The Holographic Principle

Forget everything for once the laptop you're reading this on, the solid ground, forget empty Space, forget the fact that you are lying on your bed like a sloth. Because today physics has something more of a sci-fi type topic. It's called the "Holographic Principle".

Fine, Here's the Short Version: There is a chance that the universe where you live, yes the 3D universe is nothing but a 2D projection from somewhere across the edge of the universe. Bonkers right it sounds like an upcoming sci-fi movie. Well that's what we'll debug today.

The Universe's Filing System is a mess

Let's talk about your diary. Yes, the one that you have filled with secrets, bad poetry, that embarrassing story from high school, and no I..I don't have those in my diary(P.S. Trust me, it's much worse). Now you decide it must be destroyed. So you hop in your Spaceship, set your maps to the nearest black hole and toss it in and "DONE", it's now gone forever, well that's not exactly the case and here's why.

We have two cosmic laws and both laws are basically unbreakable, those laws are fighting on whether to keep the data from your diary or to destroy it. This is the Black Hole Information Paradox and this is where you scratch your head.

On one side of the ring, we have Team Einstein. His theory of general relativity tells us that a black hole is one-way road. Once your diary crosses the event horizon, it's gone forever and there is no point of return. It gets spaghettified, crushed into a point of infinite density(Singularity) and is absolutely gone. The information it contained, your embarrassments are erased. So, a happy ending? Not really..

On the other side of the ring, we have Team Quantum mechanics, the undefeated champion of the very small. It has a set of rules that have never, ever been proven wrong. The number one, golden rule is that information can never be destroyed. According to quantum mechanics the universe is an accountant. It keeps track of every single bit of data. Well it might scramble the data, hide it, set it on fire but never deletes it. The information from your diary must continue to exist, somewhere in some form. Now it's not a happy ending.

So Team Einstein says your diary is gone. Team Quantum says it's not possible. Now this is a real problem. Physicists were stuck for decades, looks like one of them has to be proved wrong.

But then legendary Stephen Hawking walks into the ring, looked around and probably said "get ready to scratch your head even more". He proved that black holes are not prisons. They slowly and eventually leak energy also called "Hawking Radiation" and over a very-very long time they completely evaporate. They disappear. (Hawking himself once believed that black holes destroyed information forever. But later in 2004 he changed his position.)

Now this is another problem. If the black hole itself is the vault where your diary was supposed to be stored, eventually vanishes, where in the cosmos did the information go? The information was missing, this was not supposed to happen.

The Solution: The Universe Scanned Your Diary

The only way out of this cosmic problem was give an idea that will solve this huge mess.

Physicists like Gerard 't Hooft and Leonard Susskind looked at the evidence and proposed a solution. They said, the information in your diary never actually made it inside the black hole to be destroyed. Wait what? What about you getting on your spaceship and throwing it itself inside the black hole?

Instead, as your diary approached the event horizon, the universe did something, and it was fast. The intense gravitational forces and quantum effects "scanned" your diary. Every single bit of information, from the molecules of the paper to the syntax of your sentences, was lifted from the 3D paper and got imprinted onto the two-dimensional surface of the event horizon. The embarrassing stories in your diary, your poetry became a complex, scrambled, but perfectly preserved pattern, just like a hologram

But then what about the Hawking radiation leaking from the the black hole. It's the gateway vehicle for your stolen information. As each particle escapes the black hole, it picks up a tiny, piece of scrambled information of the holographic code from the surface. Over billions of years, as the black hole evaporates, the entire story of your diary is being broadcasted back out in the universe. The information is saved. And your secrets are, technically floating around the cosmos and any civilisation with a quantum decoder can read it. Sorry about that.

But it proves only one part of the Black hole information paradox that information can never be destroyed but what about Einstein's black-holes-never-let-anything-out thing? The holographic principle proposes a clever loophole. The information of your diary does not escape from inside the black hole. Instead, the information gets encoded onto the two-dimensional surface of the event horizon itself.

This whole idea is beautifully represented by the Bekenstein-Hawking formula. This equation says that the entropy(S) of a black hole is directly proportional to its 2D surface area and not its 3D volume.

What This Means For Your Non-Black-Hole-Life

Why should you care about all this, assuming that you are not currently disposing your secrets in a black hole? Because if the holographic principle is how the universe operates, it's probably everywhere. Then the Principle likely applies not just to black holes, but to any volume of space, including the room you are in right now.

The scary yet interesting conclusion: our three-dimensional reality is just a projection.

Assume you're playing GTA IX. You are running around in a detailed 3D environment. You can interact with objects and it feels real. But you know that world is just an illusion being created on a 2D screen with pixels. And that screen is controlled by lines of codes(1s and 0s), on a computer chip. The 3D game is what you are experiencing but the fundamental reality is the 2D code.

The Holographic Principle suggests that our Universe is the game. The real fundamental codes are written on a vast, 2D surface somewhere in the boundaries of our spacetime.

Physicists like Juan Maldacena have even provided a mathematical way to translate between the game and the code, which proves that this is not just a philosophical idea, but a mathematical possibility. (The holographic principle isn't just a wild guess, it's backed by strong mathematical models, especially in a framework called AdS/CFT. But it's not proven for our universe yet.)

So is the world a Hologram?

Not really in the way you would imagine or see in movies. Your coffee is still real and if you drop it yep, it'll still make a mess. And if your mom sees it? That's when the real nightmare hologram appears..

It's wild that the universe isn't just stranger than we can imagine. It's stranger than we can imagine. Now, about that diary… keep it you'll have more moments to write.