Modern Physics: Relativity, Quantum Mechanics, and Nuclear Processes

Modern Physics

This branch of physics considers the theory of relativity and quantum theory in describing microscopic systems like atoms.

Model of Modern Physics

In the late nineteenth century, it was a common belief that all phenomena of nature could be described by Newton's laws, principles of thermodynamics, and the laws of electromagnetism, which were based on a mechanical conception of the universe.

Reaffirmation of Modern Physics

In 1905, Albert Einstein produced a series of works that revolutionized physics, mainly due to the wave-particle duality of light and the theory of relativity, among others.

Classification of Modern Physics

It is generally known to study phenomena that occur at the speed of light or values close to it, or whose spatial scales are the size of an atom or smaller. It is divided into:

• Quantum mechanics
• The theory of relativity

Isotope

Two atoms are isotopic if they have the same atomic number (i.e., the same number of protons in their nucleus, which determines the element) but have different mass numbers due to different numbers of neutrons in their nucleus.

Nuclear Fission

Nuclear fission is the breakdown of an atom to form two or more species. This phenomenon is well-known. A heavy nucleus, like enriched uranium, is bombarded with particles to break it apart, with the consequent release of energy and subatomic particles.

Nuclear Fusion

Nuclear fusion is the combination of two or more atomic nuclei to form a new species. For example, the formation of helium from two hydrogen nuclei. This phenomenon occurs in the sun.

Radioactivity

Radioactivity is a natural physical phenomenon by which some bodies, called radioactive, emit radiation. This radiation has the property of impressing photographic plates, ionizing gases, passing through opaque bodies, and causing fluorescence.

Time Dilation

Time dilation is a phenomenon predicted by the theory of relativity, where an observer notes that another clock (a physically identical clock) is marking time at a slower pace than their own. This is usually interpreted as time passing slower for the other clock, but this is only in the context of the observer's reference frame. Locally, time is passing at the same pace. The phenomenon of time dilation applies to all physical processes.

Relativistic Mass

Currently, the scientific community, especially in the context of particle physics, considers the invariant mass as the only mass, while the concept of energy has replaced relativistic mass.

Theory of Relativity

The theory of relativity includes two theories (special relativity and general relativity) developed by Einstein in the early twentieth century. These theories sought to resolve the incompatibility between Newtonian mechanics and electromagnetism.