Modern Physics - Definition, Father of Modern Physics, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:32 PM IST

Modern physics is a field of physics that uses post-Newtonian notions to study the fundamental nature of the universe. Some experimental discoveries in the early twentieth century did not meet the expectations of classical physics, which describes physical phenomena on a small scale. These hypotheses eventually gave birth to modern physics. Quantum theory and the theory of relativity are the two cornerstones of modern physics. Quantum theory describes small-scale physics and gravity, whereas relativity theory describes large-scale physics and gravity. Both theories can be used to approximate the outcomes of classical theory.

This Story also Contains

Who is the Father of Modern Physics?
What is Modern Physics?
Concept of Relativity

Modern Physics - Definition, Father of Modern Physics, FAQs

Who is the Father of Modern Physics?

Physics is the scientific study of all natural phenomena, both theoretically and experimentally. Numerous scientists have contributed to the subject's advancement. The title "Father of Physics" is bestowed on three scientists at different times, based on their most significant achievements. Galileo is known as the Father of Observational Physics for his contributions to Astrophysics.

The laws of motion and gravitation were created by Sir Isaac Newton. His idea, which works fine on a small scale, is the foundation of classical physics. In mathematics, he also taught calculus theory. Newton is renowned as the Father of Physics because of his significant contributions.

Albert Einstein is widely regarded as the founder of modern physics. He established both the special and general theories of relativity. These theories explain how objects behave at great speeds (near the speed of light) and in the presence of gravity. For his explanation of the photoelectric effect, he received the Nobel Prize.

Also, read

NEET Highest Scoring Chapters & Topics

This ebook serves as a valuable study guide for NEET exams, specifically designed to assist students in light of recent changes and the removal of certain topics from the NEET exam.

Download E-book

What is Modern Physics?

Modern physics is a field of physics concerned with post-Newtonian concepts in the physical universe. It is based on two important twentieth-century breakthroughs: Relativity and Quantum Mechanics.

Modern physics frequently includes parts of quantum mechanics and Einsteinian relativity, as well as a more advanced description of nature through new theories that differ from classical descriptions. Quantum effects, for example, frequently require atomic distances. Relativistic effects, on the other hand, usually entail velocities that are slower than the speed of light.

The following are some of the most important notions in quantum theory:

Particle - Wave Light has the properties of both a wave and a particle. Photons, or energy quanta, make up light. The nature of particles is that they travel in waves. Particles are spatially delocalized.
The Uncertainty Principle states that it is impossible to measure a particle's precise position and momentum at the same time.
Problem with Measurement: Observing or measuring a system affects its condition.

Concept of Relativity

No big object can travel faster than the speed of light. For all observers, the laws of physics remain unchangeable.
The curvature of spacetime is caused by mass.
The length of an object decreases as it approaches the speed of light (length contraction). The speed of a moving clock decreases (time dilation).
The cause-effect structure (causality) or the sequence of events is preserved.
The masses of gravity and inertia are the same.

Related Topics

Topics of Modern Physics

The following are the topics that are regarded as important to the subject's foundation:

The evolution of the atomic model in general and atomic theory in particular
Radiation from a black body
Experiment with Franck and Hertz
Rutherford's experiment (Geiger–Marsden experiment)
Gravitational lensing is a type of gravitational lensing that occurs
Experiment Michelson–Morley
Effect of photoelectricity
Thermodynamics at the quantum level
In general, radioactive phenomena
Mercury's perihelion precession
Experiment Stern–Gerlach
Solid
wave-particle duality

Did you know?

Light can be bent by gravity. It creates gravitational lensing, which is the bending of light when it comes close to a huge object.
Near a large object, time slows down.
Gravitational attraction occurs as a result of spacetime bending.
Gravitational waves are created when a mass accelerates and causes ripples in spacetime. Gravitational waves were discovered in 1915.
By setting proper constraints, classical physics can be recovered from current physics.
Quantum physics is verified by electron interference, photoelectric effect, hydrogen spectrum, and blackbody radiation.
Planetary orbital anomalies, temporal gaps in satellites, and gravitational waves all fit relativity's predictions.
Gravitational force, electromagnetic force, strong and weak forces are the four primary forces in nature. The Standard model describes the last three forces.
Scientists are attempting to combine quantum theory and the theory of relativity by developing a more broad theory, dubbed the "theory of everything."

