B Is spacetime a quantum error correcting code?

This is a fascinating discussion. I know some people don't want to debate this or they can't debate it but the truth doesn't care about your feelings. This isn't speculative, it's backed by Scientific research. First paper.

Is Spacetime an Error Correcting Code. Published in the Journal of High Energy Physics.

The protected “logical” quantum information is encoded in a highly entangled state of many physical qubits. The environment can't access this information if it interacts locally with the protected system.
http://theory.caltech.edu/~preskill/talks/STOC-Montreal-2017.pdf

Again, you need a vast amount of physical qubits to protect the information encoded on logical qubits. So entanglement can act like CNOT gates and quantum error correction. Here's the second paper.

Bulk Locality and Quantum Error Correction in AdS/CFT

We point out a connection between the emergence of bulk locality in AdS/CFT and the theory of quantum error correction. Bulk notions such as Bogoliubov transformations, location in the radial direction, and the holographic entropy bound all have natural CFT interpretations in the language of quantum error correction. We also show that the question of whether bulk operator reconstruction works only in the causal wedge or all the way to the extremal surface is related to the question of whether or not the quantum error correcting code realized by AdS/CFT is also a "quantum secret sharing scheme", and suggest a tensor network calculation that may settle the issue. Interestingly, the version of quantum error correction which is best suited to our analysis is the somewhat nonstandard "operator algebra quantum error correction" of Beny, Kempf, and Kribs. Our proposal gives a precise formulation of the idea of "subregion-subregion" duality in AdS/CFT, and clarifies the limits of its validity.
https://arxiv.org/abs/1411.7041

Published in the Journal of High Energy Physics.

How does quantum error correction work? You have logical qubits (encoded information) you then need a lot of physical qubits that are entangled in order to protect this information over billions of years. So if spacetime is a quantum error correcting code, you will need a lot of space and a lot of memory. It has been shown that particles have supermemory.

Non-classicality of temporal correlations

The results of space-like separated measurements are independent of distant measurement settings, a property one might call two-way no-signalling. In contrast, time-like separated measurements are only one-way no-signalling since the past is independent of the future but not vice-versa. For this reason temporal correlations that are formally identical to non-classical spatial correlations can still be modelled classically. We define non-classical temporal correlations as the ones which cannot be simulated by propagating in time a classical information content of a quantum system. We first show that temporal correlations between results of any projective quantum measurements on a qubit can be simulated classically. Then we present a sequence of POVM measurements on a single m-level quantum system that cannot be explained by propagating in time m-level classical system and using classical computers with unlimited memory.
https://arxiv.org/abs/1501.03505

Published in Physical Review Letters

This memory will be extremely helpful with CNOT gates and quantum error correction. This would mean entangles qubits can act as control and target qubits which will protect information encoded on logical bits for billions of years.

We're trying to reverse engineer with quantum computers what's already being found in nature. It makes more sense to me that we live in computational universe rather than a purely physical one. M.I.T. Professor Seth Lloyd also agrees with this.

Universe as quantum computer

This paper shows that universal quantum computers possess decoherent histories in which complex adaptive systems evolve with high probability.
https://arxiv.org/abs/quant-ph/9912088

Published in the Journal Complexity.

As you can see, these aren't speculative ideas but in growing cases the best explanation of observations. For instance a universe that has a boundary of one less dimension without gravity is a great candidate for unifying QM and classical physics.

Quantum Computation toward Quantum Gravity

The aim of this paper is to enlight the emerging relevance of Quantum Information Theory in the field of Quantum Gravity. As it was suggested by J. A. Wheeler, information theory must play a relevant role in understanding the foundations of Quantum Mechanics (the "It from bit" proposal). Here we suggest that quantum information must play a relevant role in Quantum Gravity (the "It from qubit" proposal). The conjecture is that Quantum Gravity, the theory which will reconcile Quantum Mechanics with General Relativity, can be formulated in terms of quantum bits of information (qubits) stored in space at the Planck scale. This conjecture is based on the following arguments: a) The holographic principle, b) The loop quantum gravity approach and spin networks, c) Quantum geometry and black hole entropy. Here we present the quantum version of the holographic principle by considering each pixel of area of an event horizon as a qubit. This is possible if the horizon is pierced by spin networks' edges of spin 1\2, in the superposed state of spin "up" and spin "down".
https://arxiv.org/abs/gr-qc/0008049

Published in the Journal of General Relativity and Gravitation

As a Computer Programmer, this seems to be the best explanation of observed evidence. Is there a better one?
 

DrChinese

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This is a fascinating discussion. I know some people don't want to debate this or they can't debate it but the truth doesn't care about your feelings. This isn't speculative, it's backed by Scientific research. First paper.

...
The references you supply mostly have nothing to do with the hypothesis of "Universe as a Quantum Computer".

For example, the paper "Non-classicality of temporal correlations" does not purport in any way to support your hypothesis. It is instead discussing the idea that there are parallels between non-local correlations and correlations in time. Their work is based on standard quantum theory, applied as they have. Nothing about their work in any way relates to your hypothesis, although the word "computer" is mentioned.

Your first reference is called "Is Spacetime an Error Correcting Code" but your link is to a PowerPoint presentation that is not a suitable reference here in PhysicsForums. If you are attempting to reference an actual published paper, please provide the particulars (preferably a link to the paper itself so we can read it).

Similarly, the other 2 references discuss ideas around quantum computing, but not your central idea that the universe is a quantum computer. And in fact, the concept of quantum computing as a resource is based on the idea that quantum computers might be able to accomplish things classical computers cannot.

None of which implies our universe is itself a quantum computer. It is simply a quantum world we live in. The word "computer" adds no value to that description, and there is absolutely no physical evidence whatsoever to hint otherwise.
 
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This isn't speculative, it's backed by Scientific research.
The research you reference does not support the claim you make; your claim is speculative even if the research itself is not.

Thread closed.
 

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