Examples of modern physics

physics It has changed a lot throughout its history. Over the years, new theories and physical models have emerged, increasingly explaining the laws of the universe where we live and using them to build great technological feats.

The 20th century had what was surely the greatest splendor of physics of all centuries, giving birth to a good part of the modern physics that we know today.

want know more about what modern physics is and what branches are included?

Stay with us and we'll explain it to you!

We define modern physics as all the theories that emerged during the late 19th century, the entire 20th century and so far in the 21st century.

All physics that came after Newton's famous laws are considered theories of modern physics.

Newton revolutionized the world with his three Newton laws and the law of universal gravitation. We could explain the movement of fluids, predict the movement of celestial bodies, and predict the movement of any object in our universe.

For many years it was thought that we were already capable of calculating and predicting all the phenomena that happened in our universe.

Physicists, happy to have a complete explanation of the universe, began to investigate the smallest world, that of atoms, and the largest, that of galaxies.

And surprise...

We were wrong, Newton's laws were broken on smaller scales and on larger ones. We still didn't have a complete explanation of our world.

During the 20th century, most modern physical theories were formulated thanks to general relativity and quantum mechanics.

In the next section we will see the branches that make up today's physics and how they emerged.

Will you stay with us to find out?

The 20th century was a century of unparalleled splendor in physics. The best geniuses in this branch of science lived during that time. The most beautiful theories emerged and all modern physics of our time dates back to those years.

There is a fact that fascinates me and that is that the knowledge that humanity acquired during that century is more than during the entire history of humanity.

Isn't it amazing?

Quantum mechanics began to develop at the beginning of the twentieth century at the hands of geniuses such as Max Planck, Louis de Broglie and Werner Heisenberg.

In 1925, the Austrian physicist Erwin Schrödinger, on a retreat at a spa in Switzerland, used the wave equations that were already known at the time to formulate the Schrödinger equation. This equation allowed us to explain everything that happened in the quantum world as a wave function that evolves in time.

To test his equation, he theoretically calculated the energy spectrum of the hydrogen atom, predicting the experimental results satisfactorily.

At the same time, Werner Heisenberg formulated quantum mechanics from a matrix point of view. Therefore, there was Schrödinger's wave formulation and Heisenberg's matrix formulation. Who was right?

Years later Paul Dirac showed that these two formulations of the quantum world were equivalent.

In the same period of time, Albert Einstein formulated special relativity and general relativity. Thanks to these two theories we understood that time and space are united through space-time. Our entire universe is immersed in this space-time fabric. The matter deforms this tissue and the curvature it generates is the cause of the gravitational attraction.

We already had the theory that described the smallest world, that of atoms, and the theory that described the largest world, that of galaxies and stars.

But... What happens when quantum effects and relativistic effects take place at the same time?

In heavier atoms, the number of electrons orbiting the nucleus is greater. The repulsion between them causes them to move faster, reaching speeds close to that of light. In this situation the relativistic effects are very relevant.

We need a theory that relates relativity to quantum!

Paul Dirac managed to formulate an equation that linked the Schrödinger equation with the energy equation of special relativity. From this fusion the famous Dirac equation was born, capable of describing special relativity effects in the quantum world.

Little by little, quantum field theory began to emerge. This relativistic quantum theory described the different fundamental interactions of the universe through quantum fields, their energies and certain symmetries associated with them.

From these works, quantum chromodynamics was born. Quantum field theory that describes the strong nuclear interaction, that force that is capable of keeping atomic nuclei well together.

The quantum field theory that describes electromagnetic interaction, quantum electrodynamics, was also formulated. In this formulation the electromagnetic force is described as the exchange of photons between charged particles.

We almost had it!

We have created a theory capable of describing relativistic effects with quantum mechanics, but what about gravity?

We need to fit the theory of general relativity with quantum physics. Many famous physicists such as Stephen Hawking or Albert Einstein died without achieving their dream: the theory of everything.

During the 1960s, an Italian physicist named Gabriele Veneziano discovered a function that managed to explain certain experimental results on the strong nuclear interaction. This function was neither more nor less than Euler's beta function.

A few years later, physicists Leonard Susskind and Yoichiru Nambu interpreted Veneziano's discovery as a model of relativistic vibrating strings.

Different modes of vibrations of these strings would give rise to the different subatomic particles that we know. This is where string theory was born.

Scientists saw that for string theory to comply with the rules of quantum mechanics they would have to exist in a 26-dimensional world. This caused certain doubts among physicists of the time and this theory lost strength.

A few years later, applying what is known as supersymmetry, the theory was reduced to 10 dimensions. They made certain advances in string theory that encouraged physicists to continue their research.

In the early 90s there were 5 different superstring theories.

How could it be?

Between 1994 and 1997, what is known as the second revolution in string theory took place.

It was shown that the 5 existing superstring theories were actually different sides of the same coin. All of them were equivalent and were related through mathematical operations called dualities.