Tuesday, 10 June 2014

The city and the stars

By most people's standards, John William Burgon (1813 –1888) had an interesting and successful professional life. He was an assistant in the antiquities department of the British Museum, then Gresham Professor of Divinity before ending up as dean of Chichester Cathedral. But time, devourer of all things, would already have more or less obliterated his memory if it wasn't for one poem. Or, more precisely, one couplet from his poem, Petra:
match me such marvel save in Eastern clime,
a rose-red city half as old as time.
Lines that it's now almost obligatory to quote in any book or documentary about the remains of the eponymous Nabataean city, famous as a UNESCO World Heritage Site, but probably famouser as a film location in Raiders of the Lost Ark.

There are a couple of interesting things about 'a rose red city half as old as time.' First, Burgon's best phrase, and the one thing for which he's now remembered, seems to be mostly a quotation from another poet, Samuel Rogers, who used the 'half as old as time' trope in his poem A Farewell, when he wrote about 'many a temple half as old as Time.' As a meditation on the transience of things, Rogers' poem anticipates Edward FitzGerald's famous translation of The Rubáiyát of Omar Khayyám, with passages like this:
...Many an eye
Bright as the brightest now, is closed in night,
And many a voice how eloquent, is mute,
although some of Rogers' other lines simply make it clear why we've forgotten him and remembered FitzGerald:
And now a parting word is due from him
Who, in the classic fields of Italy,
(If haply thou hast borne with him so long,)
Through many a grove by many a fount has led thee...
Haply, I can't bear with this sort of stuff for very long.

The other interesting thing is that Burgon probably meant the ringing phrase 'half as old as time', which sounds like poetic license, quite literally. As the literary scholar, Hugh Kenner, pointed out:
Though romantic, Burgon was being workmanlike. To his generation the age of Time was quite definite; for since Adam was created in the year 4004 B.C. on October 23, Time in the year Burgon wrote, 1845, was exactly 5849 years old, going back through half of which we locate the founding of Petra at 1080 B.C.
Even in that generation, geologists were having a tough time trying to reconcile the evidence in the rocks with the Biblical account of the creation, but as a devout believer in Biblical inerrancy, Burgon's faith in his Bible-based chronology was probably immune to such challenges.

Today, people who study these things estimate that our Universe (and, presumably, time itself), came into existence some time between 12 and 14 billion years ago.
The Universe is old. According to the most recent measurements, it is 13.7 billion years old. The rise of mankind, on the other hand, is fairly recent, with Homo Erectus, the first "modern human," appearing around a million years ago and Homo Sapiens, today's humans, arriving only in the past 200,000 years. Imagine compressing the time the Universe has existed into the span of a single day with the Big Bang occurring at the stroke of midnight. Humans crash the party late - at 11:59:56pm, just four seconds before the end of the day.
From a cosmic perspective, Petra has existed for the blink of an eye, rather than being 'half as old as time.' The earth itself, which has been around for an an estimated four and a half billion years, is less than half as old as time. But the recent discovery of something really ancient reminded me of Burgon's conception of a truly epic timescale:
An international team of scientists, led by astronomers at Queen Mary University of London (QMUL), report of two new planets orbiting Kapteyn’s star, one of the oldest stars found near the Sun ...

What makes this discovery different however, is the peculiar story of the star. Kapteyn's star was born in a dwarf galaxy absorbed and disrupted by the early Milky Way. This galactic disruption event put the star in its fast halo orbit. The likely remnant core of the original dwarf galaxy is Omega Centauri, an enigmatic globular cluster 16,000 light-years from Earth that contains hundreds of thousands of similarly old suns. This sets the most likely age of the planets at 11.5 billion years, which is 2.5 times older than Earth and "only" 2 billion years younger than the universe itself (around 13.7 billion years).
Astronomy magazine

To humans, the four and a half billion year age of our own planet is an unimaginable abyss of time, but these exoplanets were already older than that when our world was still nothing but stardust. I know that astronomers have already seen objects even older than the exoplanets orbiting Kapteyn's Star, but there's something about the idea of a planet that ancient, a real place, in our cosmic back yard,* with a surface you could walk on and touch (if only you could figure out how to travel 13 light years) that sends shivers down my spine. I think 'Petra' would be an awesome** name for the planet currently known as Kapetyn b, if only 'more than 80% as old as time' didn't sound paradoxically less impressive than 'half as old as time.'

*i.e. further away than you can possibly imagine, but that's just peanuts compared to space...

**In the 'makes the hairs stand up on the back of your neck' sense of the word, as opposed to the conversational 'if you could just pass me your plate, that would be awesome' usage.