Chapter 433: Circumnavigating the Universe

The Divine Vessel Civilization continued to journey forward, flying farther and faster.

From the initial hundred times the speed of light to later a thousand times, and now ten thousand times the speed of light, the light of galaxies streaked past them, forming dazzling trails of light.

The profound depths and vast expanse of the universe were conquered by their speed at this moment, as if everything was paying homage to them.

For their goal was—circumnavigating the universe.

Regarding cosmological models, the current mainstream views mainly consist of two, namely the expanding balloon model and the expanding tire model. It's important to understand that these are topological structures rather than actual shapes of the universe.

Here we will focus on the expanding balloon model, which does not suggest that our universe resembles a real balloon.

In fact, the universe is made up of three-dimensional space plus one-dimensional time, and it is usually quite hard for us to imagine what an expanding universe looks like.

To better understand, we might first consider the three-dimensional space of the universe as being two-dimensional, then the universe would be comparable to the surface of a balloon.

The universe in which we reside is on this balloon's surface, and the dimension of time is like the radius of this balloon.

This balloon is accelerating in its expansion, and every point on its surface is continuously moving outward, and the speed is the same in all directions. Therefore, to us who are on the surface of this balloon, it feels like all the galaxies around us are accelerating away from us.

Especially at the edge of the observable universe, some galaxies are receding from us even faster than the speed of light.

In this model, the interior of the balloon represents the past, while the exterior symbolizes the future.

We may also have a misunderstanding about the collapse of the universe; it is not just the contraction of space, but more importantly, the contraction of time. That is, at the moment of this universal balloon's collapse, the fate of everything comes to an end because time recedes as well.

In theory, exploring the universe would also need to go through the same amount of time as the universe's expansion, but that has nothing to do with us; it is our past.

*

Circumnavigation of the universe is like traveling continuously in one direction on the surface of this universe balloon, eventually returning to the starting point.

The difficulty here is, as we travel along the balloon's surface, the balloon itself is also expanding, and it's doing so at the speed of light.

Imagine an ant crawling on the surface of a balloon at a speed of 1 centimeter per second while the radius of the balloon is also increasing at the same pace. In this scenario, the ant will never be able to circumnavigate the balloon.

Similarly, if the Divine Vessel Civilization traveled only at the speed of light, they too would never accomplish the magnificent journey around the universe. Due to the expansion speed of the universe exceeding the speed of light, the Divine Vessel Civilization would never reach the edge of the universe during their journey.

Therefore, circumnavigating the universe would only be possible if they were a Divine-level civilization with superluminal capabilities.

Moreover, regarding the actual size of the universe, we truly do not know. The diameter of the visible universe is approximately 93 billion light-years, but this is just a portion of what we can observe. Beyond the visible universe is an even greater expanse of unknown territory waiting for us to explore.

Taking the balloon as an example again, we are on the balloon's surface, and the light from other galaxies reaches us along the surface of the balloon. The light from the farthest points originates from 46.5 billion light-years away, which is only half the diameter of the universe.

The light from other regions (beyond the visible universe) cannot reach us.

When we observe objects 46.5 billion light-years away, we are actually looking at scenes from 13.8 billion years ago, a period of the universe's big explosion.

This is because light takes time to travel, and the expansion of the universe makes these light paths traverse a longer space to reach us.

Therefore, the radius of the universe we can observe is not 13.8 billion light-years, but 46.5 billion light-years.

One can imagine that if we can only see as far as 46.5 billion light-years on the surface of this balloon, then theoretically I could calculate the circumference of the balloon by measuring its surface curvature.

This circumference is the distance that the Divine Vessel needs to travel to circumnavigate the universe, and this distance is also increasing due to the expansion of the universe.

The Divine Vessel Civilization has also measured the curvature of the universe in various ways. Although the curvature is very slight, it has disproved the expanding tire model, which posits that the universe has no curvature.

The measuring approach is simple; locate three points in the universe, measure whether the sum of the angles is greater than 180 degrees. If it equals 180 degrees, it indicates there is no curvature.

According to the latest measurements, the size of the universe is approximately 240 trillion light-years, nearly 2500 times that of the observable universe. This expanse is unimaginably vast.

If the Divine Vessel traveled at 50,000 times the speed of light, it would still take about 7 billion years to complete the journey, considering the factors of universal expansion, instead of the straight calculation of 4.8 billion years.

And 50,000 times the speed of light is the current maximum speed of the Divine Vessel; to achieve circumnavigating the universe, they must fly even faster.

