Thursday, August 2, 2007

"Let There Be Light!" When Was That?


No astronomer had ever seen that light before. No human being had. It was altogether new.

"New to astronomers," said the man before the Story even finished. "Newly detected. But actually very old. That light left its source billions of years ago. Close to when the universe began." (from The Story of Everything, Ch.25)


The light, says the man, left its source close to when the universe began. How close? When was the first light ever?

A simple question, but try to get a simple answer. In physics, the word light refers to radiation in general, even the kind you can't see. But it also refers to the kind you can--visible radiation, in other words, light in the ordinary sense.


If light means radiation in general, then the oldest seems to date from about 380,000 years after the Big Bang. This is the cosmic microwave background radiation (CMB) that was discovered in 1965. Before 380,000 years the universe was so opaque that light (or radiation) could not pass through. The reason had to do with photons running into electrons before complete hydrogen atoms were able to form.

Now I suppose you could call those early photons light, but they really ought to travel first. CMB light does travel, and it's very old and very close to the beginning, amazingly so. 380,000 years is only .003% of the time from the Big Bang until now. Take a look at how we image this invisible light, the very first.

The oldest visible light is also close to the Bang--under 1% of elapsed time--but not as close. It's starlight, and it comes from the time when the first generation of stars turned on, ending a period known as the Dark Ages of the Universe. That period is thought to have ended about 500 million years after the Big Bang, but the date keeps getting pushed back, with some astronomers now speculating that primitive stars were forming as early as 100 million years after the Bang.

We can't see their light, however. The best we can do are some infrared smudges that reveal the presence of galaxies at about 750 million years. At the one-billion-year marker--7% of the way--galaxies are looking plentiful and surprisingly modern. See for yourself by clicking on these links.

At which of these points did the God of Genesis say, "Let there be light"? At none of them, really. This God seems to have meant several things by "light," but mostly he meant daylight, which he separated from the darkness of night. Though the Genesis writer showed no signs of knowing it, daylight requires a later generation star and a spinning earth. That star (our sun) came into being about 5 billion years ago, the spinning earth about 4.6 billion. Daylight is relatively recent. Our own began a long way from the beginning, at the 66% mark.

So you've got CMB light, starlight, and daylight. Maybe the lesson here is that no matter how you define light, there is a point before which it appears. Light is information. If that is so, I wonder how we can talk so confidently about the dark time before there is information--about the Words of Creation or, alternately, about the Big Bang. Can't the story begin in darkness?

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COPYRIGHT © 2007 JOHN N. KOTRE

7 comments:

Anonymous said...

This reminds me of when I first began studying evolution in my anthropology classes. Strict religious people in my family actually became upset with the fact that I had even signed up for a class involving evolution. Many of theses religious people were under the impression that a person could only believe in either religion or evolution, but not both.

That was when my own search began. I spoke with professors, pastors, people from other religions, and anyone interested on the topic.

It was during that time in my life that I came to the realization that science and religion could work together.


This brings me to the "Light is information" statement. In my opinion, the story can begin in darkness. After the light is added to the equation, we can use what we learn from the light to talk about what was going on before the light was involved.

Let's simplify the scenario a bit. Let's say a police officer enters a crime scene in total darkness. The scene is there prior to the police officer entering. Once there, the officer turns on a light and begins making educated guesses (based on experience and evidence) about how the crime scene came to be. The light is a path to information, for the officer would not be able to do much without it. Just the same, the story of our beginning may have started before the light came on.

The problem that people like me face is that certain religious arguments say that I am wrong because the bible does not specifically say that there was anything before the light. The bible says "In the beginning..." The beginning if what? Who is to say that that is the first beginning?

John Kotre said...

Don't ever abandon the search! How can you be looking for the truth and not be looking for God?

I very much liked the crime scence analogy and the clarity of the statement "learn from the light."

Anonymous said...

My understanding of "Let There Be Light" suggests that the light had as much of a spiritual quality as a physical. Its separation from the darkness was because God felt the wicked were unworthy of enjoying it. Furthermore, this very same Light that awaits those who choose to live their life in righteousness. Again, I'm not sure that the Light in question is as physical as your discussion makes it out to be.

Tom said...

Hey John,

I really enjoyed following the links on this article. It reminds me that I need to get more at night to enjoy the stars.

-Tom

Anonymous said...

I too like the crime scene analogy, I imagine that is precisely how God will view the world when the lights go on.

I suppose I find it hard to reconcile that there are some things that do indeed exist, and want to remain in the dark.

Ken said...

Light is information. Yes. Wow. Polkinghorne (the physicist turned anglican priest) talks a lot about the implications of information. He spins out a wonderful speculation about God holding our information in safe-keeping after death and re-membering us as a way of thinking about resurrection. Of course the Hebrew Scriptures have a big emphasis on God remembering us, and the term is much deeper than our superficial understanding of memory. I heard recently that Stephen Hawking revised his conjecture that information is lost in a black hole....not sure what that means, really and would love to see a post from you on this.

Theresa said...

Yesterday I started Hooking Up by Tom Wolfe, and wouldn't you know it, sections of it pertain to your blog about light, or information.

Wolfe talked about Teilhard de Chardin. According to Teilhard, evolutionary biology and the connectedness of the internet are similar to the Big Bang theory and the newest in physics about a expanding and contracting universe. According to TdeC, the Big Bang caused everything to expand, as did evolution (species expanded). Then, as in physics, the universe hit a certain wall of expansion, then began to contract, the same as TdeC believes happened with the introduction of such media as television, radio and now the internet. In other words, with the evolution of the human, becoming more intelligent and specific at the same time that many other species become extinct due to their having less intelligence, the human mind developed modes of communication that are making it easier to communicate with everyone around the world, creating a global village (the contracting of spaces as far as information is concerned). Now are world is contracted into a much smaller one, what with the internet, just as the universe is contracting. Apparently all this is in Teilhard's book, The Phenomonon of Man. Have you already read it? Did you already know about all this? A follower of Teilhard, Marshall McLuhan, wrote "The Christian concept of the mystical body - all men as members of the body of Christ - this becomes technologically a fact under electronic conditions."