Video spoilers history, starting with the blitzkrieg on Poland

A new celestial display begins to play, accompanied by melodious and soothing music.

The camera slowly pulls up from the coastline on the Earth's surface.

The blue-green planet rotates in the darkness.

And the voice began to provide narration:
When we look up at the starry sky, we are always struck by an ultimate question.

What lies beyond the universe?

Scientists' answers often defy common sense.

The universe is not something contained in a box.

Because it inherently encompasses all time and space; it is the sum total of all existence.

This is like asking questions about regions north of the Earth's North Pole.

The question itself loses its meaning due to the limitations of its space-time definition.

The observable universe arose because the universe is expanding at a rate exceeding the speed of light.

The intricate premise of the universe's expansion limits humanity's exploration of its full scope.

Therefore, we can only make some reasonable guesses about the appearance of the entire universe at present.

The most mainstream hypothesis compares the universe to a high-dimensional geometric object.

Imagine walking on the Earth's surface. No matter which direction you go straight, you will eventually circle back to your starting point, but you will never find the boundary.

The universe may follow a similar logic.

It could be a four-dimensional sphere, where three-dimensional space is closed on a four-dimensional scale, forming a finite but boundless structure.

[It could also be an infinitely extending space, with celestial bodies distributed without end.]

However, we can only observe the regions where light reaches the Earth, a limitation that makes both possibilities difficult to verify.

[It's easier to understand from the perspective of a two-dimensional organism like an ant:]

Imagine ants crawling on the Earth's surface.

It cannot perceive the curvature of a three-dimensional sphere and will only return to the origin within a closed-loop path.

[Thus, one comes to know a finite but unbounded world.]

[This is analogous to human three-dimensional space.]

If the spaceship continues flying and returns to its starting point, it means that our space is positively curved, forming the surface of a four-dimensional sphere.

We are like ants, trapped in a low-dimensional perspective, unable to directly perceive the full picture of the higher-dimensional universe.

The key question is: Is our space truly curved?

Current observations show that the observable universe is nearly flat, with no curvature.

But this might be an illusion of scale.

Just like how you can't see the Earth's curvature from the ground.

The real universe is likely much larger than the observable portion.

[It is speculated that if space is curved, its radius would be at least 250 times that of the observable universe, forming a super four-dimensional sphere.]

What if the space is indeed flat?

This leads to an even more revolutionary idea: a super donut universe!

In this topological structure, space is closed like a toroidal loaf of bread; traveling straight forward will bring you back to the starting point, and its size is likely only a few times larger than the observable universe.

Astronomers face two extreme possibilities when they cross the boundaries of the observable universe.

[Absolute nothingness or infinite space.]

The former is not a pitch-black void, but true nothingness.

[The absence of space, time, and matter, even the concept of darkness, this nothingness beyond cognition is called the philosopher's nightmare because it challenges humanity's definition of existence.]

Beyond the sky, during the Spring and Autumn Period.

After reading the first theory about the universe, Confucius, while once again awestruck by its vastness, also remarked with a touch of regret:

"It is indeed a great pity. If the universe is fixed and vast, then as long as people in the future master the technology of light-speed travel, they will eventually be able to traverse the entire universe."

"Use human footprints to measure the size of the universe."

"However, the key point is that the universe is still expanding."

"And its expansion speed is even faster than the speed of light."

"It should be noted that the fastest speed of travel in the known universe is the speed of light."

"But the universe is expanding faster than the speed of light."

"In this way, even if future generations have the technology to travel at the speed of light, they will still never be able to measure the size of the entire universe."

The sky continued to fall.

The second concept, the idea of ​​an infinite universe, is full of paradoxes.

If space were to extend infinitely, there might be countless versions of you, each doing the same or different things in different corners.

This stems from the infinite monkey theorem.

[In an infinite amount of time, a monkey could randomly type out the complete works of Shakespeare.]

However, physics has always maintained a cautious attitude towards infinity: if the universe originated from a singularity, how did infinite space evolve?

This contradicts existing cosmological models, such as the Big Bang theory.

Therefore, an infinite universe is more of a mathematical hypothesis.

[Rather than physical reality.]

A third possibility is that the universe could be expanded into a cosmic archipelago.

Our universe is merely an ever-expanding bubble within a larger universe.

[The parent universe continues to experience bubble explosions, with the space between each bubble expanding exponentially. Regions where the expansion stops will form new bubble universes.]

