On Edge and Beyond Universe; every pointed space has its own arbitrary observable universe with a radius of about 46 billion light years marked by a cosmic horizon. This radius is determined not by how far away the most distant objects we have seen; when their light was emitted.
All objects are getting further away from all other objects relative to each other. There is no center space. Has no boundaries, edges or walls that mark the end. So how do we go about visualizing this well. Imagine a sphere representing the universe but rather than space being on the inside it is mapped to the outside surface. As the sphere expands the surface area of the space for the outside galaxies increases at the same rate.
As such there is no center, no galaxy on this sphere surface is any more central than any other galaxy. Of course the sphere itself does have a center but this doesn’t represent a physical location within the universe. Rather it represents a point in time the big bang.
The Edge of Universe
It’s an odd concept but what this means is that even if space is finite and only occupies a certain volume you could still roam around the universe indefinitely without meeting an edge. Much like if you were to fly an airplane round the earth’s equator. You would never fall off or run out of earth to fly across. Instead gravity would just bring you back round to the same place eventually.
So if you were able to travel considerably faster than light speed in a straight line. You would still come back to the same place eventually. We can see evidence of the universe’s expansion everywhere. Thanks to a phenomenon known as Redshift. Redshift is when electromagnetic radiation such as visible light undergoes an increase in wavelength. The wave is stretched out resulting in a decrease in wave frequency and photon energy for visible light.
The Redshift Phenomenon
When analyzing a galaxy’s spectral emissions. This has the effect of shifting the absorption lines of certain elements towards the red end of the spectrum. Turning visible light red because the universe is expanding at all places at once. As the light emitted from other galaxies travels towards earth the space it travels through elongates stretching out the waves and Redshifting the light.
The more distant the galaxy the further across ever expanding space. The light has to travel and so light from more distant objects is Redshifted more. We can use this to determine how much the universe has expanded since said light was emitted. The Hubble constant a measure for the rate at which space is expanding is thought to be around 65 kilometers per second per megaparsec.
A megaparsec is equivalent to about 3.2 million light years. So the more mega parsecs there are between us and a galaxy the more space there is between the two. That is expanding causing the galaxy to recede away faster. For example 100 megaparsec away the space is receding away from us at a rate of over six and a half thousand kilometers per second, because light speed is limited to about three hundred thousand kilometers per second.
There eventually comes a distance from the earth at which galaxies are being pushed away from us faster than light speed not by breaking any laws of physics because they themselves are not moving that fast but because there is simply too much space between us and them. For their light to be able to cross the universe in time to reach us. This constitutes the edge of our observable universe.
The boundary beyond which we are unable to see any further the cosmic horizon or the particle horizon. Before this boundary light from distant galaxies has had enough time to cross the expanding universe and meet our telescopes. Beyond the cosmic horizon the light from the galaxies has either not had enough time to reach the solar system or it is so far away that it will never be able to reach the solar system.
As time passes older and more distant light has time to pass through the solar system and the observable universe grows increasing our field of view. This is entirely dependent on our position for an observer at the cosmic horizon. Space would appear much the same but relative to us the space beyond the horizon is what’s known as causally, disconnected, unreachable and undetectable to us by any known means because our observable universe is geocentric. The same is true of any planet in the universe.
Every pointed space has its own arbitrary observable universe with a radius of about 46 billion light years marked by a cosmic horizon. This radius is determined not by how far away the most distant objects we have seen; when their light was emitted. But rather how far those objects are estimated to be now as the space between us and them has grown so much since that light began traveling towards earth.
The most distant galaxies of the Hubble Ultra Deep Field have now receded to in excess of 40 billion light years away from the earth. Their light would never possibly have enough time to reach us now. Beyond the cosmic horizon light speed and the universe’s age are no longer compatible. Thus we are confined to our observable universe segmented and detached from the full scale of the cosmos.
Beyond Cosmic Horizon
We are unable to conclude on what could lie beyond the boundary. But given that the universe appears to be relatively isotropic on a large scale; one would expect more of the same clusters and super-clusters of galaxies.
The real question is how much of it is there as you might expect? That is a very difficult question to answer and the estimates we have so far depend on measurements of the universe’s curvature. Assumptions about its shape which still represents a somewhat grey area in cosmology.
Expense of Universe
In short the best estimate made so far by physicists at Oxford University is that the total area of the universe must be at least 250 times the radius of the observable universe. This puts the total diameter of the universe at over 23 trillion light years which would mean that the 93 billion light year observable universe that we can see.
Accounts for a mere one fifteenth millionth of his total expanse. If our observable universe is home to 2 trillion galaxies then the unobservable universe may house as many as 30 quintillion of them. In truth, we will probably never know the exact size of the total universe but with the numbers considered here it seems almost inevitable that somewhere else in space life must be playing out on another world.
The Growing Inflating Universe
The discovery of the universe’s expansion is one of the most important discoveries ever. But we still didn’t have the full picture for a long time afterwards. Astronomers expected that the rate of expansion would actually start slowing down as the galaxies on the inside begin to pull back against the universe’s inflation.
However as scientists questioned to establish a more accurate value for the Hubble Constant a startling discovery was made. Since Hubble Redshift surveying techniques have improved significantly and we can now detect galaxies not just millions of light years away but billions. Redshift is indicative of the universe’s expansion.
I don’t have any overwhelming qualification to write anything. No specific professional studies on the subject and this was the only reason I wanted to write. The questions became haunting voices with one striking thoughts that ‘I have only one life, only one and I can’t live with these questions’. The moment I die, I will get answers to all my questions but wouldn't be able to tell anyone. Then Let's Find Some Answers.....