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Physics, Astronomy & Cosmology / Re: What Was The Speed Of Inflation ?
« on: Yesterday at 23:29:14 »How fast was the faster than light expansion ?Expansion isn't a speed, and hence cannot be meaningfully compared to one.
Speed has units of something list distance/time, but expansion has units of distance/time/distance.
So 300000 km/sec is a speed (c), but ~70 km/sec/megaparsec is our current expansion rate (Hubble's constant, which isn't a constant), which is different units entirely and thus cannot be compared with a speed like c.
That said, it has taken about 7 billion years to expand to where we are now from when the distances were half of what they are now. During the inflation epoch, any region of space doubled in size not every 7 billion years, but every 10-64 seconds, and it kept it up for quite a while so that the portion of what is now our visible universe grew from an indescribably small dot to about the size of a grapefruit. At that point, inflation quit and normal universe expansion took over, with nearby visible universes receding from us at more or less the same rate as they are today.
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