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Is our universe infinite or closed? Because the visible Universe is expanding, the most distant visible things are much further away than its estimated 14-billion year age. In fact, the photons in the cosmic microwave background have traveled a cool 45 billion light years to get here. That makes the visible universe some 90 billion light years across.
The real universe, however, is much bigger. We now know this thanks to statistical analysis by Mihran Vardanyan at the University of Oxford and colleagues.
The key to measuring the actual size of the universe is to measure its curvature. Astronomers have come up with various methods to measure this curvature. One method according to MIT's Technology Review is to search for a distant object of known size and measure how big it looks: "If it's bigger than it ought to be, the Universe is closed; if it's the right size, the universe is flat and if it's smaller, the Universe is open."
The Vardanyan model says that the curvature of the Universe is tightly constrained around 0. In other words, the most likely model is that the Universe is flat. A flat Universe would also be infinite and their calculations are consistent with this too. These show that the Universe is at least 250 times bigger than the Hubble volume. (The Hubble volume is similar to the size of the observable universe.)
Originally posted by predator0187
reply to post by centurion1211
No kidding hey?
The universe is infinite, so it's about 250 times bigger than we initially thought it was.
Kind of funny reasoning.
Pred...
Casey Kazan, author of the article, has no understanding at all of cosmological distance measures! The truth is that 14 Gly is the supposed “light travel distance”, which is the speed of light times the cosmological time interval that passed between emission and detection of the light. 45 Gly represents the “luminosity distance”, which is how far the light source has receded from us because of the expansion of space during the 14 Gy that it took the light to reach us. A light source which is seen now at a light travel distance of 14 Gly would have been much closer when the light was emitted. That distance is called the “angular distance”; the angular size of the object in our telescopes is the angular size that it would have had if we could have seen it instantaneously (without speed of light delay) at the time when the light was emitted.
In fact, the photons in the cosmic microwave background have traveled a cool 45 billion light years to get here. That makes the visible universe some 90 billion light years across.
Good article my friend!
Originally posted by predator0187
I also think that our universe has curvature to it. If we were only on one part of the Earth and could not go anywhere but a short walking distance, we would believe it was flat, we already did this. So if you can only see the earth on such a small scale as walking distance then we would interpret the earth as flat, same theory for the universe. We are only looking at a small percentage of the universe and cannot see this curve.
The flat part sounds right.
Originally posted by centurion1211
The article also says that the best calculations show that the universe is flat and infinite.
That generates another question to me. If the universe is infinite, does that mean it is not expanding as we've been told it was for some time now? And if it is not expanding, we need another explanation for the observed red-shift in distant objects
Another question. How is something that is infinite in size "at least" 250 times bigger (or smaller) than anything else?
Originally posted by centurion1211
The article also says that the best calculations show that the universe is flat and infinite.
That generates another question to me. If the universe is infinite, does that mean it is not expanding as we've been told it was for some time now? And if it is not expanding, we need another explanation for the observed red-shift in distant objects.
The Vardanyan model says that the curvature of the Universe is tightly constrained around 0. In other words, the most likely model is that the Universe is flat. A flat Universe would also be infinite and their calculations are consistent with this too. These show that the Universe is at least 250 times bigger than the Hubble volume. (The Hubble volume is similar to the size of the observable universe.)
Another question. How is something that is infinite in size "at least" 250 times bigger (or smaller) than anything else?
In mathematics:
zero X anything = zero
null X anything = null
infinity X anything = infinity
Same for division ...
Some of that sounds logical and fact based, but other parts sound like you're telling me how many angels can dance on the head of a pin.
Originally posted by sbctinfantry
Thoughts?
I've often thought that the act of looking may create more of what we expect to find. Kind of like when we keep looking for smaller particles beyond that of an atom they keep appearing. The observer effect in action if you like.
we need another explanation for the observed red-shift in distant objects.
Originally posted by Phractal Phil
There is no contradiction in saying, “The universe may be infinite, and it is at least X times larger than the accepted size.” 1 < X < ∞.