by Samriddhi Mishra
The end of our vast and grand universe almost seems impossible. With so many galaxies, stars, celestial bodies, etc., it’s very hard to imagine a time when all of it will be gone. However, as the popular saying goes: ‘The end is inevitable’. Scientists all over the globe have come up with certain theories that give an insight into the universe’s fate.
“Some say the world will end in fire,
Some say in ice.”
The lines above were taken from the very famous poem ‘Fire and Ice’ by Robert Frost in which he discusses the end of humanity. In his poem, Frost takes a metaphorical approach towards the end of the world equating fire with desire and ice with hate. This poem is, however, based on real scientific theories that are widely recognized. So, what are the real ‘fire’ and ‘ ice’? Let’s find out!
The Big Crunch
This theory has been around ever since the expansion of the universe was discovered by Edwin Hubble and its roots lie in Einstein’s theory of General Relativity. It is based on the idea that any body, when projected against gravity, eventually comes back down and eventually, gravity wins. For example: when a ball is thrown up towards the sky against gravity it comes back down towards the earth.
In a similar fashion, cosmologists predicted that the expansion of the universe could not continue forever and that when the density of the universe reaches a particular magnitude the universe was bound to start contracting. This way the universe collapses on itself , pulling all of the matter with it until a colossal black hole is formed.
However, this theory became unpopular after scientists discovered that the universe was rapidly expanding in regions far from us. In other words, the expansion of the universe was accelerating. This mysterious force counteracting gravity was dubbed ‘Dark energy’, and it is estimated to make up about 70% of the matter-energy in our universe. As support for the Big Crunch vanished, the scientists were expected to provide a more plausible theory for the death of our beloved universe. Fortunately, they didn’t disappoint.
The Big Freeze
Also known as the ‘Heat Death’, The Big Freeze remains the most widely accepted theory regarding the fate of our universe. It is based on the idea that in an isolated body, such as our universe, the entropy (lack of energy and a measure of unpredictability) increases continuously until a compensation point is reached. In simple words, there might be a time in the future when all the chemical reactions happening in our universe would stop as it approaches a state of equilibrium. This takes place when all the energy available (from a hot source) moves to the places of less energy (to a cold source). When this equilibrium state is reached, no more work would be extracted from the universe as there would be no more heat transfer taking place. Hence, the universe will be deemed to be effectively dead.
So, finally, Will the world end in Fire or Ice? To get the answer to this complex question the scientists still need to gain adequate information about the composition, density and the shape of the universe. For example, if the density of the universe is larger than the critical density, The Big Crunch seems a more probable scenario as the universe expands forever at a decreasing rate and eventually stops. However, the recent data gathered by Wilkinson Microwave Anisotropy Probe (WMAP) , which collects Cosmic Microwave Background indicates that the density of the universe is less than the critical density. Hence, presently it seems that The Big Freeze is the more probable scenario. Fortunately, for the moment being we can breathe a sigh of relief as these processes are expected to take trillions of years. And with global issues like climate change, there is definitely the possibility that we will end up destroying ourselves before the universe can.
PhysLink.com, A. (n.d.). What exactly is the heat death? Retrieved January 27, 2021, from https://www.physlink.com/education/askexperts/ae181.cfm
Villanueva, J. (2020, March 02). The Big Crunch: The End of Our Universe? Retrieved January 27, 2021, from https://www.universetoday.com/37018/big-crunch/
Villanueva, J. (2020, March 02). What is the Big Freeze? Retrieved January 27, 2021, from https://www.universetoday.com/36917/big-freeze/