¿Cómo sabemos que la Tierra no es plana? - Todo tiene un porqué

How Do We Know the Earth is Not Flat?

Introduction to the Topic

• The program focuses on answering the question of how we know that the Earth is not flat, exploring historical and scientific perspectives.

• It highlights that throughout history, scientists have gathered evidence supporting a spherical Earth, despite our perception of it as flat.

Historical Perspectives on Earth's Shape

• Discussion includes ancient philosophical arguments for a flat Earth and early astronomers' observations of the sky.

• The significance of Copernican revolution in astronomy is mentioned, along with Léon Foucault's contributions to proving Earth's sphericity.

Understanding Perspective

• Hernán Greco Hernández explains why we perceive the Earth as flat from our perspective, using an analogy of a louse on a basketball.

• He emphasizes that our small size relative to the planet leads to this perception and that distance allows for better observation of Earth's shape.

Scientific Observations and Evidence

• The importance of scientific observation over naive intuition is stressed; gathering data helps clarify misconceptions about Earth's shape.

• Historical arguments supporting a spherical Earth are reviewed, showing how evidence has accumulated over time.

Contributions from Experts

• Cristian Karman joins the discussion, providing insights into ancient astronomy and when ideas about a spherical Earth emerged.

• He references Homer's "Iliad," which suggests an early notion of curvature rather than a perfectly flat Earth.

Philosophical Arguments in Ancient Astronomy

• Karman discusses Pythagoras's belief in a spherical Earth based on his view of perfection in shapes.

• Plato popularized these ideas further, suggesting not only that the Earth was spherical but also rotating, explaining day and night cycles.

Modern Geophysical Insights

• Francisco Ruiz provides modern geophysical perspectives on modeling Earth's shape as an ellipsoid due to its rotation.

• He explains how variations in density lead to deviations from this idealized shape, introducing concepts like geoids for accurate representation.

Geodesy: Measuring Earth's Dimensions

• Ruiz defines geodesy as the science studying Earth's forms and dimensions essential for mapping and understanding geographical boundaries.

Understanding Earth's Shape and Measurement

The Economic Relevance of Geodesy

• Discussion on how economic factors influence the study of natural resource exploration, emphasizing the need for precise geographical coordinates.

Defining the Geoide and Earth's Shape

• Introduction to the concept of geoide as a model for Earth’s shape, starting from simple models like the ellipsoid of revolution to more complex representations.

Measuring Heights and Levels

• Explanation of leveling techniques used to measure heights relative to mean sea level, highlighting challenges posed by mountainous terrains.

Historical Perspectives on Earth's Shape

• Reference to ancient Greek understanding that Earth is round; discussion on observational phenomena that led them to this conclusion.

Observational Evidence from Stars

• Notable observations include changes in star positions when moving north or south, supporting the idea of a spherical Earth.

Anaxagoras and Lunar Eclipses

• Anaxagoras' contributions include recognizing that lunar eclipses reveal Earth's shadow on the moon, further affirming its spherical shape.

Arguments Against Flat Earth Theory

• Despite some arguments favoring a flat Earth, historical texts predominantly supported a spherical view without significant opposition.

Ptolemy's Almagest and Astronomical Justifications

• Ptolemy's work begins with arguments supporting a spherical Earth based on earlier thinkers like Anaxagoras and Aristotle.

Aristotle's Metaphysical Insights

• Aristotle proposed that celestial bodies are perfect spheres while earthly elements tend toward corruption, influencing views on planetary shapes.

Gravity's Role in Planetary Formation

• Transition from Aristotelian ideas to Newtonian gravity explains how mass attracts other masses leading to spherical formations in space.

Implications for Understanding Up and Down

• Discussion about redefining concepts of 'up' and 'down' in relation to gravity’s influence across different celestial bodies.

Understanding Gravity and Eratosthenes' Experiment

The Concept of Up and Down in Different Cultures

• The speaker discusses the relativity of "up" and "down," noting that what is considered "up" for one person may be "down" for another, particularly across different cultures like China.

