Black Holes Still Emit, White Holes Also "Glow"

Research Methodology

Researchers investigated a theoretical universe configuration known as an “eternal Schwarzschild manifold.” This is a simplified mathematical model representing spacetime around a non-rotating, uncharged black hole.

• They conceptualized the inside of a black hole as a cosmic backdrop.
• The white hole was envisioned as a universe expanding in certain dimensions while contracting in others.

The team calculated the "Hawking radiation"—a type of thermal radiation theoretically emitted by black holes due to quantum effects near their event horizon—that a distant observer would detect, stemming from these quantum jitters inside the white hole. They also explored scenarios where the initial conditions deep within the white hole were not perfectly empty.

Key Findings

The study revealed that an observer situated deep inside the white hole and one far outside the black hole would perceive the same natural "empty space," or vacuum.

The number of tiny particles an observer would detect outside the black hole aligns with a "Planck spectrum"—a specific curve describing the intensity of radiation emitted by a "black body" at a given temperature. This is precisely what is expected for Hawking radiation.

This finding implies that white holes, much like black holes, are not completely isolated from the external universe.

The authors state, "The observer deep inside the white hole and the observer far outside the black hole share the same vacuum." They conclude that "if a black hole is not entirely black due to Hawking radiation, then a white hole is not entirely white either."

However, if the white hole begins with some initial quantum "noise," representing a non-vacuum state, this glow would not perfectly match the Planck spectrum, instead exhibiting an additional, distinct pattern.

Implications and Future Work

This research, though theoretical, contributes to our understanding of the fundamental nature of black holes and their mysterious counterparts, white holes—hypothetical regions of spacetime that cannot be entered from the outside but from which matter and light can escape.

The current study did not account for how waves might scatter or why the findings are primarily applicable to high-frequency radiation. Future work could address these omissions.

Ultimately, this suggests that the universe's most extreme cosmic objects might all be whispering their secrets through subtle emissions.

Reference

Hassan Firouzjahi and Alireza Talebian. "White Hole Cosmology and Hawking Radiation from Quantum Cosmological Perturbations". arXiv:2210.15186v2 [gr-qc] (2022).