All physics problems are, in the final analysis, mathematical problems.

……

Early the next morning, Pang Xuelin came directly to his office, turned on the computer, and Pang Xuelin said directly: "MOSS, give me the latest simulation results of the earth's transfer orbit today, and provide the latest research data on the influence of the earth's crustal motion on Jupiter's gravitational field!" ”

"Okay, Dr. Pang Xuelin, please wait!"

In less than a minute, various data files appeared densely on the computer desktop.

MOSS is a new generation of artificial intelligence system developed by human beings on the basis of carbon-based chips, and its main body is installed in the "Pangu" supercomputer system located in the earth's cockpit to assist the earth's joint government to control the earth's flight orbit.

One of its doppelgangers is located on the Navigator space station and is responsible for the operation of the Navigator space station.

As one of the members of the scientific committee, Pang Xuelin naturally has the authority to mobilize MOSS to serve him.

Pang Xuelin sat in front of the computer and began to quickly browse the latest research papers related to the intersection of ground and wood.

……

"Jupiter's tidal force does dramatically alter the distribution of water and atmosphere at the intersection of Earth and wood, but the atmosphere and oceans do not leave the Earth until the impact occurs. A fluid planet experiences more gravitational pull at the end near the gravitational source (near end) and less gravitational pull at the end away from the gravitational source (distal end). This gravitational difference will elongate the fluid planet, so that the gravitational pull at the near end is greater and the gravitational pull at the far end is smaller, creating a greater gravitational difference, stretching the celestial body longer until its own gravity can no longer sustain the gathering of fluids and is pulled into pieces. It's a positive feedback process. ”

"And for the earth, the ocean and the earth are extremely thin layers. Under the action of tidal forces, the atmosphere and oceans converge at opposite ends of Jupiter, and the positive feedback process is interrupted. At this time, in order to take away the sea water and atmosphere that have gathered into two lumps, it is still necessary to approach the rigid body Loch limit (the rigid body Loch limit of the Earth's intersection is 70,000 kilometers, which is less than the radius of Jupiter) and defeat the gravitational pull of the entire Earth. ”

"At a distance of 100 times Jupiter's radius (7 million kilometers), Jupiter's tidal attraction causes tides several meters high."

"At a distance of 20 times Jupiter's radius (1.4 million kilometers), if the oceans are not frozen, the Earth's tidal heights can reach hundreds of meters, and disaster begins to strike, with the two latitude zones facing Jupiter and facing away from Jupiter. At the same time, some earthquakes will be induced. ”

"When the distance is 8 times the radius of Jupiter (560,000 km). Atmospheric tides are already enough to drop the air pressure in much of the planet to a point where it can cause altitude sickness. At the same time, the stress in the plate is exhausted and tends to stabilize. Volcanic activity continues to be active in the area where the plates intersect. ”

"As we approach the Earth-Moon distance (300,000 km), Jupiter's gravitational force reaches three-thousandths of its gravity, and parts of the Earth's crust at the junction of the plates are fragmented more and more."

"At a distance of Jupiter with a Earth's diameter (12,000 kilometers), Jupiter's gravitational force reaches 28% of the Earth's gravity, and the Earth's crust is largely fragmented. And the tidal forces of the Earth are already enough to seize Jupiter's atmosphere...... Perhaps it would be more accurate to put it another way - Jupiter's atmosphere began to launch the first wave of strikes on Earth. The Earth collides with Jupiter's atmosphere, which is traveling at a speed of up to 60 kilometers per second, which is much greater than the speed of sound, and the energy cannot be dissipated in the form of sound waves. ”

……

"It's a bit interesting, this paper actually describes the whole process of the impact of the ground wood."

Pang Xuelin attached his own comments to this paper and forwarded it to the secretary of political affairs, and this kind of paper has a certain reference value for how the coalition government can deal with the crisis that may arise from the intersection of land and wood.

He then opened another file and stared at the complex system of nonlinear partial differential equations on the computer screen.

This set of nonlinear partial differential equations, which is a combination of mathematicians from all over the world, is corrected every day according to the latest supercomputing simulation results to obtain the system of ground transfer orbit equations, which is extremely computational and can only be simulated by computers.

Theoretically speaking, it is only a problem of Newtonian mechanics to calculate the safe transfer orbit when the ground and trees meet, and the evolution of the system can be determined according to the equation of motion and the initial conditions of the system, and the future can be predicted, which belongs to the deterministic system.

But in reality, even small changes can have a significant impact on the results due to too many external random factors.

For example, Jupiter's gravitational pull causes disturbances in the Earth's crust, causing strong global earthquakes that cause planetary engines to lose thrust.