• The idea of up and down should be linked to gravitational pull towards the Earth's center rather than absolute directions.

Fundamental Forces of the Universe

• Four fundamental forces govern universal phenomena: electromagnetism, strong interaction, weak interaction, and gravity.

• Gravity is responsible for celestial movements such as the moon's orbit around Earth and planets around the sun.

Historical Perspectives on Gravity

• Isaac Newton first theorized that gravity causes objects to fall at a constant acceleration on Earth while also maintaining planetary motion.

• Albert Einstein later redefined gravity in his theory of general relativity as an effect produced by the curvature of space-time rather than a direct force.

Gravitational Pull Explained

• Every mass exerts gravitational attraction; however, humans are not large enough to attract small objects significantly due to their limited gravitational pull.

• Despite Earth's high speed (29 km/s), gravity keeps us grounded instead of flinging us into space.

Eratosthenes' Calculation of Earth's Size

• A humorous analogy involving pizza illustrates how Eratosthenes calculated Earth's circumference by measuring angles between two cities using shadows cast by sunlight.

• He deduced that if sunlight creates no shadow in one city but does in another, he could calculate the angle from Earth's center based on this observation.

Implications of Eratosthenes' Methodology

• The method highlights scientific reasoning where assumptions (like parallel rays from a distant sun) must align with observations; alternative hypotheses can lead to different conclusions about Earth’s shape.

• If Eratosthenes had used three cities instead with a flat Earth assumption, it would have led him astray; only spherical Earth aligns with his findings.

Historical Context Post-Eratosthenes

• Following Eratosthenes, scientific progress stagnated during late antiquity despite continued reliance on Ptolemy's works which included geographical maps and arguments supporting spherical Earth.

The Historical Misconception of a Flat Earth

The Influence of Alberto Magno and Thomas Aquinas

• Alberto Magno is recognized not only as a theologian but also as a scientist, alongside figures like Santo Tomás de Aquino.

• Dante's "Divine Comedy" reflects the understanding of a spherical Earth, evident in representations of Christ seated on an orb.

The Myth of the Flat Earth Belief

• A common belief persists that during Columbus's time, many thought the Earth was flat; this misconception continues to be taught today.

• Geoffrey Rush's 1991 book "The Invention of the Round Earth" explores how educational materials from the 19th century reshaped this narrative.

Enlightenment vs. Medieval Thought

• The Enlightenment period is often portrayed as rational and opposed to what is seen as irrational medieval beliefs, including the idea that people believed in a flat Earth.

Significance of Magellan and Elcano’s Expedition

• Kipling's quote about knowing England connects to understanding global perspectives through exploration, highlighting how Magellan and Elcano expanded knowledge by circumnavigating the globe.

• Their journey allowed for observations beyond local environments, enhancing comprehension of natural phenomena across different regions.

Challenges Faced During Circumnavigation

• The expedition faced numerous hardships; many crew members did not survive the journey due to harsh conditions and navigational challenges.

The Journey of Ferdinand Magellan

Early Life and Ambitions

• Ferdinand Magellan was a noble Portuguese military leader who sought faster routes to spice islands by sailing westward after being rejected by King Manuel I of Portugal.

Support from Spain

• After his proposal was turned down by Portugal, he gained support from Carlos I of Spain, leading to an expedition launched in September 1519 with five ships.

Navigational Difficulties Encountered

• Initial navigation led them to Brazil before they struggled for months searching for a passage to the Pacific Ocean amidst severe winter conditions.

Harrowing Experiences at Sea

• The crew endured extreme hunger and disease while navigating through uncharted waters; upon reaching the Philippines in March 1521, Magellan met his demise shortly after.

Aftermath: Completing the Voyage

Leadership Transition Post-Magellan

• Following Magellan’s death, Juan Sebastián Elcano took command; under his leadership, they successfully reached their destination—the Spice Islands—and began their return journey.

