Physics, Astronomy & Cosmology / Re: How can Dark Energy make the Universe expand at faster than light speed?« on: 26/02/2018 20:00:20 »
Quote from: Azhar
I feel like the language used to describe this seemingly contradictory nature of things is a bit confusing for a layman like myself.An analogy often used to describe the expansion of the universe is to imagine that the galaxies are like little dots on the surface of a balloon. As you inflate the balloon, the dots move away from each other - but the dots are still where you originally put them.
And the dots that were originally farther apart are moving away from each other faster than dots that are nearby.
Like all analogies, it has severe limitations (like the surface of a balloon is 2-dimensional, while our familiar space is 3-dimensional), But if you imagine that light travels at a finite speed across the balloon surface, there is a certain distance beyond which light from these galaxy dots will never reach us, because they are expanding away from us faster than light can travel.
For a more in-depth introduction, see: https://en.wikipedia.org/wiki/Metric_expansion_of_space
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