1,630 research outputs found
Black Hole Evaporation Entails an Objective Passage of Time
Time's apparent passage has long been debated by philosophers, with no
decisive argument for or against its objective existence. In this paper we show
that introducing the issue of determinism gives the debate a new, empirical
twist. We prove that any theory that states that the basic laws of physics are
time-symmetric must be strictly deterministic. It is only determinism that
enables time reversal, whether theoretical or experimental, of
anyentropy-increasing process. A contradiction therefore arises between
Hawking's argument that physical law is time-symmetric and his controversial
claim that black-hole evaporation introduces a fundamental unpredictability
into the physical world. The latter claim forcibly entails an intrinsic
time-arrow independent of boundary conditions. A simulation of a simple system
under time reversal shows how an intrinsic time arrow re-emerges, destroying
the time reversal, when even the slightest failure of determinism occurs. This
proof is then extended to the classical behavior of black holes. We conclude
with pointing out the affinity between time's arrow and its apparent passage.Comment: 15 pages, 3 figure
Time-Reversed EPR and the Choice of Histories in Quantum Mechanics
When a single photon is split by a beam splitter, its two `halves' can
entangle two distant atoms into an EPR pair. We discuss a time-reversed
analogue of this experiment where two distant sources cooperate so as to emit a
single photon. The two `half photons,' having interacted with two atoms, can
entangle these atoms into an EPR pair once they are detected as a single
photon. Entanglement occurs by creating indistinguishabilility between the two
mutually exclusive histories of the photon. This indistinguishabilility can be
created either at the end of the two histories (by `erasing' the single
photon's path) or at their beginning (by `erasing' the two atoms' positions).Comment: 6 pages, 5 figures. Presented at the Solvay Conference in Physics,
November 2001, Delphi, Greece. To be published in Quantum Computers and
Computing, 2002 and in the Proceedings of XXII Solvay Conference in Physics.
New York: World Scientific, 200
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