Unifying the Robertson-Walker metric

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In summary, the conversation discusses the possibility of modifying the Robertson-Walker metric to satisfy both the cosmological principle and quantum mechanics. The person being spoken to suggests that quantum field theory in a Robertson-Walker background is possible, citing Stephen Hawking's work in this subject in the 80's. They also mention Alan Guth's paper on the origins of inflation and how it relates to Hawking's work. The other person is impressed by this information and admits to wondering how cosmologists address quantum fluctuations.
  • #1
Loren Booda
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As Stephen Hawking "unified" the Schwarzschild metric, yielding Hawking radiation, could one modify the Robertson-Walker metric to satisfy most generally both the cosmological principle and quantum mechanics?
 
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  • #2
Do you mean quantum field theory in a Robertson-Walker background? This is indeed possible. Actually Hawking was one of the authorities in this subject in the 80's and he did one of the first calculations of the spectrum of perturbations (as the perturbations have their origin as quantum fluctuations in an de-Sitter expanding background). There is a very nice paper of Alan Guth in arxiv.org explaining the story about their meeting in Cambridge and how the first "predictions" of inflation came into existence (you can find it searching for hawking and birthday).
 
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  • #3
Great hellfire! Your response is richer than my own considerations. I always wondered how cosmologists dealt with quantum flutuations.
 

1. What is the Robertson-Walker metric?

The Robertson-Walker metric is a mathematical representation of the expanding universe in the framework of general relativity. It describes the geometry of the universe and how space and time are related.

2. How does the Robertson-Walker metric unify different cosmological models?

The Robertson-Walker metric unifies different cosmological models by providing a single mathematical framework for describing the universe. It is a generalization of the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric, which includes both the expanding and non-expanding universe models.

3. What are the key components of the Robertson-Walker metric?

The key components of the Robertson-Walker metric are the scale factor, which describes the expansion of the universe, and the curvature of space, which can be positive, negative, or zero. These components determine the overall geometry of the universe.

4. How does the Robertson-Walker metric account for the observed expansion of the universe?

The Robertson-Walker metric includes a term for the scale factor, which represents the expansion of the universe. This term is dependent on the density of matter and energy in the universe, and can explain the observed expansion of the universe.

5. Can the Robertson-Walker metric be used to predict the future of the universe?

Yes, the Robertson-Walker metric can be used to predict the future of the universe. By solving the equations of the metric, we can determine the evolution of the scale factor and therefore, the expansion rate of the universe. This can help us understand the fate of the universe and make predictions about its future.

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