Frequently Asked Questions (FAQs)

1. What makes classical physics different from current physics?

The behaviour of matter and energy on a normal scale of observation is the focus of classical physics, but most of current physics is concerned with the behaviour of extreme conditions, or on a very big or very tiny scale, affecting matter and energy.

2. What are modern physics' two pillars?

"One of the major problems with twentieth-century physics is that so much of modern physics is built on two foundations that emerged in the early twentieth century," he explains. "One is relativity, and the other is quantum mechanics," says the author.

3. What is the name of the founder of quantum physics?

Niels Bohr and Max Planck, two of the founding fathers of quantum theory, each received the Nobel Prize in Physics for their work on quanta.

4. Who is credited with the invention of classical physics?

It comprises of physical notions based on Sir Isaac Newton's foundational works, as well as mathematical methods established in the 17th century by Gottfried Wilhelm Leibniz, Joseph-Louis Lagrange, Leonhard Euler and others used the term "motion of bodies under the influence of a system of forces" to describe how bodies move when they are subjected to a set of forces.

5. Who do you think is the father of modern physics, and why do you think that is?

Galileo Galilei was the first to utilise a refracting telescope to make key astronomical discoveries, and he pioneered the experimental scientific process. He is known as the "Father of Modern Astronomy" and "Father of Modern physics," among other titles. Galileo was dubbed the "Father of Modern Science" by Albert Einstein.

6. What is modern physics' most important contribution in the modern world?

Physics uses mathematical formulas to explain how the natural world works. The achievements in electronics that have resulted in modern computers and electronic media are due to physics theory.

7. What are the two main pillars of modern physics?

The two main pillars of modern physics are quantum mechanics and the theory of relativity. Quantum mechanics describes the behavior of matter and energy at the atomic and subatomic scales, while relativity deals with the nature of space, time, and gravity, especially at very high speeds or in strong gravitational fields.

8. How did the discovery of the photoelectric effect contribute to modern physics?

The photoelectric effect, explained by Einstein in 1905, showed that light behaves as both a wave and a particle (photon). This discovery was crucial in developing quantum theory and earned Einstein the Nobel Prize in Physics, demonstrating the quantum nature of light and matter.

9. What is the significance of the famous equation E = mc²?

Einstein's equation E = mc² expresses the equivalence of energy (E) and mass (m), with c representing the speed of light. This formula revolutionized physics by showing that mass and energy are interchangeable, leading to new understandings in nuclear physics, cosmology, and particle physics.

10. What is the Heisenberg Uncertainty Principle and why is it important?

The Heisenberg Uncertainty Principle states that it's impossible to simultaneously know both the exact position and momentum of a particle. This principle is fundamental to quantum mechanics, highlighting the probabilistic nature of the quantum world and setting limits on what can be known about quantum systems.

11. How did the development of the atomic bomb relate to modern physics?

The development of the atomic bomb was a direct application of modern physics principles, particularly nuclear fission and Einstein's mass-energy equivalence (E = mc²). It demonstrated the immense energy contained within atoms and the practical (though devastating) implications of modern physics theories.

12. How does modern physics explain the stability of atoms?

Modern physics, specifically quantum mechanics, explains atomic stability through the concept of electron orbitals. Unlike the classical model where electrons would quickly spiral into the nucleus, quantum mechanics describes electrons as existing in probability clouds around the nucleus, with discrete energy levels preventing their collapse.

13. How does modern physics explain the nature of light?

Modern physics describes light as having a dual nature: it behaves as both a wave and a particle (photon). This wave-particle duality explains phenomena like interference and diffraction (wave properties) as well as the photoelectric effect and Compton scattering (particle properties).

14. How does modern physics explain the phenomenon of radioactive decay?

Modern physics explains radioactive decay using quantum mechanics. It describes decay as a probabilistic process where unstable atomic nuclei spontaneously emit particles or energy to reach a more stable state. The exact moment of decay for an individual atom cannot be predicted, but the overall decay rate of a large sample follows statistical laws.

15. How does the theory of relativity change our understanding of time?

Einstein's theory of relativity shows that time is not absolute but relative to the observer's frame of reference. Time can dilate (slow down) for objects moving at high speeds or in strong gravitational fields. This leads to phenomena like time dilation, where time passes differently for objects moving at different speeds or experiencing different gravitational forces.

