Steady State theory facts for kids

The Steady State theory is an idea about how the universe works. It suggests that the universe has always looked pretty much the same, even though it's expanding. This idea is different from the Big Bang theory, which says the universe started from a very hot, dense point.

The Steady State theory proposes that as the universe expands, new matter is constantly being created. This new matter fills the spaces that open up. Because of this continuous creation, the overall density of the universe stays the same. It means the universe doesn't get thinner or emptier as it grows.

What is the Steady State Theory?

The Steady State theory suggests the universe is always expanding but always looks the same. Imagine a balloon that keeps getting bigger. If it were the universe, the space between points would increase. The Steady State theory says new dots would appear on the balloon to keep the number of dots per area constant.

Who Proposed This Idea?

Three scientists developed the Steady State theory in 1948. They were Hermann Bondi, Thomas Gold, and Fred Hoyle. They came up with this idea because they believed the universe should be unchanging. They thought it should look the same no matter when or where you observe it. This concept is called the "perfect cosmological principle."

How is it Different from the Big Bang?

The Steady State theory is a big alternative to the Big Bang theory. The Big Bang theory says the universe began from a tiny, super-hot point. It then expanded and cooled down, forming everything we see today. This means the universe has changed a lot over time. It was once very different from how it looks now.

The Steady State theory, however, says the universe has no beginning and no end. It has always existed and will always exist in its current state. The continuous creation of matter is key to this idea. It ensures the universe's average density never changes, even as it expands.

Why Isn't it Accepted Today?

For a while, both the Steady State and Big Bang theories were discussed. However, new discoveries in astronomy started to favor the Big Bang model. Scientists found evidence that didn't fit the Steady State idea.

Evidence Against the Steady State

One major discovery was the cosmic microwave background (CMB). This is a faint glow of radiation coming from all directions in space. Scientists believe the CMB is leftover heat from the very early universe. It's like an echo of the Big Bang. The Steady State theory couldn't easily explain the existence of the CMB.

Another piece of evidence came from observing distant galaxies. When we look at very distant galaxies, we are seeing them as they were billions of years ago. Scientists found that distant galaxies look different from nearby ones. They were often younger and less developed. This suggests the universe has changed over time, which supports the Big Bang. The Steady State theory predicted that galaxies should look the same everywhere, regardless of distance.

The Big Bang Wins Out

Because of these and other observations, most scientists now support the Big Bang theory. The evidence for a changing universe, with a definite beginning, became very strong. While the Steady State theory was an interesting idea, it couldn't explain the new discoveries.

Images for kids

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  In the Big Bang, the expanding Universe causes matter to dilute over time, while in the Steady-State Theory, continued matter creation ensures that the density remains constant over time.

See also

In Spanish: Teoría del estado estacionario para niños