„... the principle of the limiting character of the velocity of light. This statement... is not an arbitrary assumption but a physical law based on experience. In making this statement, physics does not commit the fallacy of regarding absence of knowledge as evidence for knowledge to the contrary. It is not absence of knowledge of faster signals, but positive experience which has taught us that the velocity of light cannot be exceeded. For all physical processes the velocity of light has the property of an infinite velocity. In order to accelerate a body to the velocity of light, an infinite amount of energy would be required, and it is therefore physically impossible for any object to obtain this speed. This result was confirmed by measurements performed on electrons. The kinetic energy of a mass point grows more rapidly than the square of its velocity, and would become infinite for the speed of light.“

1891 - 1953

„According to the Special Theory of Relativity, the velocity of a moving body is always less than the velocity of light. Since the energy of motion of a body depends on its inertial mass and its velocity, it follows that if the energy of a body is increased indefinitely by the continual application of a force, the inertial mass of the body must be increased too; for, if not, the velocity would ultimately increase indefinitely and exceed the velocity of light. Einstein found that, corresponding to any increase in the energy content of a body, there is an equivalent increase in its inertial mass. Mass and energy thus appeared to be different names for the same thing, the energy associated with a mass M being Mc2, where c is the velocity of light; and the mass M of a body moving with velocity v he found to be given by the following formulaM = \frac {m}{\sqrt{(1 - \frac {v^2}{c^2}}}</center“

—  Gerald James Whitrow British mathematician 1912 - 2000

„It is of interest to inquire what happens when the aviator's speed... approximates to the velocity of light.“

—  Arthur Stanley Eddington British astrophysicist 1882 - 1944
Context: It is of interest to inquire what happens when the aviator's speed... approximates to the velocity of light. Lengths in the direction of flight become smaller and smaller, until for the speed of light they shrink to zero. The aviator and the objects accompanying him shrink to two dimensions. We are saved the difficulty of imagining how the processes of life can go on in two dimensions, because nothing goes on. Time is arrested altogether. This is the description according to the terrestrial observer. The aviator himself detects nothing unusual; he does not perceive that he has stopped moving. He is merely waiting for the next instant to come before making the next movement; and the mere fact that time is arrested means that he does not perceive that the next instant is a long time coming.<!--p.26

„Relativity distorted classical expectations in a way that Clavain still did not find entirely intuitive. Slam two objects towards each other, each with individual velocities just below light-speed, and the classical result for their closing velocity would be the sum of their individual speeds: just under twice the speed of light. Yet the true result, confirmed with numbing precision, was that the objects saw each other approach with a combined speed that was still just below the speed of light. Similarly, the relativistic closing velocity for two objects moving towards each other with individual speeds of one-half of light-speed was not light-speed itself, but eight-tenths of it. It was the way the universe was put together, and yet it was not something the human mind had evolved to accept.“

—  Alastair Reynolds British novelist and astronomer 1966
Chapter 26 (p. 463)

„Let us suppose that an explosion occurs on Mars, which is observed by an astronomer on earth, who records the instant when he sees the flash. If light travelled instantaneously with an infinite velocity, this instant would coincide with the time... recorded by the... observer on Mars. In this way a meaning could be attached automatically to absolute time and the simultaneity of events at different places; indeed, the classical theory is now regarded as the limiting form of Einstein's theory when the velocity of light becomes infinite. But as there is a mass of experimental evidence supporting the view that light takes a finite time to travel... the terrestrial observer must correct the time recorded on his watch. This correction... will depend on assumptions concerning the velocity of light and the measurement of distance. Thus the concept of a world-wide simultaneity ceases to be a primitive idea.“

—  Gerald James Whitrow British mathematician 1912 - 2000
p, 125

„Velocity of transverse undulations in our hypothetical medium, calculated from the electromagnetic experiments of 'MM'. Kohlrausch and Weber, agrees so exactly with the velocity of light calculated from the optical experiments of M. Fizeau, that we can scarcely avoid the conclusion that light consists in the transverse undulations of the same medium which is the cause of electric and magnetic phenomena.“

—  James Clerk Maxwell Scottish physicist 1831 - 1879
Lecture at Kings College (1862) as quoted by F. V. Jones, "The Man Who Paved the Way for Wireless," New Scientist (Nov 1, 1979) p. 348 & Andrey Vyshedskiy, On The Origin Of The Human Mind 2nd edition

„Classical science was based upon the belief that it is possible to formulate both the position and velocity at one time of any given particle. It followed that knowledge of the position and velocity of a given number of particles would enable the future behavior of the whole collection to be accurately predicted. The principle of Heisenberg is that given the determination of position, its velocity can be stated only as of a certain order of probability, while if its velocity is determined the correlative factor of position can be stated only as of a certain order of probability. Both cannot be determined at once, from which it follows necessarily that the future of the whole collection cannot possibly be foretold except in terms of some order of probability.“

—  John Dewey American philosopher, psychologist, and educational reformer 1859 - 1952

„This velocity is so nearly that of light, that it seems we have strong reason to conclude that light itself“

—  James Clerk Maxwell Scottish physicist 1831 - 1879
Context: The general equations are next applied to the case of a magnetic disturbance propagated through a non-conductive field, and it is shown that the only disturbances which can be so propagated are those which are transverse to the direction of propagation, and that the velocity of propagation is the velocity v, found from experiments such as those of Weber, which expresses the number of electrostatic units of electricity which are contained in one electromagnetic unit. This velocity is so nearly that of light, that it seems we have strong reason to conclude that light itself (including radiant heat, and other radiations if any) is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field according to electromagnetic laws. A Dynamical Theory of the Electromagnetic Field (1864), §20.

