"The only way to set up the singularity in the real Universe is to start with it being there. Somehow the Universe has to form with ready-made singularities," explained astrophysicist Karen Masters.
"The only way to set up the singularity in the real Universe is to start with it being there. Somehow the Universe has to form with ready-made singularities," explained astrophysicist Karen Masters.
"There is no reason to suggest that the Universe started out with ready-made singularities. It would actually be quite odd if it did."
But let's ignore all that for a second, and assume that a white hole did somehow pop into existence. According to the maths, there can be no matter within the space-time that includes a black hole. As soon as matter enters that region, no matter how miniscule a speck, it can no longer include a white hole.
So if a white hole has ever existed, it probably ceased to exist pretty quickly. If the Universe had white holes from the outset, they would have been snuffed out billions of years before life on Earth was starting to wriggle in the depths of the primal ocean.
But, while white holes are purely theoretical at this stage, so too were black holes once upon a time, and fairly recently, too.
In fact, there is a type of event scientists have put forth as a candidate 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 10 seconds than the Sun can in 10 billion years.
They're accompanied by an afterglow that indicates they're created by stellar explosions, and in 2017, astronomers saw one actually occurring, caused by the now-famous collision between two neutron stars, GW170817.
But in 2011, two astrophysicists proposed that a gamma ray burst with unusual properties may have been a white hole.
NASA astronomers thought it was likely a black hole in the process of forming. The odds of it actually being a white hole are probably pretty low.
And then there's the seemingly wild idea that the Big Bang was itself a supermassive white hole. This concept has also been explored mathematically - but again, it's highly theoretical stuff.
In fact, the term 'Big Bang' might be somewhat misleading in this regard. According to the current mainstream theory, the Universe didn't explode into existence from a single point - it inflated into existence, and spent 500 million years or so in darkness, not really expanding much before the intergalactic medium ionised, and the lights switched on. That's not hugely consistent with a white hole model.
But there's more. There is a hypothesis that a white hole is what a black hole turns into at the end of its lifespan.
Black holes seem pretty long-lived, so it's possible the Universe hasn't been around long enough for that evolution to have taken place. Or it has, and the white holes wink out of existence before we see them.
Or it has, but it's only tiny, primordial black holes that have turned into tiny white holes, which now constitute a component of dark matter.
These are all mathematical possibilities, but in the real Universe we're actually living in, not the realm of pure mathematics, we've still never seen one.
If we ever do, that means we're going to have to seriously rethink our understanding of the Universe.
Won't that be exciting?
"There is no reason to suggest that the Universe started out with ready-made singularities. It would actually be quite odd if it did."
But let's ignore all that for a second, and assume that a white hole did somehow pop into existence. According to the maths, there can be no matter within the space-time that includes a black hole. As soon as matter enters that region, no matter how miniscule a speck, it can no longer include a white hole.
So if a white hole has ever existed, it probably ceased to exist pretty quickly. If the Universe had white holes from the outset, they would have been snuffed out billions of years before life on Earth was starting to wriggle in the depths of the primal ocean.
But, while white holes are purely theoretical at this stage, so too were black holes once upon a time, and fairly recently, too.
In fact, there is a type of event scientists have put forth as a candidate 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 10 seconds than the Sun can in 10 billion years.
They're accompanied by an afterglow that indicates they're created by stellar explosions, and in 2017, astronomers saw one actually occurring, caused by the now-famous collision between two neutron stars, GW170817.
But in 2011, two astrophysicists proposed that a gamma ray burst with unusual properties may have been a white hole.
NASA astronomers thought it was likely a black hole in the process of forming. The odds of it actually being a white hole are probably pretty low.
And then there's the seemingly wild idea that the Big Bang was itself a supermassive white hole. This concept has also been explored mathematically - but again, it's highly theoretical stuff.
In fact, the term 'Big Bang' might be somewhat misleading in this regard. According to the current mainstream theory, the Universe didn't explode into existence from a single point - it inflated into existence, and spent 500 million years or so in darkness, not really expanding much before the intergalactic medium ionised, and the lights switched on. That's not hugely consistent with a white hole model.
But there's more. There is a hypothesis that a white hole is what a black hole turns into at the end of its lifespan.
Black holes seem pretty long-lived, so it's possible the Universe hasn't been around long enough for that evolution to have taken place. Or it has, and the white holes wink out of existence before we see them.
Or it has, but it's only tiny, primordial black holes that have turned into tiny white holes, which now constitute a component of dark matter.
These are all mathematical possibilities, but in the real Universe we're actually living in, not the realm of pure mathematics, we've still never seen one.
If we ever do, that means we're going to have to seriously rethink our understanding of the Universe.
Won't that be exciting?