[Ultimate (OP)]

I was  looking at the big bang theory and decided to go back to basics, looking at Lemaitres Big Bang theory it is unclear what he meant by the Primeval atom? It seems he thinks it exploded due to some kind of radioactive decay presumably the explosion started off cold. There is an assumed lack of antimatter in the universe could this have been a matter-antimatter explosion?

"He spoke, rather vaguely, of some instability being produced by radioactive decay of the primal atom that was sufficient to cause an immense explosion that initiated the expansion of the universe."

According to current theory this presumed explosion from a cold primeval atom did not happen from a singularity, it happened from a region of space, 13.8billion years ago. Could there have been multiple explosions, resulting in the fluctuations of cosmic background radiation? The visible universe is 13.8 billion years old, is it likely that more universe exists which is much older over the visible horizon? ie does the universe have a beginning? Could another primeval egg form another big bang, within our universe?

Could Dark matter be a mixture of matter and antimatter a remnant of the primeval egg?

Any Clues ? 

[evan_au]

Georges Lemaître published his concept of the big bang in 1927, although he had previously corresponded with Einstein about it.
See: https://en.wikipedia.org/wiki/Georges_Lema%C3%AEtre#Career

The concept of anti-matter didn't really become concrete until 1932, so this probably didn't influence Lemaître.
See: https://en.wikipedia.org/wiki/Antiparticle#Experiment

The idea of radioactivity was discovered by Henri Bequerel in 1896, and the idea that many heavy elements were radioactive was established by Marie & Pierre Curie in the early 1900s. So the idea that a massively heavy atom would be unstable was probably the inspiration for Lemaître.
See: https://en.wikipedia.org/wiki/Radioactive_decay#History_of_discovery

Note that Lemaître was a Catholic priest, and so the idea of a beginning to the universe falls naturally out of Genesis 1:1: "In the beginning God created the heavens and the earth...". I don't think Lemaître would have been concerned about absence of a physical cause for the Big Bang.

[Ultimate (OP)]

Note that Lemaître was a Catholic priest, and so the idea of a beginning to the universe falls naturally out of Genesis 1:1: "In the beginning God created the heavens and the earth...". I don't think Lemaître would have been concerned about absence of a physical cause for the Big Bang.

I hadn't thought he was a religious nutter and have read that he kept his physics and religion separate. Having said that I take on board what you said. Genesis: in the beginning there was light, and the laws of thermodynamics can be thrown out of the window, because god did it.

Fred Hoyles nucleosynthesis and creation of the heavier elements is on solid proven ground.

Ref the primordial particle and various big bang theories, what form did the particle take. Was the radiation from the big bang photons (in the beginning there was light) , was it particles or a mixture of particles and photons ? giving a clue as to what came before?

[Bill S]

Note that Lemaître was a Catholic priest, and so the idea of a beginning to the universe falls naturally out of Genesis 1:1: "In the beginning God created the heavens and the earth...". I don't think Lemaître would have been concerned about absence of a physical cause for the Big Bang.

I hadn't thought he was a religious nutter and have read that he kept his physics and religion separate.

Not only did he keep his religious beliefs and his science separate; he openly criticised the Pope for identifying the BB as the Biblical moment of creation.  From what I can gather, he was well aware that the account of creation, produced by a group of Iron Age tribesmen might lack scientific veracity.

Perhaps he should be credited with actually making an attempt to find a physical "cause" for the Universe.

[Ultimate (OP)]

Perhaps he should be credited with actually making an attempt to find a physical "cause" for the Universe.

He did.

[Bill S]

Precisely, but to what extent did he let others pass him in the race for recognition?

[Ultimate (OP)]

Precisely, but to what extent did he let others pass him in the race for recognition?

As far as I can see he didn't, he had two jobs so wasn't a full time mathematician or cosmologist. I don't seem to be able to post links, but from wiki if you check him out. He was awarded or nominated for the following :-
"
Honors[edit]
On 17 March 1934, Lemaître received the Francqui Prize, the highest Belgian scientific distinction, from King Léopold III.[33] His proposers were Albert Einstein, Charles de la Vallée-Poussin and Alexandre de Hemptinne. The members of the international jury were Eddington, Langevin, Théophile de Donder and Marcel Dehalu. The same year he received the Mendel Medal of the Villanova University.[54]
In 1936, Lemaître received the Prix Jules Janssen, the highest award of the Société astronomique de France, the French astronomical society.[55]
Another distinction that the Belgian government reserves for exceptional scientists was allotted to him in 1950: the decennial prize for applied sciences for the period 1933–1942.[33]
In 1953, he was given the inaugural Eddington Medal awarded by the Royal Astronomical Society.

Lemaître was the first theoretical cosmologist ever nominated in 1954 for the Nobel Prize in physics for his prediction of the expanding universe. Remarkably, he was also nominated for the 1956 Nobel prize in chemistry for his primeval-atom theory.
"
As Evan_au indicated above he was both a scientist and a catholic priest. The subject (cosmic egg) of what preceded the big bang is still a hot topic, few appears to have ideas on the subject. Lemaitres first guess at the primordial egg was ahead of its time, and signed up to by the then pope.

