05 February 2020

On Spacetime (1975-1999)

"Our look is as bound by time-space as our brain. We never look, we never see beyond this limitation; we do not know how to look through and beyond these fragmentary frontiers. But the eyes have to see beyond them, penetrating deeply and widely, without choosing, without shelter; they have to wander beyond man-made frontiers of ideas and values and to feel beyond love. Then there is a benediction which no god can give." (Jiddu Krishnamurti," Krishnamurti's Notebook", 1976)

"According to the special theory there is a finite limit to the speed of causal chains, whereas classical causality allowed arbitrarily fast signals. Foundational studies […] soon revealed that this departure from classical causality in the special theory is intimately related to its most dramatic consequences: the relativity of simultaneity, time dilation, and length contraction. By now it had become clear that these kinematical effects are best seen as consequences of Minkowski space-time, which in turn incorporates a nonclassical theory of causal structure. However, it has not widely been recognized that the converse of this proposition is also true: the causal structure of Minkowski space-time contains within itself the entire geometry (topological and metrical structure) of Minkowski space-time." (John A. Winnie," The Causal Theory of Space-Time", 1977) 

"The structure of space-time, taken as a whole, is the subject matter of the science called cosmology. Since you are asking about all space and all time in cosmology, you are interested in the entire universe, everywhere and everywhen, viewed as a static geometrical object." (Rudolf B Rucker," Geometry, Relativity and the Fourth Dimension", 1977)

"Instead of thinking of space and time as a stage, on which the drama of matter unfolds, we have to imagine some ultra- modern theater, in which the stage itself becomes one of the actors." (John Stachel, "Einstein's Odyssey: His Journey from Special to General Relativity", 1979)

"It is unscientific to say that within the many billions of galactic systems, ours is the only planet that supports life in advanced form. Nature shuns one of a kind as much as it abhors a vacuum. Given infinite time and space, anything that occurs at one place or time in the universe will occur elsewhere or ‘elsewhen’." (Norman Cousins, "Rendezvous with Infinity", Cosmic Search Magazine Vol. 1 (1), 1979)

"No matter how finely you subdivide time and space, each tiny division contains infinity." (Frank Herbert, "Dune Genesis", 1980)

"The ‘eyes of the mind’ must be able to see in the phase space of mechanics, in the space of elementary events of probability theory, in the curved four-dimensional space-time of general relativity, in the complex infinite dimensional projective space of quantum theory. To comprehend what is visible to the ‘actual eyes’, we must understand that it is only the projection of an infinite dimensional world on the retina." (Yuri I Manin, "Mathematics and Physics", 1981)

"The quantum is that embarrassing little piece of thread that always hangs from the sweater of space-time. Pull it and the whole thing unravels." (Fred A Wolf, "Star Wave: Mind Consciousness of Quantum Physics", 1984)

"The nothingness ‘before’ the creation of the universe is the most complete void that we can imagine - no space, time, or matter existed. It is a world without place, without duration or eternity, without number - it is what mathematicians call ‘the empty set’. Yet this unthinkable void converts itself into the plenum of existence - a necessary consequence of physical laws. Where are these laws written into that void? What ‘tells’ the void that is pregnant with a possible universe? It would seem that, even the void is subject to law, a logic that exists prior to space and time." (Heinz R Pagels, "Perfect Symmetry: The Search for the Beginning of Time", 1985)

"The theory of relativity does, however, force us to change fundamentally our ideas of space and time. We must accept that time is not completely separate from and independent of space, but is combined with it to form an object called space-time." (Stephen Hawking, "A Brief History of Time: From the Big Bang to Black Holes", 1988)

"Theoretical physicists are accustomed to living in a world which is removed from tangible objects by two levels of abstraction. From tangible atoms we move by one level of abstraction to invisible fields and particles. A second level of abstraction takes us from fields and particles to the symmetry-groups by which fields and particles are related. The superstring theory takes us beyond symmetry-groups to two further levels of abstraction. The third level of abstraction is the interpretation of symmetry-groups in terms of states in ten-dimensional space-time. The fourth level is the world of the superstrings by whose dynamical behavior the states are defined." (Freeman J Dyson, "Infinite in All Directions", 1988)

“Symmetry is bound up in many of the deepest patterns of Nature, and nowadays it is fundamental to our scientific understanding of the universe. Conservation principles, such as those for energy or momentum, express a symmetry that (we believe) is possessed by the entire space-time continuum: the laws of physics are the same everywhere.” (Ian Stewart & Martin Golubitsky, “Fearful Symmetry: Is God a Geometer?”, 1992)

"Time and space are finite in extent, but they don't have any boundary or edge. They would be like the surface of the earth, but with two more dimensions." (Stephen Hawking, "Black Holes and Baby Universes and Other Essays", 1993)