16. How does quantum mechanics challenge our everyday understanding of the world?

Quantum mechanics challenges our intuition by introducing concepts like wave-particle duality, superposition, and entanglement. It suggests that particles can exist in multiple states simultaneously until observed, and that the act of measurement affects the outcome, ideas that seem counterintuitive in our macroscopic world.

17. Who is considered the "Father of Modern Physics" and why?

Albert Einstein is often called the "Father of Modern Physics" due to his groundbreaking contributions, particularly his theories of special and general relativity. These theories revolutionized our understanding of space, time, and gravity, laying the foundation for much of modern physics.

18. What is the significance of the uncertainty principle in quantum mechanics?

The uncertainty principle, formulated by Heisenberg, states that certain pairs of physical properties, like position and momentum, cannot be simultaneously measured with arbitrary precision. This principle is fundamental to quantum mechanics, setting limits on what can be known about quantum systems and challenging classical notions of determinism.

19. What is the significance of the Pauli exclusion principle in modern physics?

The Pauli exclusion principle, formulated by Wolfgang Pauli, states that no two identical fermions (particles with half-integer spin) can occupy the same quantum state simultaneously. This principle is fundamental to understanding atomic structure, the stability of matter, and phenomena like electron degeneracy pressure in white dwarf stars. It's crucial in explaining the periodic table of elements and the behavior of electrons in atoms and solids.

20. What is modern physics and how does it differ from classical physics?

Modern physics refers to the branch of physics developed in the early 20th century and beyond, dealing with phenomena at atomic and subatomic scales or involving very high speeds. It differs from classical physics in that it incorporates theories like quantum mechanics and relativity, which often contradict our everyday intuitions but accurately describe the behavior of matter and energy at extreme scales.

21. What is the significance of the double-slit experiment in modern physics?

The double-slit experiment demonstrates the wave-particle duality of matter and light, a key concept in quantum mechanics. It shows that particles like electrons can exhibit wave-like behavior, interfering with themselves when passing through two slits, challenging classical notions of particle behavior.

22. What is the role of the observer in quantum mechanics?

In quantum mechanics, the observer plays a crucial role. The act of observation or measurement is thought to collapse the wave function, determining the state of a quantum system. This idea, known as the "measurement problem," suggests a complex relationship between the observer and the observed in the quantum world.

23. What is the concept of wave function in quantum mechanics?

The wave function is a mathematical description of the quantum state of an object in quantum mechanics. It provides information about all possible states of a system and allows calculation of the probability of finding a particle in a specific state or position. The wave function is central to understanding quantum behavior and probability in the quantum world.

24. What is the significance of the Planck constant in modern physics?

The Planck constant (h) is a fundamental physical constant that plays a crucial role in quantum mechanics. It relates the energy of a photon to its frequency and sets the scale at which quantum effects become important. The Planck constant is essential in describing quantum phenomena and appears in many fundamental equations of quantum mechanics.

25. What is the significance of the Standard Model in particle physics?

The Standard Model is a comprehensive theory in modern physics that describes the fundamental particles and forces of the universe (except gravity). It explains how particles interact through the strong, weak, and electromagnetic forces. The model has been highly successful in predicting and explaining a wide range of phenomena, including the discovery of the Higgs boson.

26. How does modern physics explain the phenomenon of quantum entanglement?

Quantum entanglement is a phenomenon where two or more particles become correlated in such a way that the quantum state of each particle cannot be described independently. Modern physics explains this through quantum mechanics, where entangled particles share information instantaneously, regardless of distance. This "spooky action at a distance," as Einstein called it, has been experimentally verified and is a key feature of quantum systems.

27. What is the significance of the Higgs boson in modern physics?

The Higgs boson, discovered in 2012, is a fundamental particle predicted by the Standard Model. It's associated with the Higgs field, which gives mass to other fundamental particles. The discovery of the Higgs boson was crucial in validating the Standard Model and our understanding of how particles acquire mass, filling a significant gap in modern physics theory.

28. How does modern physics explain the concept of antimatter?

Modern physics, specifically quantum field theory, predicts the existence of antimatter - particles with the same mass but opposite charge and other quantum properties of ordinary matter. Antimatter is explained as a natural consequence of combining quantum mechanics with special relativity. The study of antimatter is crucial for understanding the early universe and particle-antiparticle asymmetry.

