Physics Talk

  ESA/Hubble, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons It is estimated that there are “about 100 thousand million stars in the Milky Way alone” [1] , our Sun being one of them. All life on Earth is powered by the Sun which generates energy through nuclear fusion: the process in which light nuclei combine to form heavier nuclei. The protons and neutrons in the resultant nuclei are more tightly bound than in the initial, fusing nuclei. This movement to a more stable, lower energy state means that energy is released during fusion. In order to achieve nuclear fusion, the strong nuclear force must overcome the electrostatic repulsion between the positively charged nuclei. Since the strong nuclear force is a short-range force, this only occurs when nuclei are very close together. An increase in kinetic energy of the nuclei is required to overcome the electrostatic repulsion and bring the nuclei together. [2] Therefore, stars like the Sun hav...

Credit - JohnsonMartin: https://pixabay.com/illustrations/wormhole-space-time-light-tunnel-739872/ Wave-particle duality is a key aspect of quantum mechanics. The wave characteristics of a particle are mathematically described by a quantity called the wave function. The square of the modulus (absolute value) of the wave function at a given position represents the probability of finding the particle at that point. 1 Quantum mechanics is inherently probabilistic. It is only when an observation is made that the wave function collapses. This feature is most apparent in the double-slit experiment which was talked about in the previous post ( https://phys-talk.blogspot.com/2020/09/the-problem-with-quantum-mechanics.html ). The wave-like nature of particles paves the way for an interesting phenomenon known as quantum tunnelling. Going through walls Quantum tunnelling is the phenomenon of particles passing through ‘seemingly impassable force barriers.’ 2 Consider a ball rolling up a ...

  Credit - geralt: https://pixabay.com/illustrations/physics-quantum-physics-particles-3871216/ Quantum mechanics is currently seen as ‘the best description we have of the nature of the particles that make up matter and the forces with which they interact.’ [1] The key ideas of quantum physics include wave-particle duality and quantised properties. Wave-particle duality is the concept that all physical entities behave as both waves and particles simultaneously. For instance, electrons undergo diffraction which is a wave effect. Meanwhile, radiation is emitted in small discrete packets or quanta called photons. These photons can be considered as particles. Each photon contains an amount of energy. Therefore, light energy is quantised. Quantum mechanics has been incredibly successful since its development in the early 20 th century. Most notably, they underpin the science behind transistors, fundamental to modern electronics, which are composed of semiconductors: the energy ba...

Zouavman Le Zouave / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0); https://commons.wikimedia.org/wiki/File:Light_shining1.JPG The Rayleigh-Jeans law, based on classical physics, gives the spectral radiance (linked to intensity) of blackbody electromagnetic radiation as a function of wavelength: B v (T) is spectral radiance; k B is the Boltzmann constant; T is temperature; c is the speed of light; λ is wavelength. [1] Blackbodies are defined as ‘[idealised] objects that perfectly absorb and then re-emit radiation’ [2] . The equation shows that increasing the wavelength should cause the spectral radiance of the emitted radiation to decrease and tend to zero whilst decreasing wavelength causes it to increase, tending to infinity. This graph [3] shows what the Rayleigh-Jeans law predicts (labelled ‘Classical theory’) and what actually happens at different temperatures (the blue, green and red lines). Although the law seems to coincide with exper...