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The Question

(Submitted October 30, 2003)

In a article I saw that the size of the Universe was 18 Million LYs across after only 780,000 years. Could you explain how the Universe got so big after just a short amount of time? Is it relativistic in nature? I also saw an article that stated the Universe was a few kilometers across just microseconds after the "big Bang" occured. Could you explain this anomaly? Thank you.

The Answer

What you are referring to is called "Inflation." In an early time after the Big Bang, there is evidence that the universe expanded at speeds greater than light. But special relativity was not violated, because this was an expansion of SPACE and no matter or information was carried between two points at faster than light speed. General relativity allows inflation to be incorporated into Big Bang cosmology.

For more on this, check out these other answers on our site:

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970202.html
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/070904a.html

Amy C. Fredericks and Michael Loewenstein
for "Ask an Astrophysicist"

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