29. What is the significance of Feynman diagrams in modern physics?

Feynman diagrams, introduced by Richard Feynman, are graphical tools used in modern physics to represent the mathematical expressions describing the behavior of subatomic particles. They provide a visual way to calculate and understand complex particle interactions in quantum field theory. These diagrams have become an essential tool in particle physics for computing probabilities of various processes.

30. What is the significance of the fine-structure constant in modern physics?

The fine-structure constant is a fundamental physical constant that characterizes the strength of the electromagnetic interaction between elementary charged particles. It's dimensionless and plays a crucial role in quantum electrodynamics. Its value has been measured to high precision and is important in testing the accuracy of physical theories and the possibility of varying fundamental constants.

31. How does modern physics explain the phenomenon of quantum superposition?

Quantum superposition is a fundamental principle of quantum mechanics where a quantum system can exist in multiple states simultaneously until measured. Modern physics explains this through wave functions, which describe all possible states of a system. Upon measurement, the wave function "collapses" to a single state. This principle is crucial for understanding phenomena like quantum computing and the double-slit experiment.

32. What is the significance of the Copenhagen interpretation in quantum mechanics?

The Copenhagen interpretation, developed by Niels Bohr and others, is one of the earliest and most commonly taught interpretations of quantum mechanics. It posits that quantum systems don't have definite properties prior to measurement and that quantum mechanics can only predict probabilities of measurement outcomes. This interpretation emphasizes the role of measurement and the inherent probabilistic nature of quantum phenomena.

33. What is the significance of Bell's theorem in modern physics?

Bell's theorem, proposed by John Stewart Bell, addresses the fundamental nature of quantum mechanics. It shows that no local hidden variable theory can reproduce all the predictions of quantum mechanics. The theorem has profound implications for our understanding of reality, suggesting that quantum mechanics is inherently non-local and that "spooky action at a distance" (as Einstein called it) is a fundamental aspect of nature.

34. How does modern physics explain the concept of quantum entanglement?

Quantum entanglement is a phenomenon where two or more particles become correlated in such a way that the quantum state of each particle cannot be described independently. Modern physics explains this through the mathematics of quantum mechanics, where entangled particles share a single quantum state. This leads to correlations between the particles that persist regardless of the distance between them, challenging our classical notions of locality and realism.

35. What is the significance of the many-worlds interpretation in quantum mechanics?

The many-worlds interpretation, proposed by Hugh Everett, is an attempt to resolve the measurement problem in quantum mechanics. It suggests that all possible outcomes of quantum measurements are realized in separate, branching universes. This interpretation avoids the need for wave function collapse but introduces the concept of a vast multiverse. While controversial, it has significant implications for our understanding of reality and quantum phenomena.

36. What is the significance of Feynman path integrals in modern physics?

Feynman path integrals, developed by Richard Feynman, provide an alternative formulation of quantum mechanics. They describe quantum systems by considering all possible paths between initial and final states, with each path contributing to the overall probability amplitude. This approach is particularly useful in quantum field theory and has applications in many areas of physics, offering insights into quantum behavior and particle interactions.

37. What is the significance of the Casimir effect in modern physics?

The Casimir effect, predicted by Hendrik Casimir, is a quantum mechanical phenomenon where two uncharged metallic plates in a vacuum experience an attractive force. Modern physics explains this as a result of quantum fluctuations in the vacuum between the plates. The effect demonstrates the reality of quantum vacuum fluctuations and has implications for nanotechnology, quantum field theory, and our understanding of vacuum energy.

38. What is the significance of the quantum Zeno effect in modern physics?

The quantum Zeno effect, named after the Greek philosopher Zeno, describes how frequent observations of a quantum system can inhibit its evolution. Modern physics explains this as a consequence of the measurement process in quantum mechanics, where each measurement collapses the wave function. This effect has implications for quantum control and measurement techniques, and it challenges our understanding of the relationship between observation and quantum systems.

39. How does modern physics explain the concept of quantum entanglement swapping?

Quantum entanglement swapping is a process where entanglement is transferred from one pair of particles to another without the two ever interacting directly. Modern physics explains this through quantum information theory and the manipulation of quantum states. This concept is crucial for quantum communication protocols, quantum repeaters, and the development of quantum networks. It demonstrates the non-local nature of quantum entanglement and its potential for long-distance quantum information transfer.

