What is physics?

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Traditional definition

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Before applying the newly introduced concepts, let's establish a common understanding of what physics is.

During the Scientific Revolution, key figures like Galileo Galilei, Isaac Newton, and René Descartes helped to separate physics from natural philosophy, allowing it to consolidate as an independent discipline. This new science used mathematical models to describe phenomena such as motion, optics, and mechanics. In his work Principia Mathematica (1687) [1], Newton presented a vision in which natural phenomena could be explained through universal mathematical laws, establishing a solid mathematical and empirical foundation for physics.

Galileo Galilei [2], Isaac Newton [3], René Descartes [4]



Over time, the study of phenomena such as electricity, magnetism, and thermodynamics expanded the fields within physics and strengthened the experimental approach. The contributions of Michael Faraday, James Clerk Maxwell, and Ludwig Boltzmann promoted a more quantitative physics, in which matter and energy were understood through universal laws and experimental methods, solidifying physics as a science based on measurable and reproducible principles.

Michael Faraday [5], James Clerk Maxwell [6], Ludwig Boltzmann [7]



In the 20th century, modern physics, understood as the study of matter and energy at all scales, was consolidated with the development of quantum mechanics and the theory of relativity. Figures like Albert Einstein, Niels Bohr, and Werner Heisenberg expanded the scope of physics to include phenomena on the subatomic scale, while Edwin Hubble extended its application to the cosmos and galaxies.

Albert Einstein [8], Niels Bohr [9], Werner Heisenberg [10], Erwin Hubble [11]

Thus, physics tends to be defined as the science that uses mathematical models and experiments to explain the properties and behavior of matter and energy, covering phenomena from the subatomic to the galactic level.

However, while this definition describes the vast scope of physics, it does not delve into its methodological approach, how it operates, or the types of results it can achieve.

Books

[1] Principia Mathematica (Mathematical Principles), Isaac Newton (1687)

Images

[2] Justus Sustermans, Public domain, via Wikimedia Commons

[3] James Thronill after Sir Godfrey Kneller, Public domain, via Wikimedia Commons

[4] After Frans Hals, Public domain, via Wikimedia Commons

[5] Thomas Phillips, Public domain, via Wikimedia Commons

[6] George J. Stodart, Public domain, via Wikimedia Commons

[7] Universität Wien, Public domain, via Wikimedia Commons

[8] Bettmann / Contributor via Getty Images

[9] The American Institute of Physics credits the photo [1] to AB Lagrelius & Westphal, which is the Swedish company used by the Nobel Foundation for most photos of its book series Les Prix Nobel., Public domain, via Wikimedia Commons

[10] Bundesarchiv, Bild 183-R57262 / Unknown author / CC-BY-SA 3.0

[11] Johan Hagemeyer, Public domain, via Wikimedia Commons

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How physics works

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The essence of physics lies in the fact that, as a science, it uses the scientific method to develop hypotheses that lead to models explaining how the world around us functions. It is not limited to a superficial description but allows precise estimations of the values of the parameters involved, relying on universal constants, specific constants, and mathematical relationships ideally derived from fundamental principles. These evaluations enable the rigorous application of the scientific method, as the calculated values can be measured and verified, thereby confirming the model's accuracy relative to reality.

Francis Bacon [4], René Descartes [5], Karl Popper [6]

The foundation of the modern scientific method is based on the work of Francis Bacon [1], who proposed an inductive approach, emphasizing the importance of observation and experimentation. This approach was complemented by René Descartes' [2] systematic and deductive method. Finally, the concept of falsifiability in hypotheses, introduced by Karl Popper [3], completed this framework, establishing that a scientific theory must be refutable to be considered valid.

Books

[1] Novum Organum Scientiarum (New Instrument of Science), Francis Bacon (1620)

[2] Discours de la méthode (Discourse on the Method), René Descartes (1637)

[3] The Logic of Scientific Discovery, Karl Popper (1934)

Images

[4] National Portrait Gallery, Public domain, via Wikimedia Commons

[5] After Frans Hals, Public domain, via Wikimedia Commons

[6] Lucinda Douglas-Menzies link, No restrictions, via Wikimedia Commons

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Continuous development of physics

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Its essential to remember that the scientific method requires creating empirically verifiable models; this does not imply that these models are absolutely true, but rather that, given our current knowledge, they align with what we observe in the real world. However, in the future, new situations may reveal discrepancies or demonstrate that a models foundational principles are no longer valid. In such cases, the equations, the model itself, and our understanding of how the world functions must be adjusted.

