What is old in metrology?

Luka Boršić & Mladen Boršić
Institute of philosophy, Zagreb, Croatia

The main topic of the paper is the comparison of Earth's circumference measuring by Eratosthenes approximately 2 400 years ago and the method by which the LIGO (Laser Interferometer Gravitational-Wave Observatory) scientists first measured the gravitational waves in 2016. The approaches are, of course, different, the technological level is significantly different, but there are stunning similarities that reach beyond their ingenuity. The link between Eratosthenes and the scientists from the LIGO laboratory is that they both came to their results by measuring the following:

  • a ratio of two lengths;
  • time;
  • angle (though different types of angles).

They also made use of the then newest and most advanced mathematical apparatus: Eratosthenes used the geometrical approach as discovered by a generation older Euclid and the LIGO group networked computer system for metering management and calculation of results. Further similarity is that they started from purely theoretical assumptions of which they had no evidence. Eratosthenes did not know for sure that Earth was round – at his time it was a hypotheses promulgated by natural philosophes (Aristotle et al.). The LIGO group did not know for sure whether gravitational waves as Einstein predicted indeed existed. Their measuring was preceded by hypotheses of great minds, and they had the courage to step into the unknown.