Along the way, Liu Fei and this sloppy middle-aged man had a chat without a match, in fact, most of them were middle-aged people talking, Liu Fei was listening, Liu Fei paid more attention to the troop transport suspension armored vehicle that kept passing by on the side of the road, he found that the more inside, the stronger the atmosphere of war, and, after going deep into the corridor, there was no longer a police officer, they were all soldiers wearing military uniforms and holding weapons.

From the chat, Liu Fei has a general understanding of this middle-aged man.

The sloppy middle-aged man is a scientist, mainly engaged in physical research, and what he is best at is mechanics, of course, judging from some of the complex professional vocabulary he mentioned, his knowledge is quite complex, for this kind of person, Liu Fei has never lacked respect, in addition to nodding his head to deal with it, he will occasionally answer a few questions.

"Oh, I forgot to introduce myself, everyone calls me Powell, what about you?"

"Liu Fei."

"Well, I also have some research on armor structures and materials, if you have any questions, you can ask me, maybe I can answer some doubts for you." There were nearly 100 people on the hovercar, and the middle-aged people were the only ones who were enthusiastic about Liu Fei.

"Liu Fei, he must have something to ask you for!" Xiao Qiangguang said with a sneer.

"Why?"

"Think about it, there are so many people here, he doesn't talk to you, he is close to you, he has nothing to do, he is either a traitor or a thief, hehe! I guess this guy wants you to help him pay back...... Liu Fei, this guy has a very big tone, ask a few questions, make it difficult for him, and kill his majesty......"

"How long do protons live and how do you understand them?"

"Ah......h

Powell was stunned for a moment, looking at Liu Fei speechless, Liu Fei's question is a physical puzzle that has not been solved so far, people used to think that protons are different from neutrons, it will never split into smaller particles. This was once taken to be true. In the '70s, however, theoretical physicists recognized that the theories they had proposed that could become "grand unification theories" -- theories that combined all forces except gravity in one furnace -- implied that protons must be unstable. As long as there is enough time, in the unlikely event that the proton splits, by capturing the proton that is dying. For many years, experimenters have been watching the large tanks in the underground experimental air, waiting for the protons inside the atoms to die. But in the hundreds of years of monitoring so far, the mortality rate of protons has been zero, which means that either protons are very stable or they have a very long lifespan - estimated at more than 1 billion trillion years.

To put it simply, there is no definitive evidence of how long protons are alive.

“…… Well, you can change it, I'm just an ordinary physicist. Powell paused for a few seconds and then said with a sad face.

"Why does the cosmological constant have its own numerical value? Is it zero, is it really constant? Liu Fei once again asked his own question, this question is what he has always wanted to know, because, according to the knowledge he has told him, the universe is accelerating expansion, and this expansion is related to the warp engine, theoretically, the speed of the warp engine has exceeded the expansion rate of the universe, Liu Fei imagined more than once, if you drive a warp engine spaceship, can you catch up to the end of the universe expansion?

"Ahem...... The universe should be expanding at a leaping rate. This is not the case, and there must be some mechanism that is suppressing this effect. If the universe is truly supersymmetrical, then the cosmological constant should be completely canceled out. But this symmetry, if it exists, appears to have been shattered. The situation is further complicated if this constant changes over time...... This question is too complicated to explain for a while...... That and that...... Can you ask a more practical question? Powell's old face turned red, and the little bright light brain in the dark was screaming excitedly.

"The third of Newton's laws is always equal to the opposite reaction, that is, if the horse pulls the horse, then the car also pulls the horse with the same great force, at this time, the car should stop where it was and not move, why will it move forward? This force is equal, why don't they cancel each other out? According to the third explanation of the three laws of mechanics, when attacking the enemy, according to the third law, he also suffers an equal reaction, but the fact is that the enemy is injured and he is fine, which is obviously not in line with the third law.

"Huh...... This is a good question, everyone knows this law, and many people can apply it correctly, but very few people can fully understand its meaning, even me, it took me four years to really understand it, at first, I also doubted the reliability of this law, in fact, it is right, but we did not understand it correctly...... The two forces do not cancel each other out because they are loaded on different objects: one on the horse and one on the cart. There is nothing wrong with two forces being the same, but is it true that the same force will always have the same effect? Is it possible to say that the same force can make any object get the same speed? Is it true that the effect of force on an object has nothing to do with the object itself, or the magnitude of the object's resistance......

"If this is thought of when we think of this, then it is understandable why the cart is still pulling the cart away, even though the cart is pulling the horse backwards with the same amount of force, and the force acting on the cart is equal at every instant; However, the cart had wheels and could move freely, while the horse was firmly grounded, so the cart had to follow the horse. Think about it, if the cart does not react to the horse's power, then you don't need a horse, and you can pull the cart with a very small force, but in fact, to overcome the reaction force of the car, you have to ...... horse."

"In fact, Newton's third law, 'action equals reaction' is changed to 'action equals reaction', which is easier for ordinary people to understand."

"Understand, it's like cutting muscles with a blade, no matter how sharp the blade is, it takes a lot of force to pierce the skin and muscles, just like the reaction force of a horse-drawn cart."

Liu Fei nodded thoughtfully, today, he finally figured out the problem that had puzzled him all along, and he had a feeling of being impressively cheerful.

Powell never dreamed that Liu Fei's consultation on the third law was to reach the highest level of the art of killing, because whether it is a mecha battle or a battle using Yuehua, its essence is inseparable from action and reaction......

To put it simply, Cassel's so-called art of killing is to bring the forces of action and reaction to the highest level.

"Hey, here, we may get along for a while, just ask if you have any questions." Powell was enthusiastic.

"Hmm."

At this time, the hovercar has arrived at a huge cabin, above the cabin is a huge metal dome, the metal wall below the dome is a dense metal channel, there are constantly rail cars shuttling in the passage, some equipment and armor through some bulky cargo mecha loaded into the rail car and the hovercar, the whole cabin is in full swing, it is conceivable that the dense passage on the metal wall must be like a spider web, may reach any place in the space city......

"Old five, a newcomer has arrived, be gentle, there are contract workers!" After Liu Fei got out of the car, a policeman shouted into the busy crowd.

"Gentle fart, Space City is going to end, and none of us will survive...... Contractor, contractor...... Damn contract workers, can't you just find some skilled people?! A short and fat man wearing a hard hat, shirtless, and covered in oil came over and scolded, and spat at Liu Fei and them, with a look of disdain.

"One hundred and three, you sign." The policeman impatiently handed Humpty Dumpty a paper document and a pen.