Cake? Did someone say cake?
I’ll put the coffee on.
And thank you also for the splendid book you sent me to celebrate my birthday Uncertainty, by David Lindley (2007). Im only on Chapter 3; but already theres some amazingly good stuff that sheds much light on the issues implicit in this thread. Heres a small sample:
Uncertainty was hardly new to science in 1927 [the year in which Werner Heisenberg inaugurated that term]. Experimental results always have a little slack in them. Theoretical predictions are only as good as the assumptions behind them. In the endless back-and-forth between experiment and theory, its uncertainty that tells the scientist how to proceed. Experiments probe ever finer details. Theories undergo adjustment and revision. When scientists have resolved one level of disagreement, they move down to the next. Uncertainty, discrepancy, and inconsistency are the stock-in-trade of any lively scientific discipline.To put it another way, there is a vast chasm between theory and what is experimentally possible. The experiments will always necessarily be inexact; what we draw from them can only be, at best, approximate, indeterminate, uncertain.
So Heisenberg didnt introduce uncertainty into science. What he changed, and profoundly so, was its very nature and meaning. It had always seemed a vanquishable foe. Starting with Copernicus and Galileo, with Kepler and Newton, modern science evolved through the application of logical reasoning to verifiable facts and data. Theories, couched in the rigorous language of mathematics, were meant to be analytical and precise. They offered a system, a structure, a thorough accounting that would replace mystery and happenstance with reason and cause. In the scientific universe, nothing happens except that something makes it happen. There is no spontaneity, no whimsy. The phenomena of nature might be inordinately complicated, but at bottom science must reveal order and predictability. Facts are facts, laws are laws. There can be no exceptions .
For a century or two, the dream seemed realizable. If scientists of one generation, building on the work of the last, could see that they had yet to achieve their ideal, they could equally believe that those who came after them would finish the job. The power of reason implied the ineluctability of progress. Science would become more grandiose, more encompassing in scope, yet at the same time more detailed, more scrupulous. Nature was knowable and if it was knowable then one day, necessarily, it would be known.
This classical vision, springing from the physical sciences, became in the nineteenth century the dominant model for science of all kinds. Geologists, biologists, even the first generation of psychologists, pictured the natural world in its entirety as an intricate but inerrant machine. All sciences aspired to the ideal that physics offered. The trick was to define your science in terms of observations and phenomena that led themselves to precise description reducible to numbers, that is and then to find the mathematical laws that tied those numbers into an inescapable system.
No doubt the task was hard. If ever scientists were daunted by their ambitions, it was because of the sheer complexity of the machine they were trying to tease apart. Perhaps the laws of nature would be too vast for their brains to fathom. Perhaps scientists would find they could write down the laws of nature only to discover they lacked the analytical and calculational firepower to work out the consequences. If the project of absolute scientific comprehension were to falter, it would be because the human mind wasnt up to the task, not because nature itself was intractable.
And thats why Heisenbergs argument proved so unsettling. It targeted an unsuspected weakness in the edifice of science in the substructure, so to speak, a part of the foundation that had gone unexamined because it had seemed so self-evidently secure.
Heisenberg took no issue with the perfectibility of the laws of nature. Instead, it was in the very facts of nature that he found strange and alarming difficulties. His uncertainty principle concerned the most elementary act of science: How do we acquire knowledge about the world, the kind of knowledge that we can subject to scientific scrutiny? How, in the particular example Heisenberg took, do we know where some object is and how fast it is moving? It was a question that would have baffled Heisenbergs predecessors. At any time, a moving object has some speed and position. There are ways of measuring or observing these things. The better the observation, the more accurate the result. What else is there to say?
Plenty more, Heisenberg discovered. His conclusion, so revolutionary and esoteric, has been expressed in words that have become almost commonplace. You can measure the speed of a particle, or you can measure its position, but you cant measure both. Or: the more precisely you find out the position, the less well you can know its speed. Or, more indirectly and less obviously: the act of observing changes the thing observed.
The bottom line seems to be that facts are not the simple, hard things they were supposed to be. In the classical picture of the natural world as a great machine, it had been taken for granted that all the working parts of the machinery could be defined with limitless precision and that all their interconnections could be exactly understood . This had seemed both fundamental and essential. To have a hope of comprehending the universe, you had first to assume that you could find out, piece by piece, what all the components of the universe were and what they were doing. Heisenberg was saying that you couldnt always find out what you wanted to know, that your ability to describe the natural world was circumscribed. If you couldnt describe it as you wished, how could you hope to reason out its laws?
What was lost, then, was not the underlying ideal of a deterministic physical world but the Laplacian hope for perfectibility in the scientific accounting of that world. The universe unfolds imperturbably according to its inner design. Scientists could legitimately hope to understand that design fully. What they could no longer attain was complete knowledge of how that design was realized. They could know the blueprint, but not the shape and color of every brick .
It takes a certain humility to understand the import of this new situation.
I highly recommend this book to any Freeper who wants a lucid, well-written account of the revolutionary developments in physics from the late nineteenth century forward, showcasing Einstein, Heisenberg, and Bohrs revolutionary contributions throughout: Its a superb history of the science of this fascinating period.
Anyhoot, its a marvelous book, dear Alamo-Girl, and I thank you so much for it! Im so looking forward to continuing my reading.