Quantum mechanics and General Relativity overlap

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Discussion Overview

The discussion revolves around the overlap between quantum mechanics and general relativity, particularly in contexts where both theories are needed, such as near black holes. Participants explore the effectiveness of each theory across different scales and the challenges in unifying them, as well as potential connections to quantum information theory.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions the effectiveness of general relativity and quantum mechanics at different scales, seeking to understand where each theory fails or overlaps.
  • Another participant notes that both theories are required in certain situations, such as inside black holes, but emphasizes the lack of empirical data to guide the development of a unified theory of quantum gravity.
  • A third participant mentions that combining quantum theory and general relativity in scenarios like black holes leads to mathematical inconsistencies.
  • A different participant raises the possibility of a connection between quantum information theory and general relativity, suggesting that advancements in quantum information could help address the black hole information paradox.
  • This participant also inquires about the educational background that would be most beneficial for studying the overlap between these fields.

Areas of Agreement / Disagreement

Participants express a shared understanding that both quantum mechanics and general relativity are necessary in certain extreme conditions, but there is no consensus on how to reconcile the two theories or on the implications of their overlap.

Contextual Notes

The discussion highlights the lack of experimental observations in the overlapping regions of quantum mechanics and general relativity, as well as the unresolved mathematical challenges that arise when attempting to combine the two theories.

Who May Find This Useful

This discussion may be of interest to those studying theoretical physics, particularly in the fields of cosmology, quantum mechanics, and quantum information theory.

daveian
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I am not an expert on cosmology, merely an interested layman, so I hope my question is not either too stupid or obvious.
As I understand it from reading books (currently Brian Greene's "Fabric of the Cosmos"), general relativity (GR) is used for analysing large massive objects whereas quantum mechanics (QM) works for small light objects and that the 2 theories have not yet been successfully unified. But this poses a question, What about the middle ground? At what point in the spectrum from large/ massive to small/ light does GR not function and vice versa for QM. Is it sudden or gradual fall off in effectivness for either theory.
Greene refers to the centre of a black hole (massive and tiny) where both GR and QM are needed but can't be used because they don't fit together.
 
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Yes, there are situations where you need both quantum mechanics and gravity. We have no experiments or observations that probe those situations. If we had empirical information about such situations, it would be a lot easier to construct a theory of quantum gravity.
 
When both quantum theory and general relativity are both needed (for exasmple inside a black hole) it ends up with mathematical nonsense.
 
I was wondering, is there any overlap between Quantum Information Theory and General Relativity? The black hole information paradox could be solved by devoloping knowledge about quantum information in strong gravitational field?

If someone wants to study this overlap between these 2 differentes areas of physics, what would be better: having a PhD in Quantum Information Theory or in Cosmology?

thanks for the help
 

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