40. What is the significance of the holographic principle in modern physics?

The holographic principle, proposed in the context of black hole

41. What is the significance of the Schrödinger equation in modern physics?

The Schrödinger equation is a fundamental equation in quantum mechanics that describes how the quantum state of a physical system changes over time. It's crucial for predicting the behavior of quantum systems and forms the basis for understanding atomic and molecular structure, chemical bonding, and many other quantum phenomena.

42. How does modern physics explain the nature of matter at the subatomic level?

Modern physics, particularly quantum mechanics, describes matter at the subatomic level as having both particle and wave-like properties. Subatomic particles are characterized by quantum numbers and can exist in superposition states. Their behavior is governed by probability rather than deterministic laws, and they can exhibit phenomena like entanglement and tunneling.

43. What is the role of symmetry in modern physics theories?

Symmetry plays a fundamental role in modern physics theories. In particle physics, symmetries are associated with conservation laws (like conservation of energy or charge). The concept of symmetry breaking is also crucial, explaining phenomena like the Higgs mechanism. Symmetries guide the formulation of theories and help in understanding the fundamental laws of nature.

44. How does modern physics explain the phenomenon of quantum tunneling?

Quantum tunneling is a phenomenon where particles can pass through barriers that they classically shouldn't be able to overcome. Modern physics explains this through quantum mechanics, where particles are described by wave functions. These wave functions have a non-zero probability of existing on the other side of a potential barrier, allowing for tunneling effects. This concept is crucial in explaining radioactive decay and certain electronic devices.

45. How does modern physics explain the concept of spin in particles?

Spin is an intrinsic form of angular momentum carried by elementary particles, a concept that emerged from quantum mechanics. Unlike classical spinning, quantum spin is a fundamental property of particles that can only take certain discrete values. It plays a crucial role in understanding particle behavior, atomic structure, and phenomena like ferromagnetism.

46. How does modern physics explain the concept of virtual particles?

Virtual particles are a concept in quantum field theory, describing short-lived particles that cannot be directly observed. Modern physics explains them as fluctuations in quantum fields, allowed by the uncertainty principle for very short time scales. Virtual particles play crucial roles in explaining phenomena like the Casimir effect and are important in calculations of particle interactions.

47. How does modern physics explain the concept of quantum decoherence?

Quantum decoherence is the process by which quantum systems lose their coherence or quantum behavior due to interactions with their environment. Modern physics explains this as the result of entanglement between the quantum system and its surroundings, leading to the apparent collapse of the wave function. Decoherence is crucial in understanding the transition from quantum to classical behavior and the measurement problem in quantum mechanics.

48. How does modern physics explain the concept of quantum field theory?

Quantum field theory (QFT) is a framework that combines quantum mechanics with special relativity to describe subatomic particles. In QFT, particles are viewed as excitations of underlying fields that permeate all of space. This theory explains particle interactions, the creation and annihilation of particles, and provides a unified description of fundamental forces (except gravity). QFT is crucial for understanding particle physics and forms the basis of the Standard Model.

49. How does modern physics explain the concept of quantum vacuum?

The quantum vacuum, far from being empty, is described in modern physics as a sea of virtual particles constantly popping in and out of existence. This concept arises from quantum field theory and the uncertainty principle, which allow for temporary violations of energy conservation. The quantum vacuum plays crucial roles in phenomena like the Casimir effect and vacuum polarization, and it's essential for understanding particle interactions and the nature of empty space.

50. How does modern physics explain the concept of quantum tunneling?

Quantum tunneling is a phenomenon where particles can pass through barriers that they classically shouldn't be able to overcome. Modern physics explains this through the wave-like nature of particles in quantum mechanics. The wave function of a particle has a non-zero probability of existing on the other side of a potential barrier, allowing for tunneling effects. This concept is crucial in explaining radioactive decay, certain types of chemical reactions, and the operation of scanning tunneling microscopes.

51. How does modern physics explain the concept of quantum coherence?

Quantum coherence refers to the ability of quantum systems to exist in multiple states simultaneously and maintain a definite phase relationship between different states. Modern physics explains this through the superposition principle of quantum mechanics. Coherence is crucial for phenomena like quantum computing, where it allows for parallel processing of information. Understanding and maintaining quantum coherence is a major challenge in quantum technologies.