Cataclysmic Era: I can unlock the tech tree

Under Lü Yongchang's command, the Earth slowly departed from Puller-452b and headed towards the outside of the Heng system under the drive of the warp drive.

Under Zero's control, a large number of experimental ships, supply ships, and escort ships followed closely behind the Earth.

Following the expeditionary fleet, human civilization once again dispatched a research fleet to the Enroget Alliance territory.

Neutron star.

One of the densest celestial bodies in the universe, besides black holes.

When a brilliant star reaches the end of its life and explodes as a supernova, it may become a neutron star.

Its matter density is extremely high—if an external force were to compress the Earth into a small sphere with a diameter of about 20 meters, it would become a neutron star.

Therefore, its surface gravity is also extremely exaggerated—hundreds of billions of times that of Earth's surface gravity.

This powerful force can even crush atoms and force electrons into the nucleus.

This is also where the name "neutron star" comes from; it is a star composed directly of dense neutrons.

Neutron decompression and gravity are in balance, maintaining the existence of neutron stars and preventing them from collapsing into black holes; while white dwarfs are the result of electron decompression and gravity being in balance.

This is also the destination of this research fleet, a straight-line distance of 627 light-years.

Although human civilization has long conducted scientific research near small black holes, its exploration of neutron stars remains at the stage of distant observation.

The reason...

There are no neutron stars within 500 light-years of human civilization.

As for before that... back then, human civilization didn't have the leisure to search for a neutron star for research.

Undoubtedly, the researchers inside the Earth were excited at this moment.

In particular, when they learned that there was an artificial celestial body near the neutron star with a volume close to that of a gas giant, everyone was filled with intense curiosity.

Except for Lü Yongchang.

……

Standing by the porthole, Lü Yongchang gazed at the fantastical scene unique to faster-than-light warp drive, his relaxed brows furrowing slightly.

Indeed.

Both space weapons and the remnants of advanced civilizations brought him considerable surprises.

Especially considering that this advanced civilization's ruins have been explored by predecessors for thousands of years, it can be basically confirmed that there is no advanced intelligent life inside.

As for the reason... what would you do if a bunch of bugs were scratching at your front door every day for thousands of years?

The fact that the relics didn't react at all in this situation speaks volumes.

Even so, after a brief moment of surprise, Lü Yongchang fell into deep thought.

"What's wrong?"

Just as Lü Yongchang was lost in thought, Fang Xu's voice suddenly rang out from the side.

Then, a figure appeared beside him, also gazing out the porthole at the bizarre and colorful scene.

"There's nothing going on outside... Yongchang, how long have you been watching this scene? Aren't you tired of it yet?"

Lü Yongchang chuckled and shook his head, explaining, "No, I think there's something wrong with the structure of that ruin."

"Um?"

Upon hearing about the ruins, Fang Xu's expression immediately turned serious: "What do you mean? A trap?"

Lu Yongchang pondered for a moment, organizing his thoughts.

"To put it simply, it shouldn't be this big."

"...What?"

Fang Xu's expression froze slightly, and a strange and surprised look appeared in his eyes.

Just a moment ago, he was even prepared to face a higher civilization head-on, but then Lü Yongchang pulled this stunt on him.

Lu Yongchang clearly didn't notice Fang Xu's strange look and continued talking to himself.

"We once built a model when we were studying the structure of planetary fortresses."

"While planetary fortresses have many advantages, their size is limited by factors such as mobility and other considerations."

"10 times the volume of Earth."

"This is the maximum volume of a planetary fortress calculated from the model without considering the resource consumption of construction."

"Planetary fortresses exceeding this size will experience a significant decline in both mobility and structural strength per unit volume."

"If resource consumption is taken into account, a planetary fortress with a diameter of 5000-8000 kilometers would be the best choice."

Lu Yongchang reached out and waved his hand through the air, and a holographic projection appeared in front of the two of them.

"Take a look at the ruins of this advanced civilization."

"Its size even surpasses that of Jupiter!"

"This far exceeds the optimal or even the limit volume in our model."

"However, despite its large size, its mass is not large, less than five times the mass of Jupiter."

Lu Yongchang stared intently at Fang Xu: "There's definitely something wrong here."

Fang Xu was puzzled.

Fang Xu pondered.

Fang Xu suddenly realized.

"Snapped!"

He clapped his hands forcefully and said loudly, "You mean, this site might have been constructed using some unknown material?"

"Is it possible that it has a dense structure similar to a neutron star?"

He had barely finished speaking when he frowned, shook his head, and contradicted himself: "No, no, no, such a large and dense neutron star structure... its mass must be incredible..."

"Could there be another hidden meaning?"

Lü Yongchang: "..."

Seeing that Fang Xu was going further and further astray, he quickly coughed to interrupt Fang Xu's thoughts.

"No."

"What I mean is... it might be empty inside."

He looked at Fang Xu with some surprise: "Why are you thinking about this so complicatedly?"

Fang Xu: "..."

"Empty?! This, this..."

Fang Xu stared at Lü Yongchang, speechless.

"The emptiness I'm referring to doesn't mean a vacuum."

Seeing that Fang Xu remained silent, Lü Yongchang continued to explain, "It's more that..."

"It may just be a gas giant with a shell on its outside."

Fang Xu fell into deep thought.

Although Lü Yongchang's conclusion was somewhat simplistic and crude.

But upon closer reflection, it seems that the possibility is actually quite significant.

A technological creation larger than Jupiter, yet with a mass less than five times that of Jupiter—its average density is far too low.

Jupiter's average density is only 1.326 g/cm³!

In terms of density, this technological creation is even less than that of the Earth.

This is clearly impossible.

"Then what was their purpose in building this planetary fortress?" Fang Xu asked subconsciously. "Could it be that this advanced civilization plans to take this gas giant planet with them?"

"You know what, you really shouldn't tell!"

"That's actually quite possible!"

Fang Xu looked at him with a hint of helplessness.

"Are you crazy...?"

Fang Xu muttered to himself:

"Gas giants are everywhere. Why would a civilization with such advanced technology care about a single gas giant...?"

"What if, I mean, what if..." A mysterious smile appeared on Lü Yongchang's lips, "...this gas giant planet, is it the homeworld of some civilization?"

Fang Xu's expression froze, and he fell silent.