December 4, 2023

The Big Bang and the Misconceptions Surrounding it

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By Don Lincoln, Ph.D., Fermi National Accelerator Laboratory

Mankind has been fascinated by the story of the origin of the universe since millenniums. The religions of the world have suggested many ideas about how we got here. But modern science does not agree with any of those suggestions. By using the best modern data, astronomers now understand that the universe used to be much smaller and hotter once but now it is expanding. This idea is what we call the big bang. What are the misconceptions about this idea?

The diagram shows the metric expansion of space.
The timeline of metric expansion of space, where space, including hypothetical non-observable portions of the universe, is represented at each time by the circular sections. (Image: NASA/WMAP Science Team/Public domain)

The theory was not called the big bang originally. Belgian priest and astronomer Georges Lemaître first suggested this theory in the year 1931. He named it the hypothesis of the primeval atom or the cosmic egg. He proposed that it was only in a tiny volume that the whole matter of the universe was concentrated. This volume was the one that exploded.

Lemaître was not alone to think on these lines. Many astronomers of the time had an idea that the universe was endless and had matter and energy that changed from gases to stars and back to gases and that the matter was created in the spaces between stars. 

This is a transcript from the video series Understanding the Misconceptions of Science. Watch it now, on The Great Courses Plus.

The Meaning of the Term Big Bang

British astronomer Fred Hoyle was one of the proponents of what is now known as the steady-state theory of creation. He did not agree with Lemaître’s idea of creation. As a matter of fact, it was on a radio broadcast in the year 1949 that he came up with the term big bang as a way to describe primeval atom. However, it is a matter of dispute whether he used the term to dismiss the idea or to describe it. But ultimately, it turned out that at least in broad strokes, Lemaître was right and Hoyle was wrong. The universe did surely “bang”.

So, we begin with the first misconception that is very common, which is what the term big bang exactly means. The universe exploded and is now expanding is the basic theory. Many people have common thinking that the big bang just gives the description of the literal first instant of creation and is not applicable to the present. But the fact is that every explosion starts with a hot initial state and then it expands. The explosion is not just that initial flash of light. In fact, the explosion continues until the expansion is completed. And the universe is still expanding. So in that case, the explosion is still continuing. 

For those who do not accept the big bang theory, it could perhaps be helpful in realizing that it is not a part of the distant past. The big bang is still happening and is in tune with the data that can be observed and recorded in the present time.

On the other hand, while this point is valid, it may not be one with which we need to stick faithfully. Language does not work like mathematics. Language is vague and different people use the same term to mean different things. Although the term big bang is used for the complete process that includes expansion also, people very commonly use this term to mean, “the thing that pulled the trigger”. This term is sometimes used in this way also but the context has to be noticed.

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Ideas That Support the Big Bang Theory

Prior to Lemaître proposing his primeval egg, astronomers had a belief that the universe was eternal and unchanging. They believed that the hydrogen gas somehow managed to come into existence between the stars and created more stars. To a large extent, this basic idea was similar to the Earth’s ecosystem, in which plants take nutrients from the soil and grow, animals eat plants and humans eat animals. Ultimately, the humans also die and return to the soil and feed more plants. Life is a continuously changing cycle on the Earth. As a quote from the Christian literary tradition says, “for dust thou art, and onto dust shalt thou return”.

Picture showing a WMAP setellite collecting data.
This is an artist’s depiction of the WMAP satellite gathering data to help scientists understand the big bang. (Image: Tempshill/Public domain)

The universe started as unbelievably hot but because of its expansion and cooling through billions of years, it cooled from white-hot to yellow hot, then to red hot and eventually to infrared, a light that we can’t see but can only feel as heat.

Another interesting feature is that the temperature of the universe is uniform everywhere to one part within a hundred thousand. One part in a hundred thousand is similar to a millimeter compared to a football field.

Many more observations exist that support the theory of the big bang but the expansion of the universe and the uniform temperature are quite convincing. It is highly improbable that the basics of the big bang theory would be overturned. But that does not mean that there are not a lot of wrong ideas in the world.

An extremely deep misconception about the big bang is revealed by a question that is super common, and that question is, “Where did it happen?” In the heart of this question is a belief that the big bang is a firecracker or a grenade. And in both these cases, firecrackers existed in the space and exploded there. It is obvious that there was no fuse or anything with the big bang, but if we follow this analogy it would mean that all the matter and energy were sitting somewhere in the space and blew up just like that. 

But this is not what happened. So what did exactly happen is a bit difficult to understand. And it all comes down to the link matter and energy on one hand have with the time and space on the other.

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Common Questions about the Big Bang and the Misconceptions Surrounding it

Q: Who first suggested the theory of the big bang?

Georges Lemaître, a Belgian priest and astronomer, first suggested the theory of the big bang in the year 1931.

Q: What is precisely meant by the big bang?

The big bang is the way of explaining the origin of the universe by astronomers. The idea is that the universe began as a single point and expanded to reach its current size, and some say it is still expanding.

Q: Who was Fred Hoyle?

Fred Hoyle was a British astronomer and one of the proponents of what is now known as the steady-state theory of creation. He did not agree with Lemaître’s idea of creation.

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