Vocabulary notes:

Геоцентрическая система (модель мира) - geocentric model;

пифагорейцы – Pythagoreans;

пироцентрическая модель - pyrocentric model;

Противоземля - Anti-earth;

Аристарх Самосский – Aristarkh Samossky;

гелиоцентрическая система – heliocentric model;

Эмпедокл – Empidocle;

Демокрит – Democritis;

Аристотель – Aristotle;

Ньютон – Newton;

Эпикур – Epicur;

Эллины – Hellenes;

Кеплер – Kepler.

1.3.5 Read texts 1.1 – 1.2, 1.3.4 again, find the unknown words in the dictionary and prepare the presentation of your report on “The History of Physics”. You may use Internet to add some information.

1.4 Text Emergence of experimental method and physical optics

1.4.1 Read the text and answer the questions: What is your attitude to Ibn al-Haytham? Have you read any of his books? Do you like them?

The use of experiments in the sense of empirical procedures in geometrical optics dates back to second century Roman Egypt, where Ptolemy carried out several early such experiments on reflection, refraction and binocular vision. Due to his Platonic methodological paradigm of “saving the appearances”, however, he discarded or rationalized any empirical data that did not support his theories, as the idea of experiment did not hold any importance in Antiquity. The incorrect emission theory of vision thus continued to dominate optics through to the 10th century.

Figure 1 - Ibn al-Haytham (965-1039)

The turn of the second millennium saw the emergence of experimental physics with the development of an experimental method emphasizing the role of experimentation as a form of proof in scientific inquiry, and the development of physical optics where the mathematical discipline of geometrical optics was successfully unified with the philosophical field of physics. The Iraqi physicist, Ibn al-Haytham (Alhazen), is considered a central figure in this shift in physics from a philosophical activity to an experimental and mathematical one, and the shift in optics from a mathematical discipline to a physical and experimental one. Due to his positivist approach, his Doubts Concerning Ptolemy insisted on scientific demonstration and criticized Ptolemy’s confirmation bias and conjectural undemonstrated theories. His Book of Optics (1021) was the earliest successful attempt at unifying a mathematical discipline (geometrical optics) with the philosophical field of physics, to create the modern science of physical optics. An important part of this was the intromission theory of vision, which in order to prove, he developed an experimental method to test his hypothesis. He conducted various experiments to prove his intromission theory and other hypotheses on light and vision. The Book of Optics established experimentation as the norm of proof in optics, and gave optics a physico-mathematical conception at a much earlier date than the other mathematical disciplines. His On the Light of the Moon also attempted to combine mathematical astronomy with physics, a field now known as astrophysics, to formulate several astronomical hypotheses which he proved through experimentation.