The Edge of Space

by the residentially challenged science writer, Chongo

Have you ever wondered where the edge of space lies? If, as science says, the universe (the visible one) is only so big, where then does its edge lie? Furthermore, were we to achieve the impossible and travel to this edge to examine what is there, what, exactly, would it be that we would find? And, wouldn’t there necessarily have to be “something” lying beyond this edge, if there exists such a thing as an edge, because every edge existing within our world has something lying beyond it?

That’s not all. Because the Theory of Relativity tells us flatly that time can never be separated from space and hence that no ‘where’ can ever be separated from a corresponding ‘when’, then there is yet another important idea that we must additionally consider, which is ‘when’, precisely, might we be at the ‘where’ of this edge? A particular ‘when’ must be chosen to associate with the ‘where’ that is the edge we seek to identify.

Given the need for a when, let us use a ‘when’ with which we all are most familiar and the most existent ‘when’ moment that there is, namely, the present moment to which we assign the designation of ‘now’. Appropriately, we can designate the ‘when’ of the edge as being this present moment that we call ‘now’.

Specifically, when we use the term ‘now’, we mean the universally common moment that seems to be shared by all in any direction, at any distance. Thus, searching for the edge of space, we will focus the scope of our attention on what lies at the edge of space, ‘now’, not before and not after. (Nonetheless, we should keep in mind that, by unambiguous implication, even though this edge corresponds to now, it should be no different from what this edge ever was, or ever will be, either billions of years in the past or trillions of years in the future. The edge of space would always be the same edge as at any point in time that we might choose.)

The last science article described one of the things that Einstein dreamed of doing, traveling at light speed while riding a beam of light! There is a reason why this very topic was chosen to precede the subject of this current article. The experiment it described will be key for answering the questions posed above, in the initial paragraph. Understanding what it means to travel at the speed of light answers many questions about nature. In this case, it answers our questions regarding what lies at the edge of space.

In the last article we discovered what a ride at the speed of light would be like, (ignoring its impossibility) instantaneous travel; we would experience absolutely nothing as there would be no time for experiencing anything at all. We discovered that we would simply be at the beginning of our journey in the very same moment as we would be at the end of it. We would be at both ends in exactly the same moment, ‘now’. And that is not all. We would be at every point between the beginning and end of our journey also. Being at all these places at once, we would be a streak, not an ordinary solid body located at a single place, but for a moment, a streak, being at many places (an infinitude of them) at once. This momentary streak of our existence in many places at once would correspond to a solitary moment, ‘now’, at both ends. If this streak were light instead of a solid body spread across many places that we would be, traveling at light speed, then, because a single “beam” (a photon) is so thin, we would be an extremely fine ‘line’, instead of a “thick” streak of matter.

What we call “empty” space is made of these fine lines of light. It is made of these fine lines of light in the same way that a sufficient number of opaque lines, drawn on a completely blank two-dimensional surface, can create a new opaque two-dimensional surface atop the original blank one. In nature, a collection of momentary lines of light create a single present moment of our three-dimensional space, in EXACTLY the same way. These momentary three-dimensional spaces, created from infinitely thin lines of light (again, photons), stacked upon one another with each passing moment, create the four-dimensional space-time of our universe -- that is, the visible one.

Because, as just explained, it is exactly the same moment at each end of these fine lines constituting each moment of three-dimensional space, their furthest extent should lead us to the what we are seeking, that is, the edge of space, again, now (any momentary collection of these lines being the actual, physically existent ‘now’ corresponding to any moment of our three-dimensional space*). Those that reach the farthest should reach as far as the edge of space, or at least bring us close to it, again, now. There are a particular group of lines that reach the farthest. They are called collectively by the name cosmic background radiation. Like all radiation, this radiation is a form of light. No light reaches farther that the cosmic background radiation, approximately fourteen billion light years. It is our light horizon.

And what do we see (see by means of detectors capable of seeing for us) when we look as far as can be seen? Answer: We see the bright flash of a super hot region surrounding something called the Big Bang. This region is opaque. That is, no light can penetrate this opaque region, and no light emanates from it because there is simply no light there. It is far, far too hot for light, or that matter, too hot for a number of other things too, like atoms, for example. This opaque region extends for approximately one hundred thousand light years. Then, we arrive at the Big Bang. Reaching the Big Bang, we ALMOST reach a stopping point, or a starting “point,” if you wish, which is where the edge that we have been seeking ALMOST lies. The Big Bang is a microscopically sized tiny white hole (the ONLY white hole one in the universe) from which everything in the universe, including the very material that constitutes us and our world, has its origins. From this white hole, energy pours forth, and along with that energy, space and time pour forth too. The Big Bang is a pit with an unreachable bottom, filled with even more energy that the visible universe has. But, it allows one-way travel only. Energy gets out, but once out, it can never escape back inside the Big Bang, or for that matter, escape to anywhere “else,” either. Once in the visible universe, one is destined, at least one’s matter is destined, to remain there for all of eternity.

In any direction, if you look far enough (about fourteen billion light years), and then a little bit beyond that (one hundred thousand more light years), you see the Big Bang. It is as close as we can get to an “edge” of space. Now, in order to understand how exactly the edge of our enormous visible universe can have such a microscopically tiny white hole while it is so enormous, we need only consider that at the North Pole traveling in opposite directions, one will eventually arrive at the point of the South Pole, which is very small indeed when compared to the enormity of the earth. In other words, the visible universe, meaning the space of our universe itself, is “round”, just like the earth is (that is, earth’s surface being a familiar two-dimensional sphere in three dimensions), but in one more dimension. (That is, ‘space’ at any given moment is a three-dimensional sphere in four dimensions, which is a hyper-dimensional sphere instead of a conventional one.) There is a difference however between the South Pole and the Big Bang edge of space. Unlike the South Pole, the Big Bang is moving away from us at nearly the speed of light, because the visible universe is always growing in size, again, at nearly the speed of light at its “edge”.

And what lies beyond the rapidly receding Big Bang? We may never know with certainty, but we can definitely know what MIGHT be there. According to what is among the most insightful models of nature yet conceived, quantum gravity, the ‘outside’ of a black hole may lie beyond the ‘inside’ of the Big Bang. In other words, our universe may lie within a black hole of another, grander universe, meaning that ultimately, space may continue an infinite distance, beyond the Big Bang of our sole universe.

* - The fact that three-dimensional space is made of one-dimensional lines becomes rather obvious when you look around anywhere, in any direction, no matter how far; it becomes obvious by noting that ‘now’ is the very moment when any and all light is ever seen. This is especially apparent when one considers that light can never be observed at any other time other than now (keeping in mind that ‘remembering’ seeing is not seeing, it is just remembering).

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