Portrait of Lord Melvyn Bragg, host of In Our Time

Dark concepts in astrophysics

In astrophysics, dark flow is a theoretical non-random component of the peculiar velocity of galaxy clusters. The actual measured velocity is the sum of the velocity predicted by Hubble's Law plus a possible small and unexplained (or dark) velocity flowing in a common direction.

2 episodes

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  1. Dark Energy

    Melvyn Bragg discusses the recently discovered, and mysteriously named, 'dark energy' which may make up 70% of the universe.

    17 March 2005

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    Featuring: Martin Rees, Carolin Crawford, Roger Penrose

     
  2. Dark matter

    Melvyn Bragg and his guests discuss dark matter, the mysterious and invisible substance that is believed to make up most of the universe.

    12 March 2015

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    Featuring: Carolin Crawford, Gresham Professor of Astronomy Carlos Frenk, Anne Green