14 articles
Our current estimates place the number of galaxies in the observable universe at a staggering two trillion. Counting them individually, even at one per second, would take an immense 62,000 years, highlighting the vastness of space.
The multiverse, a vast ensemble of universes, is explored as a potential explanation for cosmic fine-tuning. While criticized as unfalsifiable, proponents argue it arises naturally from theories like string theory and eternal inflation, and can be indirectly tested.
The universe's seemingly perfect tuning for life, particularly the value of the cosmological constant, might be evidence for a vast multiverse. Steven Weinberg's 1987 paper used anthropic reasoning to estimate this constant, a prediction remarkably close to later observations, suggesting we inhabit a life-permitting universe within a cosmic ensemble.
New observations using the warped light of quasars and supernovae through gravitational lensing are helping to refine measurements of the universe's expansion rate. This technique, time-delay cosmography, is crucial for understanding the accelerating expansion and potentially solving the 'Hubble tension'.
