It is a curious paradox that several of the greatest and most creative spirits in science, after achieving important discoveries by following their unfettered imaginations, were in their later years obsessed with reductionist philosophy and as a result became sterile. Hilbert was a prime example of this paradox. Einstein was another. Like Hilbert, Einstein did his great work up to the age of forty without any reductionist bias. His crowning achievement, the general relativistic theory of gravitation, grew out of a deep physical understanding of natural processes. Only at the very end of his ten-year struggle to understand gravitation did he reduce the outcome of his understanding to a finite set of field equations. But like Hilbert, as he grew older he concentrated his attention more and more on the formal properties of his equations, and he lost interest in the wider universe of ideas out of which the equations arose.

His last twenty years were spent in a fruitless search for a set of equations that would unify the whole of physics, without paying attention to the rapidly proliferating experimental discoveries that any unified theory would finally have to explain. I do not need to say more about this tragic and well-known story of Einstein's lonely attempt to reduce physics to a finite set of marks on paper. His attempt failed as dismally as Hilbert's attempt to do the same thing with mathematics. I shall instead discuss another aspect of Einstein's later life, an aspect that has received less attention than his quest for the unified field equations: his extraordinary hostility to the idea of black holes.

Einstein's breakthrough was classic in that it sought to unify the elements of a physical analysis, and it placed the older examples and principles within a broader framework. But it was revolutionary in that, ever afterward, we have thought differently about space and time, matter and energy. Space and time-no more absolute-have become forms of intuition that cannot be divorced from perspective or consciousness, anymore than can the colors of the world or the length of a shadow. As the philosopher Ernst Cassirer commented, in relativity, the conception of constancy and absoluteness of the elements is abandoned to give permanence and necessity to the laws instead.

And Einstein stood out among natural scientists in his abiding curiosity about children's minds. He had once declared that we know all the physics that we will ever need to know by the age of three.

Anyone who saw Albert Einstein trudging along the sidewalks of Princeton University with a briar pipe hanging out of his mouth might have assumed the odd fellow in the old, frumpy overcoat and socks that didn’t match was a hobo.

"Throughout his life, Albert Einstein would retain the intuition and the awe of a child. He never lost his sense of wonder at the magic of nature's phenomena-magnetic fields, gravity, inertia, acceleration, light beams-which grown-ups find so commonplace. He retained the ability to hold two thoughts in his mind simultaneously, to be puzzled when they conflicted, and to marvel when he could smell an underlying unity. "People like you and me never grow old," he wrote a friend later in life. "We never cease to stand like curious children before the great mystery into which we were born.

Much of the history of science, like the history of religion, is a history of struggles driven by power and money. And yet this is not the whole story. Genuine saints occasionally play an important role, both in religion and in science. Einstein was an important figure in the history of science, and he was a firm believer in transcendence. For Einstein, science as a way of escape from mundane reality was no pretense. For many scientists less divinely gifted than Einstein, the chief reward for being a scientist is not the power and the money but the chance of catching a glimpse of the transcendent beauty of nature.

There is a reward structure in science that is very interesting: Our highest honors go to those who disprove the findings of the most revered among us. So Einstein is revered not just because he made so many fundamental contributions to science, but because he found an imperfection in the fundamental contribution of Isaac Newton.

there’s a telling answer to the question of what Albert Einstein claimed was so remarkable it could be labeled as both “the most beautiful thing we can experience” and “the source of all true science and art.” His contention: the mysterious.

"Einstein was remarkable for his powers of concentration; he could work uninterruptedly for hours and even days on the same problem. Some of the topics that interested him remained on his mind for decades. For relaxation he turned to music and to sailing, but often his work would continue during these moments as well; he usually had a notebook in his pocket so that he could jot down any idea that came to him. Once, after the theory of relativity had been put forth, he confessed to his colleague Wolfgang Pauli, "For the rest of my life I want to reflect on what light is." It is perhaps not entirely an accident that a focus on light is also the first visual act of the newborn child."

Albert Einstein, in a classic humble brag, once remarked: “I have no special talents. I am only passionately curious.” The first half of that statement was surely false, while the second half was undoubtedly true.

I cannot imagine a God who rewards and punishes the objects of his creation, whose purposes are modeled after our own — a God, in short, who is but a reflection of human frailty. Neither can I believe that the individual survives the death of his body, although feeble souls harbor such thoughts through fear or ridiculous egotism. Albert Einstein, German-born American physicist

Thanks to his own thought experiments, his formal education, and his study of authors like Foppl, Einstein already had identified the set of issues that would occupy him for years to come: the relation between electricity and magnetism, the putative role of the ether, and conceptions of space and time, as formulated by a philosopher like Kant or a scientific thinker like Maxwell. Einstein later recalled:

What made the greatest impression upon the student, however, was less the technical construction of mechanics or the solution of complicated problems than the achievements of mechanics in areas which apparently had nothing to do with mechanics: the mechanical theory of light, which conceived of light as the wave-motion of a quasi-rigid elastic ether and above all the kinetic theory of gases.

"The ideals which have lighted my way, and time after time have given me new courage to face life cheerfully, have been kindness, beauty, and truth."
Albert Einstein (1879-1955)

After all, Rutherford had as deep a sense of the mysteries of nature as Einstein. And the human spirit expresses itself as eloquently in the work of human hands as in the work of human minds. Rutherford was supreme as an experimenter and Einstein was supreme as a theorist, but each of them held the other in deep respect. Both of them understood that the human spirit is at its best when hands and minds are working together.