Return Journey Challenges

• Only one ship managed to return home—Nao Victoria—after facing capture attempts by Portuguese vessels during its voyage back around Africa.

Historic Achievement

• Of the original fleet comprising five ships and 234 men, only Nao Victoria returned with 34 survivors who became known as the first individuals to circumnavigate the globe.

Luis Agote: Pioneer in Blood Transfusion

Contributions to Medicine

• Luis Agote was an Argentine physician noted for performing indirect blood transfusions without coagulation—a significant medical advancement during his time.

Early Life and Education

• Born on September 22, 1868, he studied medicine at Buenos Aires University and later founded an institute focused on clinical practices where he developed his blood preservation method.

Transfusion and the Copernican Revolution

The Complexity of Blood Transfusions

• Early blood transfusions were complex surgical interventions often resulting in fatal consequences due to a lack of understanding of blood incompatibilities.

• Luis Agote sought solutions for hemophiliac patients suffering from severe hemorrhages, leading to his discovery that sodium citrate could prevent clot formation.

• The first human trial using sodium citrate occurred on November 9, 1914, successfully restoring a patient who had lost significant blood.

Historical Context and Impact

• Following the discussion on blood transfusions, the conversation shifts to astronomy and the historical belief that Earth is flat.

• The program transitions into discussing the Copernican Revolution, questioning how we know Earth is not flat but rather spherical.

Understanding the Copernican Revolution

• Historically, many believed Earth was at the center of the universe; however, Nicolaus Copernicus proposed a heliocentric model during the Renaissance.

• This revolutionary idea repositioned Earth as one of several planets orbiting around the Sun instead of being stationary at the universe's center.

Implications of Heliocentrism

• The shift from an Earth-centered view challenged cultural norms and required new explanations in physics regarding celestial bodies' movements.

• The term "Copernican Revolution" refers to this paradigm shift initiated by Nicolaus Copernicus, who was born on February 19, 1473.

Contributions of Nicolaus Copernicus

• After studying in Italy and working with prominent astronomers, Copernicus developed his heliocentric theory based on seven principles outlined in his manuscript.

• His work detailed Earth's movements: daily rotation, annual revolution around the Sun, and axial tilt. He also explained retrograde motion observed in planets.

Legacy and Influence

• Although he completed his major work by 1530, it wasn't published until 1543 when he was near death; this book laid foundations for modern cosmology.

• Subsequent astronomers like Giordano Bruno and Galileo Galilei faced persecution for their support of heliocentrism; however, Copernicus's ideas remain pivotal in scientific history.

Understanding Earth's Motion and the Foucault Pendulum

The Concept of Earth's Shape and Movement

• Discussion on whether Earth is spherical or flat, emphasizing that a rotating flat Earth is difficult to conceptualize.

• Observations about the universe's regularity, noting that planets are spherical and their movements challenge our understanding of physics.

• Explanation of Earth's rotation around its axis daily and around the sun annually, alongside the galaxy's movement.

Perception of Motion

• Insight into why we do not perceive motion; we only notice changes in speed (acceleration), not constant velocity.

• Comparison between being inside a moving train versus observing external surroundings; highlights how perception can be misleading.

The Foucault Pendulum Experiment

• Introduction to Léon Foucault's pivotal experiment demonstrating Earth's rotation through a pendulum.

• Background on Foucault as a physicist known for his analytical skills, including measuring light speed and inventing the gyroscope.

Demonstration of Earth's Rotation

• Description of the first public demonstration of the Foucault pendulum in 1851 at Paris Observatory using a heavy cannonball pendulum.

• Details on how the pendulum’s oscillation plane shifts over time, illustrating Earth’s rotation by leaving marks in sand below.

Impact and Legacy of the Experiment

• Historical context regarding subsequent installations and damage to the original setup over time, including repairs made in 2017.

• Emphasis on how every 16 seconds, the pendulum visually confirms that Earth is continuously rotating.

