Unexplainable: Impossible Questions and What Happened Before the Big Bang

Key insights

• A taxonomy of unanswered questions separates those needing more data from ethical barriers, unanticipated questions, and insurmountable mysteries.
• Before time itself may have a boundary, with ideas like no boundary proposals and time concepts reframed in four dimensional spacetime.
• The Big Bounce and mirror universe theories illustrate how cosmology tries to bypass a hard start to the universe.
• The discussion highlights how resource allocation and experimental design influence what questions scientists pursue.

Introduction and framing

In the podcast, the host introduces a two episode arc centered on Scientific American's Impossible Questions issue. The aim is to unpack why some questions remain unanswered despite advances in science and technology. The host presents a taxonomy of unanswered questions, recognizing that not all unknowns are created equal, and sets the stage for a detailed discussion with a science journalist who helped develop the taxonomy. The conversation emphasizes that questions span practical research barriers, ethical considerations, questions we did not know we could ask, and the classic barriers that render some inquiries seemingly unanswerable.

Bucket 1: clear questions that require more research

The first category focuses on questions scientists are actively chasing but have not yet answered because of the magnitude of the data or the difficulty of experiments. Examples include whether extraterrestrial life exists and how certain biological mechanisms work, such as the precise mechanism of action for common medications. The point is not that these questions are unsolvable in principle, but that progress requires new data, better methods, or more time and resources. The discussion acknowledges that many considered questions are not pursued due to misaligned funding or historical neglect of certain topics such as reproductive health or endometriosis, illustrating how scientific progress is influenced by human factors as well as nature itself.

Bucket 2: morally or ethically should questions

The second bucket highlights questions we could answer but may not want to answer because they touch on deep moral or ethical issues. The conversation uses pregnancy medication safety as a focal point, illustrating how ethical considerations impede certain experiments or data collection, especially when it would entail testing drugs on pregnant people. The presenter notes how the past included unethical scientific practices and emphasizes the ongoing challenge of balancing scientific curiosity with safeguards to protect participants. The point is not to dismiss this category but to understand why some answers remain elusive because the ethical framework constrains experimental design.

Bucket 3: questions we did not know we could ask

The third bucket covers questions that became accessible only after advancements in technology, observation, or theory. The interviewer uses examples where the discovery of new methods opened up lines of inquiry that were previously unimaginable. For instance, advances in microbiology and neuroscience opened questions about the human microbiome and its potential links to mental health, which would have been inconceivable without the accompanying observational tools and theoretical frameworks. This bucket captures how scientific progress can unlock entirely new domains of inquiry by enabling measurements that were previously impossible.

Bucket 4: the classic big unsolved questions

The final bucket encompasses the grand, seemingly insurmountable questions such as the origin of life or what happened before the Big Bang. The host acknowledges the existence of barriers—data, theory, or conceptual—yet remains open to the possibility that future breakthroughs could alter what is knowable. The discussion emphasizes awe and curiosity in the face of cosmic mysteries, noting that the universe may still hold secrets we never fully uncover, and that such mysteries fuel imagination and scientific ambition.

Cosmology and the Big Bang before time

The conversation then shifts to a specific Cosmo topic: what happened before the Big Bang. The guests explain that the Big Bang marks a boundary not just of space, but of time, making the notion of “before” tricky. The no boundary proposal is discussed as a way of avoiding a time boundary by treating the universe as a four-dimensional spacetime manifold: imagining the universe as a globe rather than a line that starts at time zero. This helps frame why asking what happened before the Big Bang may be ill-posed or require reframing the question entirely.

Other theories explored include the Big Bounce, where a contracting universe could transition into an expanding one without a true beginning, and a mirror universe concept where time runs in the opposite direction on the other side of a boundary. The experts describe how these ideas attempt to reconcile observations of expansion with the absence of direct evidence about a time-before-Big-Bang epoch. The discussion emphasizes that none of these ideas have strong, definitive data that would settle the question, and that many scientists view them as speculative ways to model an unseen prehistory. The participants stress that the chances of any single proposal being correct are low, but that the value lies in the creative space opened by exploring multiple possibilities.

Interpretation, awe, and the future of the questions

Both the host and the guests reflect on the nature of unanswered questions as a source of cosmic awe. They discuss how the unknown invites imaginative theories and how different mental models can broaden our sense of the universe. The episode closes with a reminder to explore Scientific American’s Impossible Questions issue and to anticipate the second installment in the series which continues the exploration of these themes.

Conclusion

The podcast invites listeners to engage with nuanced categories of unanswered questions, illustrating how science progresses not only through data but through shifting perspectives on what questions are meaningful and tractable. It leaves the door open for further exploration, underscoring that even if definitive answers remain out of reach, the journey of inquiry can reveal surprising insights and deepen our sense of awe about the cosmos.