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Czl2 t1_ix71ioi wrote

Reply to comment by [deleted] in Someone tell me how the Big Bang began 13 billion years ago, yet the *observable* universe is 83 billion light years apart? by novacks0001

> Someone tell me how my friend and I began driving in opposite directions at 60 miles per hour two hours ago, yet now we’re 240 miles apart?

You are driving away from each other on the surface of a rapidly inflating balloon. Your velocity from each other needs to be added how fast the balloon surface is stretching / growing. Even if you both stop your cars you will continue moving apart due to continuing inflation.

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Ooops2278 t1_ix799i0 wrote

But if the universe's "surface" is expanding faster than light how do I observer something?

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Czl2 t1_ix7f4y6 wrote

> But if the universe's "surface" is expanding faster than light how do I observer something?

Those parts of the universe are not visible as they are now. However light travels at a finite speed and what you're looking at today is what happened when the light you see today long ago started traveling towards you.

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Ooops2278 t1_ix8hxgk wrote

Still doesn't work. If the observable parts expanded with the universe then the whole distance the light had to travel expanded. Either that expansion happens with less than light speed and the distance is impossible or it expands faster and the light wouldn't reach us.

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Czl2 t1_ix8ze2e wrote

> Either that expansion happens with less than light speed and the distance is impossible or it expands faster and the light wouldn't reach us.

You raise a good point which shows me you are starting to understand.

Consider that the rate of expansion is not constant but accelerating.

As time passes things that are ever closer to us will start to move away from us at the speed of light and what was once visible will no longer be.

The horizon at which the rate of expansion is at light speed is getting closer and closer to us:

https://www.space.com/einstein-gravity-variations-dark-energy

Your happy thought for today is that all you see and know will not end in a 'big crunch' but instead may be torn apart at the fundamental particle level in a 'big rip':

https://en.m.wikipedia.org/wiki/Big_Rip

Do not panic! This is not yet certain as 'heat death' may happen first. I believe only the 'big crunch' ending has been ruled so at least you can be happy about that.

https://en.m.wikipedia.org/wiki/Ultimate_fate_of_the_universe

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