This question is one that has been pondered since the dawn of human existence.
Great thinkers from ancient times often asked this question.
It seems, for the most part, the majority of people believe the universe is infinite. However, there have been some studies using computer simulations that negate that viewpoint. Not only that, several of today’s thinkers believe the universe is finite. And they have their reasons for that.
Quite frankly, this is a tough question to answer from a purely scientific perspective. There’s certainly not enough data to support any viewpoint. Scientists have proposed several scenarios and possibilities and have garnered ample support in all cases.
In order to find a potential boundary of the universe, one has first to have an idea of its size, shape, and the access that we have for observation.
What is the shape of our universe?
The shape and size of our universe would have to be correlated in some way. Cosmologists have postulated that universes would probably come in one of three shapes, all of which rely on the curvature of space.
Some theorize that the universe may be flat without any curvature but have an infinite amount of space. Or perhaps it is more open, shaped more like a saddle (having negative curvature), and endless. And then there’s a closed model, shaped like a sphere, and has distinct boundaries.
Measuring the size of the universe
The most up-to-date calculations claim that the observable universe reaches out some 46.5 billion light-years in all directions. This means it would have a diameter of around 93 billion light-years.
Here’s an interesting dilemma from this calculation. Science tells us that our universe is 13.8 billion years old. This means that light from its furthest edge took 13.8 billion light-years to reach us. But during this time, the universe continued to expand at a rate that must be getting faster. Since the edge of the observable universe has apparently moved and is now 46.5 billion light-years from us.
According to several different estimates, outer space contains anywhere from around 200 billion to 2 trillion galaxies. And there are about 100 billion stars within each one of these galaxies on average. These massive numbers are almost impossible to comprehend. So it makes us wonder how such figures were obtained.
Estimating vast distances in space
Scientists employ several methods and tools to determine distances between celestial bodies within the vastness of space. First, they begin with known distances they have been measured directly. One such way is pinging radio waves off nearby objects in the solar system and determining how long it takes for these waves to return to Earth.
For distances that are challenging and difficult to determine, such as those galaxies located on the universe’s boundaries, astronomers use inferences based on observational data and calculations.
For example, they might use “parallax measurement” that depends on measuring the shift of a star relative to celestial bodies in its background. And they may use “main sequence fitting,” which uses our existing knowledge of stellar evolution – since stars do evolve, changing their brightness and size.
Understanding how brightness is related to distance is critical in calculating the location of a distant object. And there’s also the analysis of redshift, which pertains to the measurement of observed wavelength change in the light that comes from faraway galaxies.
What about the unobservable universe?
All the numbers discussed above refer to the observable universe. These are the regions of the universe that can be observed on Earth directly or detected using our various instrumentation.
Of course, this leaves the portions of the universe we cannot observe. In addition, there are parts of the universe that are so far away; its light hasn’t reached us yet.
One study from a research team of UK scientists estimated that the ultimate size of our universe might be 250 times larger, at least when taking explanation into account. They discovered that a finite and closed universe would hold around 250 to 400 Hubble volumes when referring to space using the-called Hubble volume.
Some scientists think that the universe could have experienced multiple big bangs, followed by some big crunches. This would certainly make the size of the universe very hard to estimate.
Is there an edge to our universe?
Although there are many theories about the universe’s properties, many believe it is an expanding bubble of sorts from the big bang. Would this mean it has an edge, even if that edge is expanding?
Most likely, it does not have an edge.
Scholars claim that in the end, it must follow the so-called “cosmological principle,” and it must follow the laws of physics in every direction and have the same properties as well.