Modern physics

Modern physics
Modern physics
Modern Physics encompasses the discoveries and research that were developed at the end of the 19th century and which are still the subject of study.

Modern physics is the scientific production that occurred or was based on the discoveries of physicists from the end of the 19th century onward. Even though a lot of time has passed, many of the scientific questions raised during this period remain unanswered. Because of this, the “modern” classification is maintained.

This area of ​​knowledge has as its object of study the behavior of bodies that move at speeds close to or, theoretically, equal to that of light. It also studies bodies with dimensions equal to or smaller than those of atoms and bodies separated by astronomical distances (light years).

Some pioneers founded the greatest discoveries or questions that constitute modern physics, such as Einstein, with the theory of restricted relativity and the photoelectric effect; Marie Curie, with radioactivity; Max Planck, with quantified energy; and Niels Bohr, with the study of the hydrogen atom. Even with so many innovations, Classical or Newtonian physics is still valid, but limited to certain speeds, dimensions, and distances of the bodies under study.

Modern physics
Modern physics

Summary of Modern Physics

  • Modern Physics is the union of scientific advances that have occurred since the end of the 19th century.
  • Modern physics studies the theories of restricted relativity, quantum mechanics, and nuclear Physics.
  • Among the milestones of modern physics, we can highlight the behavior of particles with speeds close to or equal to that of light.
  • A second milestone in modern physics was the discovery of the hydrogen atom and quantified energy.
  • Classical physics is still valid for bodies with speeds much lower than that of light, dimensions much higher than those of atoms, or bodies separated by distances less than astronomical.

What is modern Physics?

Modern Physics is an overview of the innovations and inquiries that occurred after the end of the 19th century and the 20th century onwards. The classification is maintained due to the fact that many of the questions have not yet been answered, and those that have been answered have led to even more questions.

What does modern physics study?

Modern Physics encompasses the study of:

  • Special relativity theory: studies the behavior of bodies that move at speeds close to or equal to that of light and the spatial and temporal phenomena associated with this.
  • Quantum mechanics: studies the behavior of bodies equal to or smaller than the dimensions of atoms.
  • Atomic physics: its object of study is the electronic arrangement of atoms and molecules, the electromagnetic radiation they can emit, and the way in which they or the radiation interact with matter.

From these branches of study, several branches emerged, such as the study of bodies that are several light years from Earth. The study of them is possible due to advances in the behavior of light and bodies that travel at speeds close to it. Another application is the operation of microchips using quantum tunneling based on the Heisenberg uncertainty principle.

History and Milestones of Modern Physics

Modern Physics presented several relevant milestones that launched a new era for Physics, explaining or correcting gaps left by classical Physics. Next, the four main ones will be listed.

→ Max Planck — Quantization of energy

Max Planck (1858-1947) was a theoretical physicist who dedicated himself mainly to the study of thermodynamics . According to Planck, the closer to white, the higher the temperature radiated by the body. An example is the incandescent lamp filament, which reaches temperatures exceeding 2000 °C.

Planck’s calculations led him to the conclusion that bodies that have high temperatures did not emit this energy in the form of a wave as was thought, but in the form of small packets of energy, called “quantum” by him, being the smallest possible amount of energy. energy proportional to the frequency of radiation that is captured, absorbed, or emitted by the body.

During the period in which this theory was presented, it was not well received, since the explanation given by the wave seemed to be more favorable to the opinion of the scientific community, but with the contribution of the photoelectric effect presented by Einstein, the theory ended up being more accepted.

→ Albert Einstein — Special theory of relativity

Albert Einstein (1879-1955) was one of the greatest physicists in history. The special theory of relativity he proposed is based on two principles :

  • The first principle implies that the laws of Physics are valid for all inertial frames of reference.
  • The second principle says that the speed of light in a vacuum is the same for every observer, regardless of their speed.

Thus, it was concluded that for objects that move at a speed close to that of light, time dilates, that is, it is as if it passes more slowly in this condition. In the case of distance or length, it contracts. It is as if the length were shorter than the speed of light or a value close to it.

The mass of a body at a speed close to that of light tends to expand — it is as if it were larger. Thus, relativistic energy is equivalent to the product of the speed of light (c), which is approximately 3·10 8 m/s², and the difference between the mass of the body at rest (m 0 ) and its mass at maximum speed (m).

Interesting: Another relevant contribution made by Einstein, who collaborated with Planck’s theory, was the explanation of the photoelectric effect discovered by Heinrich Hertz. According to him, when light with a certain frequency is projected onto a metallic surface, the photons (quantum, according to Planck) that make up the light transmit energy to the electrons that are linked to the metal atoms, causing them to be ejected from the metal. core. This principle is widely used in solar panels.


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