Let there be light: how the Universe looked after Big Bang

Let there be light: how the Universe looked after Big Bang

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This 50-million pixel all-sky image shows relic radiation from the Big Bang ESA/Planck Collaboration/PA
  • This 50-million pixel, all-sky image
    This 50-million pixel all-sky image shows relic radiation from the Big Bang ESA/Planck Collaboration/PA
Hannah Devlin Science Editor
Last updated at 11:32AM, March 22 2013

It may not be in bad shape for its age but the Universe is even older than previously thought, according to the most detailed survey of ancient cosmic background radiation.

The first major results from Europe’s Planck space mission suggest that the Universe began 13.81 billion years ago, nearly 100 million years earlier than previous estimates. It also contains significantly more dark matter, but the precise nature of this invisible substance remains completely mysterious, scientists said.

Announcing the results at the European Space Agency headquarters in Paris, Jean-Jacques Dordain, ESA’s director-general, said: “The extraordinary quality of Planck’s portrait of the infant Universe allows us to peel back its layers to the very foundations, revealing that our blueprint of the cosmos is far from complete.”

George Efstathiou, of the University of Cambridge, suggested that while to the public the image might resemble “a dirty rugby ball or a piece of modern art”, there were “cosmologists who would have hacked our computers or maybe even given up their children to get hold of this map, we’re so excited by it”.

The all-sky map, based on 15½ months of observations from the £510 million telescope, shows tiny temperature fluctuations in the so-called cosmic microwave background. This, the oldest light in the Universe, has travelled billions of years to reach us after first being imprinted on the sky only 380,000 years after the Big Bang.

At that time the Universe was a hot dense soup of interacting protons, electrons and photons at about 2,700C (4,892F). When the protons and electrons first joined to form hydrogen atoms, the light was emitted.

This radiation acts as a “back light” that helps to illuminate the overall composition of the Universe. Charles Lawrence, a Planck scientist based at Nasa’s Jet Propulsion Laboratory, said: “As that ancient light travels to us, matter acts like an obstacle course, getting in its way and changing the patterns slightly.”

The dark blue regions on the map represent the densest patches in space that went on to seed the formation of galaxies and clusters of galaxies that exist today.

The observations suggest that the ordinary matter that forms galaxies, stars and planets contributes just 4.9 per cent of the overall mass of the Universe, while dark matter makes up 26.8 per cent, a fifth more than was previously thought. Dark energy accounts for about 69 per cent, slightly less than thought.

Dark matter is perceived only through its gravitational influence, while dark energy is pushing our universe apart. Neither has been observed directly, but scientists hope that experiments at the Large Hadron Collider will do so.

Planck’s observations also appear to support theories describing “inflation”, a dramatic faster-than-light expansion of the universe immediately after the Big Bang. In far less time than the blink of an eye, the universe inflated in volume 100 trillion trillion times, the theory suggests.

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