when gathered back together, condensed, made for the basic chemicals in our body---especially carbon, nitrogen, oxygen, and hydrogen. (Hydrogen plus oxygen makes water.) Here is a picture of what our Sun might look like in 4 billion years as it wears out, seen from a near-molten Earth. The Sun as an old star has expanded to about 150 times its previous diameter and has vaporized the near planet Mercury. It will then blow off its outer core, distributing the slightly larger atoms it has made into space. The top row below shows the red giant stars. Below those pictures are pictures of how supernovae work:..
On the upper left of the "Hertzsprung-Russel" diagram of the different types of stars, in the blue, are the massive stars. They give off a white-hot bluish light because, being ten or more times the mass of our Sun, they generate correspondingly more pressure in their core. They "burn" via fusion more hydrogen into helium and into larger elements, too. As they wear out, a large star such as this becomes a supernova. In the second row above are pictures of some stars and inter-stellar gas---in the "Tarantula Nebula" ---that in 1987 showed that one of its stars had done just this. Note the bright light in the far right picture. The energy given off by a super-nova can be greater than all the energy given off by an ordinary star over its whole lifetime. In the third row down is a picture of the "anatomy" of a super-nova and then to the right a residue of a famous one observed a about a thousand years ago and written about in detail by astronomers in China.
The thing about these supernovae is that when they begin to run out of fuel, they contract and expand, and this process makes them alchemical laboratories for building heavier atoms, the heavier elements, such as iron, which ends up coloring our red blood cells. When they explode, they sprinkle space with these atoms, too. Our galaxy produces on the average of one supernova every 50 years. One of these was our Sun's "Mother" in the sense that our local Sun as a star condensed out of the gases (and heavier atoms as well as lighter ones) expelled into space when it collapsed.
The Formation of the Sun and Our Solar System's PlanetsAround 5 billion years ago all this happened and over the next several hundred million years the gases condensed, pulled together by the weakest force in the universe, but in another sense, the most patient, and in its aggregate, perhaps the most powerful---but it takes a long time to achieve its ends. Anyway, as gravity pulled more material from interstellar space together it formed a heated disc that condensed in its center---the more it did this, the stronger the gravity, and inside, the stronger the pressure, which translates into heat, enough for fusion reactions to begin to happen. The proto-star begins to glow, then shine more brightly.
Now that we're beginning to appreciate star formation, it seems to most astronomers that a residual disc of gas and grains is a common feature, and over time these condense to become planets.
Before we describe more about the way planets form, let's note that as we've begun to use other types of telescopes to examine the sun---including, say, those attuned to just the ultra-violet wavelengths like the one below, a fascinating degree of detail emerges.
Careful interpretation reveals a most complex system with many "cells" of circulating gasses (each the size of the whole state of Texas!), and many other dynamics such as flares and sun spots. There
are special classes in upper division astronomy that spend the entire semester or more just teaching about what we've learned so far, and much more remains to be known.
Aggregation of the Rocks into PlanetsThe accretion theory of planetary formation suggests that after dust settles toward the plane of the disc, it aggregates to form bodies called planetesmals, each of which are about 5-20 km in diameter. Successive collisions lead to the formation of terrestrial planets and the cores of the giant planets. The giant planets (such as Saturn and Jupiter) accumulate gas from the solar nebula to form deep atmospheres, whereas the atmospheres of the terrestrial planets (Venus, Earth, Mars) are formed by out-gassing from within.
The speeds at which these mountains of rock traveled led to astoundingly energetic impacts. (See below left). The birth pangs of our planet and solar system were almost inconceivably powerful!
Below there is another picture of the forming solar system. On the planet on the right there are little orange spots. These are impact craters from recently arrived planetesimals, giant meteorites. They add great heat to the planet which is in other parts darker, beginning to crust over, like the surface of molten lava. But right under the surface is that lava.
In this liquid state, the heavier elements such as iron and nickel sink towards the core, displacing lighter elements such as aluminum and silicon, which find their level closer to the surface. Meanwhile, there is a lot of water, too, and nitrogen and other gaseous lighter substances, and these bubble to the surface, generating a primordial atmosphere. Oxygen is so reactive, though, that it binds with other elements to make oxides---so that the crust of the earth is largely composed of oxides of silicon and aluminum.
The theory of aggregation also suggests that many stars have planets, rather than only a few, a theory that greatly increases the probability of life on other planets.
Above is a closer picture of that dynamic of meteorite impact, keeping the Earth molten in the first few million years of its formation. Nothing could live (biological life) in this inferno.
The moon was closer as the earth began to cool, and there was still a disc of dust and planetesimals that would fall to earth or onto the moon in time.
And so ends the second webpage, the second part of this Great Story. The science of the "geosphere" is fascinating, involving meteorology, chemistry, geology, and so forth.
In the next webpage we'll continue this story, exploring in extra-brief form the history of life on this planet. To begin with, it did begin surprisingly early, and we don't know how that happened. There is research, of course, and hints, but these only provide fodder for speculation.
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