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xMonty
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if i ran towards the cosmic horizon (really fast) will i see it receding?
Chalnoth said:You can't "see" the horizon. The horizon is the limit of what you can see. But the horizon does change with time depending upon how you move (and even if you don't move at all with respect to the CMB).
Our vision is not actually limited by a horizon. It's limited by the cosmic microwave background. Before the CMB was emitted, the universe was opaque.xMonty said:Thanks! few more questions about the horizon
1) we can't see past the horizon cause exactly that far away things are receding at the speed of light, is this is only reason for horizon or is there something else.
That's basically correct: the horizon is set by the finite speed of light, and cannot be exceeded. Yes, if you could get to some distant place in our universe without actually traversing the distance, you would have a different horizon that would include regions which are beyond our horizon.xMonty said:2) we say we will never be able to see past the horizon is that a law or just that we will never be able to move at the speed of light so there is no hope of catching up with the stuff that disappeared into the horizon. So in principle "if" we could teleport instantly to far distances (beyond horizon) then we could explore the rest of the universe.
Chalnoth said:Our vision is not actually limited by a horizon. It's limited by the cosmic microwave background. Before the CMB was emitted, the universe was opaque.
Chalnoth said:You can't "see" the horizon. The horizon is the limit of what you can see. But the horizon does change with time depending upon how you move (and even if you don't move at all with respect to the CMB).
Just because the temperature of the CMB will continue to decrease with time doesn't change how it was emitted: before it was emitted, the universe was opaque, so that is the limit of our vision, now and forever.xMonty said:Ok but i heard CMB will dilute in the years to come so in distant future when there is negligible CMB what happens then
Chalnoth said:Just because the temperature of the CMB will continue to decrease with time doesn't change how it was emitted: before it was emitted, the universe was opaque, so that is the limit of our vision, now and forever.
Well, actually, due to the curvature of space-time, it isn't coming from that far away. The part of the CMB that we are observing now was emitted from matter that was, at the time, a mere 45 million light years away or so. But because our universe was expanding so rapidly back then, even though it started out rather close, the light had more and more space to travel across as time went on, such that it only finally reached us after some 13.7 billion years.xMonty said:confusing
So CMB is coming from about 14 Billion light years away because the big bang happened 14 b ly so after a billion years it will be 15 billion light years away from us right?
The Cosmic Horizon, also known as the observable universe, is the furthest distance that light has been able to travel since the beginning of time. It is constantly expanding and contains all known matter and energy in the universe.
The rate at which the Cosmic Horizon is expanding is known as the Hubble Constant. Currently, it is estimated to be around 73 kilometers per second per megaparsec. This means that for every 3.3 million light years, the universe is expanding by 73 kilometers per second.
No, we cannot see beyond the Cosmic Horizon because the light from objects beyond this point has not had enough time to reach us. The Cosmic Horizon acts as a sort of cosmic "wall" that prevents us from seeing what lies beyond.
The Cosmic Horizon is significant because it gives us a glimpse into the past and the early stages of the universe. By studying the light from objects at the Cosmic Horizon, we can learn more about the history and evolution of the universe.
The Cosmic Horizon is a key component of the Big Bang Theory. It is believed that the universe began with a sudden and rapid expansion, known as the Big Bang, and the Cosmic Horizon marks the edge of this expansion. As the universe continues to expand, the Cosmic Horizon will also move further away from us.