"Minkowski, building on Einstein's work, had now discovered that the Universe is made of a four-dimensional ‘spacetime’ fabric that is absolute, not relative." (Kip S Thorne, "Black Holes and Time Warps: Einstein's Outrageous Legacy" , 1994)

"Arm chair reflections on the concept of causation [are] not going to yield new insights. The grandfather paradox is simply a way of pointing to the fact that if the usual laws of physics are supposed to hold true in a chronology violating spacetime, then consistency constraints emerge. [To understand these constraints] involves solving problems in physics, not armchair philosophical reflections." (John Earman, “Recent Work on Time Travel", 1995) 

"Yet everything has a beginning, everything comes to an end, and if the universe actually began in some dense explosion, thus creating time and space, so time and space are themselves destined to disappear, the measure vanishing with the measured, until with another ripple running through the primordial quantum field, something new arises from nothingness once again." (David Berlinski, "A Tour of the Calculus", 1995)

"And of course the space the wave function live in, and (therefore) the space we live in, the space in which any realistic understanding of quantum mechanics is necessarily going to depict the history of the world as playing itself out […] is configuration-space. And whatever impression we have to the contrary (whatever impression we have, say, of living in a three-dimensional space, or in a four dimensional spacetime) is somehow flatly illusory." (David Albert, "Elementary Quantum Metaphysics", 1996)

"A line normally represents space, but if we reinterpret that line as representing the passage of time, then presumably we are looking at 'shapes that repeat indefinitely along a temporal line at regular intervals'. Well, nearly. 'Shape' is the wrong word for something that exists in time. What word should we use? Let's reason it out by analogy - one of the sharpest weapons in the mathematical armoury. A shape is a (more or less) complicated collection of points in space; the temporal analogue is a complicated collection of points in time. A point in time is usually called an 'event'. So instead of 'shape' we have a 'series of events'. That is, the temporal pattern corresponding to the simplest frieze is a series of events that repeats indefinitely at regular intervals of time." (Ian Stewart, "The Magical Maze: Seeing the world through mathematical eyes", 1997)

"A single snapshot of the pattern. A fixed spiral is elegant in form, but it does not possess symmetry in the mathematical sense. However, a rotating spiral does possess a dynamic symmetry - as does any continuously rotating object. It is a symmetry that takes place in both space and time. Start with the spiral, let time pass. It rotates to a new position. Now rotate it backwards through the appropriate angle, and it looks exactly as it did to begin with. This is a space-time symmetry: translate time and rotate space. Indeed, the rotating spiral has lots of space-time symmetries, because every period of time corresponds to some spatial rotation." (Ian Stewart, "The Magical Maze: Seeing the world through mathematical eyes", 1997)

"Dynamics involves a crucial element: time. Symmetry is about shapes, which are things in space. How can symmetries apply to time? [...] We can even put both together, and look at patterns in space and time combined. Turning space into time is a typical mathematician's trick, a kind of 'technology transfer'. However, the 'technology' involved is conceptual technology - ideas - rather than gadgetry. No mathematician would ever waste a good idea by restricting it to just one incarnation. Many physically different systems possess an underlying mathematical identity: they obey rules which, in the abstract, are exactly the same - and must therefore lead to corresponding conclusions." (Ian Stewart, "The Magical Maze: Seeing the world through mathematical eyes", 1997)

"From a physical point of view, time is very different from space - and this difference is often built into mathematical systems that model the physical world. Sometimes, however, we can exploit the very general nature of mathematics, and from this point of view a spatial distance and an interval of time are simply the values of certain numerical quantities, or variables. The difference between space and time then becomes a matter of interpretation - the same underlying mathematics can have several different meanings." (Ian Stewart, "The Magical Maze: Seeing the world through mathematical eyes", 1997)

"Where did those symmetries come from? From the even more extensive set of symmetries of the (idealised) uniform state in the infinite dish. The instability of that state caused certain symmetries to be eliminated, but others persist. For target patterns, some rotations and reflections persist. For spirals, what persists is the space-time symmetries 'let time pass and then rotate back'. In a very curious sense, the patterns that we see in the spirals are evidence of other patterns that might have been - the unstable uniform state with its enormous amount of (totally boring) symmetry. They are 'caused' by something that doesn't actually happen." (Ian Stewart, "The Magical Maze: Seeing the world through mathematical eyes", 1997)

"In an infinite universe, every point in space-time is the center." (David Zindell, "War in Heaven", 1998) 

"Spacetime tells matter how to move; matter tells spacetime how to curve." (John A Wheeler, "Geons, Black Holes and Quantum Foam: A Life in Physics" , 1998) 

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