For a long time, physicists believed that the universe had always existed in a stable, unchanging state. This view was based on their observations of the night sky, which seemed to suggest a timeless cosmos. However, this idea was at odds with the creation stories of many major religions, which often describe the universe as having a distinct beginning.
Enter Georges Lemaître, a Catholic priest and a brilliant mathematician and scientist. Lemaître was among the first to propose a groundbreaking scientific perspective: the universe did indeed have a beginning. His conviction was not solely based on his religious beliefs but was supported by new experimental evidence from astronomer Edwin Hubble. Hubble’s observations showed that the universe was expanding, a discovery that, when combined with the mathematics of general relativity, allowed Lemaître to “rewind” cosmic history. He calculated that as you go back in time, the universe must have been smaller and smaller, leading to the conclusion that everything we see today was once concentrated in a very small space. Lemaître called this the “primeval atom,” but today we know it as the “big bang theory.”
The term “big bang” is somewhat misleading. A more accurate name might be “the everywhere stretch.” A common misconception is that the universe was compressed into a single point and then expanded into nothingness. While it’s true that the observable universe was once incredibly small, it wasn’t a single point, nor was the entire universe confined to that space.
This is where the concept of infinity comes into play. The universe is vast—at least 20 times larger than the observable universe, and possibly infinite. With infinite space, you can shrink everything down and still have an infinite amount of space, much like zooming out on a number line that remains infinite.
Space doesn’t need to expand “into” anything; it can expand into itself and still have plenty of room. This is possible even if space isn’t infinite, thanks to the complex nature of spacetime. The event known as the big bang was a time when space was much more compressed, and the observable universe was packed into a tiny area. The entire early universe was dense and hot, causing spacetime to curve and expand rapidly. This expansion wasn’t an explosion but rather space stretching out everywhere.
The term “big bang singularity” is also misleading. “Singularity” suggests a single point, which isn’t accurate. It should be called “the part of the Everywhere Stretch where we don’t know what we’re talking about.” Our current physical models can’t fully explain what happened at the very beginning when the universe was extremely compressed. This lack of understanding conveniently addresses the question of what happened before the big bang. When space was so compressed, our mathematical models break down, and the concept of “time” loses meaning, much like how “north” loses meaning at the North Pole.
Once time began, space expanded rapidly throughout the universe. This expansion eventually slowed, the universe cooled, and over billions of years, it evolved into what we see today. However, we still don’t know why the universe started in such a compressed state or why it follows the specific laws of physics that govern its expansion.
For Lemaître, this might be where God comes in to explain the mysteries science can’t. Yet, experimental evidence doesn’t rule out the possibility of a time “before” the beginning. There might have been a previous age of the universe that ended when space collapsed, only to bounce back in a manner similar to the big bang, but without the singularity. This idea suggests that the universe might be eternal after all, prompting a reevaluation of the notion of “in the beginning.”
Create a detailed timeline of the universe’s history, starting from the “big bang” to the present day. Include major events such as the formation of galaxies, stars, and planets. Use creative tools like infographics or digital timeline software to make your timeline visually engaging. This will help you understand the sequence of cosmic events and the concept of an expanding universe.
Participate in a structured debate on the topic: “Is the universe eternal or did it have a distinct beginning?” Use evidence from the article, including Lemaître’s theories and Hubble’s observations, to support your arguments. This will enhance your critical thinking and understanding of different perspectives on the universe’s origin.
Engage in a mathematical exercise to explore the concept of the universe’s expansion. Calculate the rate of expansion using Hubble’s constant and discuss how this relates to the idea of the “everywhere stretch.” This activity will deepen your comprehension of the mathematical principles underlying cosmic expansion.
Create a 3D model or simulation to visualize the concept of spacetime and how it expands. Use software tools or physical materials to demonstrate how space can expand into itself. This will help you grasp the abstract concept of spacetime and its role in the universe’s expansion.
Research one of the unresolved mysteries of the universe, such as the nature of the “big bang singularity” or the possibility of a pre-big bang universe. Prepare a presentation to share your findings with the class, highlighting current scientific theories and open questions. This will encourage you to explore beyond the article and engage with cutting-edge scientific research.
Universe – The totality of known or supposed objects and phenomena throughout space; the cosmos; macrocosm. – The study of the universe involves understanding the fundamental laws of physics that govern everything from subatomic particles to galaxies.
Expansion – The increase in the distance between any two given gravitationally unbound parts of the observable universe with time. – The expansion of the universe is a key concept in cosmology, suggesting that galaxies are moving away from each other over time.
Spacetime – A four-dimensional continuum in which all events occur, and which is the combination of the three dimensions of space and the one dimension of time. – Einstein’s theory of general relativity describes gravity as the curvature of spacetime caused by mass.
Infinity – A concept in mathematics and physics that describes something without any bound or larger than any natural number. – In calculus, the concept of infinity is used to describe the behavior of functions as they approach very large values.
Singularity – A point in spacetime where density becomes infinite, such as the center of a black hole or the state of the universe at the very beginning of the Big Bang. – The singularity at the center of a black hole represents a point where our current understanding of physics breaks down.
Mathematics – The abstract science of number, quantity, and space, either as abstract concepts or as applied to other disciplines such as physics and engineering. – Mathematics is essential for formulating the laws of physics and for making precise predictions about the behavior of physical systems.
Physics – The natural science that involves the study of matter, its motion and behavior through space and time, and the related entities of energy and force. – Physics seeks to understand the fundamental principles governing the universe, from the smallest particles to the largest cosmic structures.
Big Bang – The prevailing cosmological model explaining the observable universe’s origin from a singularity approximately 13.8 billion years ago. – The Big Bang theory provides a comprehensive explanation for the cosmic microwave background radiation and the distribution of galaxies.
Observations – The act of noting and recording something with instruments to gather data about physical phenomena. – Astronomical observations have provided crucial evidence for the expansion of the universe.
Evidence – Information and data that support or refute a scientific theory or hypothesis. – The evidence for dark matter comes from its gravitational effects on visible matter and radiation in the universe.
