The first Friedmann equation describes how, based on what is in the universe, its expansion rate will change over time. If you want to know where the Universe came from and where it’s headed, all you need to measure is how it is expanding today and what is in it. This equation allows you to predict the rest!

## What did Friedmann do?

Ninety years ago, Russian physicist Alexander Friedmann (18881925) demonstrated for the first time that Albert Einstein’s general theory of relativity (GR) admits nonstatic solutions. It can, he found, describe a cosmos that expands, contracts, collapses, and might even have been born in a singularity.

## What did Lematre and Friedmann conclude about the universe?

Shortly after Einstein published his theory, Russian meteorologist and mathematician Alexander Friedmann and Belgian priest Georges Lematre showed that it predicted that the universe should evolve in response to all the energy it contains.

## What is the model of the universe called?

A cosmological model is a mathematical description of the Universe that attempts to explain its current behavior and evolution over time. Cosmological models are based on direct observations.

## How is the Friedmann equation used to determine the age of the universe?

The Friedmann equation includes the Hubble constant to give a much more accurate age of the universe. In this equation, G is the gravitational constant = 6.67*10-11Nm2/kg2, r is the radiation density of the universe, m is the matter density of the universe, and d is the dark energy density of the universe.

## What is the curvature parameter?

The transverse curvature parameter is defined as the ratio of the boundary-layer thickness and cylinder radius. For a very small transverse curvature parameter, the problem can be solved in two dimensions, but for a thin cylinder, the radius order can be the same as the order of the boundary-layer thickness.

## What is the oscillating theory of the universe?

A modification of the Big Bang theory, in which an expanding universe eventually reverses and collapses back to a Big Crunch before starting to expand again, forming one cycle of an endless series. In such a model, each cycle has a finite duration but the universe itself can last for an infinite time.

## Who proposed the oscillating theory?

Einstein first proposed this theory in the 1920’s in response to the model of the expanding universe.

## What is the closed universe theory?

The closed universe, which is a universe where space-time is curved back on itself, one that has a finite size but no center and no edge. The open universe, which is a model of an infinite universe involving curved space-time, which does not curve back on itself.

## What are the 4 models of the universe?

3.1 A geocentric universe

- 1 Eudoxus and a geocentric universe. …
- 2 Aristotle and a finite, eternal, and geocentric universe. …
- 3 Aristarchus and the distance to the Sun and Moon. …
- 4 Eratosthenes and the circumference of the Earth. …
- 5 Ptolemy and epicycles.

## What are four models of the universe?

See Aristotle’s geocentric universe, Ptolemy’s solar system model, and Copernicus’ heliocentrism. Understand the Ptolemaic, Geocentric, and Heliocentric models.

## What are the 2 general models of the universe?

Heliocentric and geocentric are two explanations of the arrangement of the universe, including the solar system.

## What is Hubble time in astronomy?

The time required for the Universe to expand to its present size, assuming that the Hubble constant has remained unchanged since the Big Bang. It is defined as the reciprocal of the Hubble constant, 1/H_{0}. For a Hubble constant of 71 km/s/Mpc, as given by current measurements, the Hubble time is around 14 billion years.

## What is the flatness problem in cosmology?

The flatness problem (also known as the oldness problem) is a cosmological fine-tuning problem within the Big Bang model of the universe. … This value affects the curvature of space-time, with a very specific critical value being required for a flat universe.

## What is the estimated age of the universe?

13.77 billion years old The universe is (nearly) 14 billion years old, astronomers confirm. With looming discrepancies about the true age of the universe, scientists have taken a fresh look at the observable (expanding) universe and have estimated that it is 13.77 billion years old (plus or minus 40 million years).

## What is the formula of curvature?

The curvature(K) of a path is measured using the radius of the curvature of the path at the given point. If y = f(x) is a curve at a particular point, then the formula for curvature is given as K = 1/R.

## What do you understand by curvature?

1 : the act of curving : the state of being curved. 2 : a measure or amount of curving specifically : the rate of change of the angle through which the tangent to a curve turns in moving along the curve and which for a circle is equal to the reciprocal of the radius.

## What is curvature analysis?

The CurvatureAnalysis utility uses vectors to represent the curvature at points on a curve. The vector length corresponds to the curvature value of the curve at that point, and its direction corresponds to the normal direction of the curve at that point.

## Are Universes cyclical?

The cyclic universe theory is a model of cosmic evolution according to which the universe undergoes endless cycles of expansion and cooling, each beginning with a big bang and ending in a big crunch.

## What is big freeze theory?

This term comes from the theory that, in the Universe and other isolated systems, entropy will increase until it reaches a maximum value. … During this Big Freeze, the Universe would, in theory, become so vast that supplies of gas would be spread so thin that no new stars can form.

## What is stationary theory?

In cosmology, a static universe (also referred to as stationary, infinite, static infinite or static eternal) is a cosmological model in which the universe is both spatially and temporally infinite, and space is neither expanding nor contracting.

## What is oscillation theory?

The Oscillating Universe Theory is a cosmological model that combines both the Big Bang and the Big Crunch as part of a cyclical event. … In other words, our universe can be the first of a possible series of universes or it can be the nth universe in the series.

## What are the 3 types of universe?

We will first consider the three most basic types. There are basically three possible shapes to the Universe; a flat Universe (Euclidean or zero curvature), a spherical or closed Universe (positive curvature) or a hyperbolic or open Universe (negative curvature).

## What is the difference between an open universe and a closed universe?

In such a case, the universe has no bounds, and will expand forever. This is called an open universe. If space has no curvature (i.e, it is flat), there is exactly enough mass to cause the expansion to stop, but only after an infinite amount of time. … This is called a closed universe.

## Who is the creator of this universe?

We respond with awe. We call the creator of the universe God. There are two stories in the book of Genesis (first book of the Bible) which tell of creation and the One who did the creating. The theological meaning of these stories tells us that creation emerged from God’s energy, breath, love.

Graduated from ENSAT (national agronomic school of Toulouse) in plant sciences in 2018, I pursued a CIFRE doctorate under contract with Sun’Agri and INRAE in Avignon between 2019 and 2022. My thesis aimed to study dynamic agrivoltaic systems, in my case in arboriculture. I love to write and share science related Stuff Here on my Website. I am currently continuing at Sun’Agri as an R&D engineer.