Wednesday, January 7, 2015

Are These Exoplanets Real? What’s Real?

Dennis Overbye, NYTimes, So Many Earth-Like Planets, So Few Telescopes: Astronomers are looking for earth-like planets, planets that might harbor life (as we know it), perhaps even intelligent life:
Reviewing the history of exoplanets, Debra Fischer, a Yale astronomer, recalled that the first discovery of a planet orbiting another normal star, a Jupiter-like giant, was 20 years ago. Before that, she said, astronomers worried that “maybe the ‘Star Trek’ picture of the universe was not right, and there is no life anywhere else.”

Dr. Fischer called the progress in the last two decades “incredibly moving.”

And yet we still do not have a clue that we are not alone.

So far, Kepler has discovered 4,175 potential planets, and 1,004 of them have been confirmed as real, according to Michele Johnson, a spokeswoman for NASA’s Ames Research Center, which operates Kepler.

Most of them, however, including those announced Tuesday, are hundreds of light-years away, too far for detailed study. We will probably never know any more about these particular planets than we do now.

“We can count as many as we like,” said Sara Seager, a planet theorist at the Massachusetts Institute of Technology who was not involved in the new work, “but until we can observe the atmospheres and assess their greenhouse gas power, we don’t really know what the surface temperatures are like.”
What does this mean, that 1004 of “4175 potential planets” have been “confirmed as real”? I suppose it means that the Kepler spacecraft, the instrument tasked with spotting habitable planets, has spotted 4175 objects and so far 1004 have survived further scrutiny of some kind and so might actually harbor life.

But what does that statement mean? What’s behind it? There’s a simple matter, one I might well answer through a bit of web cruising, of whether or not all 4175 objects have been examined and only 1004 have passed muster, or whether, say, only 3013 have been examined to date. That would leave 1162 more to go, and some of those might turn out to be “real.” That’s not what I’m asking.

What I’m asking is, in what sense are those 1004 “confirmed” planets real? Yes, they’re out there. If we could get there, IF, we’d be able to find out more. But there is no prospect of getting there anytime in the foreseeable future and it’s likely we’ll never get there.

So here’s what I’m asking: If we can see it, which we can, but cannot touch it and manipulate it, then how can it be really real? We can look through microscopes and see very small objects, objects so small that we cannot touch them with our hands, but we can nonetheless manipulate them. We’ve got devices that can push single atoms around. We can work with these very small things.

We can even get to the bottom of the ocean. We’ve sent cameras down there, we know there’s “stuff” down there, strange stuff, living stuff. And we’ve brought back samples, no? Heck, James “Avatar” Cameron went down to the deepest part of the Mariana Trench. It wasn’t easy, we’re not going to sending mining expeditions there any time soon, nor conducting honeymoon tours. But we can get there. We can see it, hear it, touch it, and manipulate it. It’s fully real.

But those exoplanets, not fully real, maybe never fully real. We can see, but not touch. And the not-touching, that’s not a prohibition, not a moral failing, but a mere matter of physical capability.

When Neil Armstrong set foot on the Moon, he changed humankind’s physical capability. The Moon became touchable, manipulable, perhaps even inhabitable, someday. The Moon is now real in a way those exoplanets may never be. In making the Moon real, we have changed ourselves.

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