Big Bang theory

According to the Big Bang theory, the universe emerged from an extremely dense and hot state called the original singularity.

According to the Big Bang theory, the 3 possible geometry of the universe depends on value of the cosmological constant.

The Big Bang Theory is the current dominant scientific theory explaining the acceleration of matter throughout the Universe. Big bang theories are actually a class of scientific models that describe the Universe as expanding from a very hot, dense state approximately 13.7 billion years ago (although this number has changed several times throughout recent history). It was first proposed by Georges-Henri Lemaitre and evidence for the expansion was observed by Edwin Hubble. Later George Gamow predicted that the Big Bang would leave an observable microwave background radiation (or CMBR). This radiation was subsequently discovered by Arno Penzias and Robert Wilson at Bell Labs and found to be close to that predicted by Gamow (Gamow predicted a background radiation level equivalent to a roughly 3 K black body object, and the observed level is that of a 2.725 K body). Pensiaz and Wilson were awarded a Nobel Prize in 1978 for their work.

The term "Big Bang" implies an explosion of matter into pre-existing space, but the theory actually indicates that space is dynamic and more space is constantly created in the interstices between particles as the density of the universe falls. In other words, the Big Bang describes the expansion of space and time. Big Bang theorists state that the Hubble redshift is a consequence of this stretching of the fabric of space.

Observations of distant supernovae indicate that the Universe is actually undergoing accelerated expansion and galaxy surveys and recent observations of the microwave background have corroborated these claims. Conventional wisdom is that the acceleration is caused by some sort of dark energy, which has not yet been directly observed.

Big Bang Theory Dissent Letter

The Big Bang Theory has had many dissenters including the British astronomer Sir Fred Hoyle, the Nobel Prize winner Hannes Alfven, and astronomers Geoffrey Burbidge and Halton Arp. It was Hoyle who sarcastically coined the term during a radio broadcast.

In 2004, a ‘Open Letter to the Scientific Community’ disputing the big bang theory was signed by 33 scientists and has been published on the internet and in the science journal New Scientist. The dissent letter has subsequently been signed by hundreds of individuals around the world. Professional cosmologists are actively creating models (some of which contradict the Big Bang scenario) and collecting data that probe the specific nature of the earliest observable aspects of the Universe.

Starlight Problem for the Big Bang Theory

The starlight problem is an argument against the Big Bang Theory. The creation science organization Answers in Genesis has stated the following regarding the starlight problem for the Big Bang Theory and the work of Charles W. Misner is cited who published his work in Physical Review Letters:

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The problem is this: even assuming the big bang timescale, there has not been enough time for light to travel between widely separated regions of space. So, how can the different regions of the current [cosmic microwave background] CMB have such precisely uniform temperatures if they have never communicated with each other? This is a light-travel–time problem.

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Recognizing this difficulty, physicist Alan Guth put forth a possible solution he named cosmic inflation. According to this theory, during the universe's first 10^-35 of a second, a period of extremely rapid, exponential inflation occured, expanding the universe by a factor of at least 10²⁶. It would be the equivalent of taking a pea and expanding it to the size of our solar system in a time less than a millionth of a blink of an eye. If this occurred, it would mathematically allow for the uniformity of the CMBR - the vast distances were in thermodynamical contact before the rapid inflation. The mechanism that would cause this sudden expansion is not known.

Creationist and Theistic Evolutionary Views

Young earth creationist scientists contest the Big Bang Theory stating that it is scientifically unsound.

Some Old Earth Creationists and Theistic Evolutionists argue that the Big Bang is in fact mentioned in the Bible. Some Christian apologists who believe in an old earth, such as William Craig use the Big Bang as an apologetic, arguing that it proves that the universe had a beginning.