While Leah Crane's recent New Scientist column captures the poetic appeal of cyclic cosmology—likening the universe's potential big crunch and rebound to a cosmic heartbeat—it stops short of examining how this framework directly confronts the shortcomings of cosmic inflation and grapples with entropy management across cycles. Drawing on the DESI survey's early findings, Steinhardt and Turok's foundational work, and Penrose's related ideas, a clearer picture emerges: cyclic models are not mere nostalgia but a serious contender addressing deep cosmological problems while echoing ancient philosophical debates about eternal existence.

The DESI collaboration, using a spectroscopic survey of more than 5 million galaxies to measure baryon acoustic oscillations as cosmic rulers (first-year data release, with ongoing observations), has detected mild hints (around 2.5-3 sigma) that dark energy may be weakening over cosmic time rather than remaining a constant. This is peer-reviewed in journals like JCAP but remains limited by potential systematics in galaxy bias modeling and the need for more data to reach 5-sigma certainty. If confirmed, a declining dark energy density could allow gravitational attraction to eventually halt expansion and trigger contraction—reviving the big bounce idea that Crane notes fell out of favor after Adam Riess's Nobel-winning discovery of accelerating expansion.

Crane's coverage misses how cyclic models, particularly the ekpyrotic scenario proposed by Paul Steinhardt and Neil Turok in their 2002 peer-reviewed Science paper, resolve the horizon and flatness problems without invoking a mysterious inflaton field. Inflationary theory, while successful in matching CMB patterns from Planck satellite data (full-sky maps with millions of modes analyzed), suffers from the measure problem: in an eternal inflating multiverse, probabilities for our observed universe become ill-defined. Cyclic models avoid this by having no true beginning—each contraction phase resets conditions through higher-dimensional brane collisions in string theory frameworks.

What the original piece gets wrong is overstating the 'death' of cyclic ideas post-1998. Modified versions incorporating quintessence-like fields can accommodate dark energy phases before a bounce. Synthesizing this with Roger Penrose's Conformal Cyclic Cosmology (detailed in his 2010 book and subsequent peer-reviewed papers in Proceedings of the Royal Society), we see a pattern: physicists increasingly seek singularity-free alternatives. Penrose's CCC uses conformal rescaling to connect aeons without a crunch, addressing the second law of thermodynamics by diluting entropy in the transition—precisely the entropy recycling issue Crane's column cuts off mid-sentence.

This resurgence connects to longstanding philosophical questions about eternal universes, from the Stoics' ekpyrotic cycles and Hindu cosmology's kalpas to Kant's antinomies questioning whether time had a beginning. Unlike inflationary models that imply a multiverse where our life-friendly conditions are one random outcome among infinities, cyclic cosmology suggests our epoch is typical, not special, as Riess noted. Yet genuine analysis reveals limitations: no complete quantum gravity theory (neither string nor loop quantum cosmology bounces are fully tested), and entropy accumulation across cycles risks making early universe smoothness improbable without fine-tuned reset mechanisms.

The original coverage also underplays methodological contrasts. DESI's galaxy mapping is observational astronomy at scale, not a direct test of bounce physics, which would require primordial gravitational wave signatures or specific non-Gaussianities in the CMB distinguishable from inflation's predictions. Future CMB-S4 experiments could differentiate them. Ultimately, cyclic cosmology's rebound highlights science's healthy skepticism of a one-shot universe, offering an elegant, if still speculative, alternative that bridges physics and philosophy. It reminds us that our accelerating cosmos may yet turn inward, continuing an eternal dance rather than fading into heat death.