In this context, when a discrepancy shows that a model is inadequate, recognizing its limitations and developing a new model is not a failure but an advancement in our ongoing quest to understand the universe. Each correction and adjustment brings us closer to a deeper and more accurate understanding of reality.

Sometimes, previous models continue to be used in areas where they do not show significant discrepancies, as they are often simpler than their successors. A classic example is Einsteins theory of relativity, which generalizes certain aspects of classical mechanics. However, at low speeds and in everyday situations, the Newtonian model is easier to apply, and the differences with experimental results are negligible.

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Other areas supported by physics

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Today, the scientific method in physics is applied not only in traditional areas, covering everything from the subatomic world to galaxies, but also in non-traditional areas that have adopted the principles and methods of physics to address their specific challenges.

Traditional Areas of Physics

Physics continues to advance in traditional fields such as particle physics (which studies subatomic particles and fundamental forces), nuclear physics, astrophysics, and cosmology (which explore the universe on a grand scale). It also remains active in foundational areas like mechanics, electromagnetism, optics, thermodynamics, and condensed matter physics.

Non-Traditional Areas of Physics

In recent years, physics has expanded its influence into disciplines once considered outside its scope, applying its principles to analyze complex and varied problems. This phenomenon has led to the development of what is sometimes called "topic-specific physics," where physical models are used to study phenomena in different disciplines. Examples of these areas include:

Physics in Dentistry: Focuses on the mechanics of dental materials, chewing forces, and the behavior of dental tissues, contributing to the development of prosthetics and orthodontic treatments.

Physics in Medicine: Applies physical principles to medical diagnostics and treatments, including MRI, tomography, and radiotherapy, enhancing the diagnosis and treatment of diseases.

Physics in Kinesiology: Studies human movement, analyzing biomechanics and the forces involved in locomotion and physical exercise, essential for rehabilitation and therapeutic development.

Ocean Physics: Investigates ocean dynamics, including currents, tides, and ocean-atmosphere interactions, which are fundamental for understanding climate and marine ecosystems.

Soil Physics: Examines the physical properties of soils, such as permeability and structure, which are essential in agriculture and environmental conservation.

Climate Physics: Analyzes the physical processes governing the Earth's climate, including heat transfer and atmospheric systems, to improve climate prediction and model climate change.

Biophysics: Explores biological processes through physical principles, addressing topics such as protein structure, ion flow, and DNA mechanics using quantum mechanics and thermodynamics.

Geophysics: Applies physical methods to study the Earth's structure, including seismology, terrestrial magnetism, and plate tectonics, crucial for understanding earthquakes and volcanic activity.

Neurophysics: Examines the nervous system from a physical perspective, investigating neural signal transmission and electrical processing, aiding in understanding brain function and neural activity.

Physical Chemistry: Although closely related to chemistry, physical chemistry applies physical principles to study chemical reactions and molecular properties, such as thermodynamics and kinetics.

Environmental Physics: Applies physical principles to environmental studies, analyzing pollutant dispersion, the water cycle, and solar energys impact on ecosystems.

Materials Physics: Studies mechanical, electrical, and optical properties of materials, essential for developing new materials such as semiconductors and superconductors.

Forensic Physics: Uses physical techniques in criminal investigations, such as ballistics, accident reconstruction, and isotope dating for material analysis.

Agrophysics: Applies physics to agriculture, analyzing processes like soil structure, nutrient dynamics in plants, and heat transfer in crops.

Psychophysics: Explores the relationship between physical stimuli and sensory perceptions, examining how the brain interprets stimuli such as light and sound.

Computational Physics: Uses simulations and mathematical models to solve complex problems, essential in areas like climate modeling and particle simulation.

Astrobiology and Space Life Physics: Explores the possibility of life on other planets and how living organisms adapt to extreme space conditions.

Sociophysics: Applies statistical physics methods to analyze social phenomena, such as the spread of opinions and collective behavior.

Econophysics: Uses physical theories, particularly from statistical mechanics, to model complex economic systems and phenomena such as market fluctuations and financial crises.

Impact of Physics Expansion

This expansion of physics into new applications demonstrates its versatility and relevance, as it provides tools and models capable of analyzing and understanding complex phenomena across a wide spectrum of disciplines, from natural sciences and medicine to social sciences and economics. By adopting physical approaches, these areas benefit from greater precision in their methods and a deeper understanding of the phenomena they study, significantly contributing to scientific and technological advancement.

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