Courses, talks and interviews of A. K. T. Assis in English, Portuguese, French and Spanish:

(I) Courses, talks and interviews in English:

• Course on Weber Electrodynamics and Relational Mechanics presented at the Advanced School on Sympletic Topology Meets Celestial and Quantum Mechanics Via Weber Electrodynamics which took place at the Institute of Mathematics of the University of Campinas - UNICAMP - in Brazil from the 17th to the 21st of February 2020 organized by Prof. Joa Weber. Detailed information about this Advanced School can be found at: https://freedom-and-science.neocities.org/M/20-WED/WED.html. Each talk lasted one hour. Here are the links of the presentations and the respective slides:
  • (I) Ampere Electrodynamics: https://www.youtube.com/watch?v=DqIwqzbPm7g, slides: https://www.ifi.unicamp.br/~assis/Ampere-Electrodynamics-17-02-2020.pdf;
  • (II) Weber Electrodynamics: https://www.youtube.com/watch?v=7QFEWq3X8ew, slides: https://www.ifi.unicamp.br/~assis/Weber-Electrodynamics-18-02-2020.pdf;
  • (III) The Electric Force of a Current: https://www.youtube.com/watch?v=3e7FjP8QDAI, slides: https://www.ifi.unicamp.br/~assis/The-Electric-Force-of-a-Current-19-02-2020.pdf;
  • (IV) Weber Planetary Model of the Atom: https://www.youtube.com/watch?v=tpLQkZlA6Q8, slides: https://www.ifi.unicamp.br/~assis/Weber-planetary-model-of-the-atom-20-02-2020.pdf;
  • (V) Relational Mechanics and the Diurnal Rotation of the Earth: https://www.youtube.com/watch?v=do13e1YM5JM, slides: https://www.ifi.unicamp.br/~assis/Relational-Mechanics-and-the-diurnal-rotation-of-the-Earth-21-02-2020.pdf.

• "Unicamp professor translates classic works of physics". Interview posted on January 14, 2026, at Jornal of the University of Campinas, Unicamp: https://jornal.unicamp.br/en/noticias/2026/01/14/professor-da-unicamp-traduz-obras-classicas-da-fisica/. Interview conducted by journalist Helena Tallmann, photographs by Antoninho Perri and image edition by Alex Calixto. Portuguese version of this interview: https://jornal.unicamp.br/noticias/2026/01/14/professor-da-unicamp-traduz-obras-classicas-da-fisica/. Spanish version of this interview: https://jornal.unicamp.br/es/noticias/2026/01/14/professor-da-unicamp-traduz-obras-classicas-da-fisica/. Post on Instagran: https://www.instagram.com/p/DTgNUrQE_Xt/?img_index=1. Post on Facebook: https://www.facebook.com/share/p/1CPVRed9Uh/. Post on the channel Pion of the Brazilian Society of Physics, SBF, coordinated by Leonardo Sioufi Fagundes dos Santos: https://www.sbfisica.org.br/v1/portalpion/index.php/noticias/530-professor-da-unicamp-traduz-obras-classicas-da-fisica.
• "The Experimental and Historical Foundations of Electricity". Interview lasting 3 hours conducted by Ben Sparks and Matt Finn which was posted online on November 25, 2025, in their podcast The Brainstorm: https://youtu.be/gfK3U3pT9xA. Abstract: In this interview I perform several experiments: (a) The amber effect or the attraction of paper bits by a rubbed plastic tube, (b) the rotation of a versorium (instrument due to Gilbert in 1600) by an electrified straw; (c) the attraction/contact/repulsion of an electric pendulum made by a paper disc suspended by a silk thread (instrument due to Stephen Gray in 1720 and ACR mechanism due to Du Fay in 1733); (d) the levitation of a dandelion seed with an electrified straw (experiment due to Guericke in 1672); (e) charging and discharging an electroscope (instrument due to Du Fay in 1737) made of cardboard, a thin paper strip and a plastic straw in order to distinguish conductors and insulators (discovery of Gray in 1731, but shown here utilizing an electroscope). (f) Classification as insulators or conductors of several materials (human body, rubber, glass, wood, cotton, silk, water etc.) I present some aspects related to the history of electricity which can be constructively explored in physics teaching. I show how to build these cheap and highly sensitive instruments, which were extremely important in the history of electricity. Finally, I discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years.
• Online lecture (October 12, 2025) on "The Experimental and Historical Foundations of Electricity"'. It was presented to the Rising Tide Foundation and organized by its director, Matthew Ehret. Video of the presentation (1 hour of presentation plus 1 hour of discussion): https://youtu.be/N6uGbyyV9h8. Abstract: In this presentation I perform several experiments: (a) the attraction of paper bits by a rubbed plastic tube (experiment analogous to the amber effect); (b) an electrified straw rotating a versorium, the oldest instrument for the study of electricity; (c) I show an electric pendulum made by a paper disc suspended by a silk thread, then I show its attraction/contact/repulsion by an electrified plastic tube; (d) the levitation of a dandelion seed with an electrified straw, then I discuss the importance of this experiment in the history of electricity; (e) I show an electroscope made of cardboard, a thin paper strip and a plastic straw, then I show how to charge and discharge it; (f) finally I show how to distinguish insulators and conductors with an electroscope and utilize it to classify several materials (human body, rubber, glass, wood, cotton, silk, water etc.) I present some aspects related to the history of electricity which can be constructively explored in physics teaching. I show how to build these cheap and highly sensitive instruments, which were extremely important in the history of electricity. Finally, I discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years. Discussion of this presentation by Michael Clarage, "A charged plastic rod": https://michaelclarage.substack.com/p/a-charged-plastic-rod. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Electricity-12-10-2025.pdf.
• "Unsolved Mysteries of Electrostatics". Interview of 3 hours conducted by Michael Shilo DeLay and Anastasia Bendebury and posted online in their channel The DemystifySci Podcast on September 14, 2025: https://www.youtube.com/watch?v=4mFmvVlVtzQ. Abstract: In this podcast I perform several experiments: (a) The amber effect or the attraction of paper bits by a rubbed plastic tube, (b) the rotation of a versorium (instrument due to Gilbert in 1600) by an electrified straw; (c) the attraction/contact/repulsion of an electric pendulum made by a paper disc suspended by a silk thread (instrument due to Stephen Gray in 1720 and ACR mechanism due to Du Fay in 1733); (d) the levitation of a dandelion seed with an electrified straw (experiment due to Guericke in 1672); (e) charging and discharging an electroscope (instrument due to Du Fay in 1737) made of cardboard, a thin paper strip and a plastic straw in order to distinguish conductors and insulators (discovery of Gray in 1731, but shown here utilizing an electroscope). (f) Classification as insulators or conductors of several materials (human body, rubber, glass, wood, cotton, silk, water etc.) I present some aspects related to the history of electricity which can be constructively explored in physics teaching. I show how to build these cheap and highly sensitive instruments, which were extremely important in the history of electricity. Finally, I discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years.
• Demonstration of electrostatic experiments at the International Conference DemystiCon 2025 Crisis in Cosmology (Portugal, June 12-15, 2025) organized by Michael Shilo DeLay and Anastasia Bendebury. The recording was made by Gareth Samuel of the educational channel See the Pattern: https://www.patreon.com/posts/131669639.
• "Big Bang Under Fire - Mike McCulloch, Andre Koch Torres Assis, Martin Lopez-Corredoira, Gareth Samuel of SeeThe Pattern, DemystifySci #363". Sunday Panel filmed at the International Conference DemystiCon 2025 in June in Portugal and organized by Michael Shilo DeLay and Anastasia Bendebury: https://youtu.be/IKZ8oARjsYo.
