Just When I Thought I Understood the Big Bang

[vorlon13]

[ignoramus]

Yeah, the Big Bang was an explosion like the Cambrian explosion! You shoulda been there! There was baby squid and barnacles flying everywhere!

[Gawdzilla Sama]

"A period of rapid expansion."

Boss Lady says that happens every month around here.

[Little lunch]

This book was written in 1983. So at what point  did scientists postulate that the beg bang was not an explosion, and what led them to this postulation?

Beg bang sounds like what I used to try in my previous marriage and it never worked.

[Anomalocaris]

I wanted to get a picture of what happened during the big bang, so I was reading the 5th chapter of Isaac Asimov's nonfiction book How Did We Find Out About the Universe.

He starts with something called the Cosmic Egg and goes on to say that this egg exploded and a Russian American physicist dubbed the explosion big bang.

This is astronomically opposed to what I've learned so far from the Knochel-Hawking school of cosmology.

This book was written in 1983. So at what point  did scientists postulate that the beg bang was not an explosion, and what led them to this postulation?

Cosmic egg is just a poetic way of referring to the unknown antecedent to our era in the history of the universe.

Here our era is the era when our physics can provide a meaningfully descriptive and predictive model of the forces, particles and distribution of energies in the universe. The closer to the beginning of that era, the more extreme the temperature and energy density. Hence looking ever further back is like watching an explosion played back in reverse. We’ve known this since the early 1960s. Eventually temperature and density becomes so high while distances become so short different parts of physics can no longer agree about what must have been happening. Here physics breaks down. What happened before that was and is as yet unknown.

That mysterious prior state was called by some the cosmic egg, because it is the egg from which our universe hatch’s.


E which through the process of the Big Bang into

[Rhondazvous]

"A period of rapid expansion."

Boss Lady says that happens every month around here.

And it might happen soon on Thanksgiving. Maybe I'll burn it off by pushing people out of my way on Black Friday. Yeah, the big bang upside the head.

[Cyberman]

I get periods of rapid expansion about five hundred times a day. Usually a big bang takes care of it.

[Banned]

Didn't it just?

Incidentally, the Big Bang was an explosion in the same sense as a Baby Boom. Hilarious though the image is of detonating infants.

The death of infants is "hilarious" to you?

"Out of the abundance of the heart the mouth speaks."

[Cyberman]

Yes.

[polymath257]

To answer the OP: Asimov was a writer with a PhD in biochemistry, not a cosmologist.

One problem is that not many people understood the equations and consequences of general relativity for a few decades after it was proposed and popular treatments didn't catch up until quite a bit after that. Your book by Asimov is a popular account that, unfortunately, was not up to the best descriptions even of the time the book was written.

Pretty much any serious treatment of the BB past about 1930 would have NOT had a 'cosmic egg'. At best, that is a poor characterization of an idea LeMaitre had, but it is NOT at all in the basic equations for the Big Bang model and never was. The problem is that the equations are KNOWN to break down at some point, and early writers tended to 'start' things with some sort of 'egg'. But even with that, it did NOT explode in any standard sense. The Big Bang has *always* been about the expansion of space with the galaxies 'at rest', at least approximately, in the local expansion.

So what lead to the idea that the BB is NOT an explosion? Well, the equations of general relativity (Einstein's theory of gravity) describe gravity as a curvature of spacetime. The degree of curvature is determined by the density of mass and energy. If we apply these equations to the universe as a whole, and assume a uniform density of mass and energy, we get the expansion of space directly out of the equations. This is where the expansion of space description comes from: directly out of general relativity. Later, thermodynamics and nuclear physics were added to the mix and the 'hot Big bang' model was proposed. This is the one that predicted the background radiation and is the core of modern descriptions.