What Was It Like When The Universe Made The Very First Galaxies?
“The first galaxies required a large number of steps to happen first: they needed stars and star clusters to form, and they needed for gravity to bring these star clusters together into larger clumps. But once you make them, they are now the largest structures, and can continue to grow, attracting not only star clusters and gas, but additional small galaxies. The cosmic web has taken its first major step up, and will continue to grow further, and more complex, over the hundreds of millions and billions of years to follow.”
For millions upon millions of years, there were no stars in the Universe. As the first one finally formed, the star clusters that birthed them became the largest structures in the Universe. Yet these were too small and limited to be considered galaxies. For that, we need more than one massive star cluster in the same place. We need for them to merge, triggering a starburst and creating a larger, more luminous object. It takes much longer for that to happen than to merely form stars, and the Universe was a very different place by then. The Big Bang may have started everything off uniformly and without anything more than the seeds of structure, but gravity, and time, are awfully powerful tools.
Come learn what the Universe was like when we made the very first galaxies. It’s a story you won’t soon forget!
Earliest Evidence For Stars Smashes Hubble’s Record And Points To Dark Matter
“And most importantly, this is a glimpse into what it’s like to push back the frontiers of science. The first evidence for anything new is almost always indirect, weak, and difficult to interpret. But these unexplained signals have the power to explain what we don’t yet fully understand: how the Universe came to be the way it is today. For the first time, the Universe has given us an observational clue of where and when and what to look for. It’s up to us to take the next step.”
Earlier today, a new study was released in Nature, showcasing the earliest evidence of stars in cosmic history. The previous record was held by Hubble, which had spotted a galaxy from when the Universe was just 400 million years old: 3% of its current age. Now, indirect measurements of starlight, through the technique of radio astronomy looking for a particular hydrogen transition, has shown us evidence for a tremendous population of stars from when the Universe was between 180 and 260 million years old. This could be, truly, the first stars and galaxies of all, and it’s occurring in exactly the range that the James Webb Space Telescope will be sensitive to. Moreover, the gas that we’re observing shows signs of being far cooler than we’ve anticipated, meaning that something strange is going on, and one leading candidate is that dark matter is interacting with and cooling the gas!
This is the earliest evidence for stars in the entire Universe, and it’s just smashed Hubble’s previous record. Come get the full story right now!