From the singularity(which few believe in) onward and quoting from another link on this forum
"
The singularity was so small that it has to be observed using quantum physics, which deals with things on the smallest scale scientists have ever postulated. At the beginning of existence, the universe had a temperature of 1 x 1032 degree Celsius and only covered a region of 1 x 10-33 centimeters. It’s hard to believe that expanded to become the universe spanning billions of light years we know today!
As tiny fractions of a second passed after the big bang, the universe expanded rapidly. It doubled in size several times in less than a second and cooled during the process.
At t = 1 x 10-11 seconds after the big bang began, the universe had expanded to a point where we could graduate from speculating on events from the quantum viewpoint to being able to simulate the environment in lab conditions with particle accelerators.
Then, the period of standard cosmology began .01 seconds after the big bang. Here, protons and neutrons are fully formed. After a full second,the nuclei of light elements like hydrogen, helium, and lithium were forming
"

From the above "It’s hard to believe that expanded to become the universe spanning billions of light years we know today!" Its not hard to believe the universe is expanding, the singularity and extrapoloating that all matter was formed at it and moved at speeds excedding the speed of light is a little on the edge! The distance between galaxies and particles can expand at in excess of the speed of light, but matter itself does not move in excess of the speed of light from any reference point.

Bosons in the form of photons can all occupy the same point in space, theoreticlally. Particles made of fermions can not.

The Primordial particle must therefore have occupied a region of space(which I think is inline with current understanding), and the expansion of space itself moved apart. At some stage during the process evidentially the primordial particle exploded.

"At t = 1 x 10-11 seconds after the big bang began, the universe had expanded to a point where we could graduate from speculating on events from the quantum viewpoint to being able to simulate the environment in lab conditions with particle accelerators."

At the end of the speculation of what might have been, what do we know we had. As I understand it particles are created as particle antiparticle pairs. Would these be exactly the same as we have in the standartd model? Further more when is a particle considered a virtual particle, Quark lifetimes are shorter than the times in the Big bang model, can they also be considered virtual, like unstable chips off the block. How could they survive, the big bang, and what did they form from?

[Bill S]

It is always possible to find online articles to support whatever views one might hold; and bandying quotes may be fun, but is rarely productive.  I have neither the time, nor the inclination to become involved in this, so I will restrict myself to picking one quote from the following links that I think is a positive sign that Lemaître may be moving towards well deserved recognition, and one which I find faintly amusing.

https://sciencemeetsfaith.wordpress.com/tag/georges-lemaitre/

Addendum 02 Nov 2018: Members have agreed (via e-voting) to pass the resolution to renaming the “Hubble law” as the “Hubble–Lemaître Law”.

https://gizmodo.com/georges-lemaitre-the-greatest-scientist-you-ve-never-h-1519769080

Lemaître and Einstein met for the first time in 1927 at the famed fifth Solvay Conference in Brussels. Impressed with Lemaître's findings, but not swayed, he told him, "Your calculations are correct, but your physics are abominable."

[Ultimate (OP)]

Subject of the post was "What was Georges LeMaitre's primeval atom?" .
Evan_eu answered the question, not even LeMaitre knew what it was, it was hypothetical. Still today no one knows.

@bill I am not in the slightest bit interested in discussing the metaphysics or religion. The content of the links is mixing fact and fiction, to claim Lemaitre was not known is absolute nonsense etc.

[Bill S]

Evan_eu answered the question....

The question is answered, then.  That's good. I've said in the past that it would be great if OPs acknowledged when they felt they had a satisfactory answer.  I applaud you for doing that. 

to claim Lemaitre was not known is absolute nonsense etc.

At my age, my memory is not what it was, but I'm fairly sure I didn't make that claim.

[Ultimate (OP)]

At my age, my memory is not what it was, but I'm fairly sure I didn't make that claim.

Perhaps you forgot what was in the links you posted!

You prompted me on your Higgs thread to look at extra dimensions and the Higgs field. Lots of hits ref Cern came up, a couple of which I posted on your Higgs thread. Since I want to know more about the Primordial particle(s) I became interested and stumbled on this link which I will reread a few times. It is on multiple dimensions and how particles appearing in multiple dimensions might appear to us, (there might not be a Higgs field chuckle). https://profmattstrassler.com/articles-and-posts/some-speculative-theoretical-ideas-for-the-lhc/extra-dimensions/how-to-look-for-signs-of-extra-dimensions/ [nofollow]

Could extra dimensions of spacetime cause a big bang under certain conditions ?
The link takes a long time to read, and goes into a lot of depth so I will not comment for some time?

[Ophiolite]

At my age, my memory is not what it was, but I'm fairly sure I didn't make that claim.

Perhaps you forgot what was in the links you posted!

I am very sure that posting links that contain claims is not the equivalent of making those claims. Perhaps something to remember in the future.

[Bill S]

I am very sure that posting links that contain claims is not the equivalent of making those claims. Perhaps something to remember in the future.

Especially if the link appeared in another thread.

You prompted me on your Higgs thread to look at extra dimensions and the Higgs field

[evan_au]

Not only did (LeMaitre) keep his religious beliefs and his science separate; he openly criticised the Pope for identifying the BB as the Biblical moment of creation.

LeMaitre was pretty radical in several ways - he went against the scientific wisdom of the time, which assumed that the universe was static and unchanging to see the possibility of a Big Bang in Einstein's equations.

By comparison, Einstein was a conformist. He set the value of the "cosmological constant" in his equations so that the universe would neither expand or contract - something which he later described as his greatest mistake.

It wasn't until Hubble published his results on the measurement of galactic redshifts that LeMaitre's prediction became the "new" physics (and later, a nerdy comedy on TV...)
See: https://en.wikipedia.org/wiki/Hubble%27s_law#Discovery