Friday, May 16, 2014

"the oldest place on Earth"

Survival expert Bear Grylls (I've written about him here) once stood on a patch of ground in Africa and solemnly intoned, "This is the oldest place on Earth." I had to laugh: every place on Earth is the oldest place on Earth, because it's all aging at the same time.

I slapped the above thought up on Twitter, and received a "nay" from a surprising source: fellow blogger, teacher, and e-friend Brian Dean, who's much more science-minded than I am. Brian tweeted this reply:

I disagree. Some rocks have fossils 65 MY old, others are 200 MY old. Geologically some places are older.

I responded:

But wouldn't you say that every molecule of the planet ages at the same rate, at the same time?

Brian wrote (squeezing as much info into 140 characters as he could):

Atoms are 1 age, molecules another and current placement another again.Uranium releases He -in lava, He gone-diff atom content

I had little choice but to concede Brian's technical point, so I said:

Sounds like a topic to blog about. I should've said "atoms."

And now I'm blogging about this topic.

Long story short: I'm not convinced that I'm wrong, and it's likely that Brian and I are talking past each other. Let me see whether I can unpack some random thoughts.

How old is the Earth? By most scientists' reckoning, the Earth is about 4.5 billion years old. When scientists posit this number as the Earth's age, they're assuming a rough starting point for the Earth's existence, i.e., the "moment" (it obviously took much longer than a moment) when the subset of matter that eventually became the Earth coalesced, becoming a proto-version of the oblate spheroid we all know and love.

But how old is the matter that makes up the Earth? That's really what I'm getting at. At a guess, I'd say that that matter is about as old as the universe itself, i.e., about 13.8 billion years old. By this reckoning, all matter is about 13.8 billion years old. We could get into the nitty-gritty of how all the wild energies a microsecond after the Big Bang weren't exactly matter yet, but that's an academic point that doesn't really bear on the discussion at hand. We could also bog ourselves down with a discussion of Einstein's rejection of absolute simultaneity (because of relativistic effects, time doesn't flow at the same rate everywhere in the universe), but that, too, would have little bearing on a discussion of Earth, which is a small enough clump of matter that we can dismiss those Einsteinian phenomena as trivially minuscule.

You could counterargue that, by claiming everything is the same age, I make it impossible to make any useful or meaningful distinctions between, say, a sapling that came into existence only a few months ago versus a 60-million-year-old plant fossil, or even between a toddler and a grandparent. But I have a guardian angel on my side: Carl Sagan famously said, in that sonorous voice of his, "We are the starstuff of the universe." What he meant, of course, is that the matter making up our bodies comes from elsewhere—from the ancient stars, and their matter ultimately came from somewhere even more ancient. The current arrangement of that matter into human forms is not ancient, but the matter itself is.

This feels almost like Madhyamaka ("Middle Way") Buddhism, a branch of religious thought that comes to us from the philosopher Nagarjuna (roughly a contemporary of Saint Irenaeus), who argued that there are "two truths," conventional and ultimate. Conventional truth is local, practical, and contextualized; ultimate truth is universal, eternal, and not dependent upon context. Conventionally speaking, I'm almost 45 years old and my brother Sean is almost 35; in ultimate terms, however, he and I are material aggregates that are nearly 13.8 billion years old. The arrangement, the pattern, that is conventionally called "Kevin" will cease to exist after, oh, twenty or thirty more orbits of our world around the sun, but the matter that belonged to Kevin will endure. So not only is every spot on Earth the oldest place on Earth, but every person, young or old, is the oldest person on Earth, too.

Ultimately speaking.


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8 comments:

brian dean said...

I guess we were talking past each other. One of my hobbies is following and dipping into evolution and creationism debates. In this context the age of rocks and elements becomes crucial.

"Brian wrote (squeezing as much info into 140 characters as he could):

Atoms are 1 age, molecules another and current placement another again.Uranium releases He -in lava, He gone-diff atom content"

Thank you for the very polite description of my tweet.

Should anyone be unable to figure out what I was trying to say:
Atoms are one age, molecules are another and the duration they've been at their current location is yet another.
Radioactive Uranium breaks down and releases Helium. This helium stays in the rock until the rock melts and the helium can escape. If the rock is melted, as in lava, the helium escapes and the rock is considered young again.

Kevin Kim said...

Brian,

I admit I was taken aback that you were disagreeing at all, but the disagreement itself, as you laid it out, was perfectly reasonable. Thanks for making me think a bit more deeply about this topic. Your disagreement introduces a certain interesting nuance that wouldn't have been there had you said nothing.

John said...

Geez, deep stuff. As I read along that damn Desiderata song kept playing in my head..."you are a child of the universe..."

Charles said...

K,

Carl Sagan or no, you're still saying that the distinction between "a sapling that came into existence only a few months ago versus a 60-million-year-old plant fossil" is irrelevant, aren't you? At least, you don't seem to be willing to admit that "conventional truth" has much use if you're going to laugh at Bear Grylls for saying that a certain place is the oldest on earth.

Kevin Kim said...

Charles,

Indeed! I own up to that. It's the matter that ultimately matters. So in a meaningful way, I'm both 44 years old and 13.8 billion years old.

Starstuff. That's me.

On a more practical level, I have no idea how Grylls came up with his claim. Whom do you consult on what "the oldest place on Earth" is? How do you determine it's the oldest place? How reliably can a place's age be determined? How does one define "place"? Bear's got some splainin' to do.

Kevin Kim said...

I should also note that, when scientists say the Earth is about 4.5 billion years old, they mean the whole Earth, not just this or that part of it. Perhaps the age they're assigning could be considered an "average" age, but the very use of an average assumes the entire planet is aging at the same time, such that the Earth can be described, on the whole, by a single number.

King Baeksu said...

Don't you know that Korea is the oldest place on Earth?

Charles said...

I'm pretty sure Bear drew on his mystical connection with the land. He just... felt it.