Download Getting to Know: Theories About How the Universe Formed

Getting to Know: Theories About How the
Universe Formed
Have you ever wondered about how the universe began? Since ancient times, people have speculated about the origin of the universe. Today, many scientists think that the Big Bang Theory is the best explanation for the formation of the universe. If you imagine a balloon expanding, you will have an idea of the Big Bang Theory. The main idea of the Big Bang Theory is that all known particles in the universe were once concentrated into one dense point that expanded outward forming the universe approximately 14 billion years ago.
Contrary to popular thought, the “Big Bang”
was not an explosion of matter. According to scientists, there was a period of rapid, sudden expansion of the universe from a single point known as a singularity. Although this expansion is sometimes referred to as an explosion, the idea of an expanding balloon may be a closer analogy. The balloon does not pop, but instead it continues to expand. Like the balloon, the universe is still expanding today.
This is only a theory. How do I know
the information is real?
The Big Bang Theory states that all the
matter in the universe expanded outward
approximately 14 billion years ago.
In everyday language, the word “theory” often refers to speculation, but in the context
of science, a theory is the answer to a scientific question that is accepted by a majority
of scientists. Scientific theories are supported by a lot of evidence, which is tested by
many scientists.
The universe is very old, and scientists cannot go back in time to witness its formation. Instead
they must gather evidence and develop theories. Scientists have developed several theories
about the formation of the universe over the years. One alternative to the Big Bang Theory
was the Steady State Theory. Although this theory agrees that the universe is expanding, it
also claims that the universe has no beginning, that matter is being created constantly as
old celestial objects move apart, and that the density of matter stays the same over time.
In contrast, the Big Bang Theory says that all matter was in existence before it expanded
outward. The most widely accepted theory among scientists today is the Big Bang Theory.
Misconception 1: How big was the explosion in the Big Bang?
There was not an explosion in the traditional sense. The universe began as a mass of
hot, dense material that expanded outward. The sudden expansion was like the rapid
expansion of a balloon rather than an explosion of fire.
Concept: Theories About How the Universe Formed
Getting to Know
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What is the evidence for the
Big Bang Theory?
The development of technology has helped scientists learn more about the universe. Scientists use sensitive instruments to calculate the motion of galaxies. Edwin Hubble was an astronomer who used powerful telescopes to gather evidence that galaxies were moving away from each other. Hubble’s ideas helped convince the scientific community that the Steady State Theory was not correct. Scientists think the dense area of matter that existed before the expansion was The first stars formed approximately 400 million
very hot. The original heat expanded years after the Big Bang. (Image from NASA)
outward along with the matter, and scientists are able to measure this heat. The heat is called the cosmic background radiation. Scientists think cosmic background radiation is evidence of the original heat of the Big Bang.
Misconception 2: Can other theories develop about the formation of the universe?
Theories can change over time as new ideas develop. Science is always advancing our
knowledge, and older theories are often updated based on new ideas. According to
many scientists, the Big Bang Theory is not conclusive. We do not yet know all we need
to know about the formation of the universe. In fact, the Big Bang Theory leaves many
questions unanswered and raises several others. It is possible that new ideas about the
formation of the universe may develop in the future.
When did all the parts of the universe form?
Galaxies are groups of billions of stars, and there are billions of galaxies in the universe. Many
scientists believe that galaxies began to form shortly after the Big Bang. Galaxies, stars, and
planets continue to form today. As one star dies, another star is able to form from the dust left
behind. Future scientific studies may add more ideas to the Big Bang Theory. However, today,
many scientists believe that the Big Bang Theory is the best scientific answer for how the
universe formed.
Concept: Theories About How the Universe Formed
Getting to Know
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© Discovery Education. All rights reserved.
Discovery Education is a subsidiary
of Discovery Communications, LLC.