I hate to admit it, but I have no good explanation for why the data looks like this. I’ll give a possible explanation below, but I welcome any and all suggestions about other ways to look at it. Add your comments below.

Possible Explanation

My initial thought was that these patterns have something to do with the Ethereum mining software. I thought perhaps there are three different mining algorithms that miners naturally fall into. Something to do with profits, no doubt. But how to figure out if that hypothesis was true? No idea.

I decided to look at a simpler problem: when were these blocks produced?

The three charts above have no time component. To alleviate this problem, I colored the dots by block number. Here’s the same data above with the dots colored by block number.

In this chart, earlier block numbers are colored yellow. The color tends toward dark red the higher the block number gets. Clearly, as the chain progressed, there was an early period with many empty blocks with relatively few transactions. Towards the middle of the chain’s lifespan (between December of 2016 and June of 2017, perhaps) there seems to have been a retreat.

Near the end of the early period, the number of empty blocks was decreasing as the average number of transaction rose (as yellow bleeds into orange). But then, for some reason, the chain makes a retreat. While the average number of transactions per block continued to increase, the number of non-empty blocks per 10,000 also shrank.

Why Does This Happen?

I didn’t really have a good explanation of why this retreat happened. I thought it might be possible that retreat was just an artifact of the way I was presenting the data. So I tried to dig deeper into that thought.

Next, is a chart showing the number of non-empty blocks plotted against the number of empty blocks. Obviously, if you lose on from one side, you gain one from the other, so the two lines mirror each other.

But does this explain the reason for the retreat? Perhaps it does. It looks like something happened around block 1,700,000 (the high point of the grey line near the middle of the image). What happened around block 1.7 million?

Let’s see. Could it be…oh, I don’t know…could it be….the devil? Yes! It was the devil.

The DAO hack happened at block 1,718,497. Within days of the hack, the price dropped from $21.00 US to about $8.00. Three months later, there was the October 2016 DDos attack. You can see it in the spikiness around block 2,250,00. Did these two events cause a retreat in the activity on the chain? More empty blocks with less transactions per block? It seems likely to me.