Archive for July, 2010

Earth-like exoplanets

Wednesday, July 28th, 2010

Apparently the Kepler Space Telescope has discovered a lot of candidate planets orbiting other stars, including many small “Earth-like” ones.  Kepler scientist Dimitar Sasselov showed this slide at a TED talk:

Exoplanets

That’s a few hundred planets discovered, with over 100 of them “Earth-like,” meaning at most twice Earth’s radius.

The official data release hasn’t happened yet — in fact, the Kepler team has been asking for an extension of the proprietary period before the data are released publicly — so maybe Sasselov wasn’t supposed to reveal this information publicly yet.  Certainly this is an odd way for this information to come out.

At the moment, we don’t have all the details.  I think the hard part in this whole business is removing all the possible ways to get false positives. Kepler searches for variations in the brightness of stars due to planets transiting (passing between the star and us).  There are various non-planet reasons such brightness dips can occur, and it takes a lot of effort to rule out these other possibilities.  That’s the reason the researchers want more time before going public.  So I don’t think it’s clear yet how certain they are that these planet candidates are really planets, but presumably Sasselov wouldn’t have shown this in his talk if they didn’t have good reason to think that lots of them are.

My impression is that these results are pretty consistent with what people expected.  The original discoveries of extrasolar planets mostly found very large (Jupiter-like) ones, but that’s just because the method they used to search was only sensitive to large planets.  Once a mission like Kepler came along, with the ability to detect small planets, I think people expected to see lots of small planets.  But of course, expecting isn’t the same thing as knowing!

Michio Kaku is not helping

Friday, July 23rd, 2010

I’m behind on my TV-watching these days, so I’m just getting around to watching Michio Kaku’s appearance on the Colbert Report a few weeks ago.  He says things that are exaggerated to the point of being clearly false:

  1. When asked about teleportation, he says that “we’re already teleporting atoms.”  This is a reference to the technique known as “quantum teleportation,” which is really cool, but is just plain not teleportation in the sense Colbert means or in the sense that viewers will think he means.  The fact is that we can’t teleport anything, in anything like the usual understanding of that word, and nothing on our current research horizon suggests we’re anywhere near being able to.
  2. Later, Kaku says, “Within the coming decade we will have something resembling a Harry Potter invisibility cloak.”  This is, again, simply not true.  Once again, the technique he’s referring to is pretty cool, but it’s absurd to suggest it’ll lead to anything remotely like “practical” invisibility ever, let alone in a decade.  If you stay perfectly still, are spherical, and are illuminated only with monochromatic polarized radio waves, then this technique can make you invisible.  I wouldn’t count on this to keep you from getting detention from Professor Snape.

In both cases, Kaku is not the original offender: both the quantum teleportation community and the “invisibility” researchers started the practice of overselling their goods.  But Kaku knows better, and he shouldn’t play this game. People already think that we scientists exaggerate our level of knowledge. Every time a well-known scientist does this, it lowers the credibility of all scientists.