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Could someone please explain that although we are told the universe is expanding.


Geniuscfcp
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if we see the observable universe. And watch the universe expanding ever faster. Seeing the universe 40 billion light years away. Surely the images are 40 billion light years out of date. As the images we see are how the universe was 40 billion years ago. And say it had stopped getting bigger 20 billion years ago. Surely we will have wait 20 billion years. To see the light reach our telescope. And image 40 billion light years away. Is 40 billion years out of date. Or is it could someone please explain in lamens terms. If I'm wrong. Many thanks Eddie. If they were watching us from 40 billion light years away. Surely they would see. Us as we were 40 billion years ago. I would love someone to explain if I'm wrong. 

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The universe since the beginning of the Big Bang is roughly 13.7 billion years old and thus nothing we see can have occurred more 13.7 billion years ago.

Since the universe is expanding, the light we see from distant galaxies was emitted when the galaxies were closer to us than they are now. That is, light that has been traveling toward us for 10 billion years may have originated in a galaxy that is now 40 billion light years distant from us.

The universe is believed to be roughly 93 billion light years in diameter although we can only observe things that are up to 46 billion light years away. The reason we cannot see objects further than 46 billion light years is because objects beyond that distance are receding from us at a rate greater than the speed of light (c). Since we are receding from those objects faster than light can travel, any signal coming from them will never catch up to us.

The amount of time the light takes to get to us represents how "out of date" an image is. If light from earth traveled 10 billion years to a distant star, they will see us as we were 10 billion years ago, although by then we will be much further away than 10 billion light years.

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1 hour ago, Geniuscfcp said:

if we see the observable universe. And watch the universe expanding ever faster. Seeing the universe 40 billion light years away. Surely the images are 40 billion light years out of date. As the images we see are how the universe was 40 billion years ago. And say it had stopped getting bigger 20 billion years ago. Surely we will have wait 20 billion years. To see the light reach our telescope. And image 40 billion light years away. Is 40 billion years out of date. Or is it could someone please explain in lamens terms. If I'm wrong. Many thanks Eddie. If they were watching us from 40 billion light years away. Surely they would see. Us as we were 40 billion years ago. I would love someone to explain if I'm wrong. 

Yeah, rather than distance remaining constant between most galaxies, it is actually growing as everything seperates.

Edited by Endy0816
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22 minutes ago, zapatos said:

receding from us at a rate greater than the speed of light (c). Since we are receding from those objects faster than light can travel, any signal coming from them will never catch up to us.

And explaining further (if I may 😉) that does not mean the galaxies are moving faster then light, rather it is simply due to the intervenning space expansion. And the speed of light "c" only applies to anything with mass. 

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