22 Mar 16
3 edits
Originally posted by twhiteheadLike even Einstein with his refusal to accept the implications of quantum theory.
The problem of visualization is hardly unique to lay people. Many famous scientists / mathematicians have got things wrong and or refused to accept something because they could not visualize it.
This is just words, but here is an article claiming the universe is about 50 billion ly 'across'.
http://phys.org/news/2015-10-big-universe.html
Originally posted by sonhouseNo, it doesn't. The article says the 'observable universe' is about 46 billion light years in radius. (that's 96 billion light years 'across' ).
This is just words, but here is an article claiming the universe is about 50 billion ly 'across'.
It also says:
So how big is our universe? Well we don't really know,...
It is actually possible that the universe is less than 46 billion light years in radius as that estimate for the observable universe is based on the assumption that it is actually bigger than that.
What I find interesting is you have been making the claim or similar for years in this forum and I correct you every time, but you just keep trotting it out. One would have thought you would have at least looked it up and tried to confirm it before making the claim again.
I hope that now you finally know that the size of the universe is totally unknown (as confirmed by your own reference) and there is no evidence whatsoever that it is finite or approximately what size it is. The best we can do is approximate a lower bound for the size (which is less than 46 billion light years radius, but I would have to look up the latest research to get a more accurate lower bound).
Please don't spread misinformation about it again. If you believe I am mistaken please feel free to find references that contradict me as I am more than willing to learn more about it if such evidence does exist.
22 Mar 16
Originally posted by twhiteheadIsn't it true to say the universe has a radius of at least 13.8 billion ly?
No, it doesn't. The article says the 'observable universe' is about 46 billion light years in radius. (that's 96 billion light years 'across' ).
It also says:So how big is our universe? Well we don't really know,...
It is actually possible that the universe is less than 46 billion light years in radius as that estimate for the observa ...[text shortened]... that contradict me as I am more than willing to learn more about it if such evidence does exist.
Which would be if the universe wasn't expanding, right? So doesn't it stand to reason the universe is bigger than the visual universe we can measure with telescopes?
22 Mar 16
1 edit
Originally posted by sonhouseI haven't read up on it, but I am fairly sure the answer is no. There is a possibility that we see right across the universe and back (like looking all the way around the earth if you were trying to measure the surface of the earth). If this were the case we would see repetitions of the universe, but if the scale is large enough we probably wouldn't be able to pick it up easily. For a start we would see the same part of the universe but at different times in its evolution. There may be other implications such as the temperature of the background radiation.
Isn't it true to say the universe has a radius of at least 13.8 billion ly?
Anyway a smaller than 13.8 billion radius cannot be summarily dismissed.
22 Mar 16
Originally posted by twhiteheadIf you mean that it cannot be dismissed on theoretical grounds then I think you are right, however according to Wikipedia the most distant object [1] is a galaxy called GN-z11 [2] at a redshift of 11.1 giving it a co-moving distance of 32 billion light-years. Assuming that observed redshifts are due to an expanding universe then that gives an empirical lower bound on the radius of the Universe more than twice the distance light could travel in that time if the universe were not expanding.
I haven't read up on it, but I am fairly sure the answer is no. There is a possibility that we see right across the universe and back (like looking all the way around the earth if you were trying to measure the surface of the earth). If this were the case we would see repetitions of the universe, but if the scale is large enough we probably wouldn't be ab ...[text shortened]... ackground radiation.
Anyway a smaller than 13.8 billion radius cannot be summarily dismissed.
[1] https://en.wikipedia.org/wiki/List_of_the_most_distant_astronomical_objects
[2] https://en.wikipedia.org/wiki/GN-z11
23 Mar 16
3 edits
Originally posted by DeepThoughtThat is the same as what I said earlier for the 'observable universe' which actually gives a radius of 46 billion light years and diameter of 96 billion light years. (according to the article Sonhouse referenced).
If you mean that it cannot be dismissed on theoretical grounds then I think you are right, however according to Wikipedia the most distant object [1] is a galaxy called GN-z11 [2] at a redshift of 11.1 giving it a co-moving distance of 32 billion light-years. Assuming that observed redshifts are due to an expanding universe then that gives an empirical ...[text shortened]... an twice the distance light could travel in that time if the universe were not expanding.
But that is assuming the universe does not wrap around on itself and you are not in-fact seeing our own galaxy from the other side.
I have since read that we can actually measure the flatness of the universe and that the current measurements do rule out the possibility that the universe is smaller than the observable universe. In fact the claim is that the universe is much much bigger (orders of magnitude) than the observable universe.
23 Mar 16
Originally posted by twhiteheadI have since read that we can actually measure the flatness of the universe...
That is the same as what I said earlier for the 'observable universe' which actually gives a radius of 46 billion light years and diameter of 96 billion light years. (according to the article Sonhouse referenced).
But that is assuming the universe does not wrap around on itself and you are not in-fact seeing our own galaxy from the other side.
I hav ...[text shortened]... aim is that the universe is much much bigger (orders of magnitude) than the observable universe.
Was that online and can you give the reference?
23 Mar 16
3 edits
Originally posted by DeepThoughthttps://www.researchgate.net/post/The_flatness_problem_or_why_do_we_think_the_observable_universe_is_big
I have since read that we can actually measure the flatness of the universe...
Was that online and can you give the reference?
And a more detailed source with explanations:
http://scienceblogs.com/startswithabang/2012/07/18/how-big-is-the-entire-universe/
Meaning that — even without speculative physics like cosmic inflation — we know that the entire Universe extends for at least 14 trillion light years in diameter, including the part that’s unobservable to us today.
There are errors in the article (such at the erroneous claim that atmospheric distortion is the cause of the curved appearance of the horizon in photographs).
However, the overall concept seems reasonable: if we can put an upper bound on the curvature of the universe, then we can put a lower bound on the size of the universe.
24 Mar 16
Originally posted by sonhouseThe universe is bigger than what we can observe with telescopes and radio-telescopes.
Isn't it true to say the universe has a radius of at least 13.8 billion ly?
Which would be if the universe wasn't expanding, right? So doesn't it stand to reason the universe is bigger than the visual universe we can measure with telescopes?
https://en.wikipedia.org/wiki/Chronology_of_the_universe
The reason for this is that the early universe was opaque to light and radio waves; whatever happened before the universe became transparent to light and radio waves will remain invisible to us--this therefore represents a sort of perceptual horizon beyond which we cannot observe--unless other modes of observation become available to us which give us a window into the 'dark age' of the universe. Gravitational wave observatories are a significant development in this regard because they allow us to 'see' beyond that horizon.