20-questions challenge

Commenting on this well-known guessing game, Carl Sagan once said:

Or something like that.

I’ve never played this in real life, but it just seems like a virtual improbability that somebody could guess what I have in this box, given permission to ask only twenty yes/no questions. Those would have to be some pretty skillfully chosen questions.

So let’s begin. I also invite comment on the quality of the questions asked. Let’s see if we can get our questions tuned finely enough to be able to guess in 20 questions.

I have something in this box. What is it?

Having given it a little more thought, it seems pretty obvious that question #2 should not be asked until question #1 is answered. That means that you don’t have to open this thread (assuming you’re playing) until you see that I am the most recent to post.

A dandelion seed?

First question wasted. Next?

Is it or has it ever been organic?


A photon gun, a half silvered mirror, a container of poison which can be triggered by a single photon, and a cat which is both alive and dead.


You tell me now what is in the box, or I kick your butt, yes? We wouldn’t want anything unpleasant to happen to you, no siree.

A question not about the contents of the box, but about the box itself. Was the original, Carl Sagan-esque version visual? As in, would the player know the dimensions of the box by looking at it, or need to request those as well?

With 20 well-asked questions (with yes/no answers), you can narrow down to 2^20 or approximately 1 million answers. The most optimal technique is to ask each question so that it sub-divides all the remaining possibilities into two equal groups.


Is it bigger than a breadbox?

The original question was: “I have something in my hand- what is it?” So yes, you have a good idea of its size. In that light I will conceed that the mystery box is a 10cm³ cube.


if you can create questions so well-defined that the answer immediately elminates 50% of all possible objects, then 20 Questions can cover 2 to the 20th power of objects, or slightly over 1,000,000 different objects.

The problem is in figuring out such good questions…

Is it commonly found in an everday household?

Everyone but Opus:

It seems that we should work together on this so as not to ask stupid questions. For our next question, I suggest this:

“Is this object a solid?”

N.B. folks: glass, paraffin, jello etc are NOT SOLIDS. There are more to this list, but these seem to be the most common.

I was going to ask about the bond structure, but I’m not anal. Right now.

And let’s also remember that things LIKE plastic, foam etc, since they contain carbon, are organic. Or did Opus perhaps forget this fact? Lordy, I hope not, since a helluva lot in this world is organic.

Debatable, but I would strongly lean towards NO.


I waffled on that question, but am taking the general wishy-washy position that things commonly thought of as synthetic are not organic. Of course there are always exceptions. For example, Teflon may contain carbon for all I know, but I think most would consider it inorganic.

I suppose the person who finds the most faults with/has the most gripes against my answers (once the mystery object is revealed) can be the next questioner… so get ready, iampunha.

Thanks for the link, I’m having a ball over there.

Thanks for making a link out of it. I hate code.