Ge Zi shook his head, "I don't understand, did we get to Cassini Station first, or did the group of people from twenty years ago go to Cassini Station first?" ”

"Of course we are." Dai Yue said, "Our universe is within the quasi-time line, as long as we are within the quasi-temporal line, the so-called time reversal or causal reversal is absolutely impossible." ”

"What is a timeline?" Ge Zi asked.

Dai Yue cast his eyes on Zhuozhi.

Scratching his head, he muttered, "I'm not a professional either...... I can only tell you the basic concept, what is a timeline? Let's start from the beginning, if there is a one-dimensional universe, we draw a coordinate system, the X axis represents the space position, and the Y axis represents the time position, then anything moving in this universe can find the exact position and trajectory in this coordinate, right? ”

Ge Zi continued to frown, she raised her head and thought about it carefully, physics was really not her field of expertise.

"Think of it as a progress bar." Dai Yue reminded.

Ge Zi nodded slowly.

Say the progress bar and she'll understand.

Zhuo Zhi drew a coordinate system on the floor, "Now let's set up this coordinate system, upgrade the one-dimensional space universe to the two-dimensional space universe, rotate one week based on the X axis of the coordinate system, and let it sweep a circle into a two-dimensional plane, become a three-dimensional coordinate system, and the time axis is the vertical Z-axis, so in this three-dimensional coordinate system, the position and trajectory of any object at any time in the two-dimensional universe can also be found, right?" ”

Ge Zi nodded.

"Okay, now we are objects in this two-dimensional space universe, we no longer have height, only waist circumference, moving in this flat universe like a big pie, taking Xiao Zi yourself as an example, build a coordinate system with your current time and position as the origin...... Then you go out and spend a few minutes at the door of Cassini Station, and your position in the coordinate system changes, right? We take the position you reach as point A, and the process from the origin to point A is the trajectory of your movement, which is easy to understand, right? ”

Ge Zi nodded.

Mu Mu sat on the side and chewed dry food, his face was expressionless, he was not very interested in physics class.

"Let's say your trajectory is straight and moving at a uniform speed." Zhuozhi continued, "So what does your trajectory look like in the coordinate system?" ”

"A short line segment radiating from the origin." Ge Zi replied.

"That's right." Zhuo Zhi said, "Then we continue to ascend to the dimension, back to our normal three-dimensional space universe, because we can't draw a coordinate system with four dimensions, so we can only continue to use this coordinate system to represent the motion of objects, the plane represents space, and the Z axis represents time, fortunately, Xiaozi You are only moving on the plane, so you can also use this coordinate system to approximate the representation...... So now the question is, is your trajectory in this coordinate system unlimited? ”

Ge Zi was stunned.

"What do you mean?"

"Does that mean that you can draw the trajectory of motion in this coordinate system with impunity?" Insight explained, "You can move how you want, and you can twist how you want?" ”

Ge Zi pondered for a moment and shook his head, "No." ”

Wisdom nodded, a slight smile in his eyes, "Why?" ”

"Because there's a limit to my speed." Ge Zi said.

“Bingo！” Dai Yue snapped his fingers, and he finally found a chance to speak, "That's right, in this coordinate system, there is an insurmountable boundary - that boundary is the movement of light, Xiao Zi, you stand at the origin point, holding a light bulb in your hand, then the light emitted by the light bulb will build an insurmountable wall for you in the coordinate system, because you can't be faster than the light, at the same time, you can't reach the place where the light can reach." ”

"And the speed of light is 300,000 kilometers per second." Zhuo Zhi said, "In a planar coordinate system, its trajectory is an oblique line, while in a three-dimensional coordinate system, its trajectory is a cone. ”

"That's the light cone."

"The diagonal line that makes up the light cone is called a ray-like ray." Insight went on to say, "We are all within the quasi-ray, which is called the quasi-timeline. ”

"What about beyond that kind of light?" Ge Zi asked.

"Beyond the light-like world is the faster-than-light world." Insight replied, "That's called a class empty line." ”

"As long as you are in a time-like line, going back in time, it is impossible to reverse cause and effect, there may be universes like empty lines, in their universe, the speed of light is the lowest speed, but this is not possible in our universe, Mu Mu put forward a very interesting idea." Wisdom nodded, "But that's just going to stop at imagining." ”

Of course, this is just an assumption.

They had no evidence to prove that this speculation was correct.

Even if there really exists a space-like universe, then they can't get by, and the speed of light is a greater barrier than life and death.

"It's small talk, anyway." Mu Mu shrugged his shoulders and said in a relaxed tone, "Any great scientific discovery is based on bold conjectures, and everything is possible. ”

"That's a big discovery." Dai Yue said, "The huge breakthrough that subverts the cosmology is nothing compared to this. ”

The true face of the black ball has been speculated by them to a rather inexplicable realm, in the tea party between resting and sleeping in Cassini Station, Mu Mu, Ge Zi, Zhuo Zhi and Dai Yue and others have put forward all kinds of strange opinions, what alien civilization spaceship parts, advanced wisdom observation window, unknown products of nature, condensed version of the black hole bomb, and even the universe in the shell -

These discussions are of zero value in the sense of scientific research, but on a long level, the black ball is undoubtedly a topic that will make everyone's ears prick up.

This brings us to the second doubt.

The mysterious disappearance of Lou Qi.

Compared to black balls, this is also an unexplainable problem.

Lou Qi suddenly disappeared in the P3 lab, and a living adult evaporated, and they couldn't figure out what was going on even if they wanted to break their scalps.

"Actually, I have a bold idea."

Mu Mu said.

Mumu's vision is always bold.

"What?" The rest looked up.

"Hackham razor cut this man down." Mu Mu spread his hands out, looking like a broken jar, "Instead of dwelling on how this person disappeared from the airtight P3 laboratory, it is better to simply think that he does not exist, just like magic, the magician shows you a cage that ants can't get into, and then he gets in and closes the door and locks it, and then snaps!" The magician disappeared from the cage...... Compared to the magician's ability to penetrate walls, it is more likely that he has never been in a cage at all. ”