The Constituents of Matter

Feynman begins by noting that all matter in the universe, from the stars to living creatures, is fundamentally composed of the same basic elements. The matter of the stars has been found to be the same as the matter on Earth, as evidenced by the characteristic "fingerprint" of light emitted by different atoms.

He then outlines the key constituents that make up all matter:

• Electrons: Particles found orbiting the nuclei of atoms.
• Nuclei: The dense, central cores of atoms, composed of...
• Protons: Positively charged particles.
• Neutrons: Uncharged particles.

Feynman also mentions another important particle related to the behavior of matter:

• Photons: The fundamental particles of light, responsible for the emission and absorption of energy.

[Diagram to be made of the basic structure of an atom, showing the nucleus with protons and neutrons, and the orbiting electrons.]

Interestingly, Feynman notes that all of the ordinary phenomena we observe in the universe, from the workings of living creatures to the emission of energy from stars, can be understood in terms of the interactions and behaviors of these fundamental particles.

As he states, "With the particles that I've listed here, all of the low-energy phenomena, all of in fact ordinary phenomena that happen everywhere in the universe as far as we know, with the exception of here and there, some very high-energy particle does something, or in a laboratory we've been able to do some peculiar things - but if we leave out those special cases, all ordinary phenomena aren't presumably explained by the action and emotions of these things, these kind of things."

This suggests that the key to understanding the physical world lies in unraveling the properties and interactions of these basic building blocks of matter. Of course, as Feynman will discuss in other sections, the true nature of these particles and their behavior is often deeply counterintuitive and paradoxical, leading to the ongoing challenges and mysteries of modern physics.

To learn more about the specific forces and interactions between these fundamental particles, check out the section on The Challenges of Nuclear Forces.