The white hole in space is one of those puzzles on which astrophysicists have been struggling for decades: here is what it is and how it is different from the black hole.
Space is so full of mysteries that no theory can be discarded a priori, even those on phenomena not yet scientifically proven, nor observed. This is the case of space white holes, hypothetical antagonists of black holes. Although their existence is considered a very remote hypothesis by the scientific community, the characteristics attributed to them make them undoubtedly fascinating. Let's see them in detail.
Black hole and white hole: what is the correlation?
White holes are hypothesized theoretically based on the principle of time symmetry that governs the laws of physics. A black hole has its opposite in a white hole: while the one captures matter gravitating in its orbit, sucking it in, the other repels everything that approaches by radiating light and energy.
In other words, just as you can't escape a black hole, in the same way you can't penetrate a white hole and what is absorbed by the former, is expelled by the latter. "Nothing is created, nothing is destroyed," reads Lavoisier's fundamental postulate. "
That said it is important to note a substantial difference: black holes, able with their gravitational force to trap even light, have been demonstrated through indirect evidence. Very high density mass exerts a force of attraction detectable through the observation of celestial bodies that enter in their range. Reason why the existence of black holes is universally accepted by astrophysicists. Different discussion must be done, as we will see, for white holes.
Does the white hole exist?
Till now there is no evidence of the existence of white holes in space. The lack of scientific evidence leaves room for fanciful hypotheses, typical of science fiction books rather than astrophysics ones. The first perplexity of the scientific community about this phenomenon, never observed either directly or indirectly, concerns its origin. While for black holes the theories on the formation are plausible and sustainable with mathematical models, the same cannot be said for white holes.
To begin with the creation of a white hole requires that we go against the laws of physics, as we have postulated today: in particular it would be necessary the violation of the second principle of thermodynamics. Even assuming that such a singularity was possible, the mathematical correlation with the black hole would show that even if a white hole had ever existed, it would have most likely stopped being 'alive' rather quickly. In practice, if the Universe had white holes at its beginning, they would have been exhausted billions of years before the beginning of life on Earth.
White hole: between science and science fiction
In 2011, the scientific community became agitated by the discovery of two astrophysicists, who hypothesized that a burst of gamma rays, with unusual properties, could be a clue to the existence of a white hole. Subsequent studies conducted by NASA showed that the phenomenon of singular gamma radiation could more likely be connected with the process of formation of a black hole, rather than with the existence of a white hole.
As mentioned above, where science leaves areas of doubt, fantasy finds fertile ground. The white holes have therefore become the subject of very bold theories, such as the one that assumes that the Big Bang was nothing more than a supermassive white hole. But there are also those who go beyond and think that the white hole is the final transformation of a black hole, when it ceases its life cycle. The fact is that black holes are so long-lived that it is possible that the Universe is not old enough to have ever given rise to such an evolution.
Others still speculate that a white hole may be the end of a wormhole that connects a black hole with other parallel universes or with the boundaries of our Universe. These are not demonstrable possibilities and purely theoretical that at the moment do not authorize any affirmation, nor scientific denial. In any case, if the existence of a white hole was demonstrated our conception of the Universe would be revised.