Quantum Fluctuations and the Current State of Experiments to Verify the Big Bang

What are the "quantum fluctuations" that initially created the universe (the stage before the Big Bang and inflation)?
Hiroshima University has an explanation on its website.
https://www.hiroshima-u.ac.jp/news/92660

They were the first to observe the "Unruh effect" (heat felt in a vacuum).
A vacuum is not empty. Particles are moving slightly. This is "quantum fluctuations."
When Einstein's theory of relativity, which states that "the faster you move, the more time and space change," and quantum theory, which states that "the vacuum has fluctuations," are combined, the possibility of observing the phenomena that created the universe arises, and the true nature of space-time and the vacuum will be revealed.


Experiments to verify the Big Bang are also ongoing.
Current State of Experiments to Verify the Big Bang. Immediately after the Big Bang, the universe was in an extreme state of high temperature and density, and it is believed that quarks and gluons, the smallest elementary particles that make up matter, existed in a quark-gluon plasma (QGP) state.
https://link.springer.com/article/10.1007/JHEP08(2025)075
https://www.riken.jp/press/2025/20250909_1/index.html


Less than one billion years after the Big Bang, Webb discovered a massive black hole hidden among the dust. It was revealed that the number of luminous quasars in the early universe is more than twice as many as previously thought. The birth of massive black holes is speculated to be a natural phenomenon occurring throughout the universe.
Because massive black holes themselves do not emit light, finding "quasars," which glow brightly while engulfing matter, provides conclusive evidence of their existence.
https://www.ehime-u.ac.jp/data_relese/pr_20250909_rcsce/
https://research-er.jp/articles/view/148049

Akahata reports on the discovery of a black hole in the early universe　(September 9, 2025, Akahata)