Measuring a cabbage-patch

“It’s a small world” is a cliché.  Can we measure how small?

In a book for popular audiences, a great astronomer of the mid-twentieth century refers to “the tight little cabbage-patch world in which man had lived throughout the medieval age.”  This unfortunate comment reveals both a lack of understanding of a vanished cosmology and a failure of historical imagination.  To the medieval mind the world was a vast and often terrifying place.  But it raises the question: how should we measure how big the world (or the universe) actually is?

Nowadays we can get in an airplane and fly to the far side of the world in eighteen hours or so.  A century ago that journey would have taken something like a month, so in that sense the world has gotten over a hundred times smaller, measured by travel time.  However, there are places it will take you much longer to get to (assuming you haven’t the resources to charter a jet of your own, and aren’t willing to parachute out to somewhere without an airport or road).  But are those places indeed part of your world, if you never visit them or have any kind of communication with them?  Let’s look at other definitions.

If we consider one’s world to be the area that an average person visits regularly, for almost all of history it consisted of one’s village and the neighboring ones.  In that sense it barely changed until the coming of the railroad.  But certainly there were more widely-traveled people, and even in a village you’d meet them; plus you’d be aware of places much farther off.  So we’ll propose two measurements of the size of the historical world: how far a traveler that any villager might meet would routinely go, and the most distant place from which reliable news (not legend or fable) might come.

For settled medieval times (excluding Crusades and Vikings), the second-hand world would be about the size of a province, smaller than a kingdom.  Travel time would be a number of weeks, on generally poor roads (though the Roman roads held up surprisingly well).  The larger world would be just past the borders of Christendom, Europe plus the nearby parts of Africa and Asia that the more adventurous merchants would routinely visit.  It might take them a year or two, round trip.  Beyond that was largely rumor and legend, where tales placed Prester John.

Let’s compare this with another age, that of Classical Greece.  The ancient second-hand world was much larger in miles, since each city had its colonies elsewhere in the Mediterranean and Black Seas, and there were ships passing among them regularly.  Even if you weren’t a sailor, you’d talk to them.  But it was much smaller in time.  We recall somewhere (in Thucydides?) war news being carried from the center to the periphery of the Greek world in a matter of days.  The extreme world was maybe the same size in miles as the medieval one, extending farther into Egypt and Persia and including the Black Sea coast but losing northwest Europe.  But it was smaller in time, mostly because one could use ships instead of roads.  One could travel to the edge of the world and back in one summer season.  (Of course only the desperate or foolish would risk a galley in the winter Mediterranean.)

How big are other worlds?  Other times, other places?  The answers might surprise you.