Physics:Quantum spacetime foam
Quantum spacetime foam is the idea that spacetime geometry may fluctuate strongly at extremely small distances, especially near the Planck scale. The phrase is associated with the expectation that quantum uncertainty applied to geometry could make spacetime appear smooth only after averaging over microscopic fluctuations.[1][2]
Concept
In ordinary general relativity, spacetime is represented by a smooth geometry. Spacetime-foam ideas question whether that smooth geometry remains meaningful at the shortest scales when quantum fluctuations of the gravitational field are included.[3]
Relation to quantum gravity
Different quantum-gravity approaches describe microscopic geometry in different ways. Some emphasize discrete spectra, causal structure, path integrals over geometries, or emergent spacetime rather than literal foam.
Observable challenge
Directly testing spacetime foam is difficult because Planck-scale effects are extremely small at accessible energies. Proposed searches often look for cumulative effects in high-energy photons, interferometry, or early-universe signatures.
See also
Table of contents (84 articles)
Index
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References
- ↑ "Quantum foam". https://en.wikipedia.org/wiki/Quantum_foam.
- ↑ Rovelli, Carlo (2004). Quantum Gravity. Cambridge University Press. ISBN 978-0-521-83733-0.
- ↑ "Quantum foam". https://en.wikipedia.org/wiki/Quantum_foam.
Source attribution: Physics:Quantum spacetime foam