- #1
yazanhomsi
- 19
- 0
Hello everyone!
I've been having trouble regarding the age of the universe and another small problem. This problem escalated when I first started reading Dr. Brian Greene's book "The Hidden Reality". The distinction between the two possibilities, that our universe is finite or infinite, plays no role in the age of the universe. In his book, on pages 27-28, Dr. Greene states the following:
"In an infinite universe, most regions lie beyond our ability to see, even using the most powerful telescopes possible. Although light travels enormously quickly, if an object is sufficiently distant, then the light it emits - even light that may have been emitted shortly after the big bang - will simply not have had sufficient time to reach us. Since the universe is about 13.7 billion years old, you might think that anything farther away than 13.7 billion light-years would fall into this category. The reasoning behind this intuition is right on target, but the expansion of space increases the distance to objects whose light has long been traveling and has only just been received; so the maximum distance we can see is actually longer - about 41 billion light-years. But the exact numbers hardly matter. The important point is that regions of the universe beyond a certain distance are regions currently beyond our observational reach. Much as ships that have sailed beyond the horizon are not visible to someone standing on shore, astronomers say that objects in space that are too far away to be seen lie beyond our cosmic horizon."
Can someone please explain this in details for me? Like how do we know the age of the universe? We know how old it is but we do not know how far away the big bang is because our telescopes cannot see it (beyond our cosmic horizon). Since the 13.7 billion light-years now became 41 billion light-years, doesn't that mean our universe is 41 billion light-years old? I just need a detailed explanation for all of this.
Thank you so much, in advance.
I've been having trouble regarding the age of the universe and another small problem. This problem escalated when I first started reading Dr. Brian Greene's book "The Hidden Reality". The distinction between the two possibilities, that our universe is finite or infinite, plays no role in the age of the universe. In his book, on pages 27-28, Dr. Greene states the following:
"In an infinite universe, most regions lie beyond our ability to see, even using the most powerful telescopes possible. Although light travels enormously quickly, if an object is sufficiently distant, then the light it emits - even light that may have been emitted shortly after the big bang - will simply not have had sufficient time to reach us. Since the universe is about 13.7 billion years old, you might think that anything farther away than 13.7 billion light-years would fall into this category. The reasoning behind this intuition is right on target, but the expansion of space increases the distance to objects whose light has long been traveling and has only just been received; so the maximum distance we can see is actually longer - about 41 billion light-years. But the exact numbers hardly matter. The important point is that regions of the universe beyond a certain distance are regions currently beyond our observational reach. Much as ships that have sailed beyond the horizon are not visible to someone standing on shore, astronomers say that objects in space that are too far away to be seen lie beyond our cosmic horizon."
Can someone please explain this in details for me? Like how do we know the age of the universe? We know how old it is but we do not know how far away the big bang is because our telescopes cannot see it (beyond our cosmic horizon). Since the 13.7 billion light-years now became 41 billion light-years, doesn't that mean our universe is 41 billion light-years old? I just need a detailed explanation for all of this.
Thank you so much, in advance.
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