1 trillion years is an immensely long span of time, even in the context of cosmology. It is far beyond the current estimated age of the universe, which is approximately 13.8 billion years. Therefore, discussing the state of the universe 1 trillion years ago would involve significant speculation, as our understanding of the early universe is limited to a few hundred thousand years after the Big Bang.
Based on our current understanding, the universe underwent a rapid expansion event known as cosmic inflation shortly after the Big Bang, which led to the formation of elementary particles, atoms, and eventually the first stars and galaxies. Over time, galaxies have continued to form, evolve, and interact through processes such as gravitational attraction and mergers.
However, as we extrapolate back to 1 trillion years ago, numerous factors could significantly affect the state of the universe. For instance, the expansion of the universe, dark energy, and the influence of gravity could alter the structure and composition of cosmic matter over such an immense timescale. Additionally, the potential evolution of fundamental constants, the fate of galaxies and stars, and the influence of unknown physical phenomena could all contribute to an uncertain picture.
It is important to note that our current understanding of cosmology is based on observations, theoretical models, and extrapolations from available data. Predicting the precise details of the universe 1 trillion years ago exceeds the limits of our knowledge at this time. As scientific research progresses and new insights emerge, our understanding of the universe's distant past may expand, allowing us to speculate with greater confidence.