Over 13 billion years ago there were no stars, no planets, nothing solid or liquid; gas filled the universe. The gas was very simple, only hydrogen and helium with a smattering of lithium atoms. It was very hot and its density was almost perfectly uniform. That word “almost” – not “exactly” – made all the difference to the evolution of the universe. It allowed us to exist!
The gas was patchy – here a little denser, there a little thinner. The best explanation we have is that those patches originated in the Big Bang when the universe was smaller than an atom as “quantum fluctuations”. Physicists have known for a century that the energy (therefore mass) in any tiny volume of space is always uncertain, fluctuating. The seeds were sown. Then they grew.
Whatever caused those patches, the attractive force of gravity pulled the denser regions together. A region a millionth denser became a thousandth denser, then a tenth, and so on. The matter in the universe was literally “pulling itself together” by gravity and becoming lumpy. Between vast empty voids, swirling galaxies and stars were taking shape. How did that happen? We cannot see clearly yet, but we should soon be able to study those first stars and galaxies as they were forming more than 12 billion years ago.
Hold your breath on December 18 when a rocket launches the Europe-Canada-USA collaboration’s James Webb Space Telescope. The JWST will travel to a special location 1,500,000 km from Earth, far beyond the moon, directly opposite from the Sun so always overhead at midnight. On its month-long journey a tennis court-size sunshield will unfurl. The telescope has to be kept very cold; it will never look back to see the Earth in front of the sun. Eighteen hexagonal mirror segments, folded like origami, will open and assemble themselves into one 6.5 m diameter concave mirror. This giant telescope will peer with infrared and deep red light at the first galaxies, as they were 12 billion years ago. Light took that long to reach us! They are rushing away from us due to the expansion of the universe and are both much fainter and redder than nearby galaxies. Our atmosphere absorbs most of the infrared radiation that the JWST in space will observe, and with an “eye” much bigger than the Hubble Space Telescope what wonders will be revealed?
Any signs of life? Are you still holding your breath?
