Robert McNees
Happy birthday to the name "Big Bang!”
Fred Hoyle, defending his steady state theory on the BBC, accidentally coined the term for the prevailing model of the early Universe #OTD in 1949. He was criticizing "the hypothesis that all matter of the universe was created in one big bang."
Robert McNees
The idea of a "Big Bang" goes back as far as Lemaître, who in 1927 imagined tracing an expanding universe backwards in time.
In a 1931 letter to the journal Nature he articulated how this process leads to an early state where concepts like space and time break down.
Zak's Lab
@mcnees oops!
Robert McNees
Today we use the term Big Bang in two distinct ways.
There is the "hot big bang," for which we have incontrovertible physical evidence: At some point in the far past, about 13.8 billion years ago, the universe was in an extremely hot and dense state from which expansion proceeds.
The redshift and evolution of galaxies, nucleosynthesis of light elements, and the presence and statistical properties of the cosmic microwave background all support this idea.
Robert McNees
(Hoyle's steady state theory, on the other hand, is not compatible with these observations.)
Robert McNees
Then there is the notion of the Big Bang as an initial singularity.
This involves an extrapolation beyond the period we associate with the Hot Big Bang, into a primordial regime where our best physical theories are likely to break down. All such ideas are necessarily speculative.
This is more like what Lemaître was imagining. In some ways, his insights about typical notions of space and time not being very meaningful at this point are very modern.
Robert McNees
For anyone interested in learning more about the hot big bang – this is what most physicists mean when they use the term – I encourage you to take a look at Weinberg's classic "The First Three Minutes."
My copy of this book, perenially on loan to students, has been read to pieces.
Robert McNees
"The First 3 Minutes" opens with my favorite creation story: the frost giant Ymir, the primeval cow Auðumbla, and the yawning void Ginnungagap.
Greg Albrecht W2GMD
@mcnees I've been reading Alan Guth's "Inflationary Universe"
Robert McNees
@ampledata Also very good!
Jason Perseus
Thank you for the suggestion! I have been looking for new books, watching in horror as my Audible credits stack up faster than I can find new books that interest me.
Always a pleasure to read your posts and threads!
Robert McNees
@JasonPerseus Thank you!
Robert McNees
Though I learned the story (and Norse cosmology in general) not from the "Younger Edda" or "The First 3 Minutes" but from "Norse Gods and Giants" by Ingri and Edgar Parin d'Aulaire.
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