Saturday, May 27, 2017

WHY IS THE UNIVERSE SO YOUNG?

In an earlier post I pointed out that one of the original rationales underpinning belief in a god was the notion that we occupied a special place in the universe, that the earth was in fact the center of the universe, and that we were the reason that the universe existed at all.  Science has shown that that just isn’t true.  The earth is just one of a number of planets circling a mediocre star out on one of the spiral arms of the Milky Way galaxy that includes some 200 billion other stars, billions of which have planets that are favorably situated to harbor life, including intelligent life.  Moreover, the Milky Way is just one of perhaps a trillion such galaxies.  In short, there is nothing to support the notion that we are special in any way.

Having said that, it may be that we do occupy a special place in the world or, perhaps more accurately, an unusual time.  The way I raise this point is by asking the following question:  Why is the universe so young?  Here I am not speaking of the fundamentalist Christian belief that God created the universe less than 10,000 years ago.  That position is totally unsustainable in light of everything we have learned about the history and nature of the universe.  We now know that our universe underwent a Big Bang some 13.8 billion years ago, expanding from virtually a single point to an observable universe that is now some 90 billion light years across and that continues to expand.  My fundamental question is, Why has it been only 13.8 billion years since the Big Bang?

Come on, you might say, 13.8 billion years is a very long time, probably much longer than most of us can get our heads around.  How can I say that that makes the universe “young”?

There is an extensive and growing literature regarding the history of the universe since the Big Bang.  And while there are differences of opinion as to details, there is a clear consensus regarding the broad outlines of that history.  I think there are a couple of (modestly technical) cosmological facts regarding that consensus that should be pointed out in this context.

First, it needs to be understood that the elements, particularly the heavier ones, were not present at or immediately after the Big Bang.  The very lightest elements of hydrogen and helium did predate the formation of stars, but the heavier elements formed in a different manner.  So how did such elements as silicon, aluminum, oxygen, carbon, and nitrogen, as well as much heavier elements such as gold, mercury, and uranium wind up as part of the earth’s composition?  The answer is that elements up to iron were naturally formed through nuclear fusion reactions in the interior of stars, the reactions that provide the energy that the sun and other stars pump out.  Some of those stars were unstable and underwent explosions that spewed those elements into interstellar space.  And the elements heavier than iron were created during the processes of those explosions.  The debris from those explosions then ultimately became part of new star systems, including our solar system. 

Second, our solar system began some 4.6 billion years ago as a cloud of gas, mostly hydrogen but with traces of those heavier elements resulting from prior stellar explosions.  During the following few hundred million years, that cloud coalesced into our sun and its retinue of planets.   Earth formed about 4.5 billion years ago; life began about one billion years later; and some 3.5 billion years later still, here we are.

This is what we know about the past.  What about the future?  Of course, the future is murkier than the past.  But our best understanding is that the process of stellar and solar system formation will continue for about another 100 trillion years (that’s with a “t”).  This would seem to put a limit to the opportunity for the de novo creation of intelligent agency by “natural” processes.  

And this is what I find just a bit puzzling.  If life on earth began 10 billion years into a process that could continue for another 100 trillion years, that would mean that human intelligence began at virtually the very beginning of that process, that is, during the first one tenth of one percent of that timeframe.  What are the odds of that?  If intelligent life could arise at any time during the period in which stellar formation is occurring, why is it that we find ourselves at the very beginning of that process rather than at some random point further along in that available 100 trillion year period?  It’s like asking a computer to randomly generate a number between 1 and 10,000, and it picks 2.

I realize that there are plausible answers to this question.  We could be very wrong about the future course of the universe or the timeframe for that future.  The Big Bang could be followed by a Big Crunch in an unending repetition of the entire process.  We could determine that stellar and solar system formation will end much sooner than now thought.  It’s possible that, though star formation may occur into the very distant future, most of it will occur early, so that we are closer to being in the middle of the pack, so to speak.  Or just by chance we may simply be at the very beginning of the period in the life of the universe when stars, solar systems, and intelligence can form.  After all, somebody has to be first.  

Still . . . .


© 2017 John M. Phillips

1 comment:

  1. John, You are so intelligent. I stand in awe of your "smartness." However, with my simple faith it is much easier to believe "In the Beginning God Created Heaven and Earth. " However, I am full agreement as to the age of the earth and the earth and the Universe.

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