Revisiting the Information Paradox

“As far as the laws of mathematics refer to reality, they are not certain, and as far as they are certain, they do not refer to reality.” — Albert Einstein

SRM Astrophilia
SRM Astrophilia

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Exploring into the Darkness…

Scientists work on the boundaries of the darkness, where every new piece of information forms a path into a void of uncertainty.

In a series of breakthrough papers, theoretical physicists have come tantalizingly close to resolving the Information paradox that has entranced and bedeviled them for nearly 50 years.

Throughout history, paradoxes have threatened to undermine everything we know, and just as often, they’ve reshaped our understanding of the world. Today, one of the biggest paradoxes in the universe threatens to unravel the fields of general relativity and quantum mechanics is the black hole information paradox.

To understand this paradox, we first need to define what we mean by “information.”

Information

Typically, the information we talk about is visible to the naked eye. For example, this kind of information tells us that a ball is round and shiny.

Information is nothing tangible. It’s typically understood as a property of the arrangement of particles.

What does this mean?

Imagine a bunch of carbon atoms.

“Arrange them in a certain way and you get coal.”

“Arrange them in a different way, and you get a diamond.”

The atoms are the same, what changes is the information. The basic building blocks of everything in the universe are the same. Without information everything in the universe would be the same.

But physicists are more concerned with quantum information. This refers to the quantum properties of all the particles that make up that object, such as their position, velocity and spin.

Every object in the universe is composed of particles with unique quantum properties. This idea is evoked most significantly in a vital law of physics :

“The total amount of quantum information in the Universe must be conserved.”

It might change shape, but it can never be lost. For example if you burn a piece of paper, you get ash. That ash will never become paper again.

But, if you were able to carefully collect every single carbon atom in the ash, and measured the exact properties of the smoke and heat radiating from the fire, you could, in theory reconstruct the paper.

The information of the paper is still in the universe. It’s not lost, it’s just hard to read.

Even if you destroy an object beyond recognition, its quantum information is never permanently deleted. And theoretically, knowledge of that information would allow us to recreate the object from its particle components.

If you could somehow measure every single atom and particle and wave of radiation in the universe, you could see and track every bit of information there is, hypothetically you could see the entire history of the universe right back to the Big Bang.

“Conservation of information isn’t just an arbitrary rule, but a mathematical necessity, upon which much of modern science is built.”

But around black holes, those foundations get shaken.

Black Hole

Black hole is a cosmic body of extremely intense gravity. A region of spacetime where gravity is so strong that nothing — no particles or even electromagnetic radiation such as light — can escape from it and so we perceive them as spheres of blackness.

Photo by Guillermo Ferla on Unsplash

A black hole appears when an extraordinary amount of matter is concentrated in a tiny space. At their center, gravity is almost infinitely strong and whatever gets too close is ripped into its elementary particles.

When an object enters a black hole, it seems as though it leaves the universe, and all its quantum information becomes irretrievably lost.

However, this doesn’t immediately break the laws of physics. The information is out of sight, but it might still exist within the black hole’s mysterious void.

Alternatively, some theories suggest that information doesn’t even make it inside the black hole at all.

Seen from outside, it’s as if the object’s quantum information is encoded on the surface layer of the black hole, called the event horizon.

Event Horizon

The Event Horizon is the boundary defining the region of space around a black hole from which nothing (not even light) can escape.

At the event horizon, the escape velocity exceeds the speed of light.

You can imagine this as swimming in a river that ends in an enormous waterfall. You could swim to safety, until without even noticing it, you cross the point of no return. No matter how fast you try to swim now, the stream will pull you towards certain death.

Nothing can escape a black hole waterfall once it gets too close.

This border completely separates black holes from the rest of the universe– we can’t access them unless we’re willing to never return.

But whether information is conserved inside the black hole or on its surface, the laws of physics remain intact– until you account for Hawking Radiation.

Black holes radiate their mass away, like a hot pot on a stove losing its water as steam.

This is called Hawking Radiation.

Hawking Radiation

Discovered by Stephen Hawking in 1974, this phenomenon shows that black holes are gradually evaporating.

Hawking radiation is black-body radiation that is predicted to be released by black holes, due to quantum effects near the black hole event horizon.

Black holes constantly lose an extremely tiny amount of their mass, a process that’s unbelievably slow. It will take a solar mass black hole will evaporate over ¹⁰⁶⁴ years which is vastly longer than the age of the universe.

Critically, it seems as though the evaporating particles are unrelated to the information the black hole encodes–suggesting that a black hole and all the quantum information it contains could be completely erased.

The destruction of information would force us to rewrite some of our most fundamental scientific paradigms.

This creates the information paradox, and this is a serious problem.

The Paradox

The Black hole information paradox is a puzzle resulting from the combination of quantum mechanics and general relativity.

Calculations suggest that physical information could permanently disappear in a black hole, allowing many physical states to devolve into the same state.

It’s fundamental for all our laws of physics that information can never be lost. Existing, not existing. Without information, everything is relative.

When it comes to our understanding of reality, we need absolutes.

But fortunately, in science, every paradox is an opportunity for new discoveries. Researchers are investigating a broad range of possible solutions to the Information Paradox.

Theorized Solutions

Photo by Greg Rakozy on Unsplash

There are a few possibilities of the outcome of such an event.

  1. Information is lost. — Irretrievably and forever.
  2. But there’s a third option: Information is safe after all, not lost or hidden Perhaps we’ve just been looking at this whole thing the wrong way.

Some have theorized that information actually is encoded in the escaping radiation, in some way we can’t yet understand.

This is a bit like taking a paper back, and turning it into an e-book, two things that look completely different.

But their content is the same — it’s just encoded and memorized in another way.

It turns out a black hole grows its surface by a tiny pixel for each bit of information we throw into it.

As the black hole’s mass increases, the surface of the event horizon increases as well. So it’s possible that as a black hole swallows an object, it also grows large enough to conserve the object’s quantum information.

Considering that theory, even the smallest black hole would store more information on its surface than all the data ever produced in human history.

They do this by storing information in a type of pixel that is unbelievably tiny.

This solution is what is referred to as the Holographic Principle.

The science behind it is complicated and really weird, with the existence of Quantum Gravity to the working of String theory and a lot of math which I will reconsider to decode for some later blog.

Regardless of what the true nature of the universe really is, we just know that it’s strange and complicated, and we have to accomplish a lot more physics to understand it.

Until then, Keep Exploring the Impossible…

Written by Akshad Kolhatkar, member Astrophilia

Article republished with consent of the original writer Akshad Kolhatkar

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