Space-Time: Understanding the Universe
Space and Time are considered as two independent variables. But science has proved that they are dependent coordinates that defines the universe. We can’t see it, we can’t touch it, but without space-time we wouldn’t be here. Space-time is a fabric of our reality that shapes and govern our lives. To understand the universe, it is necessary to know how space-time works.
Space Time has been active since the beginning of everything that is the key to evolution of everything. The story of space-time is the story of our universe. To know how the story plays out and how it will end, we need to go to the very beginning to a time when there was nothing, no stars, no space, a time before there was time. Then all of a sudden our entire universe was born in the Big Bang. This is the time when Space time was created. The infant universe, a tiny speck of energy and space time materializes from nowhere. Then the universe suddenly expands. The idea of inflation is that a very tiny region in a very incredibly short amount of time far shorter than a second grew by many orders of magnitude. In a fraction of a second, the universe grew from smaller than the size of an atom to the size of a baseball. In cosmic terms it is like a grain of sand growing almost to the size of the observable universe.
The universe at the instant of inflation actually expanded faster than the speed of light. It seems to be a violation of everything we have heard in physics. The fact is nothing can move faster than the speed of light in the universe. In inflation its space itself that is expanding so there is no violation and there is no paradox. Inflating fast the universe went through a phenomenal growth spurt. At the moment of Big Bang space time was that entity which was flying out in all directions. It was space itself that was expanding but the universe didn’t expand evenly. One spot in the universe was ever so slightly denser than a spot right next to it.
Fluctuations in expanding space time created areas with higher density. Conflations made these high density regions larger and this allowed our universe to take shape. As the universe cooled energy turned into matter and in the denser regions that matter started to clump together. These regions had more mass than the others.
Mass bends space time. So anything that is made of matter bends space time and the more matter you have in one place the more you bend it. Space is not constant which means it is not something that is same everywhere. It actually bends, curves and warps depending on the matter inside of it. The curving grid of space time moving and reacting to objects is actually a force that we call gravity.
Gravity is different from all other forces. It is closely connected with the curvature of space time. Something that can bend space-time has gravity. Hence, gravity is just the bending of space-time fabric. This idea was developed none other than the greatest minds ever existed Einstein. He suggested that space is something that can be bent or stretched that we are all bound together by space-time. Einstein says that its space and time have a geometry. They have a life of their own and dynamics. These dynamics we call gravity. The denser the region of matter, the greater the gravity, the deeper the curve. This connection is the foundation of our physical reality.
It’s the interaction between matter, energy and space-time that created the universe that we see around us today. But how did space-time create our majestic cosmos?
Our entire universe was created in the Big Bang 13.8 billion years ago. Everything came from nothing. But our modern universe is a complex mosaic of matter. Matter in the universe arranges itself on a vast cosmic web galaxies and galaxies are strung out on sheets and filaments. This intricate web is organized by a cosmic architect called space-time. It shaped everything, from planets to galaxies, atoms to cities.
The scientists believe that they don’t know anything about universe. But in 2015, for the first time, they heard ripples in space-time generated by one of the violent events in the history of universe. In 2016, astronomers observed a strange optical phenomenon, a weird circle of light like a cosmic halo and that is a red galaxy that is 7 billion light years away from earth. It is bending the light from a blue galaxy which should be hidden behind it. It is called gravitational lensing that is caused by objects of huge masses that distorts space-time so much that when light comes from farther objects has to pass around the galaxy clusters, the light bends. This bending of light is a true warp of space-time. Gravitational lensing gives us a way of seeing the effects of space-time on light.
Gravitational waves are vibrations from cosmic events, transmitted through the material of space-time. When two black holes collide, the energy released sends shock waves through space time across the universe. By the time they reach earth, they are so small that they are almost immeasurable.
In 2015, scientists at the LIGO observatory made a ground breaking observation. They detected ripples in space-time gravitational waves. This was indeed the first direct detection of gravitational waves seen by man-made instruments on the earth.
We think that time is something that cannot be changed, it simply flows ahead at a constant rate. But would you believe that time can even stop? It might be even possible to travel through time and go back to the future. Its part of the fabric of space-time. Time and space are two sides of the same coin. You can’t have space without time and vice versa. So when matter influences space time its not just creating deformation in space, its also affecting the flow of time. As gravity bends space, it also distorts the flow of time which means that time itself can be slow down or move faster. The stronger the gravity the stronger the distortions. Black holes has the high gravity hence around the black hole space time warps and twists slowing time down. There is a famous way of thinking this which is called twin paradox. Where two twins are born on exactly the same time so they are of the same age. But one of them zips very close to black holes where time will be slow. After few years the twin on the earth will be old enough while the one near the black hole will be still young. It concludes that time has slowed down or dilated for the twin near the black holes. When he returns to the earth he will observe that his other twin is grey-hair and old. It means he has travelled to the future.
Time travel is a staple of science fiction but it is now certain that time travel to the future is still possible at least theoretically. However, time travel to the past is ruled out.
About the Author: The writer is a mechanical engineer by qualification. He likes to read and write on various genres that includehydropower, automobiles, project management, current affairs, space warfare, manufacturing industry, comparative religion and Iqbaliyat.