Cosmic bubbles may have forged dark matter, new theory suggests

Ballooning cosmic bubbles in our early universe may have led to the current abundance of dark matter, the elusive substance that tugs on the stars, yet emits no light, a new study suggests.

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Tau.Neutrino said:

Cosmic bubbles may have forged dark matter, new theory suggests

Ballooning cosmic bubbles in our early universe may have led to the current abundance of dark matter, the elusive substance that tugs on the stars, yet emits no light, a new study suggests.

more…

Long and physicists Michael Baker, at the University of Melbourne in Australia, wanted to answer the last of these questions — when and how did dark matter form? They looked at the earliest period of the universe’s formation, a fraction of a nanosecond after the Big Bang started, a “Wild West” of particle creation and destruction, where particles collided and annihilated each other as quickly as they formed, Long said. At the time, the universe was a fiery soup of extremely high-energy elementary particles, similar to the quark-gluon plasma physicists create in the biggest particle accelerators today. This primordial soup was unimaginably hot and dense, and far too chaotic for more ordered subatomic particles such as protons and neutrons to form.

After the universe began to expand, the plasma gradually cooled and the production of new particles came to a halt. At the same time, particles grew further apart and their rate of collisions plummeted until their numbers remained fixed. The particles that were left are what scientists call “thermal relics”, and became the matter we know and love today, such as atoms, stars, and eventually, people.In addition to all of the elementary particles known today, there’s reason to imagine there were other particles present during the early universe, such as dark matter.

(So far so good, this is the standard scenario for dark matter formation).

As these cosmic bubbles expanded throughout the universe, they acted like filters that sifted dark matter particles out of the plasma. The walls of these bubbles would become barriers. Only dark matter particles with large masses would have enough energy to pass through to the other side inside the expanding bubbles and escaping the Wild West that annihilated lighter particles. This would filter out lower mass dark matter particles and could explain the abundance of dark matter observed today.

(That’s new. And actually makes sense, I think).