In the early 1980’s I spent a fair amount of time learning about the Universe.  As a religious sceptic I found some point to mankind’s existence in contemplating this vast Universe in which we find ourselves, and some comfort for my own certain personal extinction in the study of cosmology.  We are just so tiny we can’t possibly complain, and can only wonder at the vastness of this enormous thing we are unexpectedly a part of.  I mean what are the odds?  And in this shape?  Gratitude seems the only sensible reaction.  Not pissing and moaning that it’s going to end.

We were entering a time of the most fertile expansion of human knowledge.  Indeed the last century has seen the biggest expansion of our knowledge of our cosmos ever.  But back then Black holes were considered dangerous ideas, the Big Bang was a very new theory and there were three main contenders for the ultimate end of the universe: the continued expansion for ever idea, the steady state theory, and the ultimate contraction of the universe, where gravity pulls everything back into the singularity from which we seem to have sprung, where Time’s arrow reverses itself and goes backwards.  Hubble had shown us clearly that the Universe was expanding but for how long might this go on?  We had of course no knowledge of dark matter or dark energy, which we now believe comprises over 80% of the whole rapidly expanding universe….

It was fascinating for me to discover that, with no science or mathematics whatsoever, I could still understand the nature of the debate.  Even join in.  So I collected a series of known knowns and wrote a lyric.  The Galaxy Song would appear in Monty Python’s The Meaning of Life, which we filmed in 1982,  and is still a reasonable sketch of our state of knowledge of the Universe at that time.

We’re thirty thousand light-years from Galactic Central Point/ We go round every two hundred million years…

While contemplating these incredible facts I made my own scientific discovery.  I was simultaneously self-educating myself about Earth science and Biology and the origins of life on the planet and I became interested in mass extinctions, which have occurred fairly regularly in pre-historic times.  In particular the Permian extinction, which caused the loss of almost 98% of life on this planet.  What caused that?  The extinction of the dinosaurs was getting a lot of traction in public interest, although not yet proven as a cometary event.  I knew the earth passed regularly through cometary debris fields, which caused the amazing and spectacular shooting star showers that I observed with such joy in the clear summer skies of Provence, and I wondered if the sun itself might pass through similar galactic debris fields.  Might this not cause mass extinctions on our planet?   I was seeking some kind of regular pattern and was wondering vaguely if there might not be seasons of the sun: spring when life emerged, summer, fall and then winter when extinctions occurred. In order to see if that might be remotely possible I wanted to know how many times the sun had been round the galaxy and nowhere could I find such a figure.  So I made a very simple calculation.  I divided the time of our solar circumnavigation of the Milky Way Galaxy, “We go round every two hundred million years,” by the estimated age of our sun.  In those days 4.5 billion years was the accepted figure.  I was shocked by the result.  In a universe where extremely large numbers (millions of billions) were common the result of my simple maths was staggering.  The number of times the sun has been round the Galaxy is only twenty-two and a half!   That’s it.  That’s all!  I couldn’t believe it.  I checked and rechecked my figures.   4,500,000,000 divided by 200,000,000 is approximately 22.5.

A little later I was reading Timescale by the science writer Nigel Calder and on the 3rd March 1984 with much trepidation I wrote to him:

Dear Nigel Calder ,

I am enjoying Timescale very much and I know I shall continue to enjoy it for many years. On the strength of this unsolicited compliment I wonder if you can help me with a hopeless layman’s question which has been bothering me for years? If the Solar System is four and a half thousand million years old, and the period of our galactic orbit is two hundred million years, then we have only orbited the galaxy twenty two and a half times.  It seems such a ridiculously low number is it right?

He replied almost immediately on the 8^th March 1984

Dear Eric Idle

Right: it’s not many times around the galactic maypole, since the Earth began. The figure for the period of the Sun’s orbit still seems to be about 200 million years, so Mother Earth is indeed a flighty 22 galactic years old. And by my reckoning the universe itself is about 67 galactic years old, scarcely old enough to run a Coal Board. Perhaps I should have made something of this in Timescale.

I ‘m glad you like the book and it was very nice of you to write. To return the compliment: you must know that Python’s ECT has cured many a case of terminal earnestness in people like me. Seeing that science is a game played with crazy ideas, I sometimes wonder how much of the current breakneck rate of discovery is due to your cerebral anarchism….

He then went on to propose we collaborate on a musical about Halley, whose comet was due to return a year later.  He concluded:

I’d love to meet for a chat – about Halley if you like, or real science if you prefer.

I replied on May 13^th 1984

Dear Nigel Calder,

Thank you for your very kind  letter. I felt very proud that you were able to affirm my  tentative cosmological questionings.  I shall now proceed to bigger and better things – calculating the age of Fred Hoyle,  and the number of years it takes to circumnavigate  Patrick Moore.

I must also thank you for your book on Halley, which I very much enjoyed.  Your musical sounds interesting, though I personally have taken time off from delving into the past and am now optimistically researching the future.

(an obscure reference to The Road to Mars.)

I’m  sorry it has taken me  so long to reply.  Like the  comets I wander about a lot, except that  I can rarely  predict where I will turn up – clearly pre-Copernican  journeyings…. I do hope we can meet when I return…

So I was right!   And it’s possible that I was the very first to observe this.

I shared this correspondence recently with Professor Brian Cox and said on the basis of this I thoroughly expected to get my invitation to join the Royal Society.  He replied:

I will ensure that membership forms are dispatched.

So on the strength of that early discovery I think it’s time to update the figures.

We now believe the Sun is 5.7 billion years old. So to calculate the number of times our star has been round the galaxy take the age of the sun: 5,700,000,000 years and divide it by the time it takes to complete one circuit of the Milky Way: 200,000,000.

Result:   28 and a half circuits.

 

You get it all here folks….

 

 

 

 

 

 

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