The Universe, Fate, and Our Choice

M31, AKA the Andromeda galaxy

Image by Amir Hossein Abolfath

Through Astronomy Picture of the Day (APOD)

Copyright © 2019

by Ralph F. Couey

I have always enjoyed television programs about science, particularly anything about space.  I spend a lot of time (perhaps too much) on the Science Channel, in particular a program entitled "How the Universe Works."  The episodes deal with knowledge, past and current, with some healthy speculation about the unknown.  The series "stars" consist of about 145 of the most preeminent scientists working in various aspects of the astronomy/cosmology field.  The information is presented well, managing to balance on the knife-edge of comprehension for the rest of us, while still managing to teach at the same time.  The graphics are cutting edge, and if you have one of the advanced technology televisions, eye-popping as well.  

Just this past week, I learned the latest theories on the birth and evolution of our solar system, and how big it actually is.  (Hint:  It's way bigger than you think.)  I also learned what is currently known about the most distant objects, quasi-stellar objects, or Quasars.  I already knew that at the center of our galaxy exists a super-massive black hole.  I also learned that the one at the center of the Andromeda galaxy is ten times larger.  I learned what the best idea is for why the crust of the moon is twice as thick on the far side as it is on the side that perpetually faces us.  I also learned that if it wasn't for this uncommonly oversized moon, not only does it keep the earth from tumbling its axis, it is, because of its effects on earth's tides,  probably most responsible for the beginnings of the complex microbial life that eventually led to us.  

I have known folks in my life that worry about the craziest things.  I remember one acquaintance who went from concern over falling space bodies (asteroids, comets, etc.) to worry about the Yellowstone volcano erupting.  The revelation that there would be a collision between the Milky Way and Andromeda galaxies almost sent him over the edge.  While most people are not as neurotic as he was, there is still some concern, mainly based on a vast gap of knowledge between what they think and what is actually known.

Yellowstone is one of the largest volcanic systems on the planet.  It has three times erupted catastrophically about every 700,000 years.  Naturally, people worry, particularly when irresponsible journalists, or perhaps click-bait purveyors, run wildly apocalyptic articles about the terrible things that might happen if Yellowstone would erupt again.  Now, its true that such an event would forever change earth, and us, for the worse.  But despite the measured frequency of those eruptions, earth is not a clock; things don't happen on any kind of schedule.  The Yellowstone caldera rests above a geologic hot spot, a place where magma has a shorter route through the mantle to the surface.  But, the continental plate above the hot spot continues to drift and apparently the land currently over the hot spot is thicker than previously, and will get thicker.  Also, though the magma system is incredibly large, it is at current filled with a type of lava that is not prone to eruption.  There are still some really interesting geothermal things happening at Yellowstone, but any eruption will not happen for a very long time, perhaps as long as 100,000 years.  And where will we be?  Well, 100,000 years ago, the very first Homo Sapiens were beginning to migrate out of Africa.  Run that yardstick forward and just imagine what, or who will be here.

There is a danger from comets and asteroids.  We remember the Chelyabinsk surprise, and just last week, a rock about the size of a SmartCar zoomed past earth at a very close distance, beneath the orbit of the geosynchronous-orbiting satellites.  But a dedicated group of scientists are looking carefully at the sky, and have discovered some 20,000 asteroids and 100 short-period comets that could pose a threat at some point, and more are being discovered every week.  There are several plans in the works to deal with diverting any extinction-level body that might come uncomfortably close and while none of them are as yet launch-ready, that moment is closer than you might think.  Of all the existential threats out there, this is certainly the most obvious, and most likely.

Andromeda is currently about 200 million light years distant and our two galaxies are closing on each other at about 70 miles per second.  That means that in about 4.5 billion years, they will occupy the same point in space.  The word "collision" is a misnomer.  What will happen is a merger.  The distances between stars is immense.  Our closest neighbor, Proxima Centauri, is just over 4 light years away.  How far is that, you ask?  Aboard the fastest vessel humans have ever sent into space, it would take 17,000 years to go just one light year.  To get to PC would take almost 70,000 years.  It's highly unlikely that any stars or planets will actually come into contact with each other.  What will happen, however, will be an explosion of star birth as the ambient clouds of gas and dust in both galaxies crash together hard enough to induce nuclear fusion.  And when the super-massive black holes merge, that will be a event of unthinkable destructive magnitude.  

But humans will be past worrying at that point.  About that same time, our sun will be consuming that last of its hydrogen fuel.  The sun gets hotter every year, but 30 million years before that point, the sun will be 30 percent hotter.  That means the earth's oceans will be boiling away and any life will have been extinguished for some time.  Right about the time Andromeda comes calling, the sun will be transitioning to its red giant stage.  Our peaceful yellow star will expand and over the next billion years or so will consume what is left of the already-fried planets, perhaps out to the orbit of earth.  So, worrying about Andromeda is kinda pointless.  We won't be here to experience that event.

There is something else to consider, also a piece of knowledge from that Science Channel series.  

So far, the most successful species on earth has been the dinosaurs.  Their dominance of this planet lasted some 250 million years, and it took the Chicxulub asteroid to take them out.  If not for that catastrophe, it's possible that earth's dominant species today might be intelligent reptiles.  Even if you stretch the term "human" to it's limits, you only get to Australopithecus about 3.5 million years ago.  Our long-term survival chances are not good.  Everybody worries about natural disasters, but really I think the worst threat to humans is what we are capable of doing to each other.  After all, dinosaurs never developed nuclear weapons or political parties.

The point is, we can't control space, or the objects within it.  We can't stop earthquakes, volcanoes, or tsunamis.  We can, however, control ourselves.  We can control the hate. We can end most of the violence.  We can choose effective and responsible government, rather than the psychopathic liars holding office today.  We can do all that, and more.

We just have to choose to survive.