White Holes: Theoretical Counterparts to Black Holes That Could Rewrite Our Understanding of the Universe
TL;DR
White holes, the theoretical opposites of black holes, could expel matter instead of absorbing it. Unlike black holes, whose event horizon traps everything, white holes would prevent anything from entering. While no white holes have been observed, they remain an intriguing mathematical possibility. Some astrophysicists have speculated that gamma ray bursts could be linked to white holes, and even the Big Bang might be explained by a massive white hole. Although the second law of thermodynamics presents a challenge, studying these singularities could revolutionize our understanding of space-time and cosmic evolution.
Black holes may well be the most intriguing enigmas in the Universe. Believed to be the collapsed remnants of dead stars, these objects are renowned for one characteristic in particular – anything that goes in never comes out.
As we understand it, black holes are so dense that their event horizon traps everything, allowing nothing to escape. However, black holes aren’t the only kind of ‘hole’ in space.
Imagine you’re working with equations to explore the space-time around a black hole and decide to remove the collapsed star – all the mass and matter – from the equation. What you’re left with mathematically describes something known as a white hole – a singularity without mass.
As the name suggests, a white hole is the inverse of a black hole. Astrophysicists have been toying with this idea since the 1970s.
While a black hole’s event horizon is a boundary beyond which its gravity is too strong for even light to escape, a white hole’s event horizon prevents anything from entering.
You can’t escape from a black hole, and you can’t enter a white one. So while a black hole pulls matter in, a white hole would expel it. They would be incredibly bright and energetic, releasing intense radiation into space.
In theory, it would be like pressing the ‘rewind’ button on a black hole.
Erik Curiel wrote in The Stanford Encyclopedia of Philosophy: “Because the field equations of general relativity do not select a preferred direction of time, if the formation of a black hole is possible under the laws of spacetime and gravity, then those same laws allow for white holes.”
Despite this, we’ve never observed a white hole. Many physicists think they are unlikely to exist in the Universe, and there are several reasons for this.
One major issue is how they would form. We have plausible theories for how black holes come to be, but it’s not like we can reverse time in the Universe to transform black holes into white holes.
To make a white hole, you’d have to start with the singularity and work backward, with the object expelling matter until it finally becomes a star. This would require entropy to decrease, which goes against the second law of thermodynamics.
Starting with the singularity itself poses another challenge.
“The only way to introduce a singularity into the real Universe is to start with it already in place. Somehow, the Universe would need to form with ready-made singularities,” astrophysicist Karen Masters explained.
“There is no reason to think the Universe began with pre-existing singularities. It would actually be quite strange if it did.”
But let’s put those challenges aside for a moment and assume that a white hole did somehow appear. Mathematically, a region of space-time that contains a black hole cannot have any matter within it. As soon as matter enters that region, no matter how small, the white hole can no longer exist.
Therefore, if a white hole ever existed, it probably disappeared rather quickly. If the Universe once had white holes, they were likely gone billions of years before life on Earth emerged in the primordial oceans.
Still, white holes are purely theoretical at this point – much like black holes were not too long ago.
There is one type of event scientists have proposed as a potential white hole, and that’s a gamma ray burst. These are some of the brightest and most energetic events in the Universe, emitting more energy in just 10 seconds than the Sun can produce in 10 billion years.
These bursts are often followed by an afterglow, suggesting they result from stellar explosions. In 2017, astronomers witnessed one firsthand, caused by the famous collision of two neutron stars, GW170817.
However, in 2011, two astrophysicists suggested that a gamma ray burst with unusual characteristics might have been a white hole.
NASA astronomers believed it was likely a black hole forming. The chances of it being a white hole are probably quite low.
There’s also a bold theory that the Big Bang itself was a supermassive white hole. This idea has been explored mathematically, but it remains highly speculative.
In fact, the term ‘Big Bang’ might be misleading. According to current mainstream theories, the Universe didn’t explode from a single point – it inflated into existence and spent roughly 500 million years in darkness before the intergalactic medium ionized and “turned on” the lights. This doesn’t align well with the white hole model.
But there’s more. One hypothesis suggests that a black hole eventually turns into a white hole as it reaches the end of its lifespan.
Since black holes seem to live for incredibly long periods, it’s possible the Universe hasn’t been around long enough for this transformation to occur. Alternatively, the white holes could disappear before we observe them.
Another possibility is that tiny, primordial black holes might have transformed into small white holes, which could now be a part of dark matter.
All of these are mathematical possibilities. However, in the real Universe we inhabit, not the world of pure mathematics, we’ve yet to witness one.
If we ever do find a white hole, it would force us to fundamentally rethink our understanding of the Universe.
