Flamsteed Astronomy Society
The Universe — The Big Picture
Marcus Chown February 6, 2005
Marcus Chown talked to us about “The Universe — The Big Picture”, the present ‘standard’ cosmology model, with its weaknesses. Marcus is a bestselling author and cosmology consultant to New Scientist and BBC Sky ay Night magazines.
The ‘Standard Model’ holds that our Universe was created about 13.7 billion years ago in a ‘hot big bang’. What is the evidence for this?
· The Universe seems to be expanding. If we play this process of expansion in reverse, we can postulate that the galaxies were all very close together at some time in the past — now taken to be about 13.7 billion years ago.
· All around us the sky is ‘glowing’ with microwave radiation which originated in the Big Bang. Marcus gives a great explanation of this cosmic microwave background (CMB) and an account of its detection in his book “The Afterglow of Creation”.
· The amount of Helium now observed in the Universe can only be accounted for by processes that happened during the Big Bang. About 23-24% of the Hydrogen created in the Big Bang was also converted to Helium. This could not have happened in stars since.
· The night sky is dark, an effect known today as Olbers’ Paradox. In a static universe the sky should be blood red from the light of endlessly overlapping shells of stars stretching out to infinity. It’s dark because light has only had 13.7 billion years to reach us. Light from stars further away than that is still travelling here.
But… Big Bang Cosmology has its problems:
· Given the amount of matter we can observe in the universe today there hasn’t been time for the gravity of the observed masses to pull galaxies together as we see them. To account for the observed galaxies cosmologists have proposed the existence of ‘dark matter’ which exerts a gravitational pull but is invisible (doesn’t interact with light).
· Because of gravitational forces, we would now expect the expansion of the universe to be slowing down. However, studies of distant supernovae seem to show it’s speeding up! Cosmologists have proposed another add-on to the standard model known as ‘dark energy’, a repulsive force that is accelerating the expansion.
See our report on Michael Joyce’s talk for more information and links about the standard model.
Marcus ended by pointing out that the present standard model has some intriguing implications —
The universe should be infinite in extent, but we can only observe within a bubble of 13.7 billion light-years radius, a bubble in a sea of bubbles
Quantum theory implies that space must be quantised into finite chunks. Matter is randomly distributed in the squares of this quantum chessboard.
If there is a finite set of quantum regions spread over an infinite universe, then every possible ‘bubble universe’ must be replicated an infinite number of times — an infinite number of Elvises are alive and well in an infinite number of regions, at present unobservable by us. But given enough time...
Read more in these books by Marcus Chown —
“The Afterglow of Creation: From the fireball to the discovery of cosmic ripples”
University Science Books
“The Magic Furnace. The search for the origin of atoms”
“The Universe Next Door. Twelve mind-blowing ideas from the cutting edge of science”
Headline Books 2002
(paperback by Review 2003)
also by Marcus Chown —
“Stars and Planets”
“Double Planet” (with John Gribbin)
“Reunion” (with John Gribbin)
“Marcus Chown is the cosmology consultant for New Scientist magazine. He has a first-class degree in physics from the University of London and an MSc in astrophysics from the California Institute of Technology. He is author of Afterglow of Creation, runner-up for the Rhone-Poulenc Science Book Prize, and The Magic Furnace, which has won praise from readers as diverse as Dava Sobel (‘I heartily enjoyed this impressive book’) and Sir Martin Rees (‘This fascinating chronicle deserves to be widely read.’)” The Universe Next Door was selected by Booklist as one of the top ten science books of 2002. “He has been a lecturer in Madagascar, a freelance writer for The Grauniad and broadcaster for the BBC World Service and Radio 2. He is the author of a children’s book, Stars and Planets, and the co-author of two science fiction novels, Double Planet and Reunion. He is married and lives in London.”