Video: How we can see the first light from the universe
The universe’s dark age lasted for 380,000 years after the big bang. Now we’ve found ways to pierce the fog before light was set free
IT’S the universe’s first light. The cosmic microwave background (CMB) formed about 380,000 years after the big bang, when the fog of the early universe cleared enough for light to travel unimpeded through the cosmos. We cannot see beyond this curtain of light to earlier times. It’s the limit of our electromagnetic vision.
But not of all vision. Like footprints on an empty beach, imprints on the CMB tell the story of what happened before. Today we see the light, stretched in wavelength due to the expansion of the universe, as microwaves in the sky.
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These microwaves have a temperature of 2.726 kelvin. In a technical tour de force, NASA’s WMAP satellite was built to map variations in this temperature as small as 1 part in 100,000, across the entire sky. This revealed that the early universe contained relatively denser regions, which would become seeds for clusters and super-clusters of galaxies.
Events that happened even earlier, when the universe was just 10-36 seconds old, are also thought to have left their mark. This is when the universe supposedly underwent a period of blistering expansion called inflation, sending ripples through space-time that polarised the light in a characteristic pattern. Earlier this year the BICEP2 telescope at the South Pole controversially claimed to have seen this faint signature, but the European Space Agency’s Planck satellite has yet to confirm the findings.
If its results are confirmed, the BICEP2 telescope will have seen beyond the limit of cosmic sight (Image: Bicep 2)
On Earth, the Large Hadron Collider at CERN, near Geneva, Switzerland, is also helping smash the cosmic limit – by showing us what the universe might have been like just microseconds after the big bang. The LHC does this by colliding lead ions accelerated to near light speed. The collision creates energies so high, at temperatures of about 5.5 million kelvin, that all matter disintegrates into its constituent quarks and gluons – a mini big bang whose quark-gluon soup is now being analysed.
Read more: “Us vs the universe: 8 ways we bend the laws of physics“
This article appeared in print under the headline “Signatures of the invisible”