• "The Cosmic Microwave Background Radiation with a Temperature of 2.75 Kelvin Is a Proof Against the Big Bang, Since It Was Predicted Earlier and Better by an Infinite Universe Without Expansion, Than the Predictions Based on the Big Bang". Talk presented on June 13, 2025, at the Conference DemystiCon 2025 held in Portugal and organized by Michael Shilo DeLay and Anastasia Bendebury: https://www.youtube.com/watch?v=bboKmG0uUuU. Abstract: Most textbooks claim that the cosmic microwave background radiation with a temperature of 2.75 K is a proof of the Big Bang as it had been predicted by Gamow, Alpher and Herman before its discovery by Penzias and Wilson in 1965. Contrary to this statement, we show that the Big Bang predicted wrong and increasing temperatures, ranging from 5 K up to 50 K, in this order: (a) In 1948, Alpher and Herman arrived at a present temperature of the universe of 5 K based on the Big Bang. (b) In 1949, they concluded that this temperature should be greater than 5 K. (c) Gamow, in 1953, arrived at a temperature of 7 K. (d) Then Gamow finally in 1961 (just 4 years before Penzias and Wilson), predicted the actual temperature of interstellar space as 50 K. Moreover, scientists working with an infinite universe without expansion and without a Big Bang predicted this temperature earlier and better than the predictions of the Big Bang. These scientists include: (a) The Nobel prize winner Charles Édouard Guillaume (1861–1938) who calculated in 1896 an upper bound of 5.6 K for the temperature of space, before George Gamow’s birth in 1904. (b) Arthur Eddington (1882-1944) who arrived in 1926 at a temperature of 3.18 K based on a black body in equilibrium with the radiation around it. (c) Erich Regener (1881-1955) who arrived in 1933 working with cosmic rays at a temperature of intergalactic space of 2.8 K. (d) The Nobel prize winner Walther Nernst (1864-1941) who, working explicitly with an infinite Universe in a stationary space, and with a cosmological redshift not due to a Doppler effect, arrived at a temperature of intergalactic space of 0.75 K. (e) A. McKellar and Herzberg in 1941 arrived at a temperature of 2.3 K based on the degree of excitation of the CN molecules in equilibrium in a heat bath. (f) Erwin Finlay-Freundlich (1885-1964) proposed in 1953-1954 a tired light mechanism to explain the redshift of solar lines and when he applied his model to the cosmological redshift he arrived at a temperature of intergalactic space between 1.9 K and 6.0 K. (g) When the Nobel prize Max Born (1882-1970) analyzed Finlay-Freundlich’s work, he predicted in 1954 that his tired light model was linked to radio-astronomy. Only 11 years later Penzias and Wilson discovered in 1965 the CMBR with a characteristic temperature of 3.5 K utilizing a horn antenna built to study radio waves! In conclusion, the CMBR is a proof against the Big Bang, since it was predicted earlier and better by an infinite universe without expansion, than the predictions based on the Big Bang. Text in German by Manfred Pohl discussing this presentation, "Beweissichere Argumente, die das Standardmodell der Kosmologie widerlegen": https://hauptplatz.unipohl.de/Wissenschaft/Assis_Vortrag.pdf. Slides of this presentation: https://www.ifi.unicamp.br/~assis/3K-13-06-2025.pdf.
• "Delusions of Cosmic Expansion". Interview of 2 hours conducted by Michael Shilo DeLay and Anastasia Bendebury and posted online in their channel The DemystifySci Podcast on March 16, 2025: https://www.youtube.com/watch?v=upV3ZfCEISA and https://open.spotify.com/episode/1mCCzhDhotpwlxT1aC3xEI?si=xQ5ofo2BTU2MHt_fmr77nA. Abstract: We discuss the electrodynamics of Ampère and Weber. We mention the available English translations of the works of Coulomb, Ampère and Weber. We discuss the history of the 3K temperature of the cosmic microwave background radiation prior to Penzias and Wilson paper of 1965. We show that the calculations of Guillaume, Eddington, Regener, Finlay-Freundlich, Max Born and De Broglie, based on measurements of the background flux of energy from the light of the stars and cosmic radiation, and utlizing an infinite universe without expansion and without big bang, were better and earlier than the predictions of Gamow, Alpher and Hermann based on the big bang. Therefore, the discovery of Penzias and Wilson is a proof against the big bang. We also discuss the colomological points of view of Edwin Hubble. In 1929 he assumed an expanding universe when presenting his redshift-distance law. However, in all other papers and boooks, until the end of his life, he did fight against the big bang and preferred an infinite universe without expansion, without big bang. He looked for a new principle of nature, different from the Doppler effect associated with velocity, which might explain the cosmological redshift. Discussion of this interview posted by John Plaice, "A temperature for space was predicted long before the cosmic microwave background radiation was discovered and decades before the big bang was proposed": https://johnplaice.substack.com/p/a-temperature-for-space-was-predicted.
• "Did Newton & Einstein Get Gravity & Inertia All Wrong?". Interview of 2 hours conducted by Michael Shilo DeLay and Anastasia Bendebury and posted online in their channel The DemystifySci Podcast on March 17, 2024: https://youtu.be/kGHNKORQZK8. Abstract: We compare 3 competing theories of physics, namely, (a) Newtonian mechanics, (b) Einstein's theories of relativity, (c) Relational Mechanics. To this end we present 3 experiments: free fall of an apple, Newton's bucket experiment, and the flattening of the Earth due to its diurnal rotation. These experiments are analysed from the perspective of Mach's principle. We also mention the works of Coulomb, Ampère, Weber, Hubble and Schrödinger.
• "Lost Model of Electrodynamics". Interview of 2 hours conducted by Michael Shilo DeLay and Anastasia Bendebury and posted online in their channel The DemystifySci Podcast on November 16, 2023: https://youtu.be/VGql2qiRjkY and https://open.spotify.com/episode/5bFsLjKv6Ar5Mnvt241LYF?si=RgsvOICvQYCyqLahXGbz-g. Abstract: We show that Ampère never wrote the circuital law and never worked with the magnetic field concept. We present Oersted's experiment and Ampère's central force acting between two current elements. This force disappeared from the textbooks. We compare it with Grassmann-Biot-Savart's force law. We mention the English translations of the works of Coulomb, Ampère and Weber which are available in PDF format in our homepage. We present Weber's electrodynamics and his planetary model of the atom.
• "Mach's Principle". Interview of 1 hour and 20 minutes conducted by Alexander Unzicker's Real Physics channel and posted online on November 12, 2023: https://youtu.be/PIKx-fGH5e0. Abstract: We discuss the meaning of the acceleration in Newton's second law of motion. We present Leibniz' arguments against Newton's concept of absolute empty space. We perform Newton's bucket experiment. The concavity of the water is due to the rotation of the bucket relative to what?. We present Ernst Mach's critiques of the Newtonian concepts. We show Newton's prediction of the flattening of the Earth due to its diurnal rotation. What would happen to this flattening if all the stars and galaxies were annihilated? We discuss Foucault's pendulum experiment. We discuss Einstein's theories of relativity and point out that Ernst Mach rejected them. We discuss Relational Mechanics and its implementation of Mach's principle with Weber's gravitational force.
• "Experiments of Electricity with Simple and Cheap Material". Interview of 20 minutes conducted by Mr. Shah Faisal at Augsburg University, Germany, posted online on the channel Maths Volunteers on October 31, 2023: https://youtu.be/iC3bT0MO36Q. Abstract: These experiments were taken from the book ''The Experimental and Historical Foundations of Electricity'' by A. K. T. Assis, whom we feature in this video. It was recorded at Augsburg University, Germany, in October 2023. Mr. Shah Faisal sits down with his friend and co-worker, Prof. Andre Koch Torres Assis, to perform and record these fundamental experiments of electricity with simple material. We show how to construct and perform experiments with a versorium, electric pendulum and electroscope.
• "Mysteries of Electrodynamics". Interview of 1 hour conducted by Alexander Unzicker's Real Physics channel and posted online on October 29, 2023: https://youtu.be/vVJ3WHft9d8. Abstract: We show that Ampère never wrote the circuital law and never worked with the magnetic field concept. We present Oersted's experiment and Ampère's central force acting between two current elements. This force disappeared from the textbooks. We compare it with Grassmann-Biot-Savart's force law. We mention the English translations of the works of Coulomb, Ampère and Weber which are available in PDF format in our homepage. We present Weber's electrodynamics and his planetary model of the atom.
• "Weber's Planetary Model of the Atom". Talk of 1 hour presented in Prague, Czech Republic, on October 5, 2023, organized by Prof. Jan Rak: https://www.youtube.com/watch?v=wLkEzTL8nG4. This talk was followed by a session of Questions and Answers organized by Prof. Jan Rak: https://www.youtube.com/watch?v=HMIJIl2F1N8. Abstract: We present the origins of Weber’s electrodynamics (1846). Weber’s force depends not only on the distance between the interacting charges, but also on their relative velocity and relative acceleration. We discuss Ampère’s force between current elements and compare it with Grassmann-Biot-Savart’s law. We also compare Lorentz’s force with Weber’s force. We present Weber’s planetary model of the atom. It was developed before Rutherford’s experiments and Bohr’s model. In Weber’s planetary model, the positive nucleus is stabilized (or held together) by purely electrodynamic forces. According to Weber, when two positive charges are very close to one another, they behave as if they had a negative inertial mass, attracting one another instead of repelling each other. We discuss applications of Weber’s electrodynamics to superconductivity. We also present modern experiments and theoretical developments related to Weber’s electrodynamics. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Weber-Planetary-Model-of-the-Atom-05-10-2023.pdf.
