Regarding how Krypton was destroyed, different comic versions offer different explanations. Currently, there are two mainstream versions: one is the "self-destruction theory," and the other is the "planet explosion theory."
The former suggests that due to various social issues, the development of Kryptonian society came to a near standstill. The accumulation of social problems caused by class stratification reached a breaking point, leading to a sudden outbreak. A genetic catastrophe swept across the planet, causing the extinction of civilization.
The latter version is simpler: Kryptonians were living peacefully on their planet, but their mother star suddenly had a problem, and "boom," it exploded, killing all Kryptonians.
Some versions combine the two: social issues led someone to explode the planet, leading to the extinction of Kryptonians.
However, according to Green Lantern Hal's investigation, at least in their universe, Krypton did not explode. The planet remained in place, but its civilization was wiped out.
And because Krypton's technology was quite advanced, it left many traces in the cosmos. The destruction of this civilization is traceable and no secret.
After some investigation, Hal roughly understood how Krypton was destroyed back then.
Though it's attributed to social issues, a closer look reveals it was actually due to their life forms themselves.
The Kryptonian race was not a natural race, meaning they weren't a product of natural evolution. Every Kryptonian was born through strict genetic screening, and their core technology was genetic modification.
In other words, it's possible that when they were born, they were as fragile as humans. But after countless genetic modifications and screenings, they eventually became such a powerful race.
It sounds beautiful; humans often fantasize about having such genetic modification technology to make everyone strong and beautiful, and even possess infinite lifespans.
But in reality, this evolutionary path was completely wrong. The Kryptonians proved this with their lives.
Firstly, due to strict genetic screening, the vast majority of Kryptonians did not have the ability to reproduce naturally.
In other words, they couldn't reproduce like humans through mating. Natural mating, which they viewed as primitive and inefficient, had long been eliminated.
Their reproduction method was asexual reproduction, directly constructing embryos and injecting genes to get a child.
This reproduction method was indeed quite efficient. Moreover, their genetic modification technology allowed them to decide at the genetic level what a member of a certain group would do when they grew up.
For instance, Clark Kent, or Carl Ai'er, his father was a scientist, so he was implanted with the companion genes of a scientist in his childhood and was meant to become a researcher when he grew up.
And Zod's father was a soldier, so he was implanted with the companion genes of a warrior from an early age, and was meant to be a General when he grew up.
Anyone with some sociological knowledge would realize that under such a supposedly efficient reproduction method, it's impossible for society not to have class stratification.
Would the upper class of Kryptonians implant their children with the genes of a low-level laborer?
Would low-level workers have the opportunity to implant their children with the genes of a social leader or genius scientist?
Of course not. They hadn't evolved a complete collective consciousness; everyone had their own selfish desires.
The rulers would always implant various excellent genes in their children to make them rulers; while those at the bottom could only implant the most ordinary genes in their children, consigning them to a lifetime at the bottom.
With this underlying logic, society naturally had various problems. These problems were almost impossible to solve.
To solve them would mean completely overthrowing the evolutionary path they had followed for so many years and starting over.
If we use humans as a comparison, it wouldn't be like returning humans to the trees to be monkeys, but it would be like having humans decide whether or not to be vertebrates.
The sunk costs were too high, so even knowing there were myriad social problems, there was no courage to start anew. They could only try their best to maintain the status quo.
To suppress various social issues, the parliament enacted many strict laws. These laws further led to class solidification and a vicious cycle, until one day, the contradictions finally ignited.
What Hal found wasn't a lot, but it was enough to make a rough guess of the situation at the time.
It's likely that a worker who was treated unfairly tampered with the facilities Kryptonians used for reproduction. By some method, the radiation of certain equipment used for genetic modification was amplified, causing genetic disorder among all Kryptonians, resulting in a fatal allergic reaction to the star radiation of this universe. All Kryptonians on the planet perished overnight.
Since the planet was not destroyed, many historical documents were preserved, allowing us to trace Zod's activities when he was young.
He was exiled to the Phantom Zone under the charge of "illegal rebellion," fully known as "illegal guidance or organization of a rebellion."
This was also one of the many strict laws enacted by the parliament.
Due to over-exploitation of the mother star's resources during external expansion, the living conditions on Krypton were not good. And because of genetic settings, Kryptonians who could only do low-level labor from birth to death were allocated minimal resources, leading to frequent riots.
During a certain period, various rebellious revolutions appeared too frequently, significantly threatening the personal safety of the high-level members of the Parliament. As a result, they enacted a comprehensive set of "Anti-Revolution Laws."
