1900: A physics genius wandering around Europe

Chapter 130 Atomic Research and Quantum Mechanics

After coming out of Thomson's office, Li Qiwei began his busy work.

While reviewing the history of the development of atomic physics, Li Qiwei was writing his doctoral thesis.

This is a habit he developed in his previous life.

He likes to first grasp the development of physical theories from a macroscopic perspective and sort out the chronological relationship between various theories.

Only in this way, during the learning process, you will not be dazzled by the names of various people and theories and lose sight of the key points.

The development of the theory of relativity is relatively simple and clear, and there is not much to say.

However, quantum mechanics and atomic structure are extremely complex, and the most great scientists have emerged.

In 400 BC, the Greek philosopher Democritus proposed the concept of "atoms". He believed that everything is made up of atoms.

In the 16th and 17th centuries, after the establishment of the natural science system, scientists confirmed through experiments that atoms are real substances.

For some time thereafter, atoms remained the subject of chemists' investigation.

In 1789, French chemist Lavoisier defined the word atom, and since then, atom has been used to represent the smallest unit in chemical changes.

In 1803, British physicist and chemist, Dalton, founded the famous atomic theory based on the summary of the achievements of his predecessors.

This theory holds that atoms are extremely small solid spheres that are not electrically charged and have nothing inside.

Dalton also measured the masses of different atoms. He took the mass of the hydrogen atom as 1 and defined the relative masses of other atoms compared to the hydrogen atom.

Of course, his measurement results were very rough, but they also stimulated people's enthusiasm for studying atomic structure.

In 1827, British botanist Brown discovered under a microscope that dust would move irregularly on the water surface.

This further proved the particle theory, and this phenomenon is also known as Brownian motion.

In 1877, De Saulks proposed that Brownian motion was caused by the thermal motion of water molecules.

It is worth mentioning that part of Einstein's current doctoral thesis, based on De Sauerke's work, is intended to explain Brownian motion.

He also theoretically proved that atoms are a real existence.

Despite the emergence of many new phenomena, the idea that atoms are indivisible has continued to influence physicists since Dalton.

It was not until 1897 that Thomson discovered the electron, which proved that there was a subdivided structure within atoms.

The atom itself is not charged, but the electrons are negatively charged, which means that there is something positively charged inside the atom.

They exactly neutralize the negative charge carried by electrons, making the atom neutral.

Therefore, the research on the internal structure of atoms attracted many physicists to join.

Real history:
In 1911, Rutherford conducted a scattering experiment of alpha particles bombarding gold atoms, proving that atoms are divided into electrons and nuclei. (Now proposed by Ridgway)
In 1913, British chemist Soddy proposed the concept of isotopes.

He believed that there were atoms in the periodic table that had the same position but different relative atomic masses.

Soon after, Thomson invented the mass spectrometer and discovered dozens of isotopes of different elements.

In 1919, Rutherford bombarded nitrogen nuclei with alpha particles and discovered that the nucleus is composed of protons.

In 1932, Rutherford's student, British physicist Chadwick, bombarded beryllium nuclei with alpha particles and discovered the existence of neutrons.

Only then did physicists figure out the nature of isotopes, that is, atoms with the same number of protons but different numbers of neutrons are called isotopes.

It was later discovered that uranium atoms have three natural isotopes: U234, U235, and U238.

Among them, U235 is the most important isotope, which has influenced the world.

In 1939, German physicist Hahn discovered the phenomenon of nuclear fission by bombarding uranium nuclei with neutrons.

At this point, the structure of the atom was finally figured out.

An atom consists of a positively charged nucleus and negatively charged electrons.

The nucleus of an atom is composed of positively charged protons and uncharged neutrons.

During this period, along with the study of atomic structure, the framework of quantum mechanics was established and developed.

In 1900, Planck proposed quantum theory. (Now proposed by Ridgway)
In 1905, Einstein proposed the light quantum hypothesis to explain the photoelectric effect. (Now proposed by Ridgway)
In 1909, Einstein proposed that light has the dual nature of wave and particle, which is his greatest contribution to quantum mechanics. (Now proposed by Ridgway)
In 1913, Bohr proposed the quantized orbit of electrons, laying the foundation for the development of quantum mechanics.

In 1924, de Broglie proposed the concept of matter waves, believing that real particles also have the wave-particle duality.

In 1925, Heisenberg created matrix mechanics, the first version of quantum mechanics.

In 1925, Pauli proposed the Pauli Exclusion Principle.

In 1926, Schrödinger founded wave mechanics, the second version of quantum mechanics.

In 1926, Dirac proved that wave mechanics and matrix mechanics are mathematically equivalent.

In 1926, Born proposed a probabilistic interpretation of the wave function, which later became the "Copenhagen interpretation".

In 1927, Heisenberg proposed the uncertainty principle.

In 1928, Dirac combined quantum mechanics and special relativity to establish relativistic quantum mechanics, laying the foundation for later quantum field theory.

