Hey there, time traveller!
This article was published 24/1/2015 (1725 days ago), so information in it may no longer be current.
These days — thanks to the mash-up of TV characters Leonard Hofstadter and Sheldon Cooper, scientist David Saltzberg, singer Ed Robertson and the Barenaked Ladies — most everyone has heard of the big bang theory. And most everyone knows it 'all started with the big bang!' But most everyone is wrong.
Wikipedia gets it precisely right. It says: "The big bang theory is the prevailing cosmological model for the early development of the universe. The key idea is that the universe is expanding."
The big bang theory starts a fraction of a second after the beginning, with math that describes space expanding smoothly. Recent observations show the universe some 400,000 years after the beginning. They reveal a space that is expanding and is filled with hot matter — mostly hydrogen — that is going along with space for the ride.
Back in 1949, there are no such observations. British astronomer Sir Fred Hoyle is the lead proponent of the rival steady-state universe in which nothing changes. He thinks the universe has no beginning. He says the notion it began at all is a religious view. But today both observations and theory convince physicists the universe did have a beginning some 13,798,000,000 years ago and that, right after the beginning, space and its contents were expanding. The obvious question is: Why was the universe expanding? Neither the observations nor the theory have an answer for this question.
So, what happened before the big bang? How did the universe begin? Stephen Hawking is one of few physicists to tackle this question, for which he deserves much kudos. He is co-author, with American physicist Leonard Mlodinow, of The Grand Design, in which he says spontaneous creation produced the universe from nothing. He 'explains' this with a cute confection of math trickery called M-theory. He is far too smart to believe such nonsense; clearly he is putting us on. So, even Stephen has no answer.
Observations show space is still expanding and the expansion is not — as was long expected — slowing down under the pull of gravity. Indeed the expansion is accelerating. The standard model of cosmology has expansion built right into it as an odd kind of unexplained assumption. These days, cosmologists want something to explain both the expansion and its acceleration. They call their favourite somethings Dark Energy or Quintessence, but don't let these labels fool you. They literally don't know what they're talking about. So the search is still on.
Does history offer any clues? Hoyle's steady state universe was based on spontaneous creation — the concept that hydrogen atoms pop into existence at a rate that exactly compensates for expansion — so that on average the density of matter doesn't change. But observations now show the density of matter is decreasing. Bye-bye steady state; hello big bang. What we observe is not new matter, it is new space.
In 1917, Albert Einstein suggested to a student that space is not continuous; rather, it comes in tiny pieces, quanta of space. In 1954 he said much the same thing to his best friend. Like others in recent times, I am convinced he was right. If he was, what we are observing is new tiny pieces of space coming into existence. How could this be? My recent book, Time One, suggests space quanta replicate by quantum tunneling. It's hard to imagine a simpler way to get more quanta. (It surely is simpler than new hydrogen atoms from nowhere.) This one postulate explains not only why space is expanding (i.e., the big bang), but also how space came into existence, why it has three dimensions, how the infant universe inflated, and why the expansion is now accelerating.
I may be biased, but this seems like a lot of bang for a small buck.
Colin Gillespie is a physicist and author whose most recent book is Time One: Discover How the Universe Began. He writes a weekly web blog, Science Seen.