A Tribute to Galileo

Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the characters in which it is written. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures without which it is humanly impossible to understand a single word of it; without these one is wandering in a dark labyrinth.”

Il saggiatore (The Assayer) Galileo Galilei 1623, on nature’s mathematical aesthetic

The 8th of January 2017 marked the 375th anniversary of Galileo Galilei’s death. This is a moment to remember the immense contribution of Galileo to science, especially the ‘mechanical’ sciences. He was one of the the greatest polymaths in the world.


Galileo Galilei (1564-1642)

Galileo was born on 15th of February 1564 in Pisa, Italy. My first encounter with Galileo that I can remember was when I was 12, through Halliday and Resnick’s famous textbook ‘Physics’ in which they describe Galileo’s contribution to mechanics. Specifically they allude to his use of inclined planes and balls to show that gravitational acceleration is uniform and his work on projectile motion e.g. an exercise in the book is to prove Galileo’s claim that “for elevations which exceed or fall short of 45° by equal amounts, the ranges are equal”.

Galileo to me symbolises the birth of the scientific method in Europe. This is the fusion of theory, guided by intuition and mathematics, and experiment based on creative use of all resources in one’s possession. Albert Einstein wrote of him “Pure logical thinking cannot yield us any knowledge of the empirical world; all knowledge of reality starts form experience and ends in it. Propositions arrived at by purely logical means are completely empty as regards reality. Because Galileo saw this, and particularly because he drummed it into the scientific world, he is the father of modern physics — indeed, of modern science altogether.”

But Galileo also symbolises the struggle for truth against blind authority. In Dialogue Concerning Two World Systems, published in 1632, Galileo indirectly defended the Copernican theory that the Earth revolves around the Sun which conflicted with the stance of the Catholic Church that the Earth is the centre of the universe. One year later he was found “vehemently suspect of heresy” by the Inquisition and was put under house arrest for this view. He was then 68 years old and spent the rest of the 9 years of his life trapped in his house. But amazingly, despite these circumstances and eventually going blind, he managed to publish his great book Discourses and Mathematical Demonstrations Relating to Two New Sciences.


Replica of Galileo’s Study (I took this pic at Deutsches Museum, Munich 2016).

To take a lesson from Galileo into the new year, let’s look at the modern day challenges to scientific progress. Galileo had to face the authority of the church as well as the towering philosophies of Aristotle and Ptolemy and even scientific contemporaries like Tycho Brahe. Today the authorities are government, corporations, religious institutions and scientific establishment. Government has a responsibility to implement policies based on scientific consensus as well as advice from individual leading scientists. But corporate and religious lobbies play a big role in how policies are implemented.

The topics that appear to be most interfered with are evolution, climate change and cosmology. Some governments throughout Asia and Africa criminalise openly questioning certain interpretations of Quran and Hadiths, even if one has a scientific basis.  Since 2012 in Bangladesh at least 48 secular writers have been killed for criticising Islam or Islamic political parties.

In the USA in a few days Donald Trump has his Presidential inauguration after which he can follow his agenda to oppose industrial regulations like curtailing greenhouse gas emissions or basic product approvals via the FDA. On the whole this is interference in the decisions of the scientific community that certain aspects of production damage society and environment in the long term. He has also advocated for removing a common school educational system. This could allow private schools to teach their own versions of evolution based on Biblical interpretation, refuting scientific consensus and evidence.

In Australia a few years ago a small group was formed called the ‘Galileo movement’ to oppose any regulation or even mainstream institutional research into climate change. They use Galileo’s name to portray themselves as ardent skeptics against a herd of anti-scientific climate activists, just like Galileo who challenged the opinions of his time. But the analogy is inverted when we recognise that the modern parallel of the Catholic Church Inquisition must be a non-scientific organisation that interferes in the works of individuals who employ the ‘Galilean method’ of theory, experiment and publishing in a form open to scrutiny. What is this organisation? It is the band of industry lobbyists (fossil fuel, mining, livestock) who clearly aim to suppress the relatively new notion that humans are causing the world to damagingly heat up. The struggle over the last few decades has been faced by the scientists to expose global warming as a serious danger to civilisation. The struggle continues, in Australia even more so (e.g. my previous post).

