String theories describe what cosmology was like before universe origin and what happened to begin universe. String theory allows more high-frequency gravity waves than inflation theory or ekpyrotic theory, so observing gravity waves can test string theories {pre-big-bang theory}. In fact, universe has few high-frequency gravity waves and some low-frequency gravity waves. Perhaps, universe has small-scale and large-scale strings. Perhaps, universe origins involve quantum-mechanical tunneling.
dilaton
Force strengths depend on string 11th-space-time-dimension length (dilaton). Short dilatons represent weak nuclear forces. Long dilatons represent strong nuclear forces. Dilaton lengths represent electromagnetism, and dilaton length variations change electromagnetic fields.
Before universe origin, dilatons are long, and forces are strong. At universe origin, dilatons are short, and forces are weak. Observing intergalactic magnetic-field changes is a test for dilatons and so can indicate universe-origin conditions.
axion
Magnetic-field photons can make dilaton-related strings (axion) that have less than one millionth electron mass, no charge, and zero average quantum field. Magnetic-field axions can make photons. Therefore, axions allow strong nuclear forces to maintain charge-parity (CP) symmetry between antiparticles and particles.
Cosmic-microwave-background temperature fluctuations are small, have Gaussian distribution, and have same amplitude for large space regions. Cosmic-microwave-background temperature fluctuations arise mostly from density differences and partly from gravity waves. However, string theories without axions allow no density differences. Axions determine large-scale universe temperature fluctuations [Adams, 2002].
Physical Sciences>Astronomy>Universe>Cosmology>Theories>String Theory
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Date Modified: 2022.0224