Unlocking The Secrets Of Our Universe

How does gravity work in the quantum regime? A holographic duality from string theory offers a powerful tool for unraveling the mystery.


How does gravity work in the quantum regime?


Take a look.

Physicists have long set a theory that unifies quantum mechanics with Einstein's theory of gravity to understand the laws of physics at the largest and the smallest scales.

Could the link come from a holographic principle within string theory called the AdS/CFT correspondence?

Imagine watching a 3-D shark film with your 3-D glasses on.

♪♪ That was scary.

Take off your glasses and the screen looks very different.

All the information is encoded on the 2-D screen, yet we experience it differently in a higher dimension.

Some researchers think quantum gravity may work much the same way.

Gravity is a force that explains how objects interact with each other on a large scale, like how planets revolve around the Sun and why leaping sharks fall back into the water.

As Einstein described it, gravity results from a curvature in the geometry of space-time, but on a quantum level, forces are produced by an exchange of particles, and since gravity is far weaker than any other force, we haven't been able to detect a gravity particle, a graviton, that fits into our understanding of quantum mechanics.

Enter the AdS/CFT correspondence, a mathematical mapping similar to a hologram, that shows how a region of space-time with gravity emerges out of a purely quantum theory.

The AdS in AdS/CFT stands for Anti-de Sitter space.

It's the space-time region that pops up like a hologram from the conformal field theory, or CFT, that describes the particles at the gravity-free boundary of the AdS Universe.

No information is lost in the hologram.

AdS space is negatively curved.

It includes gravity and has one more dimension than CFT.

You can think of the AdS/CFT Universe as a sphere.

The 3-D AdS space-time sits inside the sphere, bounded by the 2-D gravity-free CFT.

The negative curvature of AdS space gives it a boundary, which is needed to make the holographic principle work.

The lower dimensional boundary allows for the correspondence to be a duality, two different ways of looking at a system, like seeing the shark with and without 3-D glasses.

The AdS/CFT correspondence is a strong-weak duality.

The individual particles on the weakly coupled AdS side correspond to bound states on the strongly coupled CFT side.

This means that strongly coupled materials on the CFT side that are too complex to study can be converted into questions about individual particles moving on the AdS side.

Or add a black hole on the AdS side and what you get on the CFT side is a soup of particles or plasma that physicists can learn about by studying the black holes.

And because no information is lost in the holographic principle, gravity on the AdS side maps to the quantum interactions of the CFT side, giving researchers a way to describe gravity on the quantum level.

Even though our Universe has a different geometry than the AdS/CFT picture, and no boundary, understanding quantum gravity in AdS/CFT could reveal deep insights about black holes and the laws of physics at all scales.

So next time you're watching a 3-D movie, remember how holographic principles are being used to unlock the secrets of our Universe.

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