User:Willbown

William Cullerne Bown is a research policy journalist based in London. He is the founder of two newspapers - Research Fortnight (1994) and Research Europe (1996) - the ResearchProfessional.com website, and the Research Funding Guide book.

I am currently working on a section for the Big Bang page...

Origin of the universe?

[Note on sources. Sentences without a source are either sourced further down in this section or are drawn from the existing page or have a big note in capitals with them. Sources numbered under 100 are from the existing page. Source of 100+ are new ones listed below. Generally, what I don't have sources for are the mainstream views of cosmologists, which others are much better placed to supply.]

What, if anything, the part of physics known as Big Bang theory has to say about the origin of the universe remains a source of controversy.

Popular discussion of the Big Bang theory has often considered theological and philosophical implications. As far back as 1931, the nominal initial proponent of the Big Bang theory, Georges Lemaître, suggested that the theory provided an explanation of the origin of the universe that he thought was consistent with his faith. The Roman Catholic Church has stated that the idea is consistent with its teaching. When Fred Hoyle coined the term "Big Bang" in 1959, he took specific issue with such implications. Today, physicists often make statements such as "it is 13 billion years since the Big Bang"[100]. Yet cosmologists who can predict from known and empirically tested physics the conditions present in the universe during the first fractions of second, have no agreed-upon model for what happened at the singularity predicted by general relativity that exists at t = 0. Big Bang physics tells us nothing about the origin of the universe [SOURCE REQUIRED].

[ALL OF THIS PARA MY HYPOTHESISING, BUT PROVIDES A SPACE WHERE THOSE WHO KNOW MORE ABOUT THIS BIT CAN IMPROVE]. Extending backwards in time the Big Bang model derived from observations of the expanding universe to the the point t = 0 (when the density of the universe would be infinite) takes the model to the point of a singularity, that is a physical paradox as all singularities are places where physical theories break down and become unreliable. Even if the model can be extended back to t = 0, this of itself does not say anything about first cause for the universe in the same way that the North Pole does not say anything about the origin of the lines of longitude on the Earth.

In the 1920s and 1930s almost every major cosmologist, including Einstein, preferred the theory of an eternal universe. But once Hubble's breakthrough observations in 1929 were published, a temporally finite universe as envisioned by Lemaitre seemed a real possibility. The British Science Association at the behest of Sir Arthur Eddington (then the British Association) brought Lemaitre to a London conference on the universe and spirituality. Lemaitre argued in favour of the idea of the universe originating in a "Primeval Atom", which he later described as "the Cosmic Egg exploding at the moment of the creation" [104]. He then set out his views in the journal Nature, suggesting:

"If the world has begun with a single quantum, the notions of space and time would altogether fail to have any meaning at the beginning; they would only begin to have a sensible meaning when the original quantum had been divided into a sufficient number of quanta. If this suggestion is correct, the beginning of the world happened a little before the beginning of space and time." [101]

Lemaître was a Catholic priest who was later promoted [104] to head the Pontifical Academy of Sciences, the most senior scientific position in the Vatican. This may have coloured the reception his suggestion got, with several scientists complaining that the beginning of time implied by the Big Bang imported religious concepts into physics, an objection later repeated by supporters of the steady state theory.[67]

When Hoyle coined the term "Big Bang" in 1949 it was in a radio broadcast during which he attempted to show that the steady state theory he preferred was superior [103]. He said:

"These theories were based on the hypothesis that all the matter in the universe was created in one big bang at a particular time in the remote past."

[I HAVE NO SOURCES FOR THIS PARA, BUT THINK IT CONSISTENT WITH LEMAITRE'S PAPER] Hoyle's complaints about the rival theory he disliked would later turn out to be irrelevant as observations would show a "hot Big Bang" model was most consistent with the existence of time-evolution in the universe and the existence of a uniform cosmic microwave background. Interest in running the clock back to see what the hot Big Bang model of an expanding universe meant for earlier times is still on the forefront of scientific investigation.

The phrase stuck. Proponents of the Big Bang, especially George Gammow, adopted the term invented in Hoyle's radio broadcast to describe their favored theory. In particular, the fact that the abundance of light elements in the universe could be derived from first principles as a result of the conditions which existed in the universe during the first three minutes after the singularity was a key piece of evidence that Big Bang proponents would use to argue against the steady state. However, since there are observational barriers to seeing the conditions of the universe at this time and earlier and the energy-regimes present at that time have not yet been reached in particle accelerators, there is no direct physical evidence for conditions in the universe before the epoch of inflation. Multitude of possible theories consistent with the Big Bang picture exist offering physical explanations of what came before then. Since this scaling back to the singularity is logarithmic rather than linear, cosmologists still refer to the age of the universe with statements such as "the universe is 13 billion years old" or "it is 13 billion years since the Big Bang". Such statements do not necessarily imply that the cosmologist believes the universe originated with a big bang since there are theories (e.g. eternal inflation) which allow for time to go back much further than the fiducial singularity.

In 1951, Pope Pius XII, declared at the November 22, 1951 opening meeting of the Pontifical Academy of Sciences that the Big Bang theory accorded with the Catholic concept of creation.[69] There have been a variety of reactions by other religious groups. Some accept the scientific evidence at face value, others seek to reconcile the Big Bang with their religious tenets, and others completely reject or ignore the evidence for the Big Bang theory.[70]

Today the idea of the universe originating in a Big Bang is widespread. It appears in:

• Dictionary definitions of the term. For example, Chambers today defines it as: "a hypothetical model of the origin of the universe, now generally accepted, which postulates that all matter and energy were once concentrated into an unimaginably dense state, which underwent a gigantic explosion between 13 and 20 billion years ago." [105]

• Popular books on science. For example, Stephen Hawking titled his book: "A Brief History of Time: From the Big Bang to Black Holes".

Refs

100 - See wikipedia page on age of the universe

101 - Nature, May 9, 1931.

103 - http://www.joh.cam.ac.uk/library/special_collections/hoyle/exhibition/radio/

104 - http://en.wikipedia.org/wiki/Pontifical_Academy_of_Sciences

105 Chambers dictionary, http://www.chambersharrap.co.uk/chambers/features/chref/chref.py/main?query=big+bang&title=21st