Physics Talk

Backward Black Hole (Artist's Concept); Credit - NASA/JPL:  https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA13168 You have probably heard of black holes: incredibly dense regions of space-time with such strong gravitational attraction that not even light can escape from them. They were first predicted by general relativity, but Einstein’s famous theory does not stop there. The same equations that revealed the presence of black holes point to an equally fascinating phenomenon – white holes. [1] Black holes in reverse While black holes are notoriously known for pulling matter inward, white holes do the opposite, ‘spewing [it] out.’ [2] Black holes are extraordinarily massive, with supermassive black holes ranging from ‘millions to billions of times the mass of the Sun.’ [3] White holes are born when you consider what would happen if a black hole singularity had no mass. They have not yet been discovered by astronomers and are currently just a mathematical prediction. H

The Far Side of the Moon; Credit - Apollo 16 astronauts/Public domain: https://commons.wikimedia.org/wiki/File:Back_side_of_the_Moon_AS16-3021.jpg “The dark side of the Moon.” This common phrase refers to the far side of the Moon which constantly points away from the Earth – we only ever see one side of the Moon. Above is a picture of this elusive side which you will never have seen with your own eyes from Earth. Despite what the phrase suggests, the far side of the Moon is not dark, receiving the same amount of sunlight as the Earth-facing side. [1]  So what causes this phenomenon? Tidal locking The Moon completes an orbit of the Earth once every 27.3 days. It also spins about its axis once every 27.3 days. [2] Scientists call this synchronous rotation: ‘the rotation of an orbiting body on its axis in the same amount of time as it takes to complete a full orbit.’ [3] However, this has not always been the case. After its initial formation, presumably following a collision where

  zathris (pixabay user):  https://pixabay.com/photos/cpu-chip-semiconductor-condenser-3061923/ Intrinsic to modern electronics, semiconductors are defined as ‘crystalline solids intermediate in electrical conductivity between a conductor and an insulator.’ [1] They have been incorporated in numerous devices including computers, smartphones, bank ATM’s, televisions, washing machines, trains and LED bulbs just to name a few. [2] Band theory Band theory is helpful in visualising the difference between conductors, semiconductors and insulators. Quantum physics dictates that for isolated atoms, the energy states that electrons can occupy are quantised. However, when atoms are brought together to make solids, ‘these discrete energy levels become perturbed through quantum mechanical effects’ [3] As a result, the electrons can occupy a range of energies within a certain energy band. The electrons in an atoms outer shell are situated in an energy band called the valence band. Meanwhile,

https://www.pxfuel.com/en/free-photo-xnsas In 1905, Albert Einstein published his first paper on the theory of special relativity, which is based upon two postulates:          1 .       The laws of physics are the same in all inertial frames of reference          2.      The speed of light is invariant in any inertial frame of reference Inertial frames of reference can be considered ones which are ‘neither accelerating nor rotating with respect to the distant galaxies.’ [1] Two direct consequences of these postulates are time dilation and length contraction. Time dilation refers to the apparent slowing down of a clock, from the perspective of an observer who is in relative motion with it. The factor by which time is dilated is called the Lorentz factor, calculated using the following equation [2] : Similarly, lengths of moving objects are contracted, from the perspective of a stationary observer, by the same Lorentz factor. From the above equation, you can see that the Lorentz