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Varlex t1_iue7brl wrote

>I know as a fact that the expansion of space is faster than the speed of light. But how do we know that?

That's not fully true. The expansion of the universe scales up with distance.

Current measurement of hubble constant is 68 - 74 km/s/Mpc.

That means, a object in a distance of 1Mpc "move away" by 68-74 km/s. ==> For objects next to us it's less, for objects far away it's more.

Next, there is a event horizon, when the distance is so large, that the expansion is larger in distance per seconds then 300000km/s (light speed). For Objects behind this event horizon, light can't go to earth and we don't get any new information.

For your second question and why is the (visible) universe 93 billion lightyears in diameter and just 14 billion years old.

Same reason, in the beginning the (visible) universe was much smaller. An object send out photons. This photons "travel" in our direction. Because the universe expand, the way between object and our location increase. When the light is measured on earth, the object is much more far away, when the photon was send out.

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rE3eYul t1_iuewo39 wrote

but wouldnt those objects that travel faster then light being on the edge of the expansion be physical , i.e be made of mater , how about relativity ?

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Varlex t1_iuey1gr wrote

They don't travel faster then light. The room between expend.

It's like you stretch slowly a rubber band. The distance between ends of the band increase faster then somewhere in the middle.

The expansion of the universe don't interfere SRT or ART. Lightspeed is still lightspeed, but when expansion is bigger then 300k km/s, the light can't brigde over the whole way.

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Tatti_luck OP t1_iugcc6u wrote

I understand that the light traveling to us would be what it was years ago compared to their current relative position. But how do we know that currently position is much further than we are viewing? Would we be seeing the increase in distance in real time?

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Varlex t1_iuh34kr wrote

It's the red shift.

There are 2 models for light: particles and wave. Both are equal and correct.

Because room is expending, the wave length increase. Depending how much it increase we can calculate how long it's needed and can calculate the different distances with this information.

(It's like the Doppler effect with sound)

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