Sep 16, 2026 · 29 min
Cosmologists confront the limits of asking what came first
What happened before the big bang?
The episode tests whether theories about before the Big Bang can produce evidence—or whether the question exceeds science’s reach.
- 1Scientific American’s unanswered questions range from solvable problems to questions constrained by ethics, tools, or fundamental limits.
- 2Proposals involving a no-boundary universe or an antimatter mirror universe may relocate the origin problem rather than resolve it.
- 3Evidence from before the Big Bang may be inaccessible, raising doubts about whether future experiments can settle the question.
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Sarah Scoles explains why theories about before the Big Bang may be impossible to test if their evidence is permanently inaccessible.
The brief
Rachel Feltman introduces Scientific American’s taxonomy of unanswered questions, distinguishing problems awaiting research from those limited by ethics, tools, or seemingly insurmountable barriers.
Sarah Scoles turns that framework toward cosmology: asking what preceded the Big Bang may be scientifically difficult because any evidence from before it could be inaccessible.
The discussion considers a no-boundary proposal and a mirror universe made of antimatter with reversed time, but each theory may shift the origin question elsewhere.
The episode’s central tension is whether better tools could test these ideas—or whether a time before time lies beyond both measurement and meaningful human comprehension.
The Big Bang question becomes a test of science’s limits: some mysteries await new evidence, while others may be impossible to investigate in principle.
Featuring
Rachel Feltman
Sarah ScolesMentioned
Scientific American
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