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The Laws of Physics Used to be Different, Which May Explain Why You Exist
The laws of physics were likely different in the deep past [ufl.edu]:
The laws of physics must have been different at the start of the universe than they are now, according to a mind-bending study conducted by University of Florida astronomers, which provides clues to why stars, planets and life itself managed to form in the universe.
After analyzing the distribution of a whopping million, trillion groups of galaxies, the scientists discovered that physical laws once preferred one set of shapes over their mirror images. It's as if the universe itself used to favor right-handed things instead of left-handed things, or vice versa.
The findings, made possible in part by UF's supercomputer HiPerGator, chip away at explaining perhaps the biggest question in cosmology: Why does anything exist? That's because some kind of handedness at the earliest moments of creation is necessary to explain why the universe is made of matter, the stuff that makes everything we see. The results also help confirm a central tenet of the Big Bang theory of the origin of the universe.
[...] Their study was designed to look for violation of a concept known as "parity symmetry" in physics, which refers to mirror-image reflections akin to left- or right-handedness. Many things in physics can be said to have a handedness, like the spin of an electron. The laws of physics today don't usually care if this spin is left or right handed, though. That equal, or symmetric, application of the laws of physics regardless of handedness is referred to as parity symmetry.
The only problem is that parity symmetry must have been broken at some point. Some ancient parity violation – some kind of preference for right-handed or left-handed stuff in the distant past – is required to explain how the universe created more matter than antimatter. If parity symmetry held during the Big Bang, equal portions of matter and antimatter would have combined, annihilated one another, and left the universe completely empty.
[...] So in a recent paper published in Physical Review Letters [aps.org], Slepian, Hou and Cahn proposed an inventive way to search for evidence that parity was indeed violated during the Big Bang. Their idea was to imagine every possible combination of four galaxies in the night sky. Connect those four galaxies together by imaginary lines, and you have a lopsided pyramid, a tetrahedron. This is the simplest 3D shape possible –and thus the simplest shape that has a mirror image, the key test for parity symmetry.
Their method required analyzing a trillion possible tetrahedrons for each of a million galaxies, an incredible number of combinations. "Eventually we realized we needed new math," Slepian said.
[...] Slepian's group discovered that, indeed, the universe imprinted an early preference for left- or right-handed stuff onto the material that eventually became today's galaxies. (The complex math makes it difficult to say whether that preference was for right-handedness or left-handedness, though.)
[...] "Since parity violation can only be imprinted on the universe during inflation, if what we found is true, it provides smoking-gun evidence for inflation," Slepian said.
The findings by Slepian's lab can't yet explain how the laws of physics changed, which will require new theories going beyond the Standard Model, a theory that explains our current universe. Now the race is on for scientists to produce this theory that can explain the universe's ancient handedness and the abundance of matter we see today.
Journal Reference:
Cahn, Robert N., Zachary Slepian, and Jiamin Hou, Test for Cosmological Parity Violation Using the 3D Distribution of Galaxies, Phys. Rev. Lett, 130, 2023. DOI: https://doi.org/10.1103/PhysRevLett.130.201002 [doi.org]
