How do black holes die if they are already dead stars? Black holes are strange and mysterious objects whose secrets scientists continually seek to unfold. Even though the Milky Way likely contains millions of them, black holes remain elusive and hard to detect.
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What Is a Black Hole?
Black holes are astrophysical objects with enormous gravitational attraction, not the empty, dark spaces their name implies. They’re born when energy or matter compresses into such a small volume that the escape velocity for anything to exit the black hole exceeds the speed of light.
NASA equates a black hole to a ball of energy ten times the Sun’s size squeezed down into a ball the diameter of New York City. The resulting gravitational field is so powerful that nothing can escape, not even light.
Black holes are difficult to see
Crisp photograph images require a light source; The Sun, a lightbulb, a flashlight, etc. Black holes allow no light to escape, so photographing them is difficult.
Most black hole images are artists’ renditions of what they believe a black hole looks like. The image above isn’t an actual photograph; it’s an artist’s depiction of a black hole.
Did Einstein Predict Black Holes?
Einstein predicted black holes with his theory of relativity. He surmised that a dense core is all that remains when a giant star dies. If the core’s mass is greater than three times that of the Sun, the gravity force overwhelms everything else to create a black hole.
Do Stephen Hawking’s Observations Override Einstein’s?
Einstein’s work gave astronomers the groundwork to understand how black holes exist. Then Hawking discovered a pathway for energy to leave those black holes.
“Hawking radiation” is a slow stream of particles and radiation that escape black holes. Over time, this slow and steady stream steals mass from the black hole until the black hole shrinks enough to evaporate.
Stephen Hawking’s observations do not override Einstein’s, but instead, Hawking Radiation comes from an intersection of general relativity and quantum mechanics, which is the understanding of tiny things.
When these two items meet, however, they leave questions.
What Is the Black Hole Information Paradox?
Learning about the black hole information paradox helps answer the question of do black holes die. Scientists know Hawking radiation comes from the intersection of general relativity and quantum mechanics.
Here are other known facts:
- Black holes swallow “stuff.”
- Stuff’s makeup is information.
- Therefore, black holes swallow information.
- Hawking radiation doesn’t care about that information.
- Over time, the black hole shrinks and evaporates.
- The information is lost.
Keep reading because it’s about to get trickier.
As far as humans know, information exists throughout the universe. Therefore, you can’t create or destroy it because it simply exists. Therein lies the paradox.
The black hole information paradox comes from the following possibilities about information:
- You can destroy the information or at least not preserve it.
- The current definition of information might need revising.
- Hawking radiation leaving the black hole might differ depending on the type of information entering the hole.
- Information gets sunk into the singularity and preserved, and black holes don’t completely disappear.
A problem arises because scientists and mathematicians need to learn how Hawking radiation preserves (or loses) information. Even Dr. Hawking himself couldn’t find the math to resolve this issue.
Because scientists don’t know what is at the center of black holes, no one can say that the information isn’t there. The paradox is essential because scientists would know some new physics if they could answer it.
All the above possibilities about information require new physics to answer.
The image above is an actual photograph of a black hole. In 2019 eight radio telescopes on earth collected data and stitched them together into the image above. This image is the first image of a black hole
What Happens When Black Holes Die?
As you can see, black holes are incredibly mysterious objects where even physics breaks down. Black holes don’t live forever because of the tiny radiation stream escaping them and stealing their mass.
Quantum mechanics say that positive subatomic particles and negative antiparticles constantly pop into existence. However, Hawking believed they operate differently near black holes. In essence, the black hole’s immense gravity pulls in the antiparticles, leaving the positive particles to become real.
Over time, the real positive particles stream from the black hole. The slow addition of antiparticles simultaneously sucks mass from the black hole until it eventually evaporates.
Do Black Holes Explode When They Die?
General relativity and quantum mechanics finally come together for a slow and steady stream of Hawking radiation to steal a black hole’s mass.
Black holes shrink and evaporate over time, becoming more and more unstable. The instability causes the black hole to lose the rest of its mass in quick bursts or explosions. So, yes, black holes explode when they die.
What Happens When a Black Hole Collapses?
Physics breaks down when trying to understand where the information goes when a black hole dies. The singularity at a black hole’s center is where matter compresses to a tiny point where human understanding of time and space gets muddled.
Time and space no longer exist at the singularity, but math doesn’t yet tell scientists what does.
Do Black Holes Die When They Merge?
When two black holes merge, the resulting black hole does not “die” because it continues to exist as a single black hole. The merged black hole retains the total mass of the two individuals, and its event horizon (the point of no return beyond which nothing, not even light, can escape) expands accordingly.
Scientists understand black hole mergers as the emission of gravitational waves that ripple in the fabric of spacetime. As two black holes orbit each other and eventually merge, they emit powerful gravitational waves that carry away energy and angular momentum. This gravity causes the two black holes to spiral closer and closer together until they merge into a single black hole.
In the illustration above, a binary black hole orbits a supermassive black hole. The binary black hole is in the process of merging with the supermassive black hole.
The gravitational waves produced during a black hole merger are incredibly faint and were only recently detected by the LIGO and Virgo observatories. Nevertheless, these detections have provided a new way to study black holes and their properties and have confirmed the predictions of Einstein’s theory of general relativity.
So to answer the question, do black holes die when they merge? Black holes do not “die” when combined; instead, they merge into a giant black hole with a greater mass and an expanded event horizon.
Final Thoughts: Do Black Holes Die?
While some objects in space such as planets or our sun can been easily studied and even viewed from Earth on a daily basis, such as the sun, black holes offer a bit more mystery.
Scientists consider black holes eternal objects because they do not die or disappear. Instead, according to the theory of general relativity, once matter collapses into a black hole, it compresses into an infinitely dense point called a singularity, surrounded by a boundary called the event horizon from which nothing, including light, can escape.
While black holes do not disappear independently, they can gradually lose mass over extremely long timescales through a process called Hawking radiation, a quantum mechanical effect predicted by physicist Stephen Hawking.
This process occurs when virtual particle-antiparticle pairs constantly popping in and out of existence appear on the edge of the black hole’s event horizon. One particle gets sucked into the black hole while the other escapes, gradually causing the black hole to lose mass over time.
However, the mass loss rate is very gradual, and for all practical purposes, black holes are generally stable and long-lived objects. So while black holes may lose mass over time, they likely do not “die” in the sense of completely disappearing.
When two black holes merge, they continue existing as one supermassive black hole with an expanded event horizon.