Science in a Very Large Universe

@article{Srednicki2021ScienceIA,
  title={Science in a Very Large Universe},
  author={Mark Allen Srednicki and James B. Hartle},
  journal={The Quantum Universe},
  year={2021}
}
As observers of the universe we are quantum physical systems within it. If the universe is very large in space and/or time, the probability becomes significant that the data on which we base predictions is replicated at other locations in spacetime. The physical conditions at these locations that are not specified by the data may differ. Predictions of our future observations therefore require an assumed probability distribution (the xerographic distribution) for our location among the possible… 
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19 Citations
Highly Influential Citations
2
Background Citations
12
Methods Citations
4

19 Citations

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References

SHOWING 1-10 OF 16 REFERENCES

The Xerographic Distribution: Scientific Reasoning in a Large Universe

As observers of the universe we are physical systems within it. If the universe is very large in space and/or time, the probability becomes significant that the data on which we base predictions is…

Is our universe decaying at an astronomical rate

Replication regulates volume weighting in quantum cosmology

Probabilities for observations in cosmology are conditioned both on the Universe's quantum state and on local data specifying the observational situation. We show the quantum state defines a measure…

No-boundary measure of the universe.

The no-boundary proposal for homogeneous isotropic closed universes with a cosmological constant and a scalar field with a quadratic potential predicts classical behavior at late times if the scalarField is large enough.

Insufficiency of the quantum state for deducing observational probabilities

The Born rule fails in cosmology

The Born rule may be stated mathematically as the rule that probabilities in quantum theory are expectation values of a complete orthogonal set of projection operators. This rule works for single…

The Quasiclassical Realms of This Quantum Universe

  • J. Hartle
  • Physics, Philosophy
    The Quantum Universe
  • 2021
The most striking observable feature of our indeterministic quantum universe is the wide range of time, place, and scale on which the deterministic laws of classical physics hold to an excellent…

Can the universe afford inflation

Cosmic inflation is envisioned as the 'most likely' start for the observed universe. To give substance to this claim, a framework is needed in which inflation can compete with other scenarios and the…

Boltzmann babies in the proper time measure

After commenting briefly on the role of the typicality assumption in science, we advocate a phenomenological approach to the cosmological measure problem. Like any other theory, a measure should be…

Properties of the scale factor measure

We show that in expanding regions, the scale factor measure can be reformulated as a local measure: Observations are weighted by integrating their physical density along a geodesic that starts in the…