If we were to remove everything from the universe that we know came into existence after the Big Bang, we would be left with a significantly different and simpler universe. The known entities that emerged after the Big Bang include galaxies, stars, planets, cosmic structures, and life forms. Removing these would leave us with the fundamental components that existed in the early stages of the universe.
Elementary particles: The universe would still contain fundamental particles, such as quarks, leptons (including electrons and neutrinos), and gauge bosons (such as photons). These particles are the building blocks of matter and interact through fundamental forces like gravity, electromagnetism, and the strong and weak nuclear forces.
Radiation and energy: The remnants of the cosmic microwave background radiation (CMB) would persist, which is the residual energy from the hot, dense early universe. Additionally, other forms of radiation, such as cosmic rays and background radiation from other sources, would still exist.
Dark matter: The presence of dark matter is inferred from its gravitational effects on visible matter, but its exact nature is not yet understood. If we remove the matter that formed after the Big Bang, dark matter would likely still be present. However, its distribution and properties would need further investigation.
Space and time: The fabric of space and time, known as the spacetime continuum, would persist. Space would still exist, and the expansion of the universe would continue, albeit without the familiar structures we observe today.
It's important to note that this hypothetical scenario involves removing everything known to have emerged after the Big Bang, which includes the intricate structures and complexity that evolved over billions of years. The resulting universe would be significantly different from our current universe, lacking the intricate web of galaxies, stars, planets, and life forms that we observe today.