“Although almost every theoretical physicist agrees with my prediction that a black hole should glow like a hot body, it would be very difficult to verify experimentally because the temperature of a macroscopic black hole is so low.”
- January 8, 1942 – March 14, 2018
- British
- Theoretical physicist, science writer
- Announced the black hole singularity theorem and Hawking radiation, and contributed to the popularization of science with his book “Talking about the Universe”
Quote
“Although almost every theoretical physicist agrees with my prediction that a black hole should glow like a hot body, it would be very difficult to verify experimentally because the temperature of a macroscopic black hole is so low.”
Explanation
In this quote, Stephen Hawking is referring to his groundbreaking theory of black hole radiation, now known as Hawking radiation. This theory, proposed in 1974, predicted that black holes should not be completely black, as was traditionally thought. Instead, they should emit radiation due to quantum mechanical effects near the event horizon, the boundary beyond which nothing can escape a black hole’s gravitational pull. This radiation would cause the black hole to lose mass over time, eventually leading to its evaporation.
The quote highlights a significant challenge in testing this prediction. Although the theoretical framework for Hawking radiation is widely accepted among physicists, experimentally detecting it is an enormous challenge. The temperature of a macroscopic black hole (a large black hole, like those found in the centers of galaxies) is incredibly low, on the order of a few thousandths of a degree above absolute zero, making it nearly impossible to observe with current technology. For comparison, the radiation emitted by black holes is far weaker than the cosmic microwave background radiation that permeates the universe, making it difficult to isolate in observational data.
Hawking’s prediction remains a theoretical triumph, and while micro black holes (small black holes that might have formed in the early universe or could be created in particle accelerators) could potentially be detected, the macroscopic black holes most commonly studied are far too cold to emit measurable radiation. This has made direct experimental verification of Hawking radiation elusive, though researchers are still hopeful that new technological advancements or astrophysical observations may eventually provide evidence to support or challenge Hawking’s theory. In the broader context of modern physics, the idea of black holes emitting radiation has led to important insights into the intersection of general relativity and quantum mechanics, which remains one of the most exciting areas of theoretical research.
