The story of the SEVEN LEVEL HEADED SCIENTISTS.
1. In the beginning there was a great Mathematician who invented the
sphere - a massless figment of his imagination.
2. Along came a Physicist who had been thinking heavily about mass.
He filled the sphere with a perfect fluid, but being an experimental fellow
he decided to rotate it at a uniform speed. The points at which the axis
of rotation crossed the surface he named the N pole and the S poles.
The line on the surface which was equidistant from the poles he called
the equator. He observed that the sphere became flatter at the N & S pole.
The new shape he called an ellipsoid.
3. The physicist took an apple and weighed it on a spring balance. He discovered
that the apple weighed more at the poles than at the equator.
4. Knowing that the the equator was further from the centre of object
than the N-pole, he decided to see how much energy was required to
roll the apple on the surface from the N-pole 'up' to the equator.
This proved to be very easy because he did NO WORK at all. In other
words he needed no energy, not even a bite from the apple!
5. No work had been done to the apple and yet its weight had changed!
The physicist explained this very curious result by saying that the
centrifugal force created by the ellipsoid's rotation had helped to
move the apple further from the center of mass and against the force of
gravity. He needed a new word to describe this surface which
possessed different gravities but which had no 'uphill'. He called this surface
6. A Geologist arrived on the scene, but thinking that all new words
should begin with "geo", he coined the word geoid for the
7. The geologist amused himself by chucking some big lumps of rock
into the rotating body and so created local anomalies. The geoid was no longer
an elegant mathematical shape, but it had bumps in the surface.
The physicist could still roll his apple over all the bumps
without consuming or gaining any energy. However the equipotential surface
was no longer identical to the ellipsoid.
8. Next came the Chemist who thought that the body would look much nicer covered
with a solution of sodium chloride, but because he had not stirred the
solution very well, the liquid was not of uniform density. This meant that
the liquid surface did not fit the geologist's geoid exactly. The new
surface became know as the Chemist's Level (or C-level for short).
9. It was now the Meteorologist's turn. He added winds, temperature differences,
and lots of other nasty things. This changed
the shape of C-Level to the Meteorologist's Special Level (or MSL for
10. Not to be outdone, the Oceanographer, who had been circulating,
chipped in with the observation that the sodium chloride solution
was in constant motion. He called this movement 'Ocean currents' and
found that this changed the MSL in an even more complicated way.
11. And the last to appear was the Environmentalist
with his dire warnings of global warming. He talked of melting ice and
great changes to the MSL. He said that in 100 years time everyone else
would be wrong anyway!
12. The geologist, having become bored with the conversation, went outside
to inspect his plates. When he returned a few millennia later
he proudly announced that whilst he had gone up in the world, all the others had gone down.
That explains why the seven level headed scientists are not the same height.
And if you want to know your height, it all depends in whose shoes you stand
and when you stand in them.
How GPS Utility handles altitude