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Relativity and Modern Physics

The Theory of Relativity is the set of scientific formulations developed at the beginning of the 20th century by physicist Albert Einstein.

Its objective was to resolve the theoretical incompatibility between the two primary fields of physics: Newtonian mechanics and electromagnetism.

These formulations were published as two distinct scientific theories:

Theory of Spatial Relativity: A treatise on the physics of the motion of bodies in the absence of gravitational forces, which reconciled Maxwell's equations for electromagnetism with Newton's equations for motion.

General relativity: A theoretical approach to gravity and both inertial and non-inertial reference frames. It generalizes the theory of special relativity and replaces Newtonian gravity in cases where gravitational fields are very strong.

The basic foundations of the Theory of Relativity can be summarized as the fact that the location in space and time of a given phenomenon always depends on the speed at which the observer is moving.

Or, to put it more simply: things can be perceived very differently depending on the observer's point of view, even in relation to dimensions that until now were considered absolute, such as time or space.

This, which at first seems simple, allowed us to rethink the way contemporary physics understood time and space. Furthermore, it opened the door to a whole series of new equations surrounding phenomena that, at first, seem contrary to common sense.

Among these phenomena are spatial contraction, time dilation, and the universal speed limit (equivalent to the speed of light).

On the other hand, Einstein discovered the equivalence between mass and energy, which he expressed in the famous formula E = m.c^2 (energy equals mass times velocity squared).

Importance of the theory of relativity

Einstein's theories re-established modern physics. They were quickly adopted by all the major centers of thought and physics research around the world.

They also had a significant impact on philosophy, as, among other things, they denied the existence of absolute time and allowed us to think, in serious terms, about matters that had once been the preserve of fantasy and daydreaming, such as time manipulation and high-speed space travel.

Although its concrete explanation may seem tedious or complicated, it is worth highlighting that the Theory of Relativity has been proven. In fact, it has been put into practice in matters as complex as atomic energy.

Furthermore, there is evidence of slight but undeniable differences in aging and the passage of time between astronauts and Earthlings, given that the latter, being more subject to the planet's gravity, experience time more quickly.

Einstein's theories led to the emergence of cosmology, a branch of physics dedicated to determining the conditions at the origin of the universe. His observations of the curvature of light were publicly verified in 1919 during a solar eclipse.

Activity. Answer the following questions.

Remember to review the answers to the open-ended questions at the bottom of this page.

1. What did the Theory of Relativity seek to solve?

2. What is the name of the theory that studies the motion of bodies in the absence of gravity?

3. General Relativity is mainly about:

4. What is the universal speed limit?

5. What phenomenon did General Relativity verify during a solar eclipse in 1919?

Once you click this button, the questions will close and you will not be able to change your answer.

6. What formula expresses the equivalence between mass and energy?

7. How does Earth's gravity affect the aging of astronauts?

8. Why did relativity have an impact on philosophy?

9. What is cosmology and how does it relate to relativity?

10. How can the basic foundations of the theory of relativity be summarized?

Still have questions?

We recommend visiting the following materials for further knowledge or understanding on the topic:

Answers to open-ended questions:

6. E = m.c^2

7. Time on Earth is faster because they experience less gravity.

8. Because it denied the existence of absolute time and opened the possibility of space travel and time manipulation, previously considered mere fantasy.

9. It is the branch of physics that studies the origin and evolution of the universe, made possible by the laws of General Relativity.

10. The location in space and time of a given phenomenon will always depend on the speed at which the observer is moving.

References:

1. Leskow, E. C. (2025, 20 mayo). Teoría de la Relatividad - Concepto, utilización e importancia. Concepto. https://concepto.de/teoria-de-la-relatividad/ https://concepto.de/teoria-de-la-relatividad/

2. Perkowitz, & Sidney. (1999b, julio 26). Relativity | Definition, Equations, & Facts. Encyclopedia Britannica. https://www.britannica.com/science/relativity https://www.britannica.com/science/relativity

3. Bartels, M., Tillman, N. T., & Dutfield, S. (2024, 29 octubre). What is the theory of general relativity? Understanding Einstein's space-time revolution. Space. https://www.space.com/17661-theory-general-relativity.html https://www.space.com/17661-theory-general-relativity.html

4. Institute of Physics [IOP]. (s. f.). Relativity. https://www.iop.org/explore-physics/big-ideas-physics/relativity https://www.iop.org/explore-physics/big-ideas-physics/relativity

5. Professor Dave Explains. (2017b, mayo 11). Special Relativity Part 1: From Galileo to Einstein [Vídeo]. YouTube. https://www.youtube.com/watch?v=rBmYUEnafok https://www.youtube.com/watch?v=rBmYUEnafok

6. Science ABC. (2018, 13 abril). Time dilation - Einstein’s theory of relativity explained! [Vídeo]. YouTube. https://www.youtube.com/watch?v=yuD34tEpRFw https://www.youtube.com/watch?v=yuD34tEpRFw

8. CrashCourse. (2017, 23 febrero). Special Relativity: Crash Course Physics #42 [Vídeo]. YouTube. https://www.youtube.com/watch?v=AInCqm5nCzw https://www.youtube.com/watch?v=AInCqm5nCzw