WHAT IS THE EVIDENCE FOR A BIG BANG?
The Universe has not existed forever. It was born. Around 13.82 billion years ago, matter, energy, space – and time – erupted into being in a fireball called the Big Bang. It expanded and, from the cooling debris, there congealed galaxies – islands of stars of which our Milky Way is one among about two trillion. This is the Big Bang theory.
A universe popping into existence out of nothing is so bonkers that scientists had to be dragged kicking and screaming to the idea. But the evidence is compelling. The galaxies are flying apart like pieces of cosmic shrapnel. And the heat of the Big Bang is still around us. Greatly cooled by cosmic expansion, this ‘afterglow’ appears not as visible light but principally as microwave radiation – the ‘cosmic background radiation’, which was discovered by radio astronomers in 1965.
WHERE DID THE BIG BANG HAPPEN?
When a stick of dynamite explodes, the detonation occurs in one place and shrapnel flies into the void. In the Big Bang, there was no centre and no pre-existing void, so it didn’t happen at any ‘location’. Space itself popped into existence and began expanding everywhere at once.
Astronomy books often liken the Universe to a rising cake, with raisins representing galaxies. As the cake grows, raisins recede from each other, with no centre of expansion – just like the Big Bang. But of course, a cake has an edge, unlike the Universe, which may go on forever. No analogy is perfect!
Denne historien er fra December 2020-utgaven av BBC Focus - Science & Technology.
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Denne historien er fra December 2020-utgaven av BBC Focus - Science & Technology.
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Do We Finally Know How the Egyptian Pyramids Were Built? - A number of breakthrough studies are beginning to paint a picture of how these wonders of the world were built, but much of the story still remains a mystery...
A number of breakthrough studies are beginning to paint a picture of how these wonders of the world were built, but much of the story still remains a mystery...How the Egyptian pyramids were built has long been a mystery. Constructed as tombs for the pharaohs over 4,000 years ago, more than 100 of them remain. The largest one, the Great Pyramid of Giza, was originally 147m tall (482ft). It's made up of about 2.3 million stone blocks, each weighing between 2.5 and 15 tonnes, and would have had to be transported to the building site and lifted into place with techniques available at the time. To put this into context, it's akin to lifting a double-decker London bus to the top of St Pauls Cathedral a few million times.
An Artificial Heart Inspired by Plumbing - Mechanical circulation could revolutionise transplant design and reduce waiting lists
Mechanical circulation could revolutionise transplant design and reduce waiting lists. In July, this artificial heart was successfully implanted, for the first time, into a patient with end-stage heart failure. Built by The Texas Heart Institute (THI) and BiVACOR, the replacement organ has been dubbed the Total Artificial Heart (TAH). Although, being an implant rather than transplant, it's designed to temporarily support patients while they wait for a real heart transplant.
CHANGE THE (BODY) CLOCKS
Why the end of British Summer Time can be a wake-up call for our circadian health
ARE OCTOPUSES SENTIENT?
If you've watched the Netflix documentary My Octopus Teacher or been lucky enough to encounter an octopus in the wild, you'll know there's something special about them.
THE MEXICAN MOLE LIZARD
Imagine what would happen if an earthworm, a lizard, a snake and a mole went on a night out, had too much too much tequila and let their guard down.
ECLIPSES ON DEMAND
Inside an unassuming building, behind a damp car park in Antwerp, Belgium, scientists are teaching two spacecraft to be dance partners for a performance that will take place in front of the Sun.
How light's 'secret code' reveals the story of the cosmos
The starlight we can see tells us alot about the Universe, but it's the parts we can't see that contain the biggest revelations
Major Stonehenge discovery deepens mystery around ancient monument
New findings suggest a key six-tonne stone came from over 450 miles north of the circle
THE UNEXPECTED RETURN OF PNEUMATIC TUBES
Once a pioneering technology that revolutionised deliveries, pneumatic tubes had all but disappeared. Now they're back and enjoying a resurgence
LIVING FOSSILS
FOR SOME CREATURES ALIVE TODAY TIME HAS ALMOST STOOD STILL. MEET THE 'LIVING FOSSILS' THAT GIVE US A GLIMPSE INTO LIFE IN THE DISTANT PAST
