Sunday, June 8, 2014

The Fermi Irritation

(I meant to upload this and thought I had. But I didn't. Oh, well. Sorry.)

I'm on my way home from work and I’m in a bad mood. So, I’m going to talk about something that regularly irritates me.

Like Pap in Huckleberry Finn, "Whenever his liquor begun to work he most always went for the govment." I go for the Fermi Paradox.

Enrico Fermi came up with it. Essentially, it says: the universe is unimaginably old. We arose. If we’re typical, surely in all that time some other intelligent race has, too. Why don’t we see them?

The Paradox is rather a Rorschach test. It reflects more the point of view of the person discussing the Fermi Paradox than the Paradox itself.

The Fermi Paradox has been discussed over and over, both in science and in the science fiction communities.

The science community came up with the Drake Equation, a way of formulating the variables of the problem. This comes right out of Wikipedia:

N = R_{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L

  • N = the number of civilizations in our galaxy with which radio-communication might be possible (i.e. which are on our current past light cone);
  • R* = the average rate of star formation in our galaxy
  • fp = the fraction of those stars that have planets
  • ne = the average number of planets that can potentially support life per star that has planets
  • fl = the fraction of planets that could support life that actually develop life at some point
  • fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
  • fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
  • L = the length of time for which such civilizations release detectable signals into space

But that’s really only saying what would have to know in order to figure out the probabilities. Without the content of the variables, we really know next to nothing.

There have been several SF books to explain why we haven’t heard from our neighbors. Personally, I like Larry Niven’s idea from World ofPtavvs. He suggested that intelligence was a naturally occurring phenomena. But a few million years ago a violent telepathic race of enslavers beamed out a massive command to commit suicide when they were about to be overwhelmed by a slave uprising.

It's pretty quiet out there. No escaping that.

Many people who discuss this problem one of two camps:
  1. We have no evidence of them. Therefore, human beings are a singular event.
  2. We have no evidence of them so we should keep looking. Something is surely there.

Personally, I’m in the latter camp. Not because there is any real hope of detecting them—I don’t think there is—but because if there was evidence we’d be damned fools not to check.

There are a couple of problems with the paradox itself. For one thing, it is instantaneous: it must always be analyzed in terms of the known world at the time of analysis. We didn’t have an indication until just a few years ago how many variant planets were in the Milky Way. If planets were a rare event, we would expect planetary life to be an equally rare event. Now we have a better understanding of planets—there are lots of them. The current estimate of earth like planets, at least size and mass, is about 100 millions.

About that is spread out over the whole galaxy. And it doesn’t account for time.

Life has been on this planet for nearly four billion years. But we didn’t have eukaryotic cells until only about 600-700 million years ago. Invasion of the land was about 300 million or so years later. Mammals didn’t get their start until 65 million years ago and our genus didn’t get started until about 2 million years ago. Humans have been thinking for less than 250k years and we’ve only been in a position to actually detect extraterrestrial life for a little over a century.

Of those 100 gigaplanets, how many, like Mars, had their life opportunities come and go? For all we know, Mars had a thriving civilization about a billion years ago.

All evidence points to a relativistic universe. That is, we are limited by the speed of light. Physical travel between the stars is probably beyond us—or it may require us to give up our humanity. We might end up striding across the galaxy as powerful as gods, but we’ll no longer have a human perspective.

A better detection mechanism is to detect some sort of photon emission—radio, visible light, etc. We can signal each other like candles in the dark.

But even that has a duration. The span of frequencies that we manipulate is called the spectrum. As we’ve found over the years, broad use of the spectrum is wasteful. Consequently, the radio spectrum is cut up like fine cheese. In addition, not all parts of the spectrum are created equal. Some portions—radio, for example—are particularly nice for wireless communication. Visible light is very nice for carrying signal but it doesn’t broadcast very well. You can communicate with a laser but you need to aim it particularly well—or push it down a pipe like optic fiber. Scarcity and demand determine price and spectrum has gotten expensive. It's not going to get any cheaper.

I expect that we (and by extension of our sample size of one, everybody else) will refine our use of spectrum away from broadcasts that can be picked up by our neighbors and direct more where it will be useful. That’s going to reduce our stellar footprint. In addition, we are already getting farm more efficient in how much signal we actually use. Some of our satellites barely put out more watts than a cell phone, relying instead on better receivers. Detect that Antares!

And that is presuming a detectable civilization (i.e., us.) even survives.

That, I think, is the biggest problem of Group 1 of the Fermi Paradox. They are inherently optimistic that in the broad expanse of time a single group must have survived long enough for us to detect them. Their absence must indicate our singular existence.

Think back on our own evolutionary history. Life was here for nearly four billion years before we could detect or be detected. If, say, humans lasted a million years, we could miss talking with our neighbors four thousand times by being out of sync just a little bit. They started their climb a million years after us—we miss. A million years before—we miss. And that presumes a million year life span for human beings. It doesn't take into account that evolution is always going on. We have no idea what Homo sapiens will evolve into. Only that in a million years we won't be Homo sapiens

There might be gods out there—species that were so stable and intelligent that they have lasted across the time of our ascent. But they will have a god’s perspective. Which means that there is no determining whether they would want to or be able to detect us or if we would be able to detect them. If they created a supernova to send a message over to their fellows in Andromeda, we’d never recognize it as other than random noise. Unless, of course, they took an interest in us. They just made a movie about the last time we interested a deity overmuch. It’s called Noah.

But I don’t think there are gods out there. I suspect if we have neighbors they're pretty much like us: fumbling our way into a greater universe with the meager tools evolution gave us. Putting out enough radio waves to show themselves but too far away or out of synch to be seen.

We’re probably not alone out here. But we may as well be.

No comments:

Post a Comment