Each ray of light moves in the coordinate system 'at rest' with the definite, constant velocity V independent of whether this ray of light is emitted by a body at rest or a body in motion.
Once again you are wrong sir, darkness does not exist either. Darkness is in reality the absence of light. Light we can study, but not darkness. In fact we can use Newton's prism to break white light into many colors and study the various wavelengths of each color. You cannot measure darkness. A simple ray of light can break into a world of darkness and illuminate it. How can you know how dark a certain space is? You measure the amount of light present. Isn't this correct? Darkness is a term used by man to describe what happens when there is no light present.
The opinion prevailed among advanced minds that it was time that belief should be replaced increasingly by knowledge; belief that did not itself rest on knowledge was superstition, and as such had to be opposed.
What is the meaning of human life, or, for that matter, of the life of any creature? To know the answer to this question means to be religious. You ask: Does it make any sense, then, to pose this question? I answer: The man who regards his fellow creatures as meaningless is not merely unhappy but hardly fit for life.
It seems to me that the idea of a personal God is an anthropological concept which I cannot take seriously. I also cannot imagine some will or goal outside the human sphere... Science has been charged with undermining morality, but the charge is unjust. A man's ethical behavior should be based effectually on sympathy, education, and social ties and needs; no religious basis is necessary. Man would indeed be in a poor way if he had to be restrained by fear of punishment and hope of reward after death.
I am of the opinion that all the finer speculations in the realm of science spring from a deep religious feeling, and that without such feeling they would not be fruitful.
In one's youth every person and every event appear to be unique. With age one becomes much more aware that similar events recur. Later on, one is less often delighted or surprised, but also less disappointed than in earlier years.
Weakness of attitude becomes weakness of character; it becomes lack of power to act with courage proportionate to danger. All this must lead to the destruction of our intellectual life unless the danger summons up strong personalities able to fill the lukewarm and discouraged with new strength and resolution.
[Newton wrote to Halley ... that he would not give Hooke any credit] That, alas, is vanity. You find it in so many scientists. You know, it has always hurt me to think that Galileo did not acknowledge the work of Kepler.
It is my conviction that pure mathematical construction enables us to discover the concepts and the laws connecting them, which gives us the key to the understanding of nature ... In a certain sense, therefore, I hold it true that pure thought can grasp reality, as the ancients dreamed.