Each bubble possesses unique laws of physics. Some may lack gravity, while the speed of light limit may be ineffective.

This theory is supported by data on the cosmic microwave background radiation.

[Some unusual hotspots may be traces of collisions between nearby bubbles.]

The more radical string theory of many universes posits that the universe is essentially eleven-dimensional.

Humans perceive only three-dimensional space; the other dimensions are compressed into the Calabria space, smaller than an atom.

Different ways of dimensional contraction create different universes, numbering as many as 10^500.

[Far exceeding the total number of atoms in the observable universe.]

This vision of a cosmic ocean, while dizzying, provides a theoretical framework for the diversity of physical laws.

However, to be honest...

All of humanity's conjectures about the universe are confined to the horizon of the observable universe.

We cannot reach the edge of the universe.

Because the speed of space expansion exceeds the speed of light.

The light from distant galaxies will never reach Earth.

This means that even with future technological leaps, [it won't be possible].

We can only extrapolate the possible forms of the universe at the theoretical level.

[A four-dimensional sphere, a super donut, infinite space, or a multi-dimensional bubble—each model has its logical foundation, but each also has unverifiable blind spots.]

The ultimate mystery of the universe may lie at the boundary between the knowable and the unknowable.

When we use mathematical formulas to describe high-dimensional space and telescopes to capture starlight billions of light-years away...

[It is both exploring the outline of the universe and measuring the limits of human cognition.]

Before the next breakthrough in our understanding of dimensions, all conjectures are merely a romantic tribute from human wisdom to the vastness of space and time.

As the video ended, the comments section was filled with expressions of emotion.

If the universe were a donut, what would be outside the donut?

"Even two-dimensional ants perceive curvature as flat, and humans perceive the universe as three-dimensional."

Beyond the universe lies a brain in a vat.

"The more I think about it, the more desperate I become. What exactly is humanity in the universe?"

It made me depressed.

Don't watch space-themed videos late at night!

Perhaps the universe is a black hole; at the moment of the Big Bang, matter collapsed into a black hole.

If the universe is a sphere, what would the outside of that sphere look like?

If the universe is a mother universe, and then countless cosmic bubbles, what would that mother universe look like?

What lies beyond the mother universe?

Let's explore it when technology is more advanced in the future.

"You'll never reach that level of technology, not even if you're a god-like civilization."

God: Humanity in this universe has a bit of a sense of humor.

The end of science is metaphysics, so let's just leave it at that!

……

And outside the sky.

Zhuangzi sat with his legs bent, his eyes fixed on the shimmering blue light in the sky.

Zhuangzi already had his own understanding of the universe, and at this moment he spoke slowly and deliberately according to his own views:

"This video is truly excellent."

“Wonderful! This ‘nothingness’ is not emptiness, but the very nature of which even ‘nothingness’ does not exist.”

"Transcending the interdependence of existence and non-existence, even the concept of 'non-existence' must be eliminated."

Zhuangzi showed an appreciative expression, appearing quite pleased.

But Zhuangzi continued:

"As for how big the universe is, and what lies beyond it, these questions are indeed meaningless."

"The so-called '930 billion light-years' is nothing more than the 'existence' that people measure with scales."

"But what ruler should be used to measure the boundary of that 'nothingness'?"

"Viewers of the video always feel like they are three-dimensional stargazers."

"But two-dimensional organisms cannot measure three-dimensional curvature, so naturally we three-dimensional beings cannot measure a four-dimensional sphere."

"Humans are like the ants in the video, trapped inside the sphere just like ants."

Zhuangzi then reached out and stirred the dust in front of him, piling it into a crooked sphere.

“This ball of soil is ‘finite and unbounded’ in the eyes of ants, but ‘bounded and finite’ in the eyes of humans.”

"That four-dimensional spherical universe might just be a ball of mud in a child's hand in the eyes of beings in higher dimensions."

"You can't talk about ice with a summer insect, and you can't talk about the sea with a frog in a well."

"Later scientists were obsessed with the laws of physics, but they did not know that the so-called laws were merely the laws of this world."

"Perhaps the 'gravity' and 'speed of light' in our universe are just rules of a children's game in another bubble."

"Heaven and earth were born together with me, and all things are one with me."

"These myriad bubbles are merely different manifestations of the Dao." (End of Chapter)