Monthly Archives: June 2013

There is no reason to think that there is intelligent life on other planets

Nevermind Where. *When* Are the Intelligent Aliens?

I only just came across this, from 2011, but I have to respond. Note that I’m not an astrophysicist, or a biologist, or a chemist, or… you get the idea. Seth Shostak is an astronomer at SETI. But I’ll make my arguments and you can decide for yourself.

“Indeed, it seems a good bet to guess that at least a few percent of all stars are blessed with “habitable” worlds. That would tally to billions of life-friendly sites, just in our galaxy.”

The first part is reasonable enough. Recent research has indeed found many of our near neighbors have “habitable” planets. But check the definition a few sentences earlier of “habitable”:

“…worlds with solid surfaces at the right distance from their host star to sport temperatures amenable to the presence of watery oceans and protective atmospheres…”

So we’re jumping from solid, not enormous, and in the right orbital zone, to “life-friendly.” That’s a huge leap. As far as I know the debate continues on just how big the “habitable zone” is. Take a look at the table at and note that recent estimates for both the inner and outer bounds of the region vary by 2x. That’s not certainty.

Estimates of the number of terrestrial (rocky) planets in the habitable zone in our galaxy range from 500 million to 150 billion, but again, it’s important not to read too much into “habitable” or “terrestrial.” All that means is that if you we’re there in a spacesuit, you wouldn’t collapse under your own weight, or sink into the planet’s surface, and a cup of water, at least somewhere on the planet, would neither freeze nor boil. That’s a long way from “plant some corn and build a cabin.”

Finally, all of this ignores the simple fact that given a rocky planet where the water is liquid at least some of the time, at least somewhere, assuming there’s water there in the first place, we don’t know how likely life is to spring into existence in the first place. if it does happen, we don’t know how likely it is to become multicellular, or any of the other hurdles on the way to becoming the Klingons or the Vulcans. Or us. One data point does not allow for reasonable estimation.

The article insists that there are hundreds of billions of rocky, habitable-zone planets in our galaxy. Well, my estimate of the likelihood of life coming into existence on a given planet is a trillion to one, and no argument I’ve heard can disagree except on the basis of incredulity. “A trillion to one? That’s absurd! How did we get here then?” The simple answer is that if we weren’t, we wouldn’t be here to debate this.


Apparently, other mobile OSes assume you don’t do much

Here are screen shots of four phone home screens. The question asked is: which do you prefer? But consider a different question: what do you want to do? Or, putting it another way, how many different things might you want to do?

Each home screen has a number of different icons or other items that seem as though they might launch an app, allowing you to do some separate thing. I’m not familiar with all of these platforms, so I’m guaranteed to get this wrong, but:

Android: 11, counting the notion that clicking on the clock does something, and assuming that the bar across the top does something (more than what opening Chrome and searching, one of the other options on the screen, does), and assuming that the plain icons at the bottom do something, but not counting the back arrow at the bottom left, on the assumption that it is a function, not an app.

iOS: 22, not counting the two empty spaces, which could obviously also include apps, because all of these home screens could presumably be configured to have more options.

Windows Phone 8: 13, assuming that the blue rectangle at the lower right is unused.

Ubuntu: 13, assuming that “Home,” is a command and not just a label, and that tapping the photo stream does something, and that each of the small icons at the bottom does something.

Given the “style over substance” argument often made against Apple, it’s interesting that iOS is the clear choice for presenting access to the most app choices just one tap away from the home screen.

Six towns math problem

I thought of this on my way to work and did the math in my head. When I get to a piece of paper I’ll see if I came up with the right answer.

Suppose there are six towns located at the points of a regular hexagon two miles on a side. Every town has a straight road to every other town, and there are no other roads.

People live and work along each of the roads (not just in the towns), and everyone bicycles to work along the shortest route available.

What is the longest distance anyone could possibly have to bicycle to get to work?