admin A white hole is the theoretical opposite of a black hole, emitting matter into the cosmos rather than consuming everything in its vicinity. Credit for the image goes to Artsiom P/Shutterstock.com.Almost certainly, you’ve heard of black holes. It is believed that there is one at the center of every galaxy, and we have even imaged one – perhaps even the one at the center of our own galaxy – but these objects remain a mystery. But have you ever heard of white holes, the evil twins of black holes?
What exactly is a white hole?
A white hole is a hypothetical universe feature that is the theoretical opposite of a black hole.
Black holes are objects that generate a gravitational field so intense that nothing, not even light, can escape their vicinity. In order to escape the gravitational pull of a black hole, one must move faster than the speed of light at the event horizon, which is perched on the edge of the cliff. Einstein’s theory of special relativity states that nothing in space can travel faster than the speed of light.
They consume matter, which is then compressed into an infinitely dense ball known as a singularity. The mass of a million Suns could be compressed into the size of a single Sun by a black hole. However, if you looked at one, it would be invisible because it prevents light from escaping. Instead, we determine their existence based on the way massive objects (i.e., those with enormous gravity) distort space-time around them. This is Einstein’s general theory of relativity.
White holes are believed to exist based on the same principles of general relativity as black holes. They are believed to possess gravity, so they attract matter; however, anything on a collision course with a white hole would never reach it.
This is because, unlike black holes, white holes do not allow anything to enter, including light and matter. They emit matter and energy continuously, preventing anything from reentering their event horizon. If you could observe them, they would appear identical to black holes but in reverse, with light and matter spewing out into the universe.
What would occur if one were to approach a white hole?
Theoretically, if a spacecraft approached a black hole, it would be inundated with an enormous amount of energy, which would likely destroy the ship. Even if your spacecraft could withstand gamma rays, the light itself would begin to slow you down, similar to how air resistance slows a vehicle on Earth.
And even if the spacecraft is designed to be unaffected by the energy emission, space-time would be strangely warped around a white hole; approaching a white hole would be similar to climbing a hill. The required acceleration would increase as the distance traveled decreased. There is insufficient energy in the universe to even get close, much less inside.
Obviously, this is somewhat counterintuitive. How could energy in a white hole appear to originate from nowhere other than spacetime? This is one reason their existence is highly improbable. However, there are theories in which white holes are conceivable, albeit perhaps not in the same way as they are described in general relativity.
How are white holes created?
There are several hypotheses regarding the formation of white holes. White holes are the theoretical evil twin of black holes, according to cosmologist Igor Novikov’s 1964 theory. Novikov expanded on the work of physicist Karl Schwarzchild, who postulated black holes and what we now refer to as wormholes, through which objects could theoretically pass to instantly traverse vast distances, between event horizons and a theoretical opposite version of the singularity.
However, physicists have demonstrated mathematically that white holes could exist, but not in reality, because they were unable to determine how they could form if they were the opposite of black holes. Black holes are created when a star dies and its mass collapses. In contrast, a black hole exploding into a star would be contrary to the principles of entropy.
Another theory suggests that at the end of their existence, black holes briefly transform into white holes. Theoretical physicist Carlo Rovelli developed a model in 2014 that suggests black holes transform into white holes at the end of their lives, ejecting into space all the matter they have ever consumed.
The transition from black hole to white hole would take place immediately after the formation of the initial black hole. Their model is based on a theory known as “loop quantum gravity,” in which gravity and space-time are quantized and woven from infinitely small individual loops. As a dying star continues to collapse under its own gravity, it will continue to shrink, but will eventually reach a point where it cannot shrink any further because the loops cannot compress any further.
At this point, the loops exert an outward force known as “quantum bounce” that converts the black hole into a white hole. Rovelli’s rough estimates indicate that it takes only a few thousandths of a second for a black hole to become a white hole. Even though the transformation is nearly instantaneous, black holes can appear to be billions or trillions of years old because their gravity stretches light waves and slows down time.
Exist white holes?
White holes are still considered a theoretical concept at this time, although this may depend on our current understanding of physics.
It is believed that white holes are extremely unstable. It is unlikely that a cosmic event emitting that much matter and energy could persist long enough to be detected by a telescope. Some theorize that if it collides with any other matter in the white hole’s orbit, it will collapse in on itself and transform into a black hole, creating an endless cycle of black, then white, then black holes. Stephen Hawking himself pointed out that they may behave so similarly that it would be impossible to tell them apart.
Numerous phenomena have been proposed as possible white holes. Typically, they are chosen because they are mysterious objects that we have yet to fully explain. Gamma ray bursts, pulsars with rapid rotation, and black holes at the end of their lives have all been considered. Even the Big Bang has been called a black hole.
However, white holes have never been observed directly, and even their theoretical existence raises red flags. It appears that white holes will serve as placeholders until more observations are made or a better theory is developed.
Despite the fact that Einstein published his theory of general relativity, which predicted black holes, in 1915, the first one wasn’t identified until 1971.
