Date: May 12, 2012
Title: Encore: Our Place in Space
Podcaster: Pamela Gay
Organization: Astronomy Cast, Star Stryder
This podcast originally aired on May 18th, 2010
http://365daysofastronomy.org/2010/05/18/may-18th-our-place-in-space/
Description: From the surface of the Earth, it is easy to feel safe, and in control because we have the knowledge to understand the universe. But we are small, and life is fragile in this vast universe, and there are more things in heaven and earth waiting to be discovered than are dreamt of in all our sciences. In this podcast I try and provide context on both out place in time and in space, and just how fragile our human existence really is.
Bio: Dr. Pamela Gay is a professor at Southern Illinois University-Edwardsville. She is also an astronomer, writer, and podcaster focused on using new media to engage people in science and technology. Listen to her weekly on one of the most popular astronomy podcasts, Astronomy Cast. Follow her on her blog, Star Stryder.
Sponsor:This episode of 365 days of astronomy was sponsored by iTelescope.net – Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia.
Transcript:
Welcome to 365 Days of Astronomy. This is Pamela Gay of Astronomy Cast and StarStryder.com coming to you from Southern Illinois. On this Rainy spring day it seems like all the world is in my backyard, and most of it is triggering hay fever.
The truth is, h ere on the surface of the Earth it is easy to see our universe as small and understood. Each year the seasons tick past in explainable ways, and 400 years after Kepler, the motion of the planets is just something we take for granted. Solar eclipses no longer make people tremble as the Asseryians trembled on the battlefield during the 763BC, instead the tremble in anticipation of the perfect picture during the astronomical eclipse tours. Today eclipses are just a roughly twice a year things that thousands of people turn into vacations.
From the surface of the Earth, it is easy to feel safe, and in control because we have the knowledge to understand the universe.
We have science to explain the supernovae, the comets, the every twinkle and gleam in the sky.
But we are small, and life is fragile in this vast universe, and there are more things in heaven and earth waiting to be discovered than are dreamt of in all our sciences.
Our human minds struggles to grasp at the scale of our universe. Any number over a million is simply large, and in discussing the cosmos, we discuss the billions and billions of galaxies, the billions and billions of stars, and distances so vaste that light has not yet had time to travel from most distant galaxies we see in the north to the most distant galaxies we see in our Southern skies.
In this universe defined by unimaginable billions, it is easy to lose track of our place in the context of space.
Carl Sagan referred to the earth as a Pale Blue Dot and in images taken by the Cassini space probe as orbited Saturn, we can see the distant Earth in its smallness. Sagan wrote of our world, “Look again at that dot. That’s here, that’s home, that’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, … every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ’superstar,’ every ’supreme leader,’ every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.”
Sagan worked to express our smallness, but this isn’t our only struggle. We also struggle to understand our place in the vastness of time.
Our planet is a transitory thing. Formed roughly 4.5 billion years ago, it will be able to support life for only another 50 million years before the Sun’s slow increase in temperature makes life intolerable on Earth. In roughly 5 billion years our Earth will be destroyed entirely as our Sun bloats into a red giant and either consumes the planet or simply broils it with intense solar winds. We live in the twilight years of our world, and time is ticking.
But our planet is just part of a cycle.
We live on a rocky world orbiting a star that is rich in heavy elements. If you shine sunlight through the most amazing of prisms to make a rainbow, you will be able to single out dark stripes mixed in the light, many of which arise from Iron, Titanium, and other metallic atoms in the sun’s atmosphere.
To get at this richness of atomic diversity, our universe had to be created, and generations of stars had to live and die, all before our own Sun could be born.
When our universe formed, 13.7 billion years ago, it was pure energy – pure light. Within the first fractions of a second, that energy began to solidify into particles. Mass and Energy are just two faces of the same thing, and as the universe cooled, the mass divided from the light. At first there was matter and anti-matter, but through the miracle of asymmetry, for every 1 billion anti-matter particles there was a billion and 1 matter particles. The particles collided – they destroyed one another, and they left behind matter. And that matter, at that moment, and for almost the next 3 minutes, was as hot and as dense as the center of a star and nuclear fusion was able to take place. Protons combined. Neutrons were created. Hydrogen nuclei grew into deuterium, which in turn fused to helium and trace amounts of lithium and beryllium. Our theories tell us the ratios of these reactions, and when we look out at the oldest stars, we find the correct fractions fossilized in the elemental abundances of these ancient stars’ light. This is just one of many lines of evidence proving the big bang.
After the first 3 minutes, nuclear reactions shut off, but the universe was still too hot for neutral atoms to form. Everything was an opaque mash of nuclei and electrons and light, colliding. It stayed too hot, and it stayed opaque for nearly 300,000 years, but then one day it cooled enough that the electrons could bond with the atomic nuclei, and when that happened the light was released. Today we see this escaping light as the cosmic microwave background.
The cosmic microwave background demarks the point beyond which we can never observe. It is like the barrier beyond which your headlamp just can’t reach when scuba diving, or that place in the fog your candle cannot illuminate because it’s just too far away. Our universe, within this shell, is 93 billion light years across, but what we can see is likely no more than a few percent of the whole. But it is all the universe we will ever know.
We live on just one small pale blue dot orbiting a metal rich star. We exist because matter and anti matter were formed in unequal parts. We exist because the universe’s density was just right. We exist, because other stars formed, created heavy elements, and died, distributing the elements back into space to form our world and others.
And most amazingly of all, we live in a universe that is at once something we can learn to understand and something that is beyond our imagining.
Every day we are finding new things that defy our theories and force us to expand our ideas – We now know 26% of the universe is made of dark matter – a material like nothing experienced here on earth – and 70% of the universe is contained in dark energy – something we know so little about all we can really do is say we have a name for this rather large blank are in our scientific understanding. And every day we discover new planets in places we never imaged. New galaxies. New types of objects – all things we would have never imagined in our wildest science fiction.
The most amazing thing about science is that it works, and through its equations and rules we can build an understanding a universe that it beyond the ability of a single man or woman to full understand and visualize. Our universe is vast and old, and we are but small fragile creature brief in our time on this earth. But for all our smallness, we do understand our universe through science.
In this show I only had 10 minutes to tell you about our small place in space. If you’d like to learn more, please tune in to Astronomy Cast with Fraser Cain and myself, or read my blog at starstryder.com
End of podcast:
365 Days of Astronomy
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