Grade 12
  1. Advanced mechanics  1.1. Dynamics  1.1.1. Motion in two and three dimensions  1.1.2. Advanced Projectile Motion and Range Equations  1.1.3. Relative motion in different reference frames  1.1.4. Motion of charged particles in electric and magnetic fields  1.1.5. Non-uniformly accelerated motion in multiple dimensions  1.2. Dynamics  1.2.1. Newton's laws and applications in non-inertial frames  1.2.2. Dynamics of particle systems  1.2.3. Non-conservative forces and energy dissipation  1.2.4. Momentum in variable mass systems (rocket momentum)  1.2.5. Lagrangian and Hamiltonian Mechanics (Introduction)  1.3. Work, Energy and Power  1.3.1. Work done by non-conservative forces  1.3.2. Power in rotational and translational motion  1.3.3. Advanced Conservation Laws and Applications  1.3.4. Potential energy surface and stability  1.4. Advanced rotational speed  1.4.1. Torque in three dimensions  1.4.2. Moment of inertia for irregular bodies  1.4.3. Gyroscopic motion and precession  1.4.4. Rotational work–energy theorem  1.4.5. Euler's equations of rotational motion  1.5. Gravitational force  1.5.1. Advanced Orbital Mechanics  1.5.2. Lagrange points and stability of orbits  1.5.3. Gravitational time dilation  1.5.4. Escape velocity and energy considerations  1.5.5. Tidal force and the Roche limit
  2. Fluid mechanics and thermodynamics  2.1. Fluid dynamics  2.1.1. Applications of Bernoulli's Principle  2.1.2. Navier-Stokes equations and fluid resistance  2.1.3. Turbulent vs. Laminar Flow  2.1.4. Surface tension and capillary action  2.2. Advanced Thermal Physics  2.2.1. Thermodynamic equilibrium and heat engines  2.2.2. Entropy and the Second Law of Thermodynamics  2.2.3. Maxwell's demon and statistical thermodynamics  2.2.4. Thermodynamic potential and free energy
  3. Oscillations and waves  3.1. Advanced Simple Harmonic Motion  3.1.1. Coupled oscillations and common modes  3.1.2. Damped and driven oscillations  3.1.3. Phase space and resonance  3.1.4. Anharmonic oscillations  3.2. Wave motion  3.2.1. Advanced wave equations and dispersion  3.2.2. Shock Waves and Sonic Booms  3.2.3. Doppler effect in electromagnetic waves  3.2.4. Wave–particle duality
  4. Electromagnetism  4.1. Electrostatics  4.1.1. Gauss's law in unilateral charge distribution  4.1.2. Electric potential for complex charge configuration  4.1.3. Electrostatic energy and self-energy of a system  4.1.4. Dielectrics and Polarization  4.2. Current Electricity  4.2.1. Advanced Circuit Analysis (Thevenin and Norton theorems)  4.2.2. RC, RL and RLC circuits in AC and DC  4.2.3. Superconductivity and applications  4.3. Advanced Magnetism and Electromagnetic Induction  4.3.1. Magnetic fields in conductors and plasma  4.3.2. Lenz's law in time-dependent magnetic fields  4.3.3. Eddy Currents and Applications  4.3.4. Magnetic dipole moment and torque on electric current loops  4.4. Alternating Current and Electromagnetic Waves  4.4.1. LC Circuits and Resonance  4.4.2. Maxwell's equations and electromagnetic wave transmission  4.4.3. Applications of Electromagnetic Waves  4.4.4. Polarization and reflection of EM waves
  5. Optics  5.1. Geometrical Optics  5.1.1. Aberrations in optical systems  5.1.2. Advanced lens and mirror formulas  5.1.3. Optical Instruments and Adaptive Optics  5.2. Wave optics  5.2.1. Diffraction at single and multiple slits  5.2.2. Optical Coherence and Interferometry  5.2.3. Holography and applications
  6. Modern and quantum physics  6.1. Special relativity  6.1.1. Time expansion and length contraction  6.1.2. Relativistic energy and mass  6.1.3. Relativistic Doppler effect  6.2. Quantum mechanics  6.2.1. Schrödinger equation and wave function  6.2.2. Quantum tunneling and applications  6.2.3. Heisenberg uncertainty principle  6.2.4. Quantum superposition and entanglement  6.3. Nuclear physics  6.3.1. Binding energy and mass defect  6.3.2. Neutrino physics and beta decay  6.3.3. Nuclear Fission and Fusion  6.4. Particle physics  6.4.1. Standard Model and fundamental interactions  6.4.2. The Higgs boson and symmetry breaking  6.4.3. Antimatter and CP violation
  7. Astrophysics and cosmology  7.1. General relativity and gravity  7.1.1. Einstein's field equations  7.1.2. Gravitational waves and their detection  7.1.3. Black holes and event horizons  7.2. Cosmology  7.2.1. Dark matter and dark energy  7.2.2. Cosmic microwave background radiation  7.2.3. The expansion of the universe and Hubble's law

Grade 12 ↓


Astrophysics and cosmology


Astrophysics and cosmology are fascinating branches of physics that deal with the study of the universe and its components. These fields have fascinated scientists and laypeople alike for centuries because of the vastness and mysteries of the universe. In this lesson, we explain the basics of these subjects in simple terms, suitable for anyone interested in understanding our universe and its underlying principles.

