Measurements of the cosmic microwave background radiation indicate that the observable universe is approximately flat, but scientists still do not know whether the entire universe is infinite, finite without an edge, or has a more complex topological structure.
Observations of the early universe show that space appears flat throughout the observable universe. But beyond our cosmic horizon, the universe may still be curving, closing in on itself, or connecting in surprising ways. So the true size and overall shape of the universe remain an open question.
To understand the problem, astrophysicists sometimes use the analogy of the Earth. The surface of the Earth has a finite size, and its area can be measured. Yet, when you stand on the ground, there is no “edge” to fall off. The surface is finite, but boundless. This is made possible by curvature.
The same question arises about the universe. Astronomers generally assume that the universe extends beyond what we can see. That is, if our telescopes were able to look further, we would probably see more galaxies, more stars, and more cosmic structures. But there is a fundamental limitation here: the observable horizon is also a limit to the information that can reach us. So we may never know the total size of the universe.
One possibility is that the universe is infinite. That is, it goes on forever. But there is also another possibility: that the universe is finite, yet has no end. It sounds paradoxical, but that is exactly how the surface of the Earth works.
How do we know if space is “flat” or “curved”? In mathematics, there are several tests for this. One of them is based on triangles. On a flat plane, the sum of the angles in a triangle is 180 degrees. On a curved surface, this sum changes. Another test has to do with parallel lines: on a flat plane they never meet, but on a curved surface they can meet.
Cosmologists apply similar ideas to the entire universe using the cosmic microwave background radiation, the ancient light emitted as the universe cooled from a hot, dense plasma. According to calculations, this radiation should show tiny fluctuations in temperature. And indeed, they are observed. In addition, it is possible to calculate what their angular size should be. If space were very curved, the light would change its path over billions of light years, and the patterns would appear to us to be of different sizes.
But the measurements show that the patterns appear to be almost exactly the size expected in a flat universe. This implies that the geometry of the observable universe is very nearly flat.
Does this close the debate and prove that the universe is infinite? Not necessarily. Even if the universe appears flat in the realm we can measure, it may be curved on much larger scales, far beyond the observable universe. In other words, we may be examining only a small “patch” of a larger structure.
There is also an important distinction between geometry and topology. Geometry describes whether space is flat, spherical, or saddle-shaped. Topology is concerned with whether space is “closed” on itself. For example, you can take a flat sheet and roll it into a cylinder. Locally it is still flat, but globally it is connected to itself. Similarly, a universe that is geometrically flat can also be closed in one or more directions.
Physicists have been looking for clues to this. Among other things, they have looked for repeating patterns in the cosmic microwave background radiation or galaxies that appear on different sides of the sky, as if the light has circled the universe and returned. So far, no convincing evidence has been found. So the current assessment is that the universe appears both flat and simple, with no clear signs that its dimensions are closing in on themselves.
Still, we may never know for sure. The limit of the cosmic horizon prevents us from examining what happens beyond the observable part. So the question of the true size and overall shape of the universe remains open: it may be infinite, or finite but without end, or even have a much more complex topological structure than we can currently measure.
More of the topic in Hayadan:
5 תגובות
A human being's attempt to deal with the question of what the universe is and how it is structured is likened to the attempt of a fly sitting on a pile of garbage to define for itself what the world looks like beyond the horizon it sees.
We do not have the ability and tools to understand things that are far beyond our intellectual capacity.
It would be better if we focused on looking at our immediate environment and trying to preserve and improve it.
No benefit will come from investing resources to understand what is happening hundreds of light years away.
In the story about the fly that I wrote earlier, do you think the fly should stop looking for food and mates and instead start flying towards the horizon in order to understand the world?
To me it's simple, the universe is shaped like an eye more or less in all directions, large in the middle and gradually closing in on itself at the far ends.
And in its closing places it gets dimmer with a new dimension appearing after it across trillions of light years, but the universe as we know it is finite, there is simply something else after it which of course I have no idea what. Of course I have no proof of this but it sits well with my mind.
The universe is absolutely finite.
He's not the only one either. There are, by rough estimate, about 10 to the 49th power of extraterrestrials that are millions of years ahead of us, all of which together form a perfect hexagon.
The Multiverse (the Absolute as the Pleiadians of Telsion called it) is a living body that creates universes and we are a tiny particle of it. The universes expand in the form of fractals.
The Pleiadians received the information about its shape and size from extraterrestrials who were much more advanced than them.
Everything comes from a thought, from an idea, and not by chance.
This is the great, true God.
Our God and the God of our ancestors are highly advanced extraterrestrials who know the secrets of creation, but they too are not eternal and, of course, do not have creative abilities.
Details coming soon (with lots of proof and also pictures from other stars).
The truth is that we can't know anything about the universe... We have no tools or ability... A crazy mystery... What is infinity??????((((????
And then what? After the universe ends?…