If we repeat this process, we narrow it down as follows:

4 hours: 1000 samples
6 hours: 500 samples
8 hours: 250 samples
10 hours: 125 samples
12 hours: 68 samples (always round up to account for worst case scenario) 14 hours: 34 samples
16 hours: 17 samples
18 hours: 9 samples
20 hours: 5 samples
22 hours: 3 samples
24 hours: 2 samples

I believe this is the most efficient process but leaves open a slight possibility that the alien won't be found in 24 hours. In that remote case, we murder an innocent human for the greater good. Initial order should be selected randomly to increase fairness.

Supposing we built a stairway to the moon, with 12-inch deep stairs 6 inches tall?

1) How many steps would there be?
2) If we wanted to put the entire human population on the stairs, going clear to the moon, how wide would the stairway have to be, to just fit everyone on? (Let's say we need three feet each.)

Okay, this is a little hokey and a little loose for a math puzzle. I calculate that the stairs would need to accommodate 600 people per stair, approximately. So they would need stairs 1800ft wide.

Try this at a quick guess:

3) If we lined up the entire human population two by two from here to the sun (in proper protective clothing of course), how close behind one another would each pair be standing?

The world speed record for texting seems to be held by a 27-yr British woman who reached about 60-wds/minute typing this:

"The razor-toothed piranhas of the genera Serrasalmus and Pygocentrus are the most ferocious freshwater fish in the world. In reality they seldom attack a human"

http://newslite.tv/2010/08/23/gr8-n...

But she used "SWYPE" technology--dragging her finger on a Samsung Galaxy. I wonder what speeds people have reached with just their thumbs.

2) If we wanted to put the entire human population on the stairs, going clear to the moon, how wide would the stairway have to be, to just fit everyone on? (Let's say we need three feet each.)>

Would the EPA be needed to study the stairs
impact on the environment?

If someone was afraid of heights, is prayer allowed on the stairs?

What about wheelchair access?

Would the stairs need to conform to,
Americans With Disabilities Act?

Would toll areas be necessary so that the stairs are paid for?

(a “VAT” Vertical Altitude Tax would also work)

While racist, would some type of ID be necessary to get on the stairs?

What about Easy Pass, stair stamps, stair subsidies, stair exemptions, stair waivers?

If America builds it, would it be called ObamaStair?

<(Let's say we need three feet each)>

I get three people per stair, so nine feet wide:

I calculate one stair about every 13.5 inches (a^2+b^2=c^2). which doesn't match up with your calculation.

240000*5280*12 = 15,206,400,000 inches/13.5 inches = about 1.1B steps

7.2 billion people / 1.1 billion steps = 6 per step (babies to be held by their moms)

Steps need to be 18ft wide.

(I was off by a factor of 100 with my original guess)

Maybe having a few more aliens at the party isn't such a bad idea.

He pointed to a desk globe, and said "If the earth was the size of this globe, the moon would be about the size of a grapefruit 26 feet away. The sun would be the size of the school administration building, and it would be about a mile away."

http://www.telegraph.co.uk/news/goo...

Sound levitation.

Who woulda thought. Wonder what the practical uses might be? There has to be something. Maybe many things.

The player with the highest (inactive) FIDE rating at death was Bobby Fischer. 2780, a record that will hopefully stand forever.

Who was the second highest?

FIDE ratings started in 1970 so that leaves out players like Alekhine.