White Holes Explained

Black holes! I’m sure most of us would get excited once we think about these. These are one of the most compelling mysteries in the Universe. We would get chills as we see in movies about black holes. Anything including the light cannot escape it.

Heard of a White hole? Well, just like the color black is the opposite of white, the white hole is the opposite of a black hole in every way. Our topic for today is white hole guys and let’s move on to find what’s there for us.

So ever wondered what happens to the things which go into black holes?

Theoretically, if the information is getting sucked in, it must get spat back out somewhere, and likely that’s through a white hole.

What is a White Hole?

A white hole is a hypothetical celestial object which expands outwards from a space-time singularity and emits energy, in the manner of a time-reversed black hole. These could make up a major part of the mysterious dark matter that’s thought to make up most of the matter in the universe, a new study finds.

Physicists describe a white hole as a black hole’s “time reversal,” a video of a black hole played backward. A simpler notation is like a bouncing ball is the time-reversal of a falling ball. While a black hole’s event horizon is a sphere of no return, a white hole’s event horizon is a boundary of no admission. No spacecraft will ever reach the region’s edge.

How are these formed?

The possibility of the existence of white holes was put forward by Russian cosmologist Igor Novikov in 1964.

Black holes might end their lives by transforming into their exact opposite—white holes that pour all the material they ever swallowed into space.

In 2014, Carlo Rovelli, a theoretical physicist at Aix-Marseille University in France, and his colleagues suggested black holes and white holes might be connected in another way: When black holes die, they could become white holes.

They added that once a black hole evaporated to a degree where it could not shrink any further because space-time could not be squeezed into anything smaller, the dying black hole would then rebound to form a white hole.

Rovelli and his colleagues estimated it would take a black hole with a mass equal to that of the sun about a quadrillion times the current age of the universe to convert into a white hole.

Why these could exist?

The point at the center of a black hole is known as a singularity, and it’s one place black holes get messy, mathematically speaking. Einstein and fellow physicist Nathan Rosen fixed that math in 1935 by extending the point into a path that leads to a second location. This path was called an Einstein-Rosen Bridge, but you know it as a wormhole.


But if a black hole is at one end of a wormhole, what’s at the other end? A white hole. The same math that predicts the existence of a black hole also predicts the existence of its mirror opposite: a white hole. While anything that enters a black hole can never escape, anything that escapes a white hole can never return.

While we know that black holes exist, so far, white holes (and wormholes) exist only in pages of physics papers.

Ever since Stephen Hawking realized in the 1970s that black holes leak energy, physicists have debated how the entities could shrivel up and die. If a black hole evaporates away, many ask, what happens to the internal record of everything it swallowed? General relativity won’t let the information out and quantum mechanics forbids its deletion.

This leads us to the conclusion that white holes could exist.

On the particle level, quantum randomness takes over and the black hole could transform into a white hole.

Rovelli posits that not just gravity but space-time itself that is quantized, woven from tiny, individual loops that cannot be subdivided any further. The loops in this ‘loop quantum gravity’ — a theoretical try that has yet to find experimental support — would be so tiny that to any observer space-time looks smooth. In the recent work, Rovelli and his Aix-Marseille colleague Hal Haggard have calculated that the loop structure would halt the collapse of a black hole.

The collapsing star would reach a stage at which its inside can shrink no further, because the loops cannot be compressed into anything smaller, and they would exert an outward pressure that theorists call a quantum bounce, transforming a black hole into a white hole. Rather than being shrouded by a true, eternal event horizon, a temporary ‘apparent horizon would conceal the event’, says Rovelli.

Why they might not exist?

White hole formation would require a decrease in entropy, which would violate the second law of thermodynamics.

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 minuscule 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.”A long-lived white hole, I think, is very unlikely,” said Hal Haggard.

Putting these aside, let us now see something more about these white holes.

So, if a black hole is sucking in all of this information and a white hole is spitting it out somewhere, mustn’t something be connecting the two? A wormhole, perhaps? Maybe.

The aforementioned Schwarzschild geometry implies a wormhole would connect a black hole and white hole with two distinct universes connected at their horizons, also known as an Einstein-Rosen bridge which we have seen before.

These wormholes would be highly unstable if they were even possible. It would also be impossible, with physics as we know it, for one to pass through a wormhole into another universe (also theoretical) because of several pesky things like being spaghettified when passing through a black hole’s event horizon before being compressed at the singularity.

Some have theorized that instead of a wormhole connecting two points in space, it could connect two points in time. This connection between a black hole and a white hole could allow for time travel if one could stabilize a said wormhole.

Scientists believe they may have witnessed a white hole when a sudden burst of white light appeared out of nowhere and then vanished. There haven’t been any other similar events recorded to study.

Alternatively, the aftermath of a white hole may exist everywhere. To black hole physicists, the Big Bang’s explosion of matter and energy looks like potential white hole behavior. “The geometry is very similar in the two cases,” Haggard said. “Even to the point of being mathematically identical at times.”

These white holes would not emit any radiation, and because they are far smaller than a wavelength of light, they would be invisible. If a proton happened to impact one of these white holes, the white hole “would simply bounce away,” Rovelli said. “They cannot swallow anything.” If a black hole were to encounter one of these white holes, the result would be a single larger black hole, he added.

So, those were a few things about white hole everyone need to know

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