Solving the "Before" the Big Bang: How to Depict an Unobservable Beginning: The Challenge of Numerical Relativity × Early Universe

1) Beyond the "Beginning"—The Core of the News

"The evidence for the Big Bang is overwhelming, but we don't understand the physics of that moment." IFLScience reported on August 26, 2025, about a computational strategy that breaks through this dead end. Instead of only dealing with solvable cases, it attempts to "forcibly" solve Einstein's equations using numerical relativity. Even in spacetimes that break down with paper and pencil, supercomputers can venture into them—such ambitious plans are now being seriously directed toward the early universe.IFLScience

2) What is Numerical Relativity: From Black Holes to the Early Universe

Numerical relativity emerged in the 1960s and 70s, with a proven track record of calculating the merger waveforms of black hole binaries, leading to LIGO's gravitational wave detection. It is a method of "directly solving strong gravity problems without (or unknown) analytical solutions using approximations and lattice calculations." In recent years, there have been successive ideas to extend its application range to the "unsolvable regions" of cosmology—right after the Big Bang or "before" it.ScienceDailyAOL

3) Searching "Outside the Lamp": Stepping Down from the Armchair of Symmetry

In cosmology, it is customary to assume the universe is "homogeneous and isotropic (FLRW)" to simplify calculations. However, whether this assumption truly holds is actually the core of Big Bang physics. Removing symmetry makes the equations much more complex, which is why numerical relativity is essential. Cosmologist Eugene Lim refers to the tendency to search only within solvable ranges (under the streetlight) as the "lamp post problem," emphasizing the importance of numerical relativity as a tool to venture outside the streetlight.EurekAlert!spacedaily.com

4) Is "Before the Big Bang" Possible: Big Bounce, Multiverse, Cosmic Strings

The cosmic version of numerical relativity tackles scenarios such as the following.

• Big Bounce: A depiction where the universe "reverses" from contraction to expansion, avoiding singularities. It has been examined in loop quantum cosmology (LQC) and other theories, but numerical verification including asymmetric and nonlinear effects is key.Wikipediapreposterousuniverse.comNature

• Collision of Bubble Universes (Multiverse): When "bubbles" formed by hypothetical phase transitions collide, they may leave traces in the CMB or gravitational wave background. Analytically challenging, but numerically, the collision geometry can be directly tracked.SciTechDaily

• Defects like Cosmic Strings: Calculating spacetime responses and radiation assuming topological defects were stretched across the early universe. Evaluation in the realm of strong gravity and nonlinearity is progressing.SciTechDaily

What is important is that these are becoming testable hypotheses rather than untestable speculations.ScienceDaily

5) How to Overcome the "Wall" of Observation: Matching with Indirect Traces

Electromagnetic observations hit the wall of the cosmic microwave background (CMB). Beyond that, it is "invisible." However, "background gravitational waves" and "cosmic neutrino background" may carry "tremors" that surpass that wall. By creating predictive spectra for each scenario using numerical relativity and matching them with gravitational wave backgrounds like PTA (Pulsar Timing Arrays) or future neutrino observations, this "trinity of theory × computation × observation" is the only breakthrough.IFLScience

6) The Reality of Research Plans: What Will Be Known and When

The current trend is clear.

• Maturity of Methods: Transplanting the proven framework from black hole mergers to the boundary conditions of the early universe.ScienceDaily

• Expansion of Subjects: Tackling the fine structure of inflation, non-Gaussianity, bubble collisions, defect networks, and even "reversal" dynamics, which are analytically challenging areas, with numerical approaches.SciTechDaily

• Outcomes: Quantifying the model dependence of "distortions" left in the CMB or gravitational wave background, providing upper and lower limits of "it can't be more than this." This means imposing physical constraints on "before the Big Bang."ScienceDaily

7) A Calm Perspective: Unresolved Hurdles

• Connection with Quantum Gravity: At densities like those of the Big Bang, quantum effects cannot be ignored. Bridging with LQC and others is incomplete, and the consistency between classical numerical solutions and effective quantum theories is questioned.NatureWikipedia

• Computational Resources: Resolution, order, and parameter scans are enormous. A community-based verification system is needed to evaluate the reproducibility and systematic errors of results.SciTechDaily

• Skepticism within the Theoretical Community: There has been long-standing criticism of the Big Bounce. There are persistent voices pointing out the abundance of model assumptions and the weak observational distinguishability.preposterousuniverse.com

8) Reactions on Social Media: Hope, Skepticism, Philosophy

In IFLScience's announcement post, the phrase "our science breaks down right after the Big Bang" resonated with some (X/Threads), while many others discussed it in the context of faith or philosophy. For example, on Facebook, there were comments like "God spoke…" bringing up creation, and discussions on Reddit arguing that **"time began with the Big Bang"** making "before" meaningless, highlighting clear divisions in viewpoints. Science-oriented users resonated with the metaphor of "outside the streetlight," and there were posts appreciating the significance of removing symmetry dependence with numerical relativity.X (formerly Twitter)ThreadsFacebookReddit

Representative Posts of Interest
・"Our science stops making sense a fraction of a second after the Big Bang."—Official IFLScience (X/Threads)X (formerly Twitter)Threads
・"God spoke…"—Facebook comment (short quote)Facebook
・"Time began with the Big Bang"—Summary of Reddit discussion (community post)Reddit

9) Contextualizing: A New Yet Old Question

"Before the Big Bang" is not a newcomer. In 2007, Bojowald and others discussed the phase **"before"** in the context of LQC, while Carroll and others have expressed skepticism towards