# Small-Scale Structure of Spacetime: Bounds and Conjectures

## Abstract

This review consists of two parts. The first part establishes certain astrophysical bounds on the smoothness of classical spacetime.Some of the best bounds to date are based on the absence of vacuum Cherenkov radiation in ultrahigh-energy cosmic rays. The second part discusses possible implications of these bounds for the quantum structure of spacetime. One conjecture is that the fundamental length scale of quantum spacetime may be different from the Planck length.

- Authors:

- Institute for Theoretical Physics, University of Karlsruhe (Thailand), 76128 Karlsruhe (Germany)

- Publication Date:

- OSTI Identifier:
- 21210245

- Resource Type:
- Journal Article

- Journal Name:
- AIP Conference Proceedings

- Additional Journal Information:
- Journal Volume: 977; Journal Issue: 1; Conference: 3. Mexican meeting on mathematical and experimental physics, Mexico City (Mexico), 10-14 Sep 2007; Other Information: DOI: 10.1063/1.2902784; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ASTROPHYSICS; CHERENKOV RADIATION; COSMIC RADIATION; LORENTZ TRANSFORMATIONS; QUANTUM ELECTRODYNAMICS; QUANTUM GRAVITY; RELATIVISTIC RANGE; SPACE-TIME

### Citation Formats

```
Klinkhamer, F. R.
```*Small-Scale Structure of Spacetime: Bounds and Conjectures*. United States: N. p., 2008.
Web. doi:10.1063/1.2902784.

```
Klinkhamer, F. R.
```*Small-Scale Structure of Spacetime: Bounds and Conjectures*. United States. doi:10.1063/1.2902784.

```
Klinkhamer, F. R. Thu .
"Small-Scale Structure of Spacetime: Bounds and Conjectures". United States. doi:10.1063/1.2902784.
```

```
@article{osti_21210245,
```

title = {Small-Scale Structure of Spacetime: Bounds and Conjectures},

author = {Klinkhamer, F. R.},

abstractNote = {This review consists of two parts. The first part establishes certain astrophysical bounds on the smoothness of classical spacetime.Some of the best bounds to date are based on the absence of vacuum Cherenkov radiation in ultrahigh-energy cosmic rays. The second part discusses possible implications of these bounds for the quantum structure of spacetime. One conjecture is that the fundamental length scale of quantum spacetime may be different from the Planck length.},

doi = {10.1063/1.2902784},

journal = {AIP Conference Proceedings},

issn = {0094-243X},

number = 1,

volume = 977,

place = {United States},

year = {2008},

month = {3}

}

DOI: 10.1063/1.2902784

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