Broader Implications of Earth's Motion

• Connection between Earth’s rotation and large-scale meteorological phenomena like cyclones; explains how air masses rotate due to this motion.

Unique Phenomenon Related to Building Heights

• Discussion about sunset times differing at various heights in tall buildings like Burj Khalifa due to curvature effects.

• Personal anecdote relating Ramadan practices with sunset timings observed from different floors within high-rise structures.

This structured summary captures key insights from discussions about Earth's shape, motion, significant experiments like Foucault's Pendulum, and related phenomena while providing timestamps for easy reference.

Understanding the Evidence for a Round Earth

Contributions of the Space Age to Earth's Shape

• The discussion begins with an exploration of how the space age has provided evidence supporting the idea that Earth is round, contrasting it with flat Earth theories.

• A significant modern contribution is our ability to measure distances and angles on a planetary scale, demonstrating that angles between distant cities do not sum to 180 degrees as they would in Euclidean geometry.

• Observations from space have allowed us to take photographs of Earth, providing clear visual evidence of its spherical shape, particularly when viewed from orbit.

Historical Evidence from Space

• Diego discusses one of the first images taken from space on October 24, 1946, using a V-2 rocket. This image marked a pivotal moment in understanding Earth's shape.

• The V-2 rocket was developed by German scientists post-WWII and was instrumental in early American space exploration efforts.

Formation of Planets and Their Shapes

• The formation of planets is primarily influenced by gravity, which causes mass to attract other mass until a spherical shape is achieved due to hydrostatic equilibrium.

• Smaller bodies known as planetesimals grouped together under gravitational attraction, leading to larger masses that eventually formed into planets.

Flaws in Flat Earth Models

• Diego highlights two major flaws in flat Earth models:

• First, the observation of sunsets contradicting flat Earth perspectives where the sun should not appear smaller as it sets.

• Second, he mentions how star movements cannot be accurately explained within a flat model.

This structured overview captures key insights and arguments presented regarding Earth's shape and provides timestamps for further reference.

The Intersection of Belief and Science: Understanding Flat Earth Myths

The Celestial Pole and Star Movement

• The southern celestial pole represents the intersection of Earth's imaginary rotation axis with the sky, where stars appear to rotate in a specific direction.

• In contrast, a flat Earth model fails to explain this phenomenon as all stars would need to revolve around a single point, which is inconsistent with observed star movements.

The Allure of Flat Earth Myths

• Discussion arises on why myths like flat Earth theories spread easily; they often attract certain demographics due to their simplicity and narrative appeal.

• Historical misconceptions, such as the belief that people in the Middle Ages widely accepted flat Earth ideas, are perpetuated by engaging storytelling akin to Disney movies.

Simplification vs. Complexity in Science

• Simplified explanations can be tempting but may overlook the complexities that make scientific understanding richer and more accurate.

• The internet plays a dual role by facilitating information exchange while also allowing misinformation about flat Earth beliefs to proliferate.

Internet's Role in Spreading Misinformation

• Online platforms enable small groups worldwide to connect and reinforce each other's beliefs, creating echo chambers for flat Earth ideologies.

• Despite presenting scientific evidence supporting a spherical Earth, some individuals remain resistant to changing their views due to these online communities.

Engaging with Flat Earthers: Strategies for Dialogue

• It’s noted that many individuals seem immune to factual data; discussions should focus on understanding rather than confrontation.

• Effective communication involves finding common ground and exploring how science works rather than solely debating facts about Earth's shape.

Approaching Conversations About Scientific Truth

• Engaging someone who believes in flat Earth requires patience; it’s essential first to acknowledge their right to hold differing opinions while gently guiding them toward evidence-based reasoning.

• Socratic methods suggest asking questions that lead individuals toward recognizing inconsistencies in their beliefs without direct confrontation.

Conclusion: Evidence Over Belief

• Ultimately, extraordinary claims require extraordinary evidence; current scientific consensus supports a spherical Earth based on extensive observations.