For example, Jupiter's interior changes in density due to the Earth's gravity, which in turn affects the gravitational pull between the two.

In addition, among the 72 moons of Jupiter, there are four moons with a diameter of more than 2,500 kilometers, of which Ganymede is 4,800 kilometers, second only to the Moon.

When all these external factors are superimposed, and then a system of nonlinear partial differential equations is listed, it is almost impossible to give an accurate analytical solution.

In recent years, a variety of methods have been developed to solve the exact solution of nonlinear partial differential equations under the principle of homogeneous equilibrium, such as the Tanh function method, the Sine cosine method, the Jacobi elliptic function expansion method, the Riccati equation method and the F-expansion method, etc., and then solve them with the help of computers.

However, with a pure mathematician's intuition, Pang Xuelin faintly felt that for the partial differential equation system in front of him, the accuracy of the methods currently used in the mathematical community is limited.

The main reason is that there are too many variables in this set of equations, and any small deviation can make a big difference in the results.

"No, even if you can't give an analytical solution to this set of equations, you have to give a few specific exact solutions!"

Pang Xuelin's eyes narrowed slightly.

"But which way should I solve it?"

Pang Xuelin frowned.

"Is it possible to try to use the AC=BD model in differential geometry and the Wu differential eigentrain method to give a general form of Riccati equation with various forms of solutions, and then give a mechanized method to find the solitary wave solution of nonlinear partial differential equations......

"No, although this method can transform the solution of nonlinear differential equations into the solution of nonlinear superdefinite algebraic equations, it establishes a bridge between the Wu method and the solution of differential equations. However, there is uncertainty in the variables of the equations, and the results are also not very accurate! ”

……

"So is it possible to use geometric integration methods to deal with this partial differential equation?"

Chern, one of the greatest geometricians of the twentieth century, once expressed the idea that "the essence of physics is geometry!" ”

The basic formula of Newtonian mechanics is F=ma, the F on the left is the force, which represents physics, and the a on the right is the acceleration, which is mathematically the second derivative, that is, the curvature in geometry.

Einstein's equation Rik-1/2GikR = 8πKTik.

On the right is the energy-stress tensor, which belongs to physics. On the left is the Richie curvature Rik and the scalar curvature R, which is geometry.

Yang Zhenning's gauge field theory is essentially fiber cluster geometry.

It is not uncommon to solve systems of nonlinear partial differential equations by geometric methods, the question is what kind of geometric method to use.

"What about the RKMK geometric integration method?"

"The undamped Landau-Lifshitz equation was solved numerically by the RKMK geometric integration method, and the analytical solution of the equation was compared. Then, the Landau-Lifshitz equation with an external magnetic field is solved numerically, and the error is compared with the classical Runge-Kutta method, but the problem is that although the RKMK method can maintain the square conservation characteristics of the equation better than the classical Runge-Kutta method, the RKMK geometric integral method is more difficult for the nonlinear Schrodinger equation with variable coefficients......"

……

All kinds of ideas flashed through Pang Xuelin's mind, and he has been thinking about similar things for the past year, but he has never made any progress.

Unconsciously, Pang Xuelin stood up and walked to the window.

Through the office window, a huge holographic projection of the solar system can be seen floating silently above the wheelhouse of the Earth.

Everything in this world seems to be simpler, the sun is just a faint ball of light, and the planets orbit the sun like fireflies in an eternal orbit.

Pang Xuelin seems to have returned to that cold night on Mars.

Under the starry sky, the theories of Ponzi geometry, which had been stagnant for a long time, were quickly established in Pang Xuelin's mind, and the system of partial differential equations seemed to form a wonderful connection, like a lightning bolt, illuminating the dark night sky.

Pang Xuelin shook his head and instantly grasped the fleeting inspiration.

A hint of ecstasy appeared in his eyes, and he quickly turned around, picked up the red confidential phone on the table, and dialed Liu Xin: "Old man, I need to retreat for a while, I have some new ideas and ideas about the issue of the transfer of the ground and wood!" ”

Then, he opened the door of the office again, and Li Yiyi, the technical secretary working outside: "Yiyi, I want to retreat and study during this time, don't let people disturb me, just let your sister-in-law prepare food for me every day!" ”

There is a lounge in the office, and in addition to eating, sleeping and bathing can be solved.

Without waiting for Li Yiyi to react, Pang Xuelin slammed the office door shut, and a trace of excitement flashed in his eyes.

After entering the wandering earth world for so many years, this is the first time he has had such an impatient sense of excitement in academics!