How and Why could Expansion of Space/Time Exceed the Speed of Light?

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Offline @/antic

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Hi everyone

I was just thinking:

At a certain point in its history, the universe was expanding faster than the speed of light.
So, all the particles and cosmic objects within it must have been moving along with this expanding space/time at faster than the speed of light, right?

So, how and why was that possible ?



Offline acecharly

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This is not exactly how it sounds...

When we say an object has motion, we’re referring to its change in position relative to the space-time grid. The speed of light is only a constraint for objects that exist within space-time, not for space-time itself. :)



Offline JP

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As an example of what Ace is saying, imagine you have an ant walking on the surface of a balloon.  The ant has a top speed limit its legs will carry it, which is like the speed of light.  The expansion of the universe is like blowing up the balloon. 

If the ant is running at top speed from point A to point B while you blow up the balloon, point A appears to recede from it faster than top speed.  However, if the ant looks down at its feet, it will notice that it is still moving at top speed with respect to the part of the balloon directly beneath its feet.  So the ant's top speed is the same, but the balloon itself is growing which can make things move away from the ant faster than its top speed.