| Themes > Science > Astronomy > Modern Astronomy > The Copernican Model > A Sense of Time and Scale in the Universe > Expansion of the Universe |
The galaxies are all flying apart (on very large distance scales), with the velocity of recession proportional to the distance between them. The adjacent image, taken by the Wide-Field and Planetary Camera (WFPC2) of the Hubble Space Telescope, shows many galaxies billions of light years away. Most of the fuzzy patches are galaxies containing billions of stars; click on the image to get a larger version. The galaxies in this image are receding from us at high velocities. The details of this expansion are dictated by the value of the Hubble Constant. The objects furthest away from us appear to be receding at near the velocity of light. This expansion of the universe is a result of the original explosion that created the universe-the Big Bang. The Big Bang did not happen in space and in time; our modern understanding is that space and time as we presently experience them are themselves created in the Big Bang. It makes no more sense to ask what was before the Big Bang than to ask what is north of the north pole. |
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