• Online lecture (August 06, 2023) on Weber's Electrodynamics. It was presented to the Rising Tide Foundation and organized by Matthew Ehret and John Plaice. Video of the presentation (1 hour of presentation plus 1.5 hour of discussion): https://www.youtube.com/watch?v=o05-0M8Stkg. Abstract: We present the origins of Weber’s electrodynamics (1846). Weber’s force depends not only on the distance between the interacting charges, but also on their relative velocity and relative acceleration. We discuss Ampère’s force between current elements and compare it with Grassmann-Biot-Savart’s law. We also compare Lorentz’s force with Weber’s force. We present Weber’s planetary model of the atom. It was developed before Rutherford’s experiments and Bohr’s model. In Weber’s planetary model, the positive nucleus is stabilized (or held together) by purely electrodynamic forces. According to Weber, when two positive charges are very close to one another, they behave as if they had a negative inertial mass, attracting one another instead of repelling each other. We discuss applications of Weber’s electrodynamics to superconductivity. We also present modern experiments and theoretical developments related to Weber’s electrodynamics. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Weber-Electrodynamics-06-08-2023.pdf.
• Video conference (October 29, 2022) on Weber's Electrodynamics. It was presented to the Physical Research Laboratory (India), organized by Prof. Navinder Singh. Video of the presentation (1 hour of presentation plus 1 hour of discussion): https://youtu.be/cxmDk5suw20. Abstract: We present the origins of Weber’s electrodynamics (1846). Weber’s force depends not only on the distance between the interacting charges, but also on their relative velocity and relative acceleration. We discuss Ampère’s force between current elements and compare it with Grassmann-Biot-Savart’s law. We also compare Lorentz’s force with Weber’s force. We present Weber’s planetary model of the atom. It was developed before Rutherford’s experiments and Bohr’s model. In Weber’s planetary model, the positive nucleus is stabilized (or held together) by purely electrodynamic forces. According to Weber, when two positive charges are very close to one another, they behave as if they had a negative inertial mass, attracting one another instead of repelling each other. We discuss applications of Weber’s electrodynamics to superconductivity. We also present modern experiments and theoretical developments related to Weber’s electrodynamics. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Weber-Electrodynamics-29-10-2022.pdf.
• "The Experimental and Historical Foundations of Electricity" (1 hour of presentation). Talk presented on July 20, 2021, at the International Conference Hands-on Science organized by Manuel Filipe P. C. Martins Costa and José Benito Vázquez Dorrío: http://www.ijhsci.info/hsci2021/hsci2021-presentations/20210627144058_Electricity-Assis_pq.mp4. Abstract: In this talk we make 4 experiments: (a) The rotation of a versorium by an electrified straw (instrument due to Gilbert in 1600); (b) the attraction/contact/repulsion of an electric pendulum made by a paper disc suspended by a silk thread (instrument due to Stephen Gray in 1700 and ACR mechanism due to Du Fay in 1733); (c) the levitation of a dandelion seed with an electrified straw (experiment due to Guericke in 1672); (d) charging and discharging an electroscope (made of cardboard, a thin paper strip and a plastic straw) in order to distinguish conductors and insulators (discovery of Gray in 1731 utilizing an electroscope due to Du Fay in 1737). We present some aspects related to the history of electricity which can be constructively explored in physics teaching. In particular, we discuss the amber effect, the attraction of a thin water stream by an electrified plastic, the electric attraction and repulsion, the mechanism of attraction/contact/repulsion or ACR mechanism, conductors and insulators together with some of their main properties. We show how to build cheap instruments like the versorium, the electric pendulum and the electroscope. They are simple devices but very sensitive and extremely important in the history of electricity. We compare the low-cost electroscope (made with a cardboard, a thin strip of kite paper and a plastic straw) with the gold leaf electroscope. We present the usual explanations for the amber effect and for the deflection of a thin stream of water by an electrified comb, emphasizing that we do not agree with these explanations which are present in the textbooks. Finally, we discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Electricity-20-07-2021.pdf. Information of the Italian Association of Physics Teaching related to this talk: https://www.aif.it/conferenza-prof-andre-assis-the-experimental-and-historical-foundations-of-electricity.
• Interview (October, 2020, 20 minutes of duration) conducted by Prof. Jan Rak during the Conference Physics Beyond Relativity, Prague, Czech Republic: https://youtu.be/wKlf5e4dcCU. I discuss Relational Mechanics, Newton's bucket experiment and Weber's electrodynamics.
• Talk (October 19, 2019) on Relational Mechanics presented in Prague, Czech Republic, at the Conference Physics Beyond Relativity. Video of the presentation (1 hour): https://www.youtube.com/watch?v=UNleL0Wynkg and https://science21.cz/conference/?p=878. Abstract: We present Galileo's free fall experiment and its interpretation in Newtonian mechanics. We also discuss Newton's bucket experiment. In this case we have a bucket partially filled with water hanging by a rope. When the bucket and the water are at rest relative to the ground, the surface of the water is flat. When the bucket and the water rotate together relative to the ground, the surface of the water becomes concave (the water rises towards the sides of the bucket, acquiring a parabolic shape). In Newtonian mechanics the curvature of the water surface is not due to its rotation relative to the bucket, relative to the Earth, nor relative to the distant stars and galaxies. According to Newton, this experiment proved the existence of empty and free space, which he called absolute space. According to him, the curvature of the water was due to its rotation relative to absolute space. We then discuss the criticisms of Ernst Mach against Newtonian mechanics. An emphasis is given in Mach's ideas according to which the inertia of any body is due to its gravitational interaction with the distant masses in the universe. Einstein's theories of relativity do not implement Mach's principle. This fact is one of the reasons why we are totally against Einstein’s special and general theories of relativity. Finally, we present Relational Mechanics, a theory which implements quantitatively Mach's ideas about the origin of inertia utilizing Weber's law for gravitation. We discuss Galileo's free fall experiment and Newton's bucket experiment from the point of view of Relational Mechanics. We also present experimental tests in order to distinguish Relational Mechanics from Einstein’s general theory of relativity. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Relational-Mechanics-19-10-2019.pdf.
• Talk (October 18, 2019) on Weber's Electrodynamics and His Planetary Model of the Atom. It was presented in Prague, Czech Republic, at the Conference Physics Beyond Relativity. Video of the presentation (1 hour): https://www.youtube.com/watch?v=kmyWHuN3E4E and https://science21.cz/conference/?p=810. Abstract: We present the origins of Wilhelm Weber’s electrodynamics (1846). Weber’s force depends not only on the distance between the interacting charges but also on their relative velocity and relative acceleration. We discuss Ampère’s force between current elements and compare it with Grassmann-Biot-Savart’s law. We also compare Lorentz’s force with Weber’s force. We discuss Weber’s planetary model of the atom. It was developed before Rutherford’s experiments and Bohr’s model. In Weber’s planetary model, the positive nucleus is stabilized (or held together) by purely electrodynamic forces. According to Weber, when two positive charges are very close to one another, they behave as if they had an effective negative inertial mass, attracting one another instead of repelling each other. We also present modern experiments and theoretical developments related to Weber’s electrodynamics. My next project is to publish an English translation of Weber’s main works on electrodynamics. I am looking for volunteers who might help translating any of Weber’s papers. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Weber-Electrodynamics-18-10-2019.pdf.
• Talk (July 07, 2019) on Relational Mechanics presented at the University of Bath, UK, during the International Conference Dynamic Earth 2019. Video of the presentation: https://www.youtube.com/watch?v=SjrTSP4UGFo. Abstract: We present Galileo's free fall experiment and its interpretation in Newtonian mechanics. We also discuss Newton's bucket experiment. In this case we have a bucket partially filled with water hanging by a rope. When the bucket and the water are at rest relative to the ground, the surface of the water is flat. When the bucket and the water rotate together relative to the ground, the surface of the water becomes concave (the water rises towards the sides of the bucket, acquiring a parabolic shape). In Newtonian mechanics the curvature of the water surface is not due to its rotation relative to the bucket, relative to the Earth, nor relative to the distant stars and galaxies. According to Newton, this experiment proved the existence of empty and free space, which he called absolute space. According to him, the curvature of the water was due to its rotation relative to absolute space. We then discuss the criticisms of Ernst Mach against Newtonian mechanics. An emphasis is given in Mach's ideas according to which the inertia of any body is due to its gravitational interaction with the distant masses in the universe. Einstein's theories of relativity do not implement Mach's principle. This fact is one of the reasons why we are totally against Einstein’s special and general theories of relativity. Finally, we present Relational Mechanics, a theory which implements quantitatively Mach's ideas about the origin of inertia utilizing Weber's law for gravitation. We discuss Galileo's free fall experiment and Newton's bucket experiment from the point of view of Relational Mechanics. We also present experimental tests in order to distinguish Relational Mechanics from Einstein’s general theory of relativity. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Relational-Mechanics-07-07-2019.pdf.