Difference between astrophysics and cosmology

Before delving deeper, it's important to differentiate between astrophysics and cosmology. While both fields overlap and contribute to our understanding of the universe, they focus on different aspects.

  • Astrophysics: This field focuses primarily on understanding the physical properties and processes of celestial objects such as stars, planets, galaxies, black holes, and other astronomical phenomena. It involves applying the principles of physics to data obtained from astronomical observations.
  • Cosmology: The scope of cosmology is broad, dealing with the origin, evolution, structure, and ultimate fate of the entire universe. It addresses questions related to the Big Bang theory, the expansion of the universe, dark matter, and dark energy.

The night sky: our window to the universe

Looking up at the night sky, you see countless stars and possibly a few planets. But what exactly are these objects?

Stars

Stars are giant balls of gas, mainly hydrogen and helium, where nuclear fusion takes place. This fusion produces energy, which we see as light.

E = mc^2

In this famous equation by Albert Einstein, E represents energy, m represents mass, and c represents the speed of light. This equation describes how matter is converted into energy in stars.

Planets

Planets are bodies that orbit stars and do not produce light by nuclear fusion. In our solar system, we distinguish between terrestrial planets such as Earth and Mars and gas giants such as Jupiter and Saturn.

Galaxies: Islands of the Stars

Galaxies are huge systems containing billions of stars, planets and other celestial bodies, all bound to each other by gravity. Our solar system is part of the Milky Way galaxy.

Galaxies come in a variety of shapes and sizes, including spiral, elliptical, and irregular. Our galaxy is a spiral galaxy, characterized by a spinning disk of stars and spiral arms.

The Big Bang and the Expanding Universe

Today, most scientists believe that the universe began with the Big Bang about 13.8 billion years ago. This theory states that the universe began as an extremely hot and dense point, which expanded rapidly.

Hubble's Law

In the 1920s Edwin Hubble discovered that galaxies are moving away from us, which suggests that the universe is expanding. Hubble's law can be expressed as:

v = H₀ * d

Here, v is the velocity at which the galaxy is moving away, H₀ is the Hubble constant, and d is the distance to the galaxy.

Galaxy A Galaxy B

This leads us to the conclusion that the universe was much smaller in the past and is continuously expanding, which is a core concept of cosmology.

Dark matter and dark energy

Despite the incredible advances in astronomy, many phenomena in the universe still remain unexplained. Dark matter and dark energy are two major mysteries.

Dark matter

Dark matter is a form of matter that does not emit or interact with electromagnetic radiation, making it invisible and only detectable through its gravitational effects. It is thought to make up about 27% of the universe.

Dark energy

Dark energy is an unknown form of energy that is thought to pervade all of space, causing the universe to expand faster. It is thought to make up about 68% of the universe.

dark matter Dark Energy

The rest of the universe (about 5%) is made up of ordinary matter, the building blocks of galaxies, stars, and planets.

Black holes

Black holes are regions in space where gravity is so strong that nothing, not even light, can escape. They are formed when massive stars collapse under their own gravity at the end of their life cycles.

Black holes are commonly identified by their event horizon, the point of no return, and their singularity, where the density becomes infinite.

Understanding black holes can provide insight into the behaviour of extreme gravitational fields and the nature of space and time.

Cosmic microwave background radiation

One of the key pieces of evidence for the Big Bang theory is the cosmic microwave background (CMB) radiation. This radiation is the thermal radiation left over from the Big Bang, widely believed to be the first light in the universe.

The CMB appears as a faint glow in the microwave part of the electromagnetic spectrum, which pervades the universe and provides a snapshot of the newborn universe.

The future of the universe

Cosmologists consider various possibilities regarding the ultimate fate of the universe, including the Big Freeze, the Big Crunch, and the Big Rip.

  • Grand Stabilization: If the universe continues to expand, stars will eventually burn out, galaxies will drift apart, and the universe will reach a state of thermal equilibrium.
  • Big Crunch: The opposite scenario where gravity could slow the expansion, causing the universe to collapse back into a single, compact state.
  • Big Rip: Accelerated expansion driven by dark energy could eventually tear the universe apart at the atomic level.

Conclusion

Astrophysics and cosmology provide a better understanding of the universe, from the fundamental forces of nature to its vast structures and phenomena. Exploring these fields involves an interesting mix of theoretical physics, observation, and new discoveries that continue to amaze and challenge our understanding.

As technology advances, new observations and theoretical developments are leading us into an era of astronomical discoveries. Whether it is understanding distant galaxies, mysterious black holes or the dynamics that govern the universe, the journey to understand these cosmic wonders is indeed an exciting aspect of human endeavour.


Grade 12 → 7


U
username
0%
completed in Grade 12

← Prev (6.4.3)
Antimatter and CP violation
Next (7.1) →
General relativity and gravity

Comments 



Astrophysics and cosmology

https://www.physicsflow.com/g12/7?pfal=en