Unravelling Einstein's General Theory of Relativity

Who Was Albert Einstein?

Albert Einstein is a renowned theoretical physicist, who was born in Ulm, Germany on March 14, 1879. He is widely regarded as one of the greatest scientists of all time. Einstein is best known for developing the theory of relativity, which revolutionized our understanding of space, time, and gravity. His famous equation, E=mc², introduced the concept that mass and energy are interchangeable, laying the groundwork for advancements in nuclear physics. Beyond his scientific contributions, Einstein was also a passionate advocate for peace, civil rights, and education. He received the Nobel Prize in Physics in 1921 for his explanation of the photoelectric effect. Einstein's legacy continues to inspire scientists, thinkers, and dreamers worldwide.

Einstein's General Theory of Relativity

Albert Einstein introduced the General Theory of Relativity, commonly known as general relativity, in 1915. This groundbreaking theory revolutionized our understanding of the universe by introducing the concept of spacetime. Spacetime is a mathematical model that joins space and time into a single idea called a continuum. This four-dimensional continuum is known as Minkowski space. Spacetime's four-dimensional universe comprises three spatial dimensions (space - such as length, width and height, or up/down, left/right, and forwards/backwards) and one temporal dimension (time). Every physical event occurs within these three space dimensions and at a specific moment in time. According to general relativity, mass causes spacetime to curve, and other masses follow these curves, with larger masses resulting in greater curvature. This innovative approach provided a new explanation for gravitation, now understood as gravity.

The Concept of Spacetime

One way of envisioning the spacetime continuum is to think of a large piece of fabric, such as a sheet. Einstein realized that objects with mass, such as a person or Planet Earth, create a distortion in space-time.

Imagine placing a bowling ball in the middle of the sheet. The area around the bowling ball would be pressed down, creating a dip in the sheet. These dips represent curvatures in the fabric of the space-time continuum. Einstein identified these curves in the space-time continuum as gravity.

Are these curves real, though? Although scientists can't see or measure spacetime, they have been able to confirm certain phenomena predicted by Einstein. For example, light should bend when travelling around massive objects. This phenomenon, known as gravitational lensing, has been observed by astronomers who use it to study galaxies and stars otherwise hidden behind massive objects.

Spacetime Curvature: A New Perspective on Gravity

Furthermore, general relativity laid the groundwork for cosmology, the study of the universe's structure over vast distances and timescales. Einstein speculated that the universe may have slight curvatures in both space and time, implying eternal existence and cyclic motion. He even introduced a "cosmological constant" to accommodate a static universe model. However, he later discarded this constant, dubbing it his "biggest blunder." Nevertheless, contemporary scientists acknowledge the need for the cosmological constant to reconcile current knowledge about the universe.

Global Positioning System (GPS)

Einstein also theorized that the relative nature of space and time would mean that an object in motion would experience time at a slower rate than one at rest. On Earth, we move too slowly to notice this phenomenon. However, scientists have confirmed its truth. Every day, the satellites that make up the Global Positioning System (GPS) gain about 38 microseconds compared to clocks on Earth. This time difference would affect their location accuracy by several miles if it weren't for built-in calibrations that keep their clocks synced with Earth.

The Big Bang Theory: Origin of the Universe

Einstein's theory of relativity predicts intriguing phenomena like time dilation and the bending of space around massive objects. Time dilation, for instance, implies that time appears to pass differently for observers moving at high speeds, nearing the speed of light. Additionally, objects with mass bend space around them, influencing the trajectory of nearby objects. This was exemplified by the analogy of throwing a ball next to an elephant, with its path curving towards the elephant due to its mass bending space.

In essence, Einstein's General Theory of Relativity revolutionized our understanding of the cosmos, unravelling profound insights into the nature of space, time, and gravity.