Black holes have long been in the spotlight as celestial bodies from which nothing, not even light, can escape. However, theoretical physicists propose a less understood but equally fascinating counterpart: the white hole.
Unlike black holes, which attract matter, white holes repel matter.
What are white holes?
In astrophysics, a white hole represents a theoretical phenomenon in which matter and light emerge from a certain region of space instead of being pulled in. It is the exact opposite of a black hole.
You may already know that a black hole is a region of space where gravity is so strong that the escape velocity is greater than the speed of light, making it impossible for light to escape.
Escape velocity refers to the speed a thing would have to travel in order to escape the gravitational field of a planet, such as Earth, and travel into space instead.
The theoretical basis of white holes
The idea of a white hole has its origins in the Schwarzschild solution for black holes, named after the German physicist and astronomer Karl Schwarzschild, who formulated it in response to Einstein’s general theory of relativity.
When Schwarzschild formulated equations describing black holes, he discovered that white holes could exist under the same laws of physics that govern black holes.
By extending his black hole solutions via an invariant time reversal, the black hole singularity was transformed into a white hole singularity – a region that would eject matter instead of sucking it in.
In the context of physics, time reversal means imagining a scenario in which time flows backward, reversing the order of events.
Schwarzschild’s solution to Einstein’s equations describes a point singularity surrounded by an event horizon.
Einstein’s general theory of relativity
Einstein’s general theory of relativity is a theory of gravity that describes it not as a force between objects, like Newton’s theory, but as a curvature of space and time caused by mass and energy.
According to this general theory of relativity, planets, stars, and other massive objects bend the space around them, and this curving of space is what we perceive as gravity.
Essentially, objects move along these curves in space, which is why, for example, the Earth revolves around the sun.
What is a point singularity?
A point singularity is a location in space where certain quantities (such as density or gravity) become infinitely large.
In simpler terms, it’s a point at which everything we can imagine in the entire universe – including the laws of physics themselves – falls apart as everything is crushed into an unimaginably small space.
Physicists often use this concept to describe the core of a black hole, where all of its mass is concentrated at one point.
What is an event horizon?
An event horizon is essentially a boundary around a black hole beyond which nothing can escape – not even light.
Think of it as a point of no return; once something crosses this boundary, it is pulled into the black hole with no chance of getting out. This makes the event horizon the outermost layer of a black hole, defining the boundary where gravity becomes too strong for anything to escape.
As Schwarzschild theorized, in the curious case of time reversal, such as in a white hole, this event horizon becomes a boundary from which matter and light can escape. only escape, not be absorbed.
Quantum considerations of white holes
When you think of white holes as concepts in the fields of classical gravity and quantum gravity, these ideas expand even further.
Quantum mechanics, in addition to theories of quantum gravity, predicts phenomena such as Hawking radiation, in which black holes emit radiation due to quantum effects near the event horizon.
Applying time reversal to these processes, some scientists speculate that white holes could emit matter and light in the same way as a physical process that mirrors Hawking radiation.
Do white holes exist?
The question of whether white holes exist is fraught with challenges. No observational evidence directly supports the existence of such objects in the observable universe.
However, theoretical physics offers scenarios in which white holes could theoretically appear. One possibility arises during cosmic inflation, or a “Big Bang,” in the early universe, where extreme expansion could have stretched regions of space-time and created white holes.
Another intriguing idea is the big bounce theory, which suggests that our universe began as a white hole, formed from the remains of a collapsing parent universe.
Loop Quantum Gravity Theory
Andrew Hamilton, an astrophysicist, argues that if white holes exist, they could be remnants of supermassive black holes that have undergone a quantum gravity transformation, reversing their role from absorbing to emitting mass and energy. This theory is called loop quantum gravity.
This transformation could possibly occur under the influence of dark energy or dark matter, which are known to influence the universe. However, physicists still do not have a clear understanding of the interaction between dark matter and fundamental particles.
Connections to other theoretical frameworks
Exploring the concept of white holes touches several other areas of physics. For example, gravitational lensing – a phenomenon in which light bends around massive objects such as black holes – could apply similarly to white holes, changing our perception of the space behind them.
Furthermore, the idea of a baby universe, possibly born from the outer layers of a mother universe through a white hole, fits deeply with the multiverse theory, suggesting that our universe could be just one of many.
White holes also challenge our understanding of the universe’s thermal balance.
Because they emit rather than absorb energy and matter, they could theoretically serve as cosmic seeds, spreading energy density and fundamental particles throughout the universe, influencing the formation and evolution of galaxies in ways that are fundamentally different from those of black holes .
We created this article using AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.
Original article: What is a white hole? Does the cosmic phenomenon exist?
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