Year: 2022

DERIVATIVES. “Physics abounds with examples of definitional extension, provided that the derived theory is conceived narrowly enough that it does not have properties, explanatory resources etc. that ‘ride free’ of the deriving theory, and so block the derivation.” https://lnkd.in/dMm_YkR View in LinkedIn

VICTIM OF ITS OWN SUCCESS. “It should be admitted from the outset, that the subject of quantum gravity is exceptionally difficult and problematic, both in regard to mathematical and to conceptual issues. Furthermore, these problems are compounded by the almost complete lack of any unequivocal data to guide attempts to construct such a theory. In this sense, twentieth-century physics is a victim of its own success: the empirical success of general relativity and quantum theory in their present forms means that we lack data bearing on how we might reconcile them (or more generally, replace them).” https://lnkd.in/dMm_YkR View in LinkedIn

SMALLEST LENGTH. “Quantum gravity effects should be important at about a length-scale called the ‘Planck length’.” https://lnkd.in/dMm_YkR View in LinkedIn

PLANCK UNITS. “The value of the Planck length is around 10(-33) cm, which is truly miniscule: the diameters of an atom, nucleus, proton and quark are, respectively, about 10(-8), 10(-12), 10(-13), and 10(-16) cm. So the Planck length is as many orders of magnitude from the (upper limit for) the diameter of a quark, as that diameter is from our familiar scale of a centimetre! The same point can also be made in regard to the other so-called ‘Planck scales’: the Planck time, the Planck energy, and the Planck temperature.” https://lnkd.in/dMm_YkR View in LinkedIn

THE END OF SPACE AND TIME. “These characterize physical regimes at which quantum gravity effects are expected to be important, and—perhaps—where the continuum picture of space and time breaks down. Like the Planck length, their values are such that they are empirically inaccessible except in the very early universe. For example, the Planck time LT is about 10(-42) seconds, and the Planck energy is 10(19) GeV.” https://lnkd.in/dMm_YkR View in LinkedIn

BRAIN SENSORS DECODE THOUGHT. “A man paralyzed from the neck down for almost a decade has used his mind to compose whole sentences in real-time.” https://lnkd.in/dgcGRaf View in LinkedIn

Palau de Musica in Barcelona is a candy box, simply rediculously beautiful. And it was built in just three years. View in LinkedIn

THE CONFLICT. “The central task of quantum gravity is to reconcile two of the main pillars of twentieth-century theoretical physics: general relativity and quantum theory. However, these two theories are disparate in significant ways, and they need to be reconciled.” https://lnkd.in/dMm_YkR View in LinkedIn

“GENERAL RELATIVITY is a classical theory of gravity, but—unlike all other classical theories—it does not work within the framework of a fixed space and time, but is rather a theory of space and time. Specifically, general relativity employs a continuous spacetime manifold, endowed with a spacetime metric that determines the spatial lengths and times elapsed along curves in the manifold.” https://lnkd.in/dMm_YkR View in LinkedIn

“QUANTUM THEORY is not a theory per se but is rather a certain mathematical and conceptual framework within which specific theories are constructed. Typically, these deal with various kinds of matter and the forces they exert on each other, including the fundamental forces other than gravity: the electromagnetic, weak and strong forces. “ https://lnkd.in/dMm_YkR View in LinkedIn