A theory that has been extensively tested and seems to apply everywhere in the universe si sometimes called a Law or a Natural Law.
universal theory
A theory
You needn't a scientific definition for it. Theory is something waiting to be proved in the future that it was not a theory in the past. It was a valid idea. However, if you want to go deeper on this issue, there is a link right below.
Hypothesis A hypothesis is a tentative explanation for an observation. It is tested by gathering more information to see if the explanation holds up. If not, a new hypothesis is made and tested. Note that hypotheses (and theories) can never be proven, only disproven. If a hypothesis is well-supported, it may be upgraded to a theory. However, no matter how long a hypothesis has been around; no matter how many people believe it; no matter what the prevailing consensus is, just one piece of evidence can destroy the hypothesis.
The scientist who tested and proved Oparian's theory was Stanley L. Miller and Harold Urey.
It is a scientific theory
I think hypothesis
A "no boundary" universe is a universe where the change in energy is positive or negative everywhere in the universe. Such a universe theory calls for everywhere expansion or everywhere contraction. The current central dogma in Astronomy is for such an expanding universe. The corrected Law of Gravity indicates that the universe is bounded and not expanding.
A scientific hypothesis can become a theory if the hypothesis is tested extensively and competing hypotheses are eliminated.
A scientific theory is an extensively tested hypothesis that is accepted as the best answer we can come up with, since nobody has been able to prove it wrong yet.
Pulsating Theory According to this theory, the universe is supposed to be expanding and contracting alternately i.e. pulsating. At present, the universe is expanding. According to pulsating theory, it is possible that at a certain time, the expansion of the universe may be stopped by the gravitational pull and the may contract again. After it has been contracted to a certain size, explosion again occurs and the universe will start expanding. The alternate expansion and contraction of the universe give rise to pulsating universe.
According to Kepler's Universe theory, the universe was born in 4977 BC.
The steady-state universe theory
Friedmann Universe Theory was created in 1922.
The no boundary universe theory was formulated in 1983.
The Big Bang is the theory that was developed to describe the origins of the universe.
"I believe in the oscillating universe theory."
It is similar to the Big Bang theory. The ekpyrotic theory is, a theory that their is a parallel universe (More than one) In our universe.