.. _sphx_glr_api_gallery_relativity_cosmology:

Cosmology
----------

FLRW cosmic expansion and the distance-redshift relation.


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  <div id='sg-tag-list' class='sphx-glr-tag-list'></div>


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    <div class="sphx-glr-thumbnails">

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    <div class="sphx-glr-thumbcontainer" tooltip="In 1929, Edwin Hubble found that distant galaxies recede from us at a rate proportional to their distance -- direct observational evidence that the universe is expanding, exactly as Einstein&#x27;s field equations (applied to a homogeneous, isotropic universe by Friedmann and Lemaitre) had already predicted. Plugging the Friedmann-Lemaitre-Robertson-Walker metric into Einstein&#x27;s equations for a universe filled with radiation, matter, spatial curvature, and a cosmological constant \Lambda gives the Friedmann equation for the expansion rate H(a) = \dot a / a in terms of the scale factor a (normalized to a=1 today):">

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  .. image:: /api/gallery/relativity/cosmology/images/thumb/sphx_glr_plot_flrw_expansion_thumb.png
    :alt:

  :doc:`/api/gallery/relativity/cosmology/plot_flrw_expansion`

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      <div class="sphx-glr-thumbnail-title">The expanding universe: Hubble's law and the Friedmann equations</div>
    </div>


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    </div>


.. toctree::
   :hidden:

   /api/gallery/relativity/cosmology/plot_flrw_expansion