• Talk (July 06, 2019) on Weber's Electrodynamics presented at the University of Bath, UK, during the International Conference Dynamic Earth 2019. Video of the presentation: https://www.youtube.com/watch?v=3XgOjlySh64. Abstract: We present the origins of Weber’s electrodynamics (1846). Weber’s force depends not only on the distance between the interacting charges but also on their relative velocity and relative acceleration. We discuss Ampère’s force between current elements and compare it with Grassmann-Biot-Savart’s law. We also compare Lorentz’s force with Weber’s force. We discuss Weber’s planetary model of the atom. It was developed before Rutherford’s experiments and Bohr’s model. In Weber’s planetary model, the positive nucleus is stabilized (or held together) by purely electrodynamic forces. According to Weber, when two positive charges are very close to one another, they behave as if they had an effective negative inertial mass, attracting one another instead of repelling each other. We also present modern experiments and theoretical developments related to Weber’s electrodynamics. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Weber-Electrodynamics-06-07-2019.pdf.
• Interview (October 17, 2017, 40 minutes of duration) conducted by David de Hilster of the Dissident Science channel: https://youtu.be/bW-RRH5X7sc. I discuss Relational Mechanics, Newton's bucket experiment, Weber's electrodynamics and Ampère's force between current elements.
• Video seminar (March, 2017) discussing Relational Mechanics, Weber's Electrodynamics and Weber's planetary model of the atom (1 hour of discussion) at the graduate course "History of Physics: Shaping Electromagnetism". Lecturers of this course: Ricardo Karam and Helge Kragh, University of Copenhagen, Denmark. Video seminar: https://youtu.be/E24rJr_PSJI.
• Video conference (February 04, 2017) on Relational Mechanics (1 hour of presentation plus 1 hour of discussion) presented at the John Chappell Natural Philosophy Society: https://youtu.be/L6A59tWV6EM, https://www.youtube.com/watch?v=L6A59tWV6EM&feature=youtu.be and also the fuze meeting: https://www.fuzemeeting.com/replay_meeting/5f20f4f5/8195442. In this talk we present Galileo's free fall experiment and its interpretation in Newtonian mechanics. We also present Newton's bucket experiment. In this case we have a bucket partially filled with water hanging by a rope. When the bucket and the water are at rest relative to the ground, the surface of the water is flat. When the bucket and the water rotate together relative to the ground, the surface of the water becomes concave (the water rises towards the sides of the bucket, acquiring a parabolic shape). In Newtonian mechanics the curvature of the water surface is not due to its rotation relative to the bucket, relative to the Earth, nor relative to the distant stars and galaxies. To Newton this experiment proved the existence of empty and free space, which he called absolute space. According to Newton, the curvature of the water was due to its rotation relative to absolute space. We then discuss the criticisms of Ernst Mach against Newtonian mechanics. An emphasis is given in Mach's ideas according to which the inertia of any body is due to its gravitational interaction with the distant masses in the universe. Einstein's theories of relativity do not implement Mach's principle. This fact is one of the reasons why we are totally against Einstein’s special and general theories of relativity. Finally we present Relational Mechanics, a theory which implements quantitatively Mach's ideas about the origin of inertia utilizing Weber's law for gravitation. We discuss Galileo's free fall experiment and Newton's bucket experiment from the point of view of Relational Mechanics. We also present experimental tests in order to distinguish Relational Mechanics from Einstein’s general theory of relativity. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Relational-Mechanics-04-02-2017.pdf.
• Video conference (September 03, 2011) on The Electric Force of a Current (1 hour of presentation plus 1 hour of discussion) presented at the John Chappell Natural Philosophy Society. Abstract: Is there a force between a stationary resistive circuit carrying a steady current and a stationary charge outside the circuit? Does this circuit generate an electric field outside it? Is this wire with a DC current electrically neutral along its length? These are the main questions discussed in this presentation. We present the opinion of some scientists like Clausius and Feynman who believed there was no force between a charge and a circuit carrying a constant current when they were at rest relative to one another. It is shown theoretically and experimentally that this force is different from zero and that there is a distribution of surface charges along the closed circuit carrying a steady current. We present the potential and electric field outside this circuit in different geometries: a straight wire, a coaxial cable, a twin-lead, a solenoid and a ring. The history of this subject is briefly reviewed, including a discussion of the pioneering and revolutionary works of Wilhelm Weber and Gustav Kirchhoff. Slides of this presentation: https://www.ifi.unicamp.br/~assis/The-Electric-Force-of-a-Current-03-09-2011.pdf
• Video conference (November 06, 2010) on Weber’s Electrodynamics (1 hour of presentation plus 1 hour of discussion) presented at the John Chappell Natural Philosophy Society: https://youtu.be/raG5kr5ba4c and https://www.youtube.com/watch?v=raG5kr5ba4c&t=1279s. In this talk we present the origins of Weber’s electrodynamics (1846). Ampère’s force between current elements is discussed and compared with Grassmann-Biot-Savart’s law. Lorentz’s force is compared with Weber’s force. We discuss a different prediction given by these two formulations, namely, the force upon an accelerated test charge generated by a uniformly charged spherical shell at rest around the test charge. According to Weber’s electrodynamics the test charge should behave as having an effective inertial mass depending upon the charge of the surrounding spherical shell. Nothing of this should happen according to Lorentz’s force. Orders of magnitude for this predicted effect are presented. Modern experiments and theoretical developments related to Weber’s electrodynamics are also discussed. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Webers-Electrodynamics-06-11-2010.pdf
• Video conference (October 24, 2009) on Relational Mechanics (1 hour of presentation plus 1 hour of discussion) presented at the John Chappell Natural Philosophy Society. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Relational-Mechanics-24-10-2009.pdf
• Talk (May 24, 2002) on Weber's Electrodynamics (1 hour of presentation plus 1 hour of discussion) presented at Fondation Louis de Broglie, in Paris: Part I: https://youtu.be/tD73YuWich8. Part II: https://youtu.be/-4bomtmkRic. Part III: https://youtu.be/8-qpWrNSuLI. Part IV: https://youtu.be/Wsx6Kv48v40. Part V: https://youtu.be/t_ZZLsBC4Vo. We also discuss Relational Mechanics, Mach's principle, Newton's bucket experiment and Ampère's force between current elements.

(II) Talks and interviews in Portuguese:

• "Tradução de físicos renomados". Interview lasting 1 hour and 45 minutes made on May 18, 2026, in which I present annotated translations of the works of Archimedes, Stephen Gray, Isaac Newton, Coulomb, Ampère and Wilhelm Weber: https://www.youtube.com/watch?v=DqgyhM8hQEg&t=270s. Interview conducted by Giovane Santos Siqueira of the AntenadoHz channel of the Faculty of Electrical Engineering of the University of Campinas - Unicamp.
• "Professor da Unicamp traduz obras clássicas da física". Interview posted on January 14, 2026, at Jornal of the University of Campinas, Unicamp: https://jornal.unicamp.br/noticias/2026/01/14/professor-da-unicamp-traduz-obras-classicas-da-fisica/. Interview conducted by journalist Helena Tallmann, photographs by Antoninho Perri and image edition by Alex Calixto. English version of this interview: https://jornal.unicamp.br/en/noticias/2026/01/14/professor-da-unicamp-traduz-obras-classicas-da-fisica/. Spanish version of this interview: https://jornal.unicamp.br/es/noticias/2026/01/14/professor-da-unicamp-traduz-obras-classicas-da-fisica/. Post on Instagran: https://www.instagram.com/p/DTgNUrQE_Xt/?img_index=1. Post on Facebook: https://www.facebook.com/share/p/1CPVRed9Uh/.
• "IFGW Memoria, video 1: Prof. Andre Assis (DRCC)". Interview posted on November 19, 2025 on the channel IFGW Play of the Institute of Physics of the University of Campinas - Unicamp in which I remember a talk presented by Prof. Cesar Lattes (1924-2005) in 1980 in which he discussed his experiments which were against Einstein's theories of relativity: https://www.youtube.com/shorts/oZc8oNiWOtk. Poster advertising this 1980 lecture in JPG and PDF formats: https://www.ifi.unicamp.br/~assis/Lattes-1980.jpg and https://www.ifi.unicamp.br/~assis/Lattes-1980.pdf. A photograph of a seminar given by Lattes at the Physics Institute of the University of São Paulo - USP in 1980, probably on the same topic, is available on the internet: https://memoriadafisica.ufpa.br/galeria/imagens/seminario-do-prof-cesar-lattes-no-instituto-de-fisica-da-usp-1980. Interview given by Lattes on June 20, 1999, to journalist Chico Pinheiro, in which Lattes, 20 years after that lecture, still maintained that the experiments he conducted in 1980 contradicted Einstein: https://youtu.be/1NkwEAGp4eU?t=428. My own arguments explaining why I am completely opposed to Einstein's theories of special and general relativity are described in two chapters of the book "Relational Mechanics and Implementation of Mach's Principle with Weber's Gravitational Force". This book is available for free in PDF format, in Portuguese and English: https://www.ifi.unicamp.br/~assis/Mecanica-Relacional-Mach-Weber.pdf and https://www.ifi.unicamp.br/~assis/Relational-Mechanics-Mach-Weber.pdf.
