934 citations · 3.5k across the 98 of their papers we have counts for
49 papers · 1 filter
Slowly Rotating Relativistic Stars: VII. Gravitational Radiation from the Quasi-Radial Modes
James B. Hartle, Kip S. Thorne
When a relativistic star rotates slowly and rigidly, centrifugal forces flatten it slightly, thereby catalyzing a small admixture of quadrupolar vibration into its radial modes and…
Simplicial Quantum Gravity
James B. Hartle
Simplicial approximation and the ideas associated with the Regge calculus.provide a concrete way of implementing a sum over histories formulation ofquantum gravity. A four-dimensio…
Prediction in Quantum Cosmology
James B. Hartle
Lectures by the author at the 1986 Cargese summer school modestly corrected and uploaded for greater accessibility. Some of the author's views on the quantum mechanics of cosmology…
A Measure of Classicality
James B. Hartle, Murray Gell-Mann
A striking feature of our fundamentally indeterministic quantum universe is its quasiclassical realm -- the wide range of time place and scale in which the deterministic laws of cl…
Classical Physics and Hamiltonian Quantum Mechanics as Relics of the Big Bang
James B. Hartle
In a fundamental formulation of the quantum mechanics of a closed system such as the universe as a whole, three forms of information are needed to make predictions for the probabil…
The Conformal Rotation in Linearised Gravity
James B. Hartle, Kristen Schleich
We consider the quantum mechanics of Einstein gravity linearised about flat spacetime. The two transverse-traceless components of the metric perturbation are the true physical degr…
Arrows of Time and Initial and Final Conditions in the Quantum Mechanics of Closed Systems Like the Universe
James B. Hartle
A model quantum cosmology is used to illustrate how arrows of time emerge in a universe governed by a time-neutral dynamical theory constrained by time asymmetric initial and final…
How Nature is Conformable to Herself: A View from Quantum Cosmology
James B. Hartle
In his essay "Nature Conformable to Herself" the late Murray Gell-Mann expands on an observation of Newton that theories of seemingly disparate phenomena in the universe often make…
The Impact of Cosmology on Quantum Mechanics
James B. Hartle
When quantum mechanics was developed in the '20s of the last century another revolution in physics was just starting. It began with the discovery that the universe is expanding. Fo…
Computability and Physical Theories
Robert Geroch, James B. Hartle
The familiar theories of physics have the feature that the application of the theory to make predictions in specific circumstances can be done by means of an algorithm. We propose…
The Quantum Mechanics of Cosmology
James B. Hartle
Notes from the lectures by the author at the 7th Jerusalem Winter School 1990 on Quantum Cosmology and Baby Universes. The lectures covered quantum mechanics for closed systems lik…
Damped perturbations in the no-boundary state
Juan Diaz Dorronsoro, Jonathan J. Halliwell, James B. Hartle +3
We evaluate the no-boundary path integral exactly in a Bianchi IX minisuperspace with two scale factors. In this model the no-boundary proposal can be implemented by requiring one…
Quantum Mechanics in the Light of Quantum Cosmology
Murray Gell-Mann, James B. Hartle
We sketch a quantum mechanical framework for the universe as a whole. Within that framework we propose a program for describing the ultimate origin in quantum cosmology of the quas…
Quantum Multiverses
James B. Hartle
A quantum theory of the universe consists of a theory of its quantum dynamics and a theory of its quantum state The theory predicts quantum multiverses in the form of decoherent se…
The Real No-Boundary Wave Function in Lorentzian Quantum Cosmology
Juan Diaz Dorronsoro, Jonathan J. Halliwell, James B. Hartle +2
It is shown that the standard no-boundary wave function has a natural expression in terms of a Lorentzian path integral with its contour defined by Picard-Lefschetz theory. The wav…
Why Our Universe is Comprehensible
James B. Hartle
Einstein wrote memorably that `The eternally incomprehensible thing about the world is its comprehensibility.' This paper argues that the universe must be comprehensible at some le…
The Observer Strikes Back
James Hartle, Thomas Hertog
In the modern quantum mechanics of cosmology observers are physical systems within the universe. They have no preferred role in the formulation of the theory nor in its predictions…
Generalizing Quantum Mechanics for Quantum Spacetime
James B. Hartle
Familiar textbook quantum mechanics assumes a fixed background spacetime to define states on spacelike surfaces and their unitary evolution between them. Quantum theory has changed…
Excess Baggage
James B. Hartle
Many advances in physics have in common that some idea which was previously accepted as fundamental, general, and inescapable was subsequently seen to be consequent, special, and d…
General Relativity in the Undergraduate Physics Curriculum
James B. Hartle
Einstein's general relativity is increasingly important in contemporary physics on the frontiers of both the very largest distance scales (astrophysics and cosmology) and the very…
Anthropic Reasoning and Quantum Cosmology
James B. Hartle
Prediction in quantum cosmology requires a specification of the universe's quantum dynamics and its quantum state. We expect only a few general features of the universe to be predi…
The Physics of 'Now'
James B. Hartle
The world is four-dimensional according to fundamental physics, governed by basic laws that operate in a spacetime that has no unique division into space and time. Yet our subjecti…
Generalized Quantum Theory of Recollapsing Homogeneous Cosmologies
David Craig, James B. Hartle
A sum-over-histories generalized quantum theory is developed for homogeneous minisuperspace type A Bianchi cosmological models, focussing on the particular example of the classical…
Theories of Everything and Hawking's Wave Function of the Universe
James B. Hartle
If a cat, a cannonball, and an economics textbook are all dropped from the same height, they fall to the ground with exactly the same acceleration under the influence of gravity. T…