Steady-State Theory Definition
We all know about the Big Bang theory of how the universe came into existence. The steady-state universe theory is put forward as an alternative to the Big Bang theory. The steady-state theory states that the universe is always expanding, but it maintains the same density. We know that the state of matter depends on how dense its particles are. Thus, if the density of an object remains the same while its size continues to increase, we can say that that object is in a constant or steady state. The same concept when applied to the universe gives us a steady-state hypothesis.
A formal statement for the steady-state theory:
It states that the universe is constantly expanding while retaining a constant average density.
Steady-State Theory Explanation
It can be a bit confusing to understand how the steady-state universe theory could make sense. Let’s break it down here so that it’s simpler to understand.
The universe is filled with various kinds of celestial objects and collections of these celestial objects. It has stars, planets, asteroids, moons, meteors, and so many other such celestial bodies. The proponent of steady-state theory in simpler terms is that as the universe grows or expands, the number of celestial bodies also proportionally increases.
To put it differently, if the size of the universe is increasing but the number of celestial bodies is not, there will be a decrease in the density. Now, alongside the increasing size of the universe, the number of planets and stars, and other bodies are also increasing, and thus, the density remains more or less the same.
Steady-State Theory Evidence, or Lack Thereof
The steady-state theory proponents were Sir Fred Hoyle, Sir Hermann Bondi, and Thomas Gold. It was taken forward by Sir Hoyle after the propounding of the theory. The model used since the 1950s for any observations, which is the Cosmic Microwave Background, does not count much for evidence which is mostly because it comes from the Big bang theory, to which the steady-state theory was propounded as an alternative.
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Features of Steady State Universe Theory
This theory assumes that all the galaxies existing in the universe are moving slowly away from one another. Because of what the theory states, that as the universe expands, the galaxies and other celestial bodies in the universe also proportionately expand, the steady-state universe theory also assumes that new matter is constantly being created in the universe. The propounders of the theory also put forth the speed derived at which new matter is created, which is at the rate of 1 atom of hydrogen per 6 cubic kilometers of space per year, which is an incredibly minuscule amount. Another one of the features of steady-state theory is that it considers the universe to be stable and steady, as the name suggests.
The Drawbacks of the Steady State Theory
Unfortunately, there is more evidence against this theory than there are steady-state theory facts and tangible evidence. While there are definite predictions that could be tested via observation, those observations were the reason why it did not gain much clout in cosmology. The radio observations made went far into the universe, and returned with information from billions of light-years ago with evidence of a changing universe, which is pretty much the opposite of what the theory propounds. The cosmic microwave background also could not provide much evidence for this theory. These are the two main reasons that the big bang theory has been looked at as the origin of the universe and the steady-state theory put aside.
FAQs on Steady-State Theory
1. What is the Steady-State theory of the universe?
The Steady-State theory is a cosmological model which proposes that the universe, while expanding, maintains a constant average density. To achieve this, the theory suggests that matter is continuously created throughout space to form new stars and galaxies, filling the gaps left by expansion. This model is based on the Perfect Cosmological Principle, which states that the universe appears the same from every location and at all times.
2. What is the main difference between the Steady-State theory and the Big Bang theory?
The main difference lies in their fundamental assumptions about the universe's origin and evolution. The Big Bang theory posits that the universe began from a single, extremely hot and dense point and has been expanding and cooling ever since. In contrast, the Steady-State theory proposes that the universe has no beginning or end and has always existed, maintaining a constant density through the continuous creation of matter. You can learn more about the prevailing model on the Big Bang model page.
3. Who were the main proponents of the Steady-State theory?
The Steady-State theory was primarily proposed in 1948 by three key scientists: Fred Hoyle, Thomas Gold, and Hermann Bondi. They developed it as an alternative to the emerging Big Bang model, aiming to explain the expansion of the universe without requiring a singular origin event.
4. Why is the Steady-State theory no longer the accepted model of the universe?
The Steady-State theory was largely disproven by several key pieces of observational evidence that strongly supported the Big Bang model. These include:
Cosmic Microwave Background (CMB) Radiation: The discovery of this faint, uniform radiation throughout space is considered the leftover heat from the Big Bang, which the Steady-State theory could not explain.
Observation of Distant Galaxies: Telescopes revealed that distant galaxies and quasars are different from nearby ones, indicating that the universe has evolved over time. This contradicts the Perfect Cosmological Principle that the universe is unchanging.
Abundance of Light Elements: The observed proportions of hydrogen, helium, and lithium in the universe match the predictions of the Big Bang's nucleosynthesis, not the continuous creation model.
5. How does the concept of a 'steady state' in cosmology differ from a 'steady state' in an electrical circuit?
These two concepts describe fundamentally different phenomena. The cosmological Steady-State refers to a theory where the entire universe maintains a constant large-scale density over cosmic time, despite its expansion. In contrast, a steady state in physics, such as in an LR circuit, describes a condition where variables within a specific system (like current or voltage) become constant after an initial transient phase. The circuit's steady state is a stable equilibrium reached by a small, local system, whereas the cosmological theory described a dynamic but unchanging universe.
6. What is the Perfect Cosmological Principle, and why is it important to the Steady-State theory?
The Perfect Cosmological Principle is the core assumption of the Steady-State theory. It extends the standard Cosmological Principle (which states the universe is the same everywhere) by adding a dimension of time. It asserts that the universe is not only homogeneous (uniform in all locations) and isotropic (the same in all directions) but also unchanging over time on a large scale. This principle is crucial because it necessitates the continuous creation of matter to keep the density constant as the universe expands.
