Thursday, June 26, 2008

A good day to be an alien

Hunting for evidence of extraterrestrial life? Check the New York Times Science section: It's full of reasons for astrobiological optimism.

First, the Mars Phoenix Lander team reports that Martian soil is chock full of the nutrients required to sustain plant life. The pH of the soil favors plants like asparagus and turnips. (Think deeply about that, aspiring Mars astronauts.) This follows last week's report of melty water ice at Phoenix's landing spot.

A little further down the science page, Natalie Angier reports on the discovery of a triple system of "super earths" orbiting a star just 42 light years away. But the big takeaway isn't this scorched solar system--it's that the search team discovered similarly sized planet-candidates around about a third of the stars they checked. A third! That's good news for the next generation of planet searches, which will seek out planets even more like our own.

Saturday, June 21, 2008

Parallel worlds

I've had parallel universes on the brain this week, thanks to a bit of convergence between Job Number 1 and Job Number 2. First, courtesy of Job Number 1, there's the many worlds interpretation of quantum mechanics, which suggests that what we call wavefunction collapse is, in reality, the branching off of a new universe.

Then, over at Job Number 2, there's the "multiverse" advanced by cosmologists like Tufts' Alexander Vilenkin, in which our Big Bang is just one of many which occur at other points in space and time; with inflation continuing to pop the cork on new universes all the time--for eternity--there must be infinitely many universes in existence. As Vilenkin says in one interview:

...[I]f you have a finite number of histories that are unfolding in an infinite number of regions, it follows that every history that can possibly happen will happen and it will happen an infinite number of times. So there are an infinite number of regions where we have exactly the same planet, like our Earth, with exactly the same people and we are having exactly the same conversation. This is not something that would affect your daily life, but it's something to ponder.

All of which makes me think of those Choose Your Own Adventure books that used to populate the elementary school library; at the end of each chapter, you had to make a multiple-choice selection (e.g. "If you decide to slay the tiger, turn to page 23; If you decide to run away from the tiger, turn to page 41; If you decide to gently pet the tiger, turn to page 45") that would create a unique story.

Of course, there was a finite number of stories in those little books, but if you agree that there is a fininte number of particles in the universe, then one could conceivably create a "choose your own adventure" book that encompassed every possible configuration of the universe. It would be very long and very boring ("If this particle is spin up, turn to page 1,000,002; if this particle is spin down, turn to page 132,332,837,113"), but it would be finite.

In the many worlds interpretation, each "adventure" in this book plays out in a private universe which can't touch any of the others. But in Vilenkin's view, there is the potential for two independent storylines to intersect, as "bubble universe" collide.

In fact, Vilenkin and his collaborators Jaume Garriga and Alan Guth (who, incidentally, first proposed the theory of cosmic inflation), have calculated how often bubble universes should bump in to each other--and how often a bubble's inhabitants should notice the collision. The answer is complicated, but boils down to: it depends.

"It depends" on things like where you live inside the bubble, which is actually pretty surprising, since one of the basic tenets of modern cosmology is that no location in the universe is more "special" than any other. (Kind of like what you learned in 7th grade health class.)

Can it explain why a bubble universe hasn't yet crashed in to our own? Why we haven't had a momentary glimpse of some alternate universe in which, say, dinosaurs are driving around in hovercars, chatting on rotary cell phones--before that universe slammed into us and knocked us out of existence? Ask me a week from Wednesday!

Pluto's consolation prize

It was back to Pluto this week at the Visible Universe (the column):

Poor, sad, spit-upon Pluto. Once a planet, now a ... what?

Scientists and writers toyed with "transneptunian dwarf planet," "ice dwarf" and "planetoid." Detractors dubbed it a "lump of rock" (not accurate, really, since Pluto may have nitrogen ice on its surface, as well as a thin atmosphere). Now, the International Astronomical Union, the body that stripped Pluto of its planetary mantle, has officially given it a new one: plutoid.

A special note to old friends: There's some Huntington Woods lore in this one, too! Read the whole column at the Boulder Daily Camera.

Wednesday, June 18, 2008

The not-paying gig

In addition to writing for FQXi, I keep myself busy writing the Visible Universe column! Here are a few recent columns:

The Physics of Flying High and Fast Extreme physics encountered by air travelers every day

Lunar dust more than a cleaner's problem In which I get revenge on my former landlord for long-ago wrongs

Matter's evil twin, antimatter Evil twins!!

Made in Canada: Space robots a source of pride In which I tease my parents

The paying gig

What do I do when I'm not writing this blog? (Which is to say, what I have been up to for the past two months?) I've been busy writing for the Foundational Questions Institute, which sponsors cutting-edge research in theoretical physics and cosmology. Here are a couple of recent articles:

A Blackboard at Brunch Meet the researchers who are taking discoveries from condensed matter physics and applying them to the question of quantum gravity.

The Cosmic Puzzle What is dark energy, anyway? Is our cosmic bubble about to burst?

Down the Rabbit Hole Are we living in a computer simulation? Some scientists say its a statistical near-certainty.


In the Slightly Old News column, here's a story I read about a few weeks ago but didn't get a chance to write on: an art installation that connects London and New York via an oversized intercontinental telectroscope. One end of the scope emerges near the banks of the Thames in London; the other pops out by the Brooklyn Bridge. New Yorkers peer in and see Londoners, and vice versa. It's up to the viewer to imagine the subterranean tunnel connecting the two ports. Only spoilsports would point out that its sculptural Skype.

I know, it's not astronomy, but it captures the thrill of looking in to a telescope and finding a whole other world on the opposite end of the scope.

For pictures, click here.