- Dr. Netta Engelhardt and her team at the Massachusetts Institute of Technology claim to have found an explanation for Hawking’s famous black hole information paradox.
- The new theory explains the fate of information that is swallowed by black holes and hence provides scope for research on the probability of time travel.
- Many companies including Google, have started exploiting the knowledge of quantum physics which comments on the unitarity of time and hence the fate of time travel through the quantum realm, to build and demonstrate time crystals.
The world of modern physics is based on two major theories. Firstly, we have quantum physics which describes events at the “micro” level. This level is one of the subatomic particles of an atom such as the protons, neutrons, and electrons. Next, we have Einstein’s theory of relativity. This theory describes events at the macro level, of large bodies which possess notable mass.
Each of the two theories acts in completely separate fields and at what appear to be completely different magnitudes. One on mere particles such as electrons and light waves, versus the other on massive objects such as stars and galaxies. That being said, in practice, there happens to be at least one common meeting place wherein these theories collide. That place is the black hole.
What is a black hole?
A black hole is essentially a cosmic phenomenon that is created when a star exhausts its nuclear fuel. Stars usually implode due to the force of gravity. Insufficiently massive stars, this collapse compacts the star’s material into a single point. Due to the colossal gravitational force exerted by the compacted point, almost nothing can escape or be emitted from it, not even light. This gives birth to a black hole. The black hole is tiny but exerts a colossal gravitational pull, and therefore both the laws of quantum mechanics and the laws of the theory of relativity are relevant to it.
Theories regarding consumption of information and the famous “Information Paradox”
The backbone pertaining to the concept of time travel is based on two factors. Number one is the frame of reference. While in our day-to-day reality, time happens to be a very rigid concept, incapable of being turned back and forth, the same is not applicable in the realm of quantum physics. According to definitions of quantum physics, time appears to be a pretty malleable variable in itself.
The second factor which influences the probability of time travel was explained in the past by none other than the world-renowned physicist, Stephen Hawking. According to the theories set forth by Hawking and his team who did extensive research into the existence and functionality of black holes, the radiation emitted by one is not a function of the material swallowed by the hole. This means, that two black holes formed by the consumption of the same type or amount of information will emit different radiation. The further implications of this theory are more devastating. If Hawking was to be correct, this would imply that the information on every physical particle swallowed by a black hole, whether it be its properties such as mass, speed, and so on, would simply disappear.
Hence, according to Hawking, once information enters into a black hole, it’s simply lost in the universe. This theory was considered to be the “Information Paradox”. There were many renowned theoretical physicists who came to renounce Hawking’s observations. One very famous among the same lot was Dr. John Preskill of the California Institute of Technology.
Dr. Preskill became well known as the one behind the Preskill- Hawking bet. He challenged Hawking’s principles and made the blatant proposition of the loser sending the winners an encyclopedia. Preskill eventually made the heavyweight concede to the fact that indeed in the realm of quantum mechanics, objects don’t simply get deleted from the universe all the while receiving an encyclopedia on baseball in return for his achievements.
An intriguing twist to an age-old paradox
For a long time, scientists have debated over and over regarding the significance of the “Information Paradox” set forth by Stephen Hawking. Now an intriguing twist has been proffered by Professor Netta Engelhardt, an Israeli-born physicist at the Massachusetts Institute of Technology, with colleagues. In 2019 two separate research teams including Dr. Engelhardt’s came out with a new theory regarding the persistence of information traveling through black holes. Both teams published research papers that were within 24 hours of each other wherein they explained how the information which appears to be deleted, is only for all intents and purposes, becoming unavailable for the universe. Both the teams working independently ended up sharing the 2021 New Horizons Breakthrough Prize for Fundamental Physics. This prize is one of the most prestigious prizes granted to young researchers in the world of physics, for complex, original calculations that bring the world of science a step closer to resolving the paradox posed by Hawking.
In practice, Engelhardt and her colleagues calculated the quantity of information amassed in black holes at various stages of their lives. In doing so, they achieved the feat of managing to reconcile the effects of the two major theories of physics in one place in their calculations. They published their work in the Journal of High Energy Physics.
Opening of doors to time travel
Hawking discovered that despite the colossal gravitational force exerted by black holes which absorb nearly all information surrounding it such as light, some radiation manages to “escape” from the black hole. This energy is eventually responsible for leading the hole’s evaporation. Based on the theory of relativity, according to Hawking, the radiation emitted by the hole is solely thermal, that is heat. Hence, this energy does not contain any information about the material that has been swallowed up inside the black hole.
This is where Dr. Engelhardt’s new theory comes into play. For understanding its implications, we need to understand a term known as unitarity. According to Professor Hagai Eisenberg of the Racah Institute of Physics at the Hebrew University, any shift from one state to another, for instance from left to right, or from the before-change to after-change, can be described in mathematical language. In the field of quantum mechanics, the mathematical description of advancing in time is defined as unitary.
Since Dr. Engelhardt and her team have already demonstrated the existence of information in black holes even during its evaporation, this clearly proves that information simply doesn’t get deleted. That being said, unitarity can be demonstrated for information swallowed in black holes. If black holes cannot actually render information irreversible this implies that there is nothing that can physically stop a man from time travel. Also, this means that other processes which we see in quantum mechanics can be explained through classical physics as well.
Time travel is possible in quantum mechanics. Google recently demonstrated the same theory by building time crystals that work on the principle of molecular time travel. They collaborated with physicists at Stanford, Princeton, and other reputable universities to demonstrate a time crystal in Google’s quantum computer. Time crystals not only evade the second law of thermodynamics but also simultaneously break the time-translation symmetry. A time crystal is both stable and ever-changing and refutes the usual rule that a stable object should remain stable over time. All such feats in the world of physics will surely turn time travel into reality in the near future.