Nevertheless, scientists should learn from Galileo to be critical of one’s colleagues and predecessors. As a physics student and researcher I am used to the language of quantum mechanics and general relativity, the foundations of modern physics. Relativity, in particular, emerged due to Einstein’s critique of Galilean ideas. Einstein realised that the Galilean transformations were incorrect for fast moving particles, but also understood the importance of Galileo’s principle of relativity and notion that an object’s free fall rate is independent of its mass.

Here is a list of Galileo’s contributions:


-Realisation that period of swing of a pendulum is independent of amplitude

-Experiment to put lower bound on speed of light

-Principle of relativity, that the laws of physics are the same between systems moving at constant velocity

-Realisation that objects fall on Earth with almost uniform acceleration independent of mass and that the distance travelled is proportional to time squared. Used to predict projectile motion.

-Realised principle of inertia (Newton’s first law of motion): without an external force like friction an object will move at constant speed

Astronomical Observations:

– Kepler’s supernova, which showed that celestial objects can change form

– Jupiter’s moons, which showed that not all objects orbit the Earth (this is the cover photo of this post, taken by Alexander West and John Stetson)

– Venus’ phases, which cast doubt on Ptolemy’s geocentric model


-Moon’s imperfections and interpretation of them as craters and mountains

-Observation of stars in the Milky Way



-Hydrostatic balance

-Galilean telescope

-Galilean microscope

-Military compass

-Idea to use Jupiter’s moons as clocks

-Design of the first pendulum clock

-Horse-driven pump

-Material science

His greatest blunder: to disregard Kepler. He thought the tides were a key evidence of the Earth’s motion; he dismissed Kepler’s correct theory that they were due to the moon. He also maintained that planetary orbits are circular even though Kepler had already realised they are elliptical.

An interesting insight is that Galileo originally trained in medicine but later switched to mechanical sciences. He published his greatest works towards the end of his life, unlike other fellow greats like Newton and Einstein who were in their early 20’s when they began shifting paradigms. But as science becomes more demanding and dense, discoveries tend to be made in later stages of individuals’ lives.

P.S. Obama yesterday commuted whistleblower Chelsea (formerly Bradley) Manning’s 35 year sentence, Chelsea will be released in May this year! To me, Chelsea has a similarity to Galileo in that Chelsea published material that revealed hidden truths about our world but the government punished Chelsea by isolating Chelsea from society. Though Obama hasn’t openly commended Chelsea his action implies that he believes that the whistleblowing sentence is unjust. Society should honour deeds that reveal secrets that authorities try to suppress, and it’s always better to realise early that you’re wrong; it took the Catholic Church 350 years to openly acknowledge that its treatment of Galileo was unjust.

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6 Responses to A Tribute to Galileo

  1. serenitynay says:

    I appreciate the depth with which you took this topic! I found your post incredibly informative, and enjoyed it. Thank you for sharing your thoughts on Galileo.

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  3. Thanks for this thought provoking article on Galileo. I have recently been studying the evolution of correct tidal theory – Galileo did assign them to the effect of the sun – but his breakthrough was at least to recognise that it was the influence of a heavenly body by some kind of rational effect, rather than a mystical effect. Kepler correctly identified that the moon was the cause – but his model could only predict one tide per day. The full principle, developed by Newton is fascinating : https://global-scientist.com/2017/02/11/tides-in-free-fall/

    • helloparth says:

      Actually Galileo thought tides are entirely due to Earth’s motion, not due to any heavenly body influence (as per my sources). Indeed Newton figured it out, but some sources (like Strabo’s Geographica) show that even before Kepler a few astronomers from ancient Greece and Persia realised that the moon was the cause.

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