• "Mecânica Relacional e Implementação do Princípio de Mach com a Força de Weber Gravitacional". This talk (1 hour presentation and 1 hour debate) was presented on October 23, 2025, at the channel Aether Tenebris organized by Rodrigo F. Santos and Alexandre Lisboa: https://youtu.be/C6GhEhrUM5c. Abstract: I discuss Mach's principle and the origin of inertia. I compare Newtonian mechanics (based on the concept of motion of a test body in relation to empty space), Einstein's general theory of relativity, and relational mechanics (based on the concept of motion of a test body in relation to the distant bodies in the cosmos). I present the experiment of free fall and Newton's bucket experiment. I also discuss Ampère's force between current elements, Weber's electrodynamics and cosmological questions. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Mecanica-Relacional-23-10-2025.pdf.
• "Debate on Relational Mechanics and the Cosmic Microwave Background". This 2-hour debate, which took place at the Institute of Physics of the University of São Paulo, USP, on August 22, 2025, is available at: https://www.youtube.com/watch?v=DNV5BtzcBrY. It was organized by Filipe Pamplona, Osvaldo Pessoa Jr., the Philosophy of Physical Sciences Study Group (FiCiFi) (DF - FFLCH), and the Theory and History of Contemporary Sciences Group (TeHCo - USP). Weber's electrodynamics, Ampère's force between current elements, and an infinite universe in space and time without expansion and without a big bang were also discussed.
• "The Experimental and Historical Foundations of Electricity" (1 hour of presentation and 1 hour of discussion). Talk presented on May 06, 2025, at the Institute of Physics of the University of Campinas, Unicamp, for the course FM003 (Seminários sobre a Profissão) coordenated by Prof. Sandro Guedes: https://www.youtube.com/watch?v=JXySN43gMKo. Abstract: In this talk I make 5 experiments: (a) the attraction of small bits of paper with an electrified plastic straw, (b) the rotation of a versorium by an electrified straw (instrument due to Gilbert in 1600); (c) the attraction/contact/repulsion of an electric pendulum made by a paper disc suspended by a silk thread (instrument due to Stephen Gray in 1700 and ACR mechanism due to Du Fay in 1733); (d) the levitation of a dandelion seed with an electrified plastic straw (experiment due to Guericke in 1672); (e) charging and discharging an electroscope (made of cardboard, a thin paper strip and a plastic straw) in order to distinguish conductors and insulators (discovery of Gray in 1731, electroscope due to Du Fay in 1737). We present some aspects related to the history of electricity which can be constructively explored in physics teaching. In particular, we discuss the amber effect, the attraction of a thin water stream by an electrified plastic, the electric attraction and repulsion, the mechanism of attraction/contact/repulsion or ACR mechanism, conductors and insulators together with some of their main properties. We show how to build cheap instruments like the versorium, the electric pendulum and the electroscope. They are simple devices but very sensitive and extremely important in the history of electricity. We compare the low-cost electroscope (made with a cardboard, a thin strip of kite paper and a plastic straw) with the gold leaf electroscope. We present the usual explanations for the amber effect and for the deflection of a thin stream of water by an electrified comb, emphasizing that we do not agree with these explanations which are present in the textbooks. Finally, we discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years. Slides of this presentation: https://www.ifi.unicamp.br/~assis/eletricidade-06-05-2025.pdf.
• "Relational Mechanics" (presentation of 30 minutes). Interview available since October 14, 2024. Interview presented to the History of Science Channel, organized by Roberto Machado Junior and Carlos Adriano Cardoso, promoted by Coimbra University and Aveiro University, Portugal: https://youtu.be/eTh6QoQxzxU. Abstract: We present Relational Mechanics. In order to distinguish Newtonian mechanics (motion in relation to empty space) from relational mechanics (motion in relation to the distant bodies in the cosmos) we discuss the free fall of an apple and Newton's bucket experiment. We also discuss cosmological issues.
• "Relational Mechanics and Implementation of Mach's Principle with Weber's Gravitational Force" (1 hour of presentation and half an hour of discussion). Talk presented on March 12, 2024, for the Institute of Advanced Studies of the University of Sao Paulo (USP, Brazil), organized by Prof. Gildo Magalhães dos Santos Filho: https://youtu.be/F0FptdW9U0I. Abstract: We discuss Mach's principle and the origin of inertia. We compare two formulations of mechanics, namely, (1) Newtonian mechanics (based on the concept of the motion of a test body relative to empty space) and (2) relational mechanics (based on the concept of the motion of a test body relative to the distant bodies in the cosmos). To this end we present and discuss four experiments: (a) the free fall of an apple, (b) Newton's bucket experiment, (c) the flattening of the Earth due to its diurnal rotation, (d) Foucault's pendulum. We also discuss several cosmological topics.
• "The Experimental and Historical Foundations of Electricity" (1 hour of presentation). Talk presented on May 11, 2023, at the Federal Institute of Sao Paulo, campus of Boituva, organized by Prof. Eduardo Luis Estrada: https://youtu.be/gX2sLGVVrmI. Abstract: In this talk we make 4 experiments: (a) The rotation of a versorium by an electrified straw (instrument due to Gilbert in 1600); (b) the attraction/contact/repulsion of an electric pendulum made by a paper disc suspended by a silk thread (instrument due to Stephen Gray in 1700 and ACR mechanism due to Du Fay in 1733); (c) the levitation of a dandelion seed with an electrified straw (experiment due to Guericke in 1672); (d) charging and discharging an electroscope (made of cardboard, a thin paper strip and a plastic straw) in order to distinguish conductors and insulators (discovery of Gray in 1731 utilizing an electroscope due to Du Fay in 1737). We present some aspects related to the history of electricity which can be constructively explored in physics teaching. In particular, we discuss the amber effect, the attraction of a thin water stream by an electrified plastic, the electric attraction and repulsion, the mechanism of attraction/contact/repulsion or ACR mechanism, conductors and insulators together with some of their main properties. We show how to build cheap instruments like the versorium, the electric pendulum and the electroscope. They are simple devices but very sensitive and extremely important in the history of electricity. We compare the low-cost electroscope (made with a cardboard, a thin strip of kite paper and a plastic straw) with the gold leaf electroscope. We present the usual explanations for the amber effect and for the deflection of a thin stream of water by an electrified comb, emphasizing that we do not agree with these explanations which are present in the textbooks. Finally, we discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years. Slides of this presentation: https://www.ifi.unicamp.br/~assis/eletricidade-11-05-2023.pdf.
• "Weber's Electrodynamics" (1 hour of presentation and half an hour of discussion). Talk presented on August 26, 2022, for the Institute of Advanced Studies of the University of Sao Paulo (USP, Brazil), organized by Prof. Gildo Magalhães dos Santos Filho: https://youtu.be/6kVvTUd35sE. Abstract: We present the origins of Weber's electrodynamics and of Ampere's force between current elements. We compare Lorentz's force with Weber's force. We discuss Weber's planetary model of the atom. We present some experiments and new theoretical developments related to Weber's law. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Eletrodinamica-de-Weber-26-08-2022.pdf.
• "The Experimental and Historical Foundations of Electricity" (1 hour of presentation plus 1 hour of discussion). Talk presented on May 17, 2022, at the Federal Institute of Sao Paulo, campus of Caraguatatuba, organized by Prof. Ricardo Roberto Plaza Teixeira, Prof. Alex Lino and student Indalecio Luiz Borges: https://youtu.be/j-5at9Y_CgI. Abstract: In this talk we make 4 experiments: (a) The rotation of a versorium by an electrified straw (instrument due to Gilbert in 1600); (b) the attraction/contact/repulsion of an electric pendulum made by a paper disc suspended by a silk thread (instrument due to Stephen Gray in 1700 and ACR mechanism due to Du Fay in 1733); (c) the levitation of a dandelion seed with an electrified straw (experiment due to Guericke in 1672); (d) charging and discharging an electroscope (made of cardboard, a thin paper strip and a plastic straw) in order to distinguish conductors and insulators (discovery of Gray in 1731 utilizing an electroscope due to Du Fay in 1737). We present some aspects related to the history of electricity which can be constructively explored in physics teaching. In particular, we discuss the amber effect, the attraction of a thin water stream by an electrified plastic, the electric attraction and repulsion, the mechanism of attraction/contact/repulsion or ACR mechanism, conductors and insulators together with some of their main properties. We show how to build cheap instruments like the versorium, the electric pendulum and the electroscope. They are simple devices but very sensitive and extremely important in the history of electricity. We compare the low-cost electroscope (made with a cardboard, a thin strip of kite paper and a plastic straw) with the gold leaf electroscope. We present the usual explanations for the amber effect and for the deflection of a thin stream of water by an electrified comb, emphasizing that we do not agree with these explanations which are present in the textbooks. Finally, we discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years. Slides of this presentation: https://www.ifi.unicamp.br/~assis/eletricidade-17-05-2022.pdf. Divulgation of this talk at Portal Píon of the Brazilian Society of Physics, SBF, coordinated by Leonardo Sioufi Fagundes dos Santos: http://www.sbfisica.org.br/v1/portalpion/index.php/noticias/466-fundamentos-experimentais-e-historicos-da-eletricidade-ifsp. Photos and divulgation of this talk at IFSP: https://www.ifspcaraguatatuba.edu.br/noticias/web-conferencia-abordou-os-aspectos-experimentais-e-historicos-da-eletricidade.
