When you throw a ball in the air, the equations of classical physics will tell you exactly what path the ball will take as it falls, and when and where it will land. But if you were to squeeze that same ball down to the size of an atom or smaller, it would behave in ways beyond anything that classical physics can predict. MIT scientists have now shown that certain mathematical ideas from everyday classical physics can be used to describe the often weird and nonintuitive behavior that occurs at the quantum, subatomic scale. In a paper appearing today in the journal Proceedings of the Royal Society, the team shows that the motion of a quantum object can be calculated by applying an idea from classical physics known as 'least action.' With their new formulation, they show they can arrive at exactly the same solution as the Schrodinger equation ' the main description of quantum mechanics ' for a number of textbook quantum-mechanical scenarios, including the double-slit experiment and quantum tunneling....
Although the basic idea of quantum physics dates back to the earliest years of the twentieth century, it wasn't until 1925, on the German island of Heligoland, that Werner Heisenberg had the inspiration that marked the true dawn of quantum theory. With stunning speed over a few short years, a whole new paradigm of material reality emerged to overturn all of the classical physics that preceded it. This quantum world is one that is fundamentally at odds with our intuitions: particles and waves shape-shift into one another; nothing can ever be completely certain; and the act of observing seems to play a central part in determining what is observed. The questions this world raises are immense, and its relationship with the other pillar of modern physics ' Albert Einstein's general theory of relativity ' is uneasy. Yet the promise of quantum computers and other technologies built on the back of it are enough to convince that, a century on, quantum theory is here to stay....
A novelist transforms the physicist John von Neumann into a scientific demon....
Imagine using your cellphone to control the activity of your own cells to treat injuries and disease. It sounds like something from the imagination of an overly optimistic science fiction writer. But this may one day be a possibility through the emerging field of quantum biology. Over the past few decades, scientists have made incredible progress in understanding and manipulating biological systems at increasingly small scales, from protein folding to genetic engineering. And yet, the extent to which quantum effects influence living systems remains barely understood. Quantum effects are phenomena that occur between atoms and molecules that can't be explained by classical physics. It has been known for more than a century that the rules of classical mechanics, like Newton's laws of motion, break down at atomic scales. Instead, tiny objects behave according to a different set of laws known as quantum mechanics. For humans, who can only perceive the macroscopic world, or what's visible to the naked eye, quantum mechanics can seem counterintuitive and somewhat magical. Things you might not expect happen in the quantum world, like electrons 'tunneling' through tiny energy barriers and appearing on the other side unscathed, or being in two different places at the same time in a phenomenon called superposition....
