scholarly journals SPACETIME FOAM

2002 ◽  
Vol 11 (10) ◽  
pp. 1585-1590 ◽  
Author(s):  
Y. JACK NG

Spacetime is composed of a fluctuating arrangement of bubbles or loops called spacetime foam, or quantum foam. We use the holographic principle to deduce its structure, and show that the result is consistent with gedanken experiments involving spacetime measurements. We propose to use laser-based atom interferometry techniques to look for spacetime fluctuations. Our analysis makes it clear that the physics of quantum foam is inextricably linked to that of black holes. A negative experimental result, therefore, might have non-trivial ramifications for semiclassical gravity and black hole physics.

2005 ◽  
Vol 20 (06) ◽  
pp. 1328-1335 ◽  
Author(s):  
Y. JACK NG ◽  
H. VAN DAM

Spacetime foam, also known as quantum foam, has its origin in quantum fluctuations of spacetime. Arguably it is the source of the holographic principle, which severely limits how densely information can be packed in space. Its physics is also intimately linked to that of black holes and computation. In particular, the same underlying physics is shown to govern the computational power of black hole quantum computers.


2015 ◽  
Vol 24 (12) ◽  
pp. 1544007 ◽  
Author(s):  
Shahar Hod

The holographic principle has taught us that, as far as their entropy content is concerned, black holes in (3 + 1)-dimensional curved spacetimes behave as ordinary thermodynamic systems in flat (2 + 1)-dimensional spacetimes. In this paper, we point out that the opposite behavior can also be observed in black-hole physics. To show this we study the quantum Hawking evaporation of near-extremal Reissner–Nordström (RN) black holes. We first point out that the black-hole radiation spectrum departs from the familiar radiation spectrum of genuine (3 + 1)-dimensional perfect black-body emitters. In particular, the would be black-body thermal spectrum is distorted by the curvature potential which surrounds the black-hole and effectively blocks the emission of low-energy quanta. Taking into account the energy-dependent gray-body factors which quantify the imprint of passage of the emitted radiation quanta through the black-hole curvature potential, we reveal that the (3 + 1)-dimensional black holes effectively behave as perfect black-body emitters in a flat (9 + 1)-dimensional spacetime.


2009 ◽  
Vol 24 (18n19) ◽  
pp. 3414-3425 ◽  
Author(s):  
PARTHASARATHI MAJUMDAR

The issues of holography and possible links with gauge theories in spacetime physics is discussed, in an approach quite distinct from the more restricted AdS-CFT correspondence. A particular notion of holography in the context of black hole thermodynamics is derived (rather than conjectured) from rather elementary considerations, which also leads to a criterion of thermal stability of radiant black holes, without resorting to specific classical metrics. For black holes that obey this criterion, the canonical entropy is expressed in terms of the microcanonical entropy of an Isolated Horizon which is essentially a local generalization of the very global event horizon and is a null inner boundary of spacetime, with marginal outer trapping. It is argued why degrees of freedom on this horizon must be described by a topological gauge theory. Quantizing this boundary theory leads to the microcanonical entropy of the horizon expressed in terms of an infinite series asymptotic in the cross-sectional area, with the leading 'area-law' term followed by finite, unambiguously calculable corrections arising from quantum spacetime fluctuations.


2020 ◽  
Vol 29 (14) ◽  
pp. 2030013
Author(s):  
Samir D. Mathur

Cosmology presents us with several puzzles that are related to the fundamental structure of quantum theory. We discuss three such puzzles, linking them to effects that arise in black hole physics. We speculate that puzzles in cosmology may be resolved by the vecro structure of the vacuum that resolves the information paradox and the “bags of gold” problem for black holes.


2010 ◽  
Vol 25 (34) ◽  
pp. 2859-2872 ◽  
Author(s):  
SPENTA R. WADIA

We discuss the AdS/CFT correspondence in which spacetime emerges from an interacting theory of D-branes and open strings. These ideas have a historical continuity with QCD which is an interacting theory of quarks and gluons. In particular, we review the classic case of D3 branes and the non-conformal D1 brane system. We outline by some illustrative examples the calculations that are enabled in a strongly coupled gauge theory by correspondence with dynamical horizons in semiclassical gravity in one higher dimension. We also discuss implications of the gauge fluid/gravity correspondence for the information paradox of black hole physics.


2005 ◽  
Vol 14 (12) ◽  
pp. 2257-2261 ◽  
Author(s):  
HRVOJE NIKOLIĆ

During the black hole radiation, the interior contains all the matter of the initial black hole, together with the negative energy quanta entangled with the exterior Hawking radiation. Neither the initial matter nor the negative energy quanta evaporate from the black hole interior. Therefore, the information is not lost during the radiation. The black hole mass eventually drops to zero in semiclassical gravity, but this semiclassical state has an infinite temperature and still contains all the initial matter together with the negative energy entangled with the exterior radiation.


2019 ◽  
Author(s):  
Vitaly Kuyukov

Hawking and Beckenstein’s theory of the thermodynamics of black holes indicates that there is a connection between quantum information and gravity. In general, their result is called the holographic principle. According to it, the entropy of a black hole is proportional to the area of the sphere of the event horizon. In this paper, noncommutative geometry is generalized using the holographic principle. Under certain assumptions, it is possible to obtain results from this synthesis regarding the geometry of the Minkowski space-time. To do this, we consider two main provisions for the generalization of noncommutative geometry.


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