There Is an Edge to What We Can See & Nobody Knows What's On the Other Side

Summary

• The video distinguishes the observable universe from the entire universe. The observable universe extends roughly 46 billion light-years in every direction. This is not a physical wall: beyond the cosmic horizon, expansion means light from some regions can never reach us.
• The full universe could be infinite or finite but vastly larger than the observable part. The video cites a calculation suggesting that if space is finite and curves back on itself, it would be at least 250 times larger than the observable universe. In a finite, curved universe, there might be no “outside”; traveling far enough could eventually bring someone back to their starting point.
• If the universe is infinite, some cosmological arguments suggest that matter could form repeating configurations—including versions of Earth or people. The video presents this as a consequence of assumptions about an infinite universe and a limited number of possible arrangements, not as something directly observed.
• The James Webb Space Telescope (JWST), which observes infrared light, has detected early galaxies that appear more developed than expected so soon after the Big Bang. The video describes these findings as challenges to existing models of how quickly galaxies form.
• The video also discusses the Hubble tension: expansion rates inferred from the early universe differ from rates measured using nearby galaxies and supernovae. It says Webb observations have not eliminated the discrepancy. Dark energy is the name given to the phenomenon associated with the universe’s accelerating expansion, though its underlying nature remains unknown.
• Some theories, including versions of cosmic inflation, allow for other universes with different physical properties. The video notes that such universes may be impossible to observe or confirm.
• The central conclusion is that we do not know whether the universe has a true edge or what, if anything, lies beyond the observable horizon. The speaker also questions whether an infinite multiverse would necessarily contain copies of us, rather than entirely different forms of existence.

Researchers and Sources Featured

Researchers

• Max Tegmark — cosmologist at MIT
• Steven Finkelstein — University of Texas at Austin
• Christopher Conselice — University of Manchester
• Adam Riess — Nobel Prize-winning astrophysicist
• An unnamed UK research group, cited for the estimate that a finite universe would be at least 250 times larger than the observable universe

Sources Listed with the Video

• Sky at Night Magazine — “Has Webb Broken Cosmology?”
• Universe Today — “Universe 250 Times Bigger”
• PBS NewsHour — “Webb Prompts Scientists to Rethink the Universe”
• The Debrief — article on the Hubble tension
• Max Tegmark — Our Mathematical Universe
• Brian Greene — The Fabric of the Cosmos
• Lawrence Krauss — A Universe from Nothing