Dark matter: one of the most perplexing puzzles in the field of astrophysics. Its mystery has compelled science to delve into the hidden corners of the universe in search of answers. Dark matter accounts for approximately twenty seven percent of the total cosmic mass-energy content. It is undoubtedly present, but -- due to its elusive nature -- evades direct detection. It is important for us to know the impact of dark matter on cosmic structure, gravitational dynamics , and the profound implications that it holds for our understanding of the universe.
Firstly, we must understand how dark matter shapes the cosmic web? The cosmic web is a network of filaments of dark matter, believed by many astronomers to form the basis of the universe. Dark matter acts as the cosmic scaffolding upon which galaxies and galaxy clusters are constructed. Its gravitational influence orchestrates the formation of large-scale structures, known as the cosmic web. Astronomers are unable to see dark matter , but they are able to detect its influence by observing how gravity bends and distorts light from more-distant objects (this phenomenon is known as gravitational lensing). Thus, as it interacts with entities in the universe, it can be observed.
Secondly, it is important to understand how dark matter affects gravitational dynamics. Ordinary matter, including stars, planets and interstellar gas contribute to the visible mass of galaxies. The gravitational effects observed exceed what can be visibly seen by the luminous components alone. Dark matter, being invisible and non-interacting with light, provides the gravitational pull necessary to account for the observed rotational velocities of galaxies and the cohesion within galactic clusters. If a galaxy has little or no dark matter at all, the gravitational effects of nearby galaxies will tear the galaxy apart. It can therefore be concluded that, without the gravitational contribution of dark matter , galaxies would not be able to maintain their structure.
Cosmic microwave background (CMB), refers to the cooled remnants of the first light that could ever travel freely throughout the universe. This 'fossil' radiation was released after the Big Bang. Dark matter’s imprint is evident in the Cosmic microwave background. It is believed that one month after the Big Bang, there was a second cosmic explosion that may have given the universe dark matter. When scientists were analysing the Cosmic microwave background they were able to detect the presence of dark matter through comparing the electromagnetic spectrum with gravitational imprints. The distribution of dark matter influences the Cosmic microwave background’s temperature fluctuations, thus providing us with incredibly rich insight into the initial conditions of the cosmos and the seeds of cosmic structure formation.
Though dark matter continues to be elusive , various candidate particles, such as Weakly Interacting Massive Particles (WIMPS) and axions (a hypothetical elementary particle that could convert photons into magnetospheres of neutron stars) have been proposed. There are currently experimental efforts, in which underground detectors and particle accelerators aim to indirectly detect these elusive particles. It is essential that we unravel the mysteries of dark matter so that we can advance fundamental physics past the Standard Model.
Dark matter, apart from its elusive nature, has the theoretical possibility of acting as a fuel:
Jia Liu , a New York University-trained physicist, raised the idea of using dark matter as an energy source to power spacecraft in one of his publications (2009). His concept is based on the pending (at the time of writing) assumption that dark matter is made up of 'neutralinos' (hypothetical particles without electrical charge). Neutralinos also have antiparticles, meaning that they could potentially annihilate, releasing energy. If this is proven to be true , 1 pound of dark matter (around 450g) could produce nearly five billion times more energy than the equivalent mass of dynamite. A 'dark matter reactor' would thus be able to easily power any spacecraft for long journeys. Liu’s dark matter engine would be different from a conventional rocket engine. It would be a box with a door that would open in the direction of the rocket’s movement to scoop up dark matter, whereupon the box will shrink to increase the rate of annihilation, allowing for energy output. After the particles are turned into energy , the door will, once again, open, and the energy will propel the rocket.
It is obvious that dark matter truly does 'matter'. If it weren't for dark matter, we may never have existed. If it weren't for dark matter, we may never have the opportunity to see the universe.
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