Time is an Illusion, says physicist Carlo Rovelli
Physicists calling time an illusion is not a new idea. Julian Barbour, in his 1999 book argued for the same hypothesis. Contrary to this idea, physicist Lee Smolin proposed that time is real. He suggested that laws of physics are not fixed in the universe but evolve over time. The principle argument in support of his theory is that mathematical models provide an abstraction of reality and ignore time dimension. Carlo Rovelli observes that since theory of general relativity assumes spacetime is smooth and continuous, and quantum theory describes matter and energy in discrete quantities which implies that spacetime is also quantized. i.e. they exist in discrete quanta. These two realities are unconnected because quantum physics cannot deal with the continuous spacetime, and general relativity cannot reconcile with quantization of space and time. In fact, space, time and gravity are suggested as emergent properties of a system. Emergent properties are not identical with, reducible to, or deducible from the other physical properties. Examples include, temperature, pressure, viscosity, spacetime and gravity. Therefore, the author concludes that Isaac Newton’s picture of a universally ticking clock, and Albert Einstein’s relativistic space-time that bends so that local times differ depending on one’s relative speed or proximity to a mass is an over simplification. According to Rovelli, the time; the sequences of past, present and future is an emergent phenomenon of thermodynamics.
One of the principal arguments Rovelli advances is the Wheeler-De Witt equation which describes quantum gravity, but it has no time variable associated with it. Quantum mechanics and general relativity, taken together, imply the possibility of quantum superposition of different spacetimes. But the Wheeler-de Witt equation, which is based on a wave function Ψ[q] over geometries offers new perspectives.
In this book, Rovelli often muses about metaphysics, poetry and spirituality but fails to convince the reader that his idea is on the right track. It reminds me of Einstein’s famous saying that “God does not play dice,” Which makes me believe that if time is an illusion, then space would also be an illusion. There is a beauty and symmetry in the universe, and time alone could not be an illusion without space. Elon Musk, founder of SpaceX and Mars explorer suggest that this universe is a computer simulation on someone’s computer. And black hole physics suggests that the information in 3D world could be described in 2D dimension, in fact reality is a hologram. In quantum reality, the wave functions of a reality must be collapsed by physical observation (conscious observers), until then the reality is smeared out in spacetime. In fact, reality is in the eyes of beholder. Taken together, reality of matter and energy in spacetime could be an illusion (Maya), as interpreted by the Vedanta School of Hindu philosophy.
Tuesday, May 8, 2018
Thursday, May 3, 2018
Book Reviewed: Before Time Began: The Big Bang and the Emerging Universe, by Helmut Satz
Cosmos and emerging realities
In this book, the author discusses as how different horizons, on Earth and in the heavens define our perception of physical reality. This book is not meant to give a systematic presentation of recent developments in cosmology but discusses with an emphasis on emerging realities such as gravity in terms of laws thermodynamics.
Emergent phenomenon contrasts with reductionism. A new outcome such as gravity from space and time is different from spacetime. Two basic approaches have dominated physics and cosmology; the reduction approach to divide and subdivide matter to its most fundamental particles governed by its quantum nature, and building and extensions of quantum particles into stars, galaxies, universe and multiverse according relativistic physics. Thermodynamics is a framework that describes how very large numbers of individual constituent particles behave. Since then, physicists have tried to figure out whether this similarity of relativity and thermodynamics is a formal coincidence or hints of a deeper truth. Because space-time is made of small elements whose collective motion gives rise to the force we call gravity. In this case, gravity would not be a truly fundamental phenomenon, but an emergent one like temperature, pressure, and viscosity. The microscopic constituents of space-time push inwards on matter and this pulls normal matter in by its gravitational attraction. In the thermodynamic formulation of gravity, the entropy is the number of possible microscopic configurations. Entropic gravity, also known as emergent gravity is an entropic force, a force with macro-scale homogeneity but which is subject to quantum-level disorder, and not as a fundamental interaction. This theory is based on string theory, black hole physics, and quantum information theory describes gravity springs from the quantum entanglement of small bits of spacetime information.
Entropy is really about the level of information we need to describe a system. An ordered system (say, marbles evenly spaced in a grid) is easy to describe because the objects have simple relations to each other. On the other hand, a disordered system (marbles randomly scattered) take more information to describe, because there isn’t a simple pattern to them. So, when the second law says that entropy can never decrease, it is to say that the physical information of a system cannot decrease. In other words, information cannot be destroyed.
Considering infinite space, there is a growing acceptance among physicists that we live in multiverse and our existence is a part of space with eternal inflation which is creating billions of parallel universes. According to Stephen Hawking’s last paper, the evidence of the multiverse exists in cosmic microwave background (CMB) radiation.
The last chapter, entitled “The Last Veil,” the author presents an interesting discussion of space and time and its cosmic connections. The introductory part of the book briefly discusses the cosmos according to the two major schools of Hindu philosophy, and the Greek natural philosophy. Highly readable and very energizing book.
In this book, the author discusses as how different horizons, on Earth and in the heavens define our perception of physical reality. This book is not meant to give a systematic presentation of recent developments in cosmology but discusses with an emphasis on emerging realities such as gravity in terms of laws thermodynamics.
Emergent phenomenon contrasts with reductionism. A new outcome such as gravity from space and time is different from spacetime. Two basic approaches have dominated physics and cosmology; the reduction approach to divide and subdivide matter to its most fundamental particles governed by its quantum nature, and building and extensions of quantum particles into stars, galaxies, universe and multiverse according relativistic physics. Thermodynamics is a framework that describes how very large numbers of individual constituent particles behave. Since then, physicists have tried to figure out whether this similarity of relativity and thermodynamics is a formal coincidence or hints of a deeper truth. Because space-time is made of small elements whose collective motion gives rise to the force we call gravity. In this case, gravity would not be a truly fundamental phenomenon, but an emergent one like temperature, pressure, and viscosity. The microscopic constituents of space-time push inwards on matter and this pulls normal matter in by its gravitational attraction. In the thermodynamic formulation of gravity, the entropy is the number of possible microscopic configurations. Entropic gravity, also known as emergent gravity is an entropic force, a force with macro-scale homogeneity but which is subject to quantum-level disorder, and not as a fundamental interaction. This theory is based on string theory, black hole physics, and quantum information theory describes gravity springs from the quantum entanglement of small bits of spacetime information.
Entropy is really about the level of information we need to describe a system. An ordered system (say, marbles evenly spaced in a grid) is easy to describe because the objects have simple relations to each other. On the other hand, a disordered system (marbles randomly scattered) take more information to describe, because there isn’t a simple pattern to them. So, when the second law says that entropy can never decrease, it is to say that the physical information of a system cannot decrease. In other words, information cannot be destroyed.
Considering infinite space, there is a growing acceptance among physicists that we live in multiverse and our existence is a part of space with eternal inflation which is creating billions of parallel universes. According to Stephen Hawking’s last paper, the evidence of the multiverse exists in cosmic microwave background (CMB) radiation.
The last chapter, entitled “The Last Veil,” the author presents an interesting discussion of space and time and its cosmic connections. The introductory part of the book briefly discusses the cosmos according to the two major schools of Hindu philosophy, and the Greek natural philosophy. Highly readable and very energizing book.
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