The law generally stipulates that on Krypton, any behavior that could possibly incite a revolution is illegal.
Furthermore, not only actions but even the suspicion that you might engage in such behavior means you have committed a crime.
For example, if people engaged in physical labor gather to discuss politics, it is considered suspicious of revolution, with the maximum penalty being exile.
Disobedience, talking back to superiors, or even simply working without due diligence can be judged based on severity, with the highest penalty being exile.
At one point, it even reached the extent that simply telling children about the nature of your work was deemed illegal revolutionary education, with exile as the maximum penalty.
All of the above fall under "suspicion crimes." Although exile is the maximum penalty, generally, as long as the situation is not particularly severe, exile would not be the actual punishment.
However, the "crime of illegal revolution" committed by Zod is not a suspicion crime but an actual crime. This means he truly did it.
The life record of Zod uncovered by Hal indicates that this guy was once an extraordinary revolutionary leader, never living a day in peace since he was young.
To compare to human lifespans, it's akin to organizing protests in elementary school before turning 10; forming a revolutionary group just entering middle school; and getting expelled from high school for organizing fights and destroying government public facilities.
Since his father was also a General, during his college education, his father entered him into the military, and within a year he instigated a mutiny at the battalion level. Later he transferred to a security team, leading the security personnel in the area to strike and protest.
By the age of 25, he'd been arrested 16 times, acquitted 11 times due to insufficient evidence, served jail time 5 times, totaling around three years. Later, he was sentenced to five years for organizing a riot, and was marked as a dangerous individual by the Parliament.
Even as he became a key subject of Parliamentary attention, Zod did not cease his path of resistance.
In his last appearance, he led his personal guard to besiege the Parliament Building, directly threatening the Parliament, engaging the Parliament's Forbidden Army in a fierce battle for over 60 hours without losing ground.
It can be said that his life record could entirely warrant a special episode of "Hardcore Tough Guy." If not for a bit of bad luck, he should now be the Lord of Krypton.
Unfortunately, he was ultimately one move short and was caught. Yet he skillfully utilized his legal knowledge to clear himself of over 160 charges, leaving only one charge of illegal revolution, sentenced to the lightest penalty among all charges—200 years of exile in the Phantom Zone.
To be honest, this punishment is akin to being sentenced to 200 hours of community service after bombing the Twin Towers.
Moreover, he didn't go alone. His beautiful and loyal female adjutant, deeply moved by his charismatic personality, voluntarily went to prison with him and even bore him a child.
After reading this record, Hal truly began to admire this Krypton General.
Then, he felt a bit puzzled. By logic, such a ruthless person shouldn't be so irrational as to search the cosmos for a replacement for Krypton, insisting on using force to invade there.
Although humans view Kryptonians as aliens and thus show no mercy, Kryptonians view humans the same way. Zod couldn't possibly have any sympathy for humans.
But if Zod is indeed such a person, his so-called motive for reviving Krypton makes no sense.
When Krypton was alive, he was causing chaos there; when Krypton died, he wanted to revive it. Isn't that contradictory?
Of course, it's possible he wants to rebuild a better Krypton. But first, the issue was not even the place to live since the planet Krypton didn't blow up. Wouldn't it be better to rebuild there? Why come to Earth from such a long distance?
Realizing there were too many inexplicable points, Hal became aware there must be something the Justice League didn't know.
Therefore, after discussing with Lex, they urgently changed their plan, deciding to talk to Zod after subduing him to clarify what really happened back then.
After receiving the low-temperature cabin from Gotham's inner world, Hal transported it to Metropolis, and in front of the Justice League members, opened the cabin door.
By right, the Supermen from the other two universes should feel a sense of satisfaction seeing Zod in his current miserable state. However, seeing Zod pierced like a porcupine, they couldn't help but take a step back.
They had been Superman much longer than Clark, and various invaders used numerous tricks to deal with the strongest force in the Justice League.
Additionally, their teammate, Batman, planned innumerable strategies to guard against such superhumans as well.
But the most extreme among those was merely burying them under a massive amount of Kryptonite or creating a Kryptonite prison.
However, this universe was different. They had taken a groundbreaking step in utilizing Kryptonite—transforming external application into internal ingestion.
The sharp tiny spikes embedded in Zod's body dissolved directly into his bloodstream, causing his skin to faintly glow green.
Superman genuinely wanted to grab the collar of the person who invented this and ask—how is this different from lethal injection?!