ChatterBank1 min ago
Paradox of age and size of visible universe.
Please excuse me, this might seem to be a very convuluted question, but I think I know what I mean.
Incidentally, I am speaking in round numbers to simplify the question.
1. The edge of the visible universe is approximately 14 billion light years away.
2. The universe is approximately 14 billion years old.
I understand this to mean that the light travelling from the most distant visible object took 14 billion years to reach us. If this is the case, to calculate the age of the universe, surely you must add to this the time the object took to reach its "present" position.
Assuming that these objects did not exceed the speed of light, I see the two statements as a paradox. Can anyone explain what I am misunderstanding?
Incidentally, I am speaking in round numbers to simplify the question.
1. The edge of the visible universe is approximately 14 billion light years away.
2. The universe is approximately 14 billion years old.
I understand this to mean that the light travelling from the most distant visible object took 14 billion years to reach us. If this is the case, to calculate the age of the universe, surely you must add to this the time the object took to reach its "present" position.
Assuming that these objects did not exceed the speed of light, I see the two statements as a paradox. Can anyone explain what I am misunderstanding?
Answers
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For more on marking an answer as the "Best Answer", please visit our FAQ.There are a number of ways of measuring the age of the observable universe. One of the most used, but often revised is the use of the Hubble Constant to determine the actual expansion of the universe. The Hubble Constant is depicted as 1/Ho and currently estimated to be 72 km/sec/Megaparsec or between 12 and 14 billion years. Another way of saying it is it means is that every million years, all the distances in the universe stretch by 0.007%. The expansion of the universe is observed by the Wilkinson Microwave Anistropy Probe (WMAP). WMAP creates a picture of the microwave radiation using temperature difference measured from opposite directions (anisotropy). The radiation (observed by the snow on an untuned TV set) is believed to have originated about 400,000 years after the creation of the universe. Other determinations are made by observing white dwarf stars and other methods. While they are not in agreement, they do approximate the 12 to 14 billion (Bya) years of age.
So, long winded but neccessary way of saying the age is not dependent on your description.
As a matter of fact, though, within a few billionths of trillionths of a second following the creation event, the universe went through inflation and enlarged from the size of a beachball to well over the size of our galaxy, clearly exceeding, by magnitudes of order the speed of light... the speed continues somewhat abated, but is accelerating. The bottom line is that different pairs of galaxies are moving at different speeds with respect to each other; the further the galaxies are, the faster they move apart.
So, long winded but neccessary way of saying the age is not dependent on your description.
As a matter of fact, though, within a few billionths of trillionths of a second following the creation event, the universe went through inflation and enlarged from the size of a beachball to well over the size of our galaxy, clearly exceeding, by magnitudes of order the speed of light... the speed continues somewhat abated, but is accelerating. The bottom line is that different pairs of galaxies are moving at different speeds with respect to each other; the further the galaxies are, the faster they move apart.
You're making a common but incorrect assumption that there was once a great void and the big bang exploded into it propelling all matter through space.
In fact the big bang was the creation of space and time too not just matter.
In a very real sense these furthest objects have not moved (much) it is space that has expanded taking them with it.
The light reaching us now from them was emitted when the universe was very very much smaller.
There are lots of complicating factors like inflation but I don't think they're necessary to resolve your problem
In fact the big bang was the creation of space and time too not just matter.
In a very real sense these furthest objects have not moved (much) it is space that has expanded taking them with it.
The light reaching us now from them was emitted when the universe was very very much smaller.
There are lots of complicating factors like inflation but I don't think they're necessary to resolve your problem
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