We can write the Minkowski metric as(adsbygoogle = window.adsbygoogle || []).push({});

[tex]ds^2 = -c^2dt^2 + d\mathbf{x}^2[/tex]

or if we wanted different units for the metric

[tex]ds^2 = -dt^2 + \frac{d\mathbf{x}^2}{c^2}[/tex]

If we make c a function of time we have

[tex]ds^2 = -dt^2 + \frac{d\mathbf{x}^2}{c(t)^2}[/tex]

Which looks exactly like the FRW metric where c(t) = 1/a(t). So two questions: is my logic here correct? and if so, is it possible to tell the difference, in a purely gravitational way, between an FRW universe and a Minkowski universe with variable speed of light?

**Physics Forums - The Fusion of Science and Community**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Random thought

Loading...

Similar Threads - Random thought | Date |
---|---|

B The universe is shrunk a little bit more than we thought | Aug 24, 2016 |

Random Walk Question re Inflation | Sep 30, 2015 |

Randomness and the life cycle of events of our Universe | Jul 17, 2013 |

Gaussian random fields | Apr 19, 2013 |

Amount of dark matter present random or does it correlate w/ cluster characteristics | Aug 25, 2012 |

**Physics Forums - The Fusion of Science and Community**