Because according to Lin Sen's calculations, this universe might welcome Returner in 3 billion years.

Moreover, the wars in this universe are becoming increasingly intense, and no one knows how this universe will be in 3 billion years.

*

During their future voyage, the Divine Vessel Civilization will traverse the Laniakea Supercluster, spanning 500 million light-years in length.

They will continue their journey, crossing the Pisces-Cetus Supercluster Complex, with its vast span of 150 million light-years in width and 1 billion light-years in length.

They will even stride across the Hercules-Corona Borealis Great Wall, which is the largest cosmic structure discovered to date at a length of 10 billion light-years.

Each crossing is an utmost exploration of the unknown. The Divine Vessel Civilization kept moving forward, and 100 million years later, they sailed into the region of the unobservable universe, reaching speeds up to 100,000 times the speed of light.

The unobservable universe is no different from the observable universe; the only difference is that its light has not reached Earth.

The farther the Divine Vessel Civilization flew, the more the visible universe in the same direction increased, with always a visible universe of 46.5 billion light-years ahead of them.

And the scenes encountered by the Divine Vessel Civilization played out at an accelerating pace of one hundred thousand times, so fast that even their most advanced computers could only record a ten-thousandth of them.

Galaxies, nebulae... various cosmic spectacles rapidly evolved before their eyes, as if they were attending a visual feast of the universe.

And the speed of the Divine Vessel Civilization kept accelerating...

*

Era of the Divine Vessel 3 billion years.

In the 3 billionth year of the Era of the Divine Vessel, after a long cosmic journey, the Divine Vessel Civilization finally faced a shocking moment.

The scenes before them suddenly became familiar, and upon close study, they were surprised to find that these were scenes from the Hercules-Corona Borealis Great Wall at the moment of the universe's birth.

This discovery made everyone in the Divine Vessel Civilization realize that their cosmic circumnavigation was nearing completion.

Now, they saw the Hercules-Corona Borealis Great Wall as it was at the dawn of the universe, because the light from its inception continued spreading in the opposite direction of the universe. After traveling nearly 17 billion years, this light finally entered the vision of the Divine Vessel Civilization as they returned from their circumnavigation.

The Divine Vessel continued to advance, and the Divine Vessel Civilization watched in full the evolutionary scene of the Hercules-Corona Borealis Great Wall, as if they were witnessing the growth of the universe with their own eyes.

The speed of the Divine Vessel gradually slowed, and afterward, the early evolutionary scenes of the Laniakea Supercluster appeared before the Divine Vessel Civilization, displaying the magnificent vista of chaos and order interwoven in the early universe.

Subsequently, familiar galaxies such as the Virgo Cluster and the Milky Way Galaxy unfolded one by one before the Divine Vessel Civilization.

The Divine Vessel Civilization even had a complete view of the entire evolutionary history of the Milky Way Galaxy from its birth until the time the Divine Vessel left.

As the speed of the Divine Vessel decreased, they received more and more information, to the point where they were now viewing the Milky Way Galaxy after they had departed, continuing all the way until 3 billion years after their departure.

That was a history of the Milky Way Galaxy's solitary evolution, the time the Divine Vessel Civilization had missed.

But at last, the Divine Vessel Civilization came to a halt, ultimately reaching the end point of this voyage, 3 billion years away from the Milky Way Galaxy.

When the Divine Vessel Civilization finally completed their circumnavigation of the universe, they seemed to undergo a qualitative change, as if emitting an indescribable radiance.

PS: In the original text, it says that Cheng Xin entered the Small Universe when the universe was 17 billion years post-creation, whereas our actual universe is thought to be approximately 13.8 billion years old. Of course, this observation might not be accurate.

The author provides two explanations for the mentioned 17 billion years: first, the Trisolaran Universe and our real universe are not the same, so it's normal for their timelines to be different.

Second, Cheng Xin's memoir might have an error, and the 17 billion years could refer to when they exit the Small Universe, which is when the Returners sent out the last cosmic broadcast, with the universe on the verge of collapse at that time.

This book uses the second explanation so that the current observed data of the universe can be directly applied without the author needing to calculate the size of such a universe.

Regarding the size of the universe, because the current measured curvature of the universe is close to zero, with an error of one ten-thousandth, the author directly uses one ten-thousandth as its curvature. After all, the author does not like a universe model shaped like a tire.

Perhaps writing this book without a Dark Forest for Divine-level Civilizations is something many readers dislike. The author describes the Dark Forest as more than just the result of civilization wars, but rather the "will" of the universe itself.