• Interview (April 2022, 10 minutes of duration) Interview of April 2022 in which I present the book in Portuguese about Coulomb's Main Works on Electricity and Magnetism (Tradução Comentada das Principais Obras de Coulomb sobre Eletricidade e Magnetism) presented to the channel IFGW-Play of the Institute of Physics of the University of Campinas - Unicamp: https://www.youtube.com/watch?v=HFVpZZsI0ug.
• "How Archimedes Utilized the Law of the Lever to Calculate the Volume of a Sphere" (1 hour of presentation plus half an hour of discussion). Talk presented on February 24, 2022, at the Research Symposion of the Department of Physics of the State University of Paraiba - UEPG, organized by Prof. Ana Paula Bispo da Silva: https://youtu.be/CzY6BOYirPw?t=16080. In this talk we presented some aspects of the life and work of Archimedes (287-212 b.C.). We showed his formulation of the law of the lever according to which two weights equilibrate one another at distances from the fulcrum of the lever inversely proportional to the weights. We analysed how he obtained the main mathematical results related to the circle and the sphere (length and area of the circle, volume and area of the sphere). In particular, we showed how he obtained the volume of a sphere utilizing the law of the lever. The reasoning which he followed to make this calculation has only been known since 1906 with the discovery of one of his lost works, namely, his method on mechanical theorems. It was presented in a letter addressed to Eratosthenes of Alexandria. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Arquimedes-24-02-2022.pdf.
• "The Experimental and Historical Foundations of Electricity" (1 hour of presentation plus 1 hour of discussion). Talk presented on November 08, 2021 at the Federal University of Juiz de Fora, Brazil: https://youtu.be/C7dF5okXefc. Abstract: In this talk we make 4 experiments: (a) The rotation of a versorium by an electrified straw (instrument due to Gilbert in 1600); (b) the attraction/contact/repulsion of an electric pendulum made by a paper disc suspended by a silk thread (instrument due to Stephen Gray in 1700 and ACR mechanism due to Du Fay in 1733); (c) the levitation of a dandelion seed with an electrified straw (experiment due to Guericke in 1672); (d) charging and discharging an electroscope (made of cardboard, a thin paper strip and a plastic straw) in order to distinguish conductors and insulators (discovery of Gray in 1731 utilizing an electroscope due to Du Fay in 1737). We present some aspects related to the history of electricity which can be constructively explored in physics teaching. In particular, we discuss the amber effect, the attraction of a thin water stream by an electrified plastic, the electric attraction and repulsion, the mechanism of attraction/contact/repulsion or ACR mechanism, conductors and insulators together with some of their main properties. We show how to build cheap instruments like the versorium, the electric pendulum and the electroscope. They are simple devices but very sensitive and extremely important in the history of electricity. We compare the low-cost electroscope (made with a cardboard, a thin strip of kite paper and a plastic straw) with the gold leaf electroscope. We present the usual explanations for the amber effect and for the deflection of a thin stream of water by an electrified comb, emphasizing that we do not agree with these explanations which are present in the textbooks. Finally, we discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years. Slides of this presentation: https://www.ifi.unicamp.br/~assis/eletricidade-08-11-2021.pdf.
• "The Experimental and Historical Foundations of Electricity" (1 hour of presentation plus 1 hour of discussion). Talk presented on October 22, 2021, at the Federal University of Ouro Preto, Brazil, organized by Prof. Danny Tonidandel: https://youtu.be/MvX0IlieKlc. Abstract: In this talk we make 4 experiments: (a) The rotation of a versorium by an electrified straw (instrument due to Gilbert in 1600); (b) the attraction/contact/repulsion of an electric pendulum made by a paper disc suspended by a silk thread (instrument due to Stephen Gray in 1700 and ACR mechanism due to Du Fay in 1733); (c) the levitation of a dandelion seed with an electrified straw (experiment due to Guericke in 1672); (d) charging and discharging an electroscope (made of cardboard, a thin paper strip and a plastic straw) in order to distinguish conductors and insulators (discovery of Gray in 1731 utilizing an electroscope due to Du Fay in 1737). We present some aspects related to the history of electricity which can be constructively explored in physics teaching. In particular, we discuss the amber effect, the attraction of a thin water stream by an electrified plastic, the electric attraction and repulsion, the mechanism of attraction/contact/repulsion or ACR mechanism, conductors and insulators together with some of their main properties. We show how to build cheap instruments like the versorium, the electric pendulum and the electroscope. They are simple devices but very sensitive and extremely important in the history of electricity. We compare the low-cost electroscope (made with a cardboard, a thin strip of kite paper and a plastic straw) with the gold leaf electroscope. We present the usual explanations for the amber effect and for the deflection of a thin stream of water by an electrified comb, emphasizing that we do not agree with these explanations which are present in the textbooks. Finally, we discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years. Slides of this presentation: https://www.ifi.unicamp.br/~assis/eletricidade-22-10-2021.pdf.
• "The Experimental and Historical Foundations of Electricity" (1 hour of presentation and discussion). Talk presented on May 24, 2021, at the Instituto Federal, Birigui, Brazil: https://youtu.be/m_6CCJxMAZM. Abstract: In this talk we make 4 experiments: (a) The rotation of a versorium by an electrified straw (instrument due to Gilbert in 1600); (b) the attraction/contact/repulsion of an electric pendulum made by a paper disc suspended by a silk thread (instrument due to Stephen Gray in 1700 and ACR mechanism due to Du Fay in 1733); (c) the levitation of a dandelion seed with an electrified straw (experiment due to Guericke in 1672); (d) charging and discharging an electroscope (made of cardboard, a thin paper strip and a plastic straw) in order to distinguish conductors and insulators (discovery of Gray in 1731 utilizing an electroscope due to Du Fay in 1737). We present some aspects related to the history of electricity which can be constructively explored in physics teaching. In particular, we discuss the amber effect, the attraction of a thin water stream by an electrified plastic, the electric attraction and repulsion, the mechanism of attraction/contact/repulsion or ACR mechanism, conductors and insulators together with some of their main properties. We show how to build cheap instruments like the versorium, the electric pendulum and the electroscope. They are simple devices but very sensitive and extremely important in the history of electricity. We compare the low-cost electroscope (made with a cardboard, a thin strip of kite paper and a plastic straw) with the gold leaf electroscope. We present the usual explanations for the amber effect and for the deflection of a thin stream of water by an electrified comb, emphasizing that we do not agree with these explanations which are present in the textbooks. Finally, we discuss some mysteries related to the amber effect which have not yet been completely solved, although this is the oldest experiment in electricity with some 2400 years. Slides of this presentation: https://www.ifi.unicamp.br/~assis/eletricidade-24-05-2021.pdf.
• "Archimedes, the Center of Gravity and the Law of the Lever" (1 hour of presentation plus 1 hour of discussion). Talk presented on April 12, 2021, for the course FM003 (Seminários sobre a Profissão) coordenated by Prof. Thiago Pedro Mayer Alegre from the Institute of Physics of the University of Campinas - Unicamp: https://youtu.be/N2cP-_B2C9k. In this talk we presented some aspects of the life and work of Archimedes (287-212 b.C.). We showed his formulation of the law of the lever according to which two weights equilibrate one another at distances from the fulcrum of the lever inversely proportional to the weights. We analysed how he obtained the main mathematical results related to the circle and the sphere (length and area of the circle, volume and area of the sphere). In particular, we showed how he obtained the volume of a sphere utilizing the law of the lever. The reasoning which he followed to make this calculation has only been known since 1906 with the discovery of one of his lost works, namely, his method on mechanical theorems. It was presented in a letter addressed to Eratosthenes of Alexandria. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Arquimedes-12-04-2021.pdf.
• Exchange of ideas about Ampère and Weber Electrodynamics. This live event took place on September 16, 2020, with colleagues and students of the State University of Paraiba (UEPB) and Federal Institute of Paraiba (IFPB). It was organized by Prof. Ana Paula Bispo da Silva of the Research Group of Science and Science Teaching (GHCEN-UEPB) and by Prof. Luciano Feitosa do Nascimento (IFPB): https://youtu.be/dH0dcRvMtmA.
• "Open Dialogue about Science" (2 hours of an exchange of ideas about Relational Mechanics, cosmology and physics in general with colleagues and students of the Federal University of Mato Grosso in Brazil). This live event took place on August 27, 2020. It was organized by the Graduate Programm of Science Teaching of UFMT (Programa de Pós-Graduação em Ensino de Ciências Naturais da Universidade Federal de Mato Grosso - PPGECN/UFMT). The presentation was coordinated by Prof. Frederico Ayres de Oliveira Neto: https://youtu.be/o2oumqWf5po.
