Contriving

So, yesterday I shared this post on Google+:

This boulder on the moon was set a-rollin’ by whatever process. The interesting thing to me is that you can see some craters overlapping the track it created as it rolled.

From this, scientists estimate this track was created 50-100 million years ago.

Notice the impact craters overlapping the track created by the rolling boulder.

This got me to thinking about how they determined the age.  While I haven’t talked to the scientists who came up with this age figure, I imagine it went something like this:

1. Have a model for frequency of asteroid impacts over time per unit of area of Moon surface.
2. Determine area of tracks.
3. Count impact craters overlapping tracks.
4. Using impact frequency model determine how much time would have to pass before you would see the number of overlapping impact craters.

The interesting thing here is that, going by a layperson’s definition of “wrong”, the number you come up with in this scenario could be completely wrong.  I think a lot of reporting on science, and even the statements scientists make to the public, are “wrong” in the same manner.

You see, the 50-100 million year figure doesn’t make a lot of sense in isolation.  It should have probabilities assigned to it.  The real answer isn’t “50-100 million years”, it’s a, for example, (rough and dirty) graph like this:

You see, it’s possible that the asteroid impacts all happened yesterday.  It’s unlikely, but it’s possible.

So anyway, this is usually acknowledged when actually doing Science-with-a-capital-S, it’s just that this is often lost when communicating with the public.  The thing I find interesting about this, is that, this view of things having probabilities attached to them is the way the word actually works and yet the general attitude people have doesn’t acknowledge this.

Most people operate as if things either happened or not.  Of being real or not real.  Even things that you would say you’re 100% sure of…like the color of the sky…have a probability assigned to them.  You may be 100% sure, but that 100% is a measure of your over-confidence, not of reality.  For example, there’s a non-zero chance you may be living in a dream or hallucination.

What about your values, your religion, your politics?  Are your values self-consistent?  Is there a God?  Do your political leanings actually lead to the type of world you want?  There’s probabilities assigned to all of ’em, and that probability is a lot lower than the previous example about the color of the sky.