angech says:
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July 20, 2022 at 6:35 am
izen says: July 18, 2022 at 2:16 pm
“One is the comment that we can see galaxies 13.8 billion years ago.
No one explains how the further out we look we find galaxies and stars That we compare to our own even though they have not existed as such for 13.8 billion years.”
The universe is much larger than 13.8 billion years across due to space expansion, the most recent estimate I have seen is around 95 billion light years.”
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Size of the visible universe is partly dependent on how good our “optics” are.
If something is out there 14.2 billion light years away we probably would not see [detect ]it with our current science.
As DM said “How bright would a mega star have to be”.
Even other universes from other big bangs [if we consider our “universe” to have a single origin would be hard pressed to trouble the cosmic microwave background radiation let alone be seen.
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The size of the visible universe is thus only double the 13.8 billion years, 27.6 billion years.
Since it has been expanding at less than the speed of light [caveat] the actual universe would be only perhaps 54 billion years old at the moment.
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“The universe is around 95 billion light years across.” is an estimate based on maths and physics theories and until everyone agrees on those we might be better sticking to the speed of light time and distance observations.
Thank you for putting it and the concept up.
The big bang itself had so much matter and energy that our current concepts of time and the speed of light back then go out the window.
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angech says:
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July 20, 2022 at 6:56 am
…and Then There’s Physics says: July 18, 2022 at 7:29 am
“As I understand it, the galaxies in the galaxy cluster that was imaged by JWST were about 4.6 billion years old”.
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The articles being written by journalists seem to be conflating such galaxies with the concept of being able to look back a lot further in time.
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The original hot explosion or event being that long ago that the first clumps of plasma for want of a better word were supposed to form mega stars of very short life span which threw out clumps of matter [including some heavier elements than H, He] to form the original galaxies which were also very large [hence visible faintly] and then possibly another two iterations to get to our young star and young galaxy.
The materials greater than iron on the periodic table, gold being the best example, are thought to have come from arcane processes in past supernovae.
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It is hard to imagine our sun being the remnant of a 13.8 billion year chunk of hop plasma cooling down over that length of time.
Further such explosions cause escape speed velocities which mean that the galaxies should never have come back together.
–
An alternative view is that space was filled with large amounts of cooled down matter in waves of explosions that crossed each other causing focal points of reaccumulation resulting in newer smaller galaxies.
This would explain suns forming from gigantic masses of cold hydrogen, etc hitting or passing through each other leaving focal eddies of matter which could then coalesce to form suns and planets.
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and how elliptical orbits of planets and stars can come into being.
Your comment is awaiting moderation.
July 20, 2022 at 6:35 am
izen says: July 18, 2022 at 2:16 pm
“One is the comment that we can see galaxies 13.8 billion years ago.
No one explains how the further out we look we find galaxies and stars That we compare to our own even though they have not existed as such for 13.8 billion years.”
The universe is much larger than 13.8 billion years across due to space expansion, the most recent estimate I have seen is around 95 billion light years.”
–
Size of the visible universe is partly dependent on how good our “optics” are.
If something is out there 14.2 billion light years away we probably would not see [detect ]it with our current science.
As DM said “How bright would a mega star have to be”.
Even other universes from other big bangs [if we consider our “universe” to have a single origin would be hard pressed to trouble the cosmic microwave background radiation let alone be seen.
–
The size of the visible universe is thus only double the 13.8 billion years, 27.6 billion years.
Since it has been expanding at less than the speed of light [caveat] the actual universe would be only perhaps 54 billion years old at the moment.
–
“The universe is around 95 billion light years across.” is an estimate based on maths and physics theories and until everyone agrees on those we might be better sticking to the speed of light time and distance observations.
Thank you for putting it and the concept up.
The big bang itself had so much matter and energy that our current concepts of time and the speed of light back then go out the window.
–
angech says:
Your comment is awaiting moderation.
July 20, 2022 at 6:56 am
…and Then There’s Physics says: July 18, 2022 at 7:29 am
“As I understand it, the galaxies in the galaxy cluster that was imaged by JWST were about 4.6 billion years old”.
–
The articles being written by journalists seem to be conflating such galaxies with the concept of being able to look back a lot further in time.
–
The original hot explosion or event being that long ago that the first clumps of plasma for want of a better word were supposed to form mega stars of very short life span which threw out clumps of matter [including some heavier elements than H, He] to form the original galaxies which were also very large [hence visible faintly] and then possibly another two iterations to get to our young star and young galaxy.
The materials greater than iron on the periodic table, gold being the best example, are thought to have come from arcane processes in past supernovae.
–
It is hard to imagine our sun being the remnant of a 13.8 billion year chunk of hop plasma cooling down over that length of time.
Further such explosions cause escape speed velocities which mean that the galaxies should never have come back together.
–
An alternative view is that space was filled with large amounts of cooled down matter in waves of explosions that crossed each other causing focal points of reaccumulation resulting in newer smaller galaxies.
This would explain suns forming from gigantic masses of cold hydrogen, etc hitting or passing through each other leaving focal eddies of matter which could then coalesce to form suns and planets.
–
and how elliptical orbits of planets and stars can come into being.