‘How We Know’

To the Editors:

Like so many others (physicists and laymen alike), I am awed by Freeman Dyson’s early work and fascinated by his varied interests. That being said, in his recent review of James Gleick’s The Information: A History, a Theory, a Flood [NYR, March 10], Dyson follows established practice in erroneously describing what Moore had set forth:

The event that made the flood plainly visible occurred in 1965, when Gordon Moore stated Moore’s Law…. His law said that the price of electronic components would decrease and their numbers would increase by a factor of two every eighteen months.

Since God is in the details, I thought it may be appropriate to correct this misperception. Here’s what Gordon Moore had to say in 2000 (see D.J. Yang, “On Moore’s Law and Fishing: Gordon Moore Speaks Out,” U.S. News Online):

I never said 18 months. I said one year, and then two years…. Moore’s Law has been the name given to everything that changes exponentially in the industry…. If Gore invented the Internet, I invented the exponential.

Alex Gezerlis
Department of Physics
University of Washington
Seattle, Washington

Freeman Dyson replies:

Thanks to Alex Gezerlis for correcting my mistake. The true history of Moore’s Law is more complicated than my oversimplified version. An analogous situation arose in the history of Hubble’s law of expansion of the universe. Hubble discovered that distant objects are receding with speeds that are proportional to their distances. His first announcement of the law gave a value of the ratio of speed to distance (known as Hubble’s constant) that later turned out to be much too large. The true value is about seven times smaller than Hubble’s first estimate. Similarly, Moore’s law of exponential growth was first announced with too short a doubling time. In both cases, the discovery was important because the law of increase was correct, and the exact value of the rate of increase was a comparatively minor detail to be determined later.