Of course, I've been reading Glubb and his essay on Empires.
A cursory look would say that what he says fills conservative narrative dreams. What do historians think of the "phases" of Empires and how long they last? Would such things be easily definable? I imagine the 'explosive' start and decline seem to be things that would exist and be observable.
What is the average life expectancy of an Empire? What of the causes of decline that Glubb names: to include selfishness and other matters that seem close to a conservative's talking points list? Is there some legitimacy to that.
He's aware that he hasn't studied all empires. He doesn't include China. Would China refute his findings?
I'd also like to know whether, in historian circles, people dismiss this Glubb essay as silly, or do people hold such views?
Page 2 lists the empires he's looked at and the years they existed. The list appears to be entirely arbitrary and to be constructed in such a way that all empires last 200-250 years regardless of how long they actually lasted. The dates are patently wrong [Roman Republic 260-27 BC and Roman Empire 27 BC - 180 AD? Come on. And why would "Greece (Alexander and his successors)" last until 100 BC?]. I haven't read any further but I'm guessing he's going to conclude that empires last about 200-250 years.
To put it mildly, this paper's methodology does not meet modern academic standards.