• "Questions for a Scientist". Interview of 30 minutes that took place on August 15, 2020, conducted by Fernanda Albuquerque Magalhães of the University of Campinas - UNICAMP: https://youtu.be/SFJcvfRO5mk.
• "Scaling Law or Power Law" (1 hour of presentation). Class taught in April 2020 in the discipline Experimental Physics I, F129, at the Institute of Physics of the University of Campinas - UNICAMP: https://www. youtube.com/watch?v=sxoFWRCoG_w. Abstract: I present how to obtain the coefficients "c" and "d" of the scaling law y = cx^d. In the first method, the logarithm is applied to both sides of this equation, the values of these logarithms are plotted in a normal graph paper. In the second method, the values of x and y are plotted on a dilog or log-log paper. Finally, a concrete example is presented using six given experimental points. Slides for this class: https://www.ifi.unicamp.br/~assis/aula-lei-de-escala-04-2020.pdf.
• "The Experimental and Historical Foundations of Electricity" (1 hour of presentation plus 30 minutes discussion). Talk presented on April 06, 2020, for the course FM003 (Seminários sobre a Profissão) coordenated by Prof. Thiago Pedro Mayer Alegre from the Institute of Physics of the University of Campinas - Unicamp: https://youtu.be/kc1McKlvHEM. Abstract: We present some aspects related to the history of electricity which can be constructively explored in physics teaching. In particular, we discuss the amber effect, the attraction of a thin water stream by an electrified plastic, the electric attraction and repulsion, the mechanism of attraction/contact/repulsion or ACR mechanism, conductors and insulators together with some of their main properties. We show how to build cheap instruments like the versorium, the electric pendulum and the electroscope. We perform some experiments like the attraction of small bits of paper by an electrified piece of plastic and the flotation of a dandelion seed above an electrified acrylic tube. We compare the low-cost electroscope (made with a cardboard, a thin strip of kite paper and a plastic straw) with the gold leaf electroscope. We present the usual explanations for the amber effect and for the deflection of a thin stream of water by an electrified comb, emphasizing that we don’t agree with these explanations which are present in the textbooks. Finally, we discuss some mysteries related to the amber effect which have not yet been completed solved. Slides of this presentation: https://www.ifi.unicamp.br/~assis/eletricidade-06-04-2020.pdf.
• "Application of the History of Electricity in Physics Teaching" (1 hour of presentation plus 30 minutes discussion). Talk presented on September 14th, 2018, at the Post-Graduate Program in Scientific Education and Technology of the Federal University of Santa Catarina, PPGECT/UFSC: https://youtu.be/o4wesai8BNQ. Abstract: We present some aspects related to the history of electricity which can be constructively explored in physics teaching. In particular, we discuss the amber effect, the attraction of a thin water stream by an electrified plastic, the electric attraction and repulsion, the mechanism of attraction/contact/repulsion or ACR mechanism, conductors and insulators together with some of their main properties. We show how to build cheap instruments like the versorium, the electric pendulum and the electroscope. We perform some experiments like the attraction of small bits of paper by an electrified piece of plastic and the flotation of a dandelion seed above an electrified acrylic tube. We compare the low-cost electroscope (made with a cardboard, a thin strip of kite paper and a plastic straw) with the gold leaf electroscope. We present the usual explanations for the amber effect and for the deflection of a thin stream of water by an electrified comb, emphasizing that we don’t agree with these explanations which are present in the textbooks. Finally, we discuss some mysteries related to the amber effect which have not yet been completed solved. Slides of this presentation: https://www.ifi.unicamp.br/~assis/eletricidade-14-09-2018.pdf.
• "Utilization of the History and Philosophy of Science in Physics Teaching" (1 hour of presentation). Talk presented at Universidade Franciscana de Santa Maria, RS, Brazil, on August 31, 2018: https://vimeo.com/289479865. Slides of this presentation: https://www.ifi.unicamp.br/~assis/historia-e-filosofia-da-ciencia-no-ensino-de-fisica-31-08-2018.pdf.
• Talk presented at the Center of Helenic Studies Arete, Sao Paulo, Brazil (June 23, 2018) on "Archimedes and the Law of the Lever" or on "How Archimedes Utilized the Law of the Lever to Calculate the Volume of a Sphere" (1 hour of presentation plus 1 hour of discussion). Part I: https://youtu.be/9go2-vrackA, part II: https://youtu.be/z5Bq287wHII. In this talk we presented some aspects of the life and work of Archimedes (287-212 b.C.). We showed his formulation of the law of the lever according to which two weights equilibrate one another at distances from the fulcrum of the lever inversely proportional to the weights. We analysed how he obtained the main mathematical results related to the circle and the sphere (length and area of the circle, volume and area of the sphere). In particular, we showed how he obtained the volume of a sphere utilizing the law of the lever. The reasoning which he followed to make this calculation has only been known since 1906 with the discovery of one of his lost works, namely, his method on mechanical theorems. It was presented in a letter addressed to Eratosthenes of Alexandria. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Arquimedes-23-06-2018.pdf.
• Talk (April 27, 2018) on the Principle of Physical Proportions (1 hour of presentation and discussion). Presented at the Centro Brasileiro de Pesquisas Físicas, CBPF, in Rio de Janeiro, Brazil: https://www.youtube.com/watch?v=Wen_jP9zj9o. Abstract: We presented the principle of physical proportions, a generalization of Mach's principle. According to the principle of physical proportions, all laws of physics should depend only on the ratio of known magnitudes of the same type (ratios of masses, ratios of electric charges, ratios of distances, ratios of frequencies etc.) An alternative formulation of this principle states that dimensional constants should not appear in physical laws. This principle can also be expressed by saying that all constants of physics (like the universal constant of gravitation, light velocity in vacuum, Planck's constant, Boltzmann's constant etc.) must depend on cosmological or microscopic properties of the material universe. We present laws following this principle (Archimedes's law of the lever, law of inclined plane, Kepler's law of areas etc.) and other laws which do not follow this principle (acceleration of free fall, law of ideal gases, flattening of the Earth etc.). These last examples show that the theories leading to these laws must be incomplete. We show how to implement this principle in some of these laws utilizing Relational Mechanics, which is a theory based on Weber's force applied to gravitation. We also suggest a procedure in order to implement this principle in the incomplete laws. Slides of this presentation: https://www.ifi.unicamp.br/~assis/PPF-27-04-2018.pdf. Papers on this subject: The principle of physical proportions and Das Prinzip der physikalischen Grössenverhältinisse.
• Video conference (September 18, 2017) on The Electric Force of a Current (1 hour of presentation plus 1 hour of discussion): https://youtu.be/j0qGTMr1_FU. This talk was presented to the group Philosophysics of the Federal University of São Carlos and USP of São Carlos, Brazil. Abstract: We present an important controversy connected to a very simple problem of electricity. Consider a resistive wire at rest in the laboratory and carrying a constant electric current. This wire exerts a force on an external charge at rest relative to the wire? Related questions: This wire generates an electric field? Is the wire neutral on all points alongs its surface? We present the opinion of several scientists and textbooks claiming that this wire exerts no force on stationary charges and that it is neutral along its surface. We show that this force is different from zero and present its main components: (I) a force due to image charges induced on the surface of the wire by the external charge, and mainly (II) a force proportional to the voltage of the battery connected to the circuit. We consider several geometries (straight wire, coaxial cable, transmission line, solenoid, ring) and calculate the distribution of surface charges and the electric field outside these circuits carrying constant currents. We compare these calculations with several experiments. We show that Wilhelm Weber had predicted many of these effects for 150 years, although his pioneering work has been forgotten. Slides of this presentation: https://www.ifi.unicamp.br/~assis/A-Forca-Eletrica-de-uma-Corrente-18-09-2017.pdf.
• Talk on Weber's Electrodynamics (1 hour of presentation plus 30 minutes of questions). It did take place at Federal University of Itajubá, UNIFEI, Brazil (April 06, 2017): https://youtu.be/bI0n0U5T-EE. Abstract: We present the origins of Weber's electrodynamics. We discuss Maxwell's equations, Lorentz's force and the meaning of the velocity which appears in this force. Ampère's force between current elements is compared with the force of Grassmann-Biot-Savart. We show how Weber and Kirchhoff deduced the wave equation BEFORE Maxwell. Lorentz's force is compared with Weber's force. It is presented a different prediction of these two formulations, namely, the force acting on a test charge exerted by an unformly charged spherical shell around the test particle. According to Weber's electrodynamics, the test charge, when accelerated in relation to the spherical shell, should behave as if it had an effective inertial mass which depends on the value of the charge spread on the spherical shell around it. According to Lorentz's force, on the other hand, nothing of this should happen as the spherical shell exerts no force on the internal test charge, no matter its acceleration. We present orders of magnitude for this effect. We also present Weber's planetary model of the atom which was developed BEFORE Rutherford's experiments and also before Bohr's model. In Weber's model the positive nucleous is stabilized by purely electrodynamic forces. After all, when charges of the same sign are moving at a very close distance, they should behave as if they had a negative inertial mass, attracting one another instead of repeling each other. Weber's model is a unification of the forces of nature. After all, it is not necessary to postulate nuclear forces in order to stabilize the positively electrified nucleous. We discuss modern experiments and recent theoretical developments related with Weber's electrodynamics. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Eletrodinamica-de-Weber-06-04-2017.pdf. Audio of this presentation: https://www.ifi.unicamp.br/~assis/Eletrodinamica-de-Weber-06-04-2017.WAV.
