The NEW Ultimate Energy Limit of the Universe

A newly observed quasar, labeled LD 568, is shining about 4,000 times brighter than the theoretical “Eddington limit” for how fast a black hole can feed—an apparent violation that forces astronomers to rethink how the earliest supermassive black holes grew so quickly. The stakes are high: quasars in the first billion years after the Big Bang should have been powered by smaller black holes, yet observations show several far-too-massive engines. LD 568 adds a sharper clue by showing a black hole that appears to be accreting at an extreme, “super-Eddington” rate.

The Eddington limit is named after astrophysicist Sir Arthur Stanley Eddington and is rooted in a balance of forces. As gas falls toward a black hole, it heats up and radiates. That outgoing radiation exerts outward pressure that can counteract gravity’s pull. Under the simplest assumptions, the maximum steady feeding rate and corresponding luminosity occur when radiation pressure exactly balances gravity, making faster growth impossible. LD 568’s brightness suggests either the limit is being circumvented—or the real accretion environment differs from the idealized spherical picture that underpins the limit.

The transcript traces the limit’s logic back to stars, where Eddington originally reasoned about how gravity and pressure support a collapsing object. For ordinary stars, gas pressure dominates; for very massive stars, radiation pressure becomes increasingly important. But even in that stellar context, the key idea is the same: radiation can resist further infall once it becomes strong enough.

Black holes, however, rarely feed in a simple spherical way. Instead, infalling matter typically forms an accretion disc. In the standard “thin disc” model (developed by Nikolai Shakura and Rashid Sunyaev), matter orbits the black hole while viscous interactions and turbulence slowly drain angular momentum, allowing gas to spiral inward. Thin discs can be extremely luminous, but they tend to feed the black hole inefficiently—angular momentum acts like a bottleneck—so they usually operate below the Eddington feeding rate.

To exceed the Eddington limit, the transcript points to thicker disc geometries—often described as “Polish donuts” or “slim discs.” When the accretion rate rises, radiation pressure can puff up the inner disc. In these thicker flows, radiation doesn’t immediately escape outward; instead, it can be advected inward with the plasma. Eventually, energy escapes through narrow funnels near the poles, where radiation is channeled upward and downward. This geometry reduces the effective radiation pressure opposing gravity in the inflow region, allowing the black hole to keep swallowing matter at super-Eddington rates.

Computer simulations support the existence of these super-Eddington accretion modes, though they come with a tradeoff: thicker discs produce less energy per unit mass swallowed. Still, if the black hole consumes enough additional mass, the overall luminosity can remain enormous. Applied to LD 568, this framework offers a plausible path to rapid early growth, making it easier to explain how the universe’s earliest black holes became “chunky” fast enough to power the brightest quasars seen at cosmic dawn.