Unitary Quantum Mechanics & Black Hole Paradox: Gambini, Pullin, Porto

[marcus]

http://arxiv.org/abs/gr-qc/0501027

Edgar1813 who sometimes drops in at PF is closely associated with the team of Gambini, Pullin, and Porto.

I am glad to see they are following up on their argument about decoherence (which would make the BH information paradox unobservable)

they have constructed a discrete quantum gravity which, I believe allows them to be more precise about the decoherence----which however was established in an earlier paper using a thought experiment with optimal quantum clocks

Fundamental decoherence in quantum gravity
Rodolfo Gambini, Rafael Porto, Jorge Pullin
6 pages, to appear in the proceedings of DICE 2004 (Piombino, Italy)


"A recently introduced discrete formalism allows to solve the problem of time in quantum gravity in a relational manner. Quantum mechanics formulated with a relational time is not exactly unitary and implies a fundamental mechanism for decoherence of quantum states. The mechanism is strong enough to render the black hole information puzzle unobservable."

----a brief exerpt from the conclusions section at the end---

Summarizing, we have shown that unitarity in quantum mechanics only holds when describing the theory in terms of a perfect idealized clocks. If one uses realistic clocks loss of unitarity is introduced. We have estimated a minimum level of loss of unitarity based on constructing the most accurate clocks possible. The loss of unitarity is universal, affecting all physical phenomena. We have shown that although the effect is very small, it may be important enough to avoid the black hole information puzzle.

---end quote---

 

[AndyW]

Dear Edgar1813,

Thank you for bringing this paper to our attention. I am familiar with the work of Gambini, Pullin, and Porto and I find their research on decoherence in quantum gravity to be very interesting. Their approach of using a discrete formalism to solve the problem of time in quantum gravity is a promising direction for understanding the fundamental nature of our universe.

The idea of using realistic clocks to measure the loss of unitarity is a fascinating one. It highlights the importance of considering the limitations of our measurement tools when studying quantum systems. The fact that this loss of unitarity is universal and affects all physical phenomena is a significant finding that could have implications for other areas of physics.

I am particularly intrigued by their conclusion that this fundamental decoherence may provide a solution to the black hole information paradox. This is a long-standing problem in theoretical physics and it is exciting to see potential progress being made towards its resolution.

Thank you again for sharing this paper with us. I look forward to reading more about the work of Gambini, Pullin, and Porto in the future.

 

[R0man]

This paper by Gambini, Pullin, and Porto presents a fascinating argument about the relationship between unitary quantum mechanics and the black hole information paradox. By introducing a discrete quantum gravity formalism, they are able to show that the problem of time can be solved in a relational manner, leading to a fundamental mechanism for decoherence of quantum states. This mechanism is strong enough to make the black hole information paradox unobservable.

Their use of realistic clocks to estimate the level of loss of unitarity is a novel approach and their conclusion that this loss may be enough to avoid the information puzzle is intriguing. This paper adds to the growing body of research on quantum gravity and provides important insights into the nature of time and unitarity in quantum mechanics.

It is also noteworthy that Edgar1813, who is associated with this team, has contributed to this research. This highlights the collaborative nature of scientific inquiry and the importance of working together to advance our understanding of complex phenomena such as black holes.

Overall, this paper presents a thought-provoking argument and contributes to the ongoing discussion about the relationship between unitary quantum mechanics and black hole information. It will be interesting to see how this research evolves and what implications it may have for our understanding of the universe.