• Talk on Relational Mechanics (1 hour of presentation plus 30 minutes of questions). It did take place at Federal University of Alfenas, UNIFAL, Brazil (November 03, 2016): https://www.youtube.com/watch?v=GEMkxXi7rlc. In this talk we presented Galileo's free fall experimenta and Newton's bucket experiment. In Newton’s bucket experiment we have a bucket partially filled with water hanging by a rope. When the bucket and the water are at rest relative to the ground, the surface of the water is flat. When the bucket and the water rotate together relative to the ground, the surface of the water becomes concave (the water rises towards the sides of the bucket, acquiring a parabolic shape). It is shown that in Newtonian mechanics this curvature of the water surface is not due to its rotation relative to the bucket, relative to the Earth, nor relative to the distant stars and galaxies. To Newton this experiment proved the existence of empty and free space, which he called absolute space. According to Newton, the curvature of water should be due to its rotation relative to this absolute space. The criticisms of Ernst Mach against Newtonian mechanics are discussed. An emphasis is given in Mach's ideas according to which the inertia of any body is due to its gravitational interaction with the distant universe. Einstein's theories of relativity do not implement Mach's principle. This fact is one of the reasons why we are against Einstein’s special and general theories of relativity. Finally we present Relational Mechanics, a theory which implements quantitatively Mach's ideas about the origin of inertia utilizing a Weber's law for gravitation. We discuss Galileo's free fall experiment and Newton's bucket experiment from the point of view of Relational Mechanics. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Mecanica-Relacional-Unifal-3-11-2016.pdf. Discussion with the professors and students of the Federal University of Alfenas (November 04, 2016): https://m.facebook.com/story.php?story_fbid=285217098540864&id=262170374178870
• Talk on the Mechanics and Optics of Newton (1 hour of presentation plus 20 minutes of questions). It did take place at the Science Center of the Federal University of Juiz de Fora - UFJF, Brazil (November 27, 2015): http://www.ufjf.br/centrodeciencias/2016/06/27/palestras-da-4a-jornada-de-divulgacao-cientifica/ and https://www.youtube.com/watch?v=49zxFqU8HVI. Slides of this presentation: https://www.ifi.unicamp.br/~assis/mecanica-optica-27-11-2015.pdf
• Talk on Relational Mechanics (1 hour of presentation plus 1 hour of questions). It did take place at the Catholic University of Brasília, UCB, Brazil (September 19, 2012): https://youtu.be/JZKo426iFCo. In this talk we presented Galileo's free fall experimenta and Newton's bucket experiment. In Newton’s bucket experiment we have a bucket partially filled with water hanging by a rope. When the bucket and the water are at rest relative to the ground, the surface of the water is flat. When the bucket and the water rotate together relative to the ground, the surface of the water becomes concave (the water rises towards the sides of the bucket, acquiring a parabolic shape). It is shown that in Newtonian mechanics this curvature of the water surface is not due to its rotation relative to the bucket, relative to the Earth, nor relative to the distant stars and galaxies. To Newton this experiment proved the existence of empty and free space, which he called absolute space. According to Newton, the curvature of water should be due to its rotation relative to this absolute space. The criticisms of Ernst Mach against Newtonian mechanics are discussed. An emphasis is given in Mach's ideas according to which the inertia of any body is due to its gravitational interaction with the distant universe. Einstein's theories of relativity do not implement Mach's principle. This fact is one of the reasons why we are against Einstein’s special and general theories of relativity. Finally we present Relational Mechanics, a theory which implements quantitatively Mach's ideas about the origin of inertia utilizing a Weber's law for gravitation. We discuss Galileo's free fall experiment and Newton's bucket experiment from the point of view of Relational Mechanics.
• Talk on Relational Mechanics (1 hour of presentation plus 1 hour of questions). It did take place at the Pontifícia Universidade Católica de Minas Gerais, PUC-Minas, Brazil (October 03, 2005). Part I: https://youtu.be/KxP9eNR3hQY. Part II: https://youtu.be/2q_E4URxiDA. We discuss relational mechanics, Weber's electrodynamics, Mach's principle and Newton's bucket experiment.

(III) Talks and interviews in French:

• "L'Électrodynamique d'Ampère". Talk presented on December 12, 2025, at the Ampère Colloquium, Lyon University, France, organized by Prof. Alfonso San Miguel: https://youtu.be/gzwI--nLgFw?list=PLyNzFbZnwwp1nLH3FSEGHgYSB3p1BggO4. Abstract: Nous allons explorer la loi de la force électrodynamique telle que déduite par le savant lyonnais André-Marie Ampère (1775-1826). Cette histoire débute en 1820, lorsque Hans Christian Oersted a réalisé son expérience révolutionnaire : un fil conducteur de courant capable de dévier l'aiguille d'une boussole. Cette observation a suscité un grand intérêt et a conduit à différentes interprétations de l'expérience par des scientifiques tels qu'Oersted lui-même, Biot, Faraday et, bien sûr, Ampère. Ampère, avec sa vision novatrice, a avancé deux hypothèses cruciales : premièrement, il a postulé l'existence de forces d'attraction et de répulsion entre les conducteurs de courant, une idée jamais évoquée auparavant. Deuxièmement, il a suggéré que des courants électriques existaient non seulement dans les fils conducteurs, mais également à l'intérieur des aimants et même au sein de la Terre. Pour déduire sa force centrale, qui agit entre deux éléments de courant, Ampère a mené une série d'expériences ingénieuses. Il a mis au point la méthode du point zéro, dans laquelle un circuit mobile est maintenu en équilibre entre deux forces opposées ou entre deux couples opposés. En 1822, Ampère a formulé sa célèbre loi de force, une loi centrale conforme à la troisième loi du mouvement de Newton, c'est-à-dire la loi d'action et de réaction. Selon cette loi, la force entre deux éléments de courant est proportionnelle au produit de leurs intensités, au produit de leurs éléments infinitésimaux et varie en inverse du carré de leur distance. De plus, cette force dépend de trois angles. Selon James Clerk Maxwell, la loi de force d'Ampère devrait toujours rester l'une des formulations les plus essentielles de l'électrodynamique. Cependant, malgré son évaluation positive, la force d'Ampère entre les éléments de courant a été reléguée aux oubliettes des manuels modernes, remplacée par la loi de force de Grassmann-Biot-Savart de 1845, qui ne respecte pas la troisième loi du mouvement de Newton. Maxwell, tout en étant au courant de ces deux expressions (les forces d'Ampère et de Grassmann), a expressément préféré la loi de force d'Ampère. Nous allons maintenant explorer des expériences modernes qui cherchent à distinguer les lois de force d'Ampère et de Grassmann, en mettant notamment l'accent sur la force longitudinale prédite par Ampère, qui est absente dans la force de Grassmann. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Electrodynamique-Ampere-12-12-2025.pdf.
• "L'Électrodynamique d'Ampère". Talk presented on December 01, 2023, at the Department of Physics of Lyon University, France, organized by Prof. Alfonso San Miguel: https://www.youtube.com/watch?v=3NMZ6Zijtdg. Abstract. Slides of this presentation: https://www.ifi.unicamp.br/~assis/Electrodynamique-Ampere-01-12-2023.pdf.

(IV) Talks and interviews in Spanish:

• "Professor de la Unicamp traduce obras clásicas de la física". Interview posted on January 14, 2026, at Jornal of the University of Campinas, Unicamp: https://jornal.unicamp.br/es/noticias/2026/01/14/professor-da-unicamp-traduz-obras-classicas-da-fisica/. Interview conducted by journalist Helena Tallmann, photographs by Antoninho Perri and image edition by Alex Calixto. English version of this interview: https://jornal.unicamp.br/en/noticias/2026/01/14/professor-da-unicamp-traduz-obras-classicas-da-fisica/. Portuguese version of this interview: https://jornal.unicamp.br/noticias/2026/01/14/professor-da-unicamp-traduz-obras-classicas-da-fisica/. Post on Instagran: https://www.instagram.com/p/DTgNUrQE_Xt/?img_index=1. Post on Facebook: https://www.facebook.com/share/p/1CPVRed9Uh/.

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