„The laws of economics are subject to the laws of physics. The physical processes that govern this planet and the continued life upon it place as stringent an upper limit on economic growth as the speed of light does on our knowledge of the universe.“

—  Ian McDonald British science fiction novelist 1960
Ch. 9 (p. 93).

„I must now explain what I mean by the quantity of action. A certain action is necessary for the carrying of a body from one point to another: this action depends on the velocity which the body has and the space which it describes; but it is neither the velocity nor the space taken separately. The quantity of action varies directly as the velocity and the length of path described; it is proportional to the sum of the spaces, each being multiplied by the velocity with which the body describes it. It is this quantity of action which is here the true expense (dépense) of nature, and which she economizes as much as possible in the motion of light.“

—  Pierre Louis Maupertuis French mathematician, philosopher and man of letters 1698 - 1759
Histoire de l'Academie (1744) p. 423; Les Oeuvres De Mr. De Maupertuis (1752) vol. iv p. 17; as quoted by Philip Edward Bertrand Jourdain, The Principle of Least Action https://books.google.com/books?id=y3UVAQAAIAAJ (1913) p. 5.

„After ten years of reflection such a principle resulted from a paradox upon which I had already hit at the age of sixteen: If I pursue a beam of light with the velocity c (velocity of light in a vacuum), I should observe such a beam as a spatially oscillatory electromagnetic field at rest. However, there seems to be no such thing, whether on the bases of experience or according to Maxwell's equations.“

—  Albert Einstein German-born physicist and founder of the theory of relativity 1879 - 1955
Context: Reflections of this type made it clear to me as long ago as shortly after 1900, i. e., shortly after Planck's trailblazing work, that neither mechanics nor electrodynamics could (except in limiting cases) claim exact validity. By and by I despaired of the possibility of discovering the true laws by means of constructive efforts based on known facts. The longer and the more despairingly I tried, the more I came to the conviction that only the discovery of a universal formal principle could lead us to assured results.... How, then, could such a universal principle be found? After ten years of reflection such a principle resulted from a paradox upon which I had already hit at the age of sixteen: If I pursue a beam of light with the velocity c (velocity of light in a vacuum), I should observe such a beam as a spatially oscillatory electromagnetic field at rest. However, there seems to be no such thing, whether on the bases of experience or according to Maxwell's equations. From the very beginning it appeared to me intuitively clear that, judged from the stand-point of such an observer, everything would have to happen according to the same laws as for an observer who, relative to the earth, was at rest.

„I have also cleared the electromagnetic theory of light from all unwarrantable assumption, so that we may safely determine the velocity of light by measuring the attraction between bodies kept at a given difference of potential, the value of which is known in electromagnetic measure.“

—  James Clerk Maxwell Scottish physicist 1831 - 1879
Letter to C. Hockin, Esq. (Sept 7, 1864) as quoted by Lewis Campbell, William Garnett, The Life of James Clerk Maxwell: With Selections from His Correspondence and Occasional Writings https://books.google.com/books?id=B7gEAAAAYAAJ (1884)

„If the definition of simultaneity is given from a moving system, the spherical surface will result when Einstein's definition with є = 1/2 is used, since it is this definition which makes the velocity of light equal in all directions.“

—  Hans Reichenbach American philosopher 1891 - 1953

„The universe has a finite velocity which limits not only the spread of its events, but also the speed of our perceptions. The moment of actuality slips too fast by the slow, coarse net of our senses.“

—  George Kubler American art historian 1912 - 1996
p. 18; as cited in Lee (2001, p. 47)

„One can find meaning in poetry as well as in science in the contemplations of a flower as well as in the grasp of an equation. We can be filled with wonder as we stand under the majestic dome of the night sky and see the myriad lights that twinkle and shine in its seemingly infinite depths. We can also be filled wit awe as we behold the meaning of the formulae that define the propagation of light in space, the formation of galaxies, the synthesis of chemical elements, and the relation of energy, mass and velocity in the physical universe. The mystical perception of oneness and the religious intuition of a Divine intelligence are as much a construction of meaning as the postulation of the universal law of gravitation.“

—  Ervin László Hungarian musician and philosopher 1932
p. 3.

„The way that the background fields generates mass is rather like the way in which when light passes through a transparent medium like glass or water, it gets slowed down. It no longer travels with the fundamental velocity of light c. And that's the way to think of the generation of mass.“

—  Peter Higgs British physicist 1929
in video Meet Peter Higgs by CERN (July 2004).

„A question which has long troubled astronomers and physicists is what becomes of the energy that is continually being poured out into space by the sun and the stars. To this question a complete answer is given by the new theory. It is used up, diluted, or degraded, by the expansion of the universe.... the light travelling through the expanding universe and, so to say, trying to reach a particular star, or stellar system, which is continually receding with great velocity, is losing energy in trying to catch up with it. It is this degradation of the light, technically known as the redshift of the spectral lines, by which we become aware of the receding velocities of the extra-galactic nebulae. It can be shown that the decrease of the total amount of radiant energy in the universe by this degradation exceeds the increase by the radiation of the stars. It would not be correct, however, to conclude that the expansion is caused by the energy thus lost by the radiation...“

—  Willem de Sitter Dutch cosmologist 1872 - 1934