In 1935, Schrödinger proposed the famous thought experiment "Schrödinger's cat", which extrapolated the quantum behavior of the microscopic world to the macroscopic world.

In 1948, Feynman established the path integral form of quantum mechanics, which is the third version of quantum mechanics.

It can be said that 1925-1928 was the peak period of development of quantum mechanics.

During this period, a most important event took place: the school led by Einstein and Schrödinger and the Copenhagen school led by Bohr.

At the fifth Solvay Conference in 1927, the most exciting and thrilling showdown in the 2000-year history of physics broke out regarding quantum mechanics.

The famous saying "God does not play dice" came from that meeting and has been talked about by countless people since then.

After the theory of quantum mechanics was fully mature, research on atomic structure continued to advance.

Physicists discovered the weak force in the 30s and the strong force in 1947, both of which are related to the atomic nucleus.

This explains the essential principle of radioactive decay of matter.

In the mid-to-late 20th century, physicists discovered that protons and neutrons are made up of even smaller structures, called quarks.

During that period, quantum field theory dominated the world, including quantum electrodynamics, quantum chromodynamics, electroweak theory, the standard model, and so on.

In his later years, Einstein devoted himself to the grand unified theory, and all he wanted to unify was gravity and electromagnetic force.

Because the weak force had not yet been recognized and the strong force had not yet been discovered.

A true grand unified theory should unify the four fundamental forces: gravity, electromagnetism, strong force, and weak force.

In the future, physicists will only be able to unify the electromagnetic force and the weak force, namely the electroweak theory.

The next step is to try to unify the strong force again and complete the so-called weakened version of the grand unified theory.

As for unifying gravity, it is extremely difficult.

This is also the reason why Einstein failed. He picked the most difficult cupid right away, and his IQ was not enough.

Later generations have a misunderstanding about Einstein, thinking that apart from the theory of relativity and the photoelectric effect, he is just an ordinary physicist with nothing to show for himself.

This statement is totally wrong. He also has the following achievements:

In 1905, he explained the nature of Brownian motion and gave a method to calculate Avogadro's constant.

In 1907, he solved the problem of specific heat of solids and became the founder of solid mechanics.

In 1916, the laser principle was proposed, providing a theoretical basis for the birth of lasers in later generations.

In 1917, the static cosmological model was proposed, which became the beginning of later cosmology.

In 1924, he proposed Bose-Einstein condensation and was the pioneer of cold atom physics.

These achievements are actually of advanced level, but compared with the theory of relativity, they can only be regarded as small contributions.

So many people only know Einstein's theory of relativity and ignore his other achievements.

In fact, after a comparison, I was surprised to find how awesome Einstein was in real history.

Relativity and quantum mechanics are equally profound and important theories.

The former was created by Einstein alone, while the latter was perfected by more than a dozen geniuses.

Sit down!

This is also why in Li Qiwei's T series classification, Einstein can be ranked alongside Newton and Maxwell, while others can only be demoted one level.

But no matter what, it was these physics giants who jointly created the grand history of physics in the early 20th century.

However, it is only 1902 and history has already been changed by Ridgway.

He proposed the concept of atomic nucleus and the planetary model of atoms nearly ten years ahead of schedule.

This will undoubtedly accelerate the development of physics as a whole, and even he himself doesn't know how it will develop.

As a witness and participant in this life, and possibly even a leader in the end, how could Li Qiwei not be excited?

At present, he has mastered the special theory of relativity and quantum theory, and can be regarded as the founder and first elder of the two major theories.

As for publishing general physics later, I will consider guiding Bohr, de Broglie and others to achieve results in quantum mechanics.

He could no longer imagine how the history of physics in the future would evaluate him.

Not to mention, he will also be present in future cosmology and atomic physics.

Even across disciplines, including chemistry, biology, medicine, etc.

The more Li Qiwei thought about it, the more excited he became. The more he thought about it, the more outrageous it seemed, and he almost laughed out loud.

This scene happened to be seen by Wilson who came to look for him, "Bruce, what good thing have you thought of now?"

Then he said mysteriously, "I heard that your doctoral research results overturned Professor Thomson?"

Li Qiwei asked: "How did you know?"

Wilson said with a bitter face: "The professor just came to me and said that you and Rutherford have done groundbreaking work for the laboratory and asked me to work harder."

Li Qiwei: “Hahahaha”

Facing the ridicule of the genius, Wilson was naturally in a good mood and as steady as an old dog. He continued to ask: "Bruce, are you about to graduate with a doctorate?"

Li Qiwei thought for a moment and said, "I should apply to defend my doctorate at the end of this year or early next year."

He smiled slightly and thought that it was time to get a doctorate title, otherwise he would be embarrassed to introduce himself when he went out.

This chapter is still necessary. As you can see, there is actually nearly 20 years between the next stage of the plot. If it is advanced, then those celebrities will not appear. If the original time is kept, then the ability to control the plot will be very high, so Urobuchi will carefully think about the subsequent story.

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(End of this chapter)