It's the question that always comes up when thinking about the origin of the Universe: what came before? And if there was no 'before', what was the cause of the Big Bang in the first place?
Until a few centuries ago, the answer was easy: some eternal deity set everything in motion. Even Isaac Newton believed that God created the Universe, some 6,000 years ago. Later, many scientists, including young Albert Einstein, assumed the Universe itself to be eternal and everlasting.
But when cosmic expansion was discovered, Belgian cosmologist (and Jesuit priest) Georges Lemaître realised there must have been a beginning - a scientific version of Genesis, so to speak.
Not that everyone immediately agreed. Well into the 1960s, Fred Hoyle's steady-state theory was quite popular among iconoclastic scientists as well as lay people. Hoyle accepted cosmic expansion, but he didn't believe in the Big Bang. Instead, he assumed that a slow, continuous creation of new matter could keep the average density and the general properties of the Universe constant over time.
The 1964 discovery of the cosmic microwave background was the major nail in the coffin of the steady-state theory. Ever since, supporting evidence for the Big Bang origin of our Universe has accumulated to a point where there's hardly any doubt left.
This story is from the June 2023 edition of BBC Sky at Night Magazine.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 8,500+ magazines and newspapers.
Already a subscriber ? Sign In
This story is from the June 2023 edition of BBC Sky at Night Magazine.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 8,500+ magazines and newspapers.
Already a subscriber? Sign In
Water, Water, Everywhere?
Penny Wozniakiewicz investigates why astronomers are so concerned with finding water in the Solar System, and why it is vital to our exploration of space
O&A WITH AN ECLIPSE CHASER
On 14 October 2023, an annular eclipse passed across mainland USA. Comedian and stargazer Jon Culshaw was there to witness it
Bresser ISA Space Exploration NASA 70/700 AZ telescope
This beginners' package has everything you need to see the Sun, Moon and planets
Ursa Major 6-inch f/8 Planetary Dobsonian
A decent option for would-be planetary observers on a limited budget
Use freeware to create star trail images
How to turn your frames into beautiful star trail photos in a few clicks
Venus's hostile atmosphere
Katrin Raynor takes a look at a planet where the skies boil and the clouds rain acid
Build your EYEPIECE COLLECTION
Great eyepieces are crucial to any astronomical setup. Here Tim Jardine arms you with the info you need to choose the best ones to invest in
THE BIG THREE
The top sights to observe or image this month
The remains of CREATION UNDERSTANDING THE CMB
Left over from the Big Bang, the cosmic microwave background gives astronomers an insight into the entire history of our Universe. Ezzy Pearson explains
A December GRAND TOUR
Just like the epic journeys of the Voyager probes to our Solar System's outer planets, this tour takes you to the gas and ice giants as they line up in the night sky this month. Stuart Atkinson is your guide