Salzburg-born physicist and mathematician Christian Johann Doppler (1803-1853) observed, that the wavelengths of light and sound decrease in relation to the recipient as they approach and increase as their source moves away. This explains the change in pitch of a police siren or an ambulance when the car passes us at high speed.. This rule, called the Doppler effect, was used to discover, that other galaxies are moving away from ours and therefore the universe is expanding.
The Vienna Circle (The Vienna Circle) the scholars entered (mainly philosophers, mathematicians, physicists and logicians) concentrated around the capital city's university in 20. i 30. XX w. Their views are often referred to as logical empiricism or neo-positivism. They considered the Austrian philosopher and scientist Ernst Mach as their precursor (his name is associated with the so-called. Mach number, determining the ratio of the velocity of the gas flow or a body moving in it to the velocity of sound in the gas). The members of the Vienna Circle formulated the principle of verifiability, which is the basis for assessing the truthfulness of various concepts. Mathematical operations (np. 2 + 2 = 4) they're real, because they are tautological and cannot be denied. Science is also real, because its formulas find their solutions and can be empirically verified. However, the metaphysical questions are untrue (type: "Is there a God?”), because they cannot be verified. Many members of the group emigrated with the occupation of Austria by the Nazis in 1938 r. This direction has retained its influence, however, it lost its impact, when philosophers failed to come to an agreement, whether the principle of verifiability itself is to be subject to empirical verification, or not.
Another outstanding Austrian philosopher, Karl Popper (1902-1994), was born in Vienna, he also lived and worked there until a while, when he had to, fearing the Nazis, like many others, emigrate from the country. He was associated with the Vienna Circle quite loosely and rather on the contrary. He modified the neopositive criterion of the meaningfulness and verifiability of scientific sentences, introducing the so-called. the principle of falsification, that is, the theory's susceptibility to disproval. According to him, it is impossible to completely prove the truth of a scientific statement, it can only be proved that it is false after the possible appearance of data, which contradict him.
This is why theories have been accepted by scientists for so long, until they are proved to be false. Then new ones are looked for in their place, but they too may be falsified and replaced with better ones in the future (as Newtonian physics was perfected by Einstein). So we owe the progress in science to this, that we are trying to prove the falsehood of existing scientific theories. Popper is also known for his outstanding work in the field of social and political philosophy.
The most outstanding Austrian philosopher is certainly Ludwig Wittgenstein (1889-1951), whose main work, Tractatus Logico-Philosophicus, exerted a significant influence on the development of the Vienna Circle and the philosophy of the 20th century. He was born in Vienna, and he died at Cambridge, where he spent the last years of his life as a university lecturer. Most of his work was devoted to the philosophy and limitations of language. His Tractatus is a serious scientific treatise in the form of a series of logical statements. By making a logical analysis of the language, Wittgenstein came to a paradoxical conclusion: he had to say it with his tongue, what he claimed, could only be presented with the help of analyzes beyond the language of the language. Nevertheless, he was convinced, that in the aforementioned work everything that could be achieved in philosophy, was achieved by him. So he moved away from the world, by taking a teaching position at a rural school in western Austria. After a few years, however, he returned to philosophy, however, changing his original views (the so-called. Wittgenstein II). His new theory of language as a system of language games of a primarily pragmatic nature, was less categorical and emphasized the creative possibilities of the language itself. Wittgenstein is considered one of the most influential philosophers of the 20th century., although in his private life he was a rather lonely man. His greatest fear was the obsessive vision of his works being destroyed by fire (during his lifetime, only Tractatus logico-philosophicus appeared in print), therefore he kept them in a fireproof safe.