Several recent posts offered a solution to the Black Hole information paradox. In these posts the argument was made that the Black Hole information conundrum was a just a different version of the overall information problem associated with an expanding space time. This problem has been discussed extensively in a recent paper by Max Tegmark.
How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem
Authors: Max Tegmark (MIT)
(Submitted on 15 Aug 2011 (v1), last revised 22 Sep 2011 (this version, v2))
Abstract: We analyze cosmology assuming unitary quantum mechanics, using a tripartite partition into system, observer and environment degrees of freedom. This generalizes the second law of thermodynamics to “The system’s entropy can’t decrease unless it interacts with the observer, and it can’t increase unless it interacts with the environment.” We show that because of the long-range entanglement created by cosmological inflation, the cosmic entropy decreases exponentially rather than linearly with the number of bits of information observed, so that a given observer can reduce entropy by much more than the amount of information her brain can store. Indeed, we argue that as long as inflation has occurred in a non-neglible fraction of the volume, almost all sentient observers will find themselves in a post-inflationary low-entropy Hubble volume, and we humans have no reason to be surprised that we do as well, which solves the so-called inflationary entropy problem. An arguably worse problem for unitary cosmology involves gamma-ray-burst constraints on the “Big Snap”, a fourth cosmic doomsday scenario alongside the “Big Crunch”, “Big Chill” and “Big Rip”, where an increasingly granular nature of expanding space modifies our life-supporting laws of physics. Our tripartite framework also clarifies when it is valid to make the popular quantum gravity approximation that the Einstein tensor equals the quantum expectation value of the stress-energy tensor, and how problems with recent attempts to explain dark energy as gravitational backreaction from super-horizon scale fluctuations can be understood as a failure of this approximation.
The problem identified in the case of an expanding space time or the local inverse of this process, the formation of a Black Hole is the loss of Quantrum Unitarity. It was argued in the previous posts that the reason we have issues with Unitarity is because these processes are not Unitary in any given Decoherent history, our particular O region. It was argued that Unitarity could only be restored in the context of the Biverse , an idea posted on extensively on this list and in Vic’s popular books. (Victor Stenger)
In a serious of posts I proposed the idea that both gravity and dark energy might be the result of an imbalance in the action density of the normal and “ghost” sector of
Quantum fields vacuum Zero Point Fluctuations. This idea is related to a class of Gravity theories which see Gravity not as a fundamental force, but as a force induced by the collective action of the Quantum fields zero point vacuum fluctuations, Induced Gravity.
In this context we can think of gravity as a measurement process resulting from the loss of information across a boundary. Based on this, we can re write the Einstein Gravity Field Equations in terms of vacuum energy density. This post on this is included at the end of this.
In a series of papers, three South Korean physicists Jae-Weon Lee , Hyeong-Chan Kim and Jungjai Lee have offered a proposal remarkably similar to several of my posts on this.
Gravity as Quantum Entanglement Force
(Submitted on 24 Feb 2010)
Abstract: We conjecture that quantum entanglement of matter and vacuum in the universe tend to increase with time, like entropy, and there is an effective force called quantum entanglement force associated with this tendency. It is also suggested that gravity and dark energy are types of the quantum entanglement force, similar to Verlinde’s entropic force. If the entanglement entropy of the universe saturates the Bekenstein bound, this gives holographic dark energy with the equation of state consistent with current observational data. This connection between quantum information and gravity gives some new insights on the origin of gravity, dark energy, the holographic principle and arrow of time.
Gravity from Quantum Information
(Submitted on 29 Jan 2010 (v1), last revised 21 Mar 2010 (this version, v2))
Abstract: It is suggested that classical Einstein gravity can be derived by using the Landauer’s principle applied to an information erasure at causal horizons and Jacobson’s idea linking the Einstein equation to thermodynamics. Our result implies that gravity has a quantum informational origin.
On the Origin of Entropic Gravity and Inertia
Authors: Jae-Weon Lee
(Submitted on 23 Mar 2010 (v1), last revised 10 May 2012 (this version, v4))
Abstract: It was recently suggested that quantum field theory is not fundamental but emerges from the loss of phase space information about matter crossing causal horizons. Possible connections between this formalism and Verlinde’s entropic gravity and Jacobson’s thermodynamic gravity are proposed.
The holographic screen in Verlinde’s formalism can be identified as local Rindler horizons and its entropy as that of the bulk fields beyond the horizons. This naturally resolves some issues on entropic gravity.
The quantum fluctuation of the fields is the origin of the thermodynamic nature of entropic gravity.
It is also suggested that inertia is related to dragging Rindler horizons.
Quantum entanglement from the holographic principle
Authors: Jae-Weon Lee
(Submitted on 16 Sep 2011)
Abstract: It is suggested that quantum entanglement emerges from the holographic principle stating that all of the information of a region (bulk bits) can be described by the bits on its boundary surface. There are redundancy and information loss in the bulk bits that lead to the nonlocal correlation among the bulk bits. Quantum field theory overestimates the independent degrees of freedom in the bulk. The maximum entanglement in the universe increases as the size of the cosmic horizon and this could be related with the arrow of time and dark energy.
Obviously this is a very different way to think about gravity, hence the title of the post below. Gravity in this proposal is emergent , resulting from the entanglement of quantum fields. In essence Gravity is the result of quantum decoherence. Therefore , this proposal explains why there exist an information conundrum with black holes and the expansion of space time. These are inherently non unitary processes. However, on the global scale we can still describe physical reality as a Unitary Quantum process. The Global state is a “ Timeless Quantum” as revealed by the Wheeler De Witt equation, which is really describing the superposition of time reversed histories.