What was it like when the last antimatter disappeared?
<p>Things happen fast in the earliest stages of the Universe. In the first 25 microseconds after the start of the hot Big Bang, a number of incredible events have already occurred. The Universe created all the particles and antiparticles — known (as part of the Standard Model) and unknown (including whatever makes up dark matter) — it was ever capable of creating, reaching <a href="https://bigthink.com/starts-with-a-bang/universe-at-its-hottest/" rel="noopener ugc nofollow" target="_blank">the highest temperatures</a> it ever attained. Through a still-undetermined process, it <a href="https://bigthink.com/starts-with-a-bang/matter-defeated-antimatter/" rel="noopener ugc nofollow" target="_blank">created an excess of matter over antimatter</a>: just at the 1-part-in-a-billion level. The electroweak symmetry broke, allowing <a href="https://bigthink.com/starts-with-a-bang/higgs-gave-particles-mass/" rel="noopener ugc nofollow" target="_blank">the Higgs to give mass</a> to the Universe. The heavy, unstable particles decayed away, and <a href="https://bigthink.com/starts-with-a-bang/protons-and-neutrons-formed/" rel="noopener ugc nofollow" target="_blank">the quarks and gluons bound together</a> to form protons and neutrons.</p>
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