Scientists have recently made headlines for allegedly generating a wormhole. The study, published in the journal Nature, used quantum computers to simulate wormholes in a simplified physics model. Shortly after the news broke, physicists and quantum computing experts expressed doubt that wormholes really exist. What's going on here?
This article is compiled from The Conversation at：
01Wormholes and entanglement
The universe is vast and so large that it is impractical to get from one side to the other using conventional methods. Wormholes are shortcuts between two regions of the universe, potentially traversing vast distances in much less time. Einstein's theory of relativity allows for wormholes, but no wormholes have ever been found in nature.
Diagram of a wormhole
Recently, physicists have been considering the idea that wormholes are related to another phenomenon known as "entanglement". Entanglement is a peculiar quantum phenomenon involving particles. When a particle is in an entangled state, a measurement of one particle will immediately affect the other particle. This is true even when the two particles are too far apart to have a causal relationship.
Some physicists believe that wormholes may be just one way to describe some kind of quantum entanglement. If correct, this would establish a connection between two important theories of physics: quantum mechanics and general relativity. Among other things, general relativity explains how gravity works and describes the universe on large scales. Quantum mechanics explains the other fundamental forces and describes the universe on very small scales.
In quantum mechanics, "entanglement" is a connection between particles that may be very far apart.
Both are extremely successful theories, but a unified theory has not yet been developed. A unified theory would preserve the insights of quantum mechanics and general relativity, while providing an explanation of how gravity works in the quantum realm, which we do not currently understand. Wormholes are unique to general relativity and entanglement is unique to quantum mechanics, so the potential similarities between them are exciting. This suggests that the two theories may somehow describe the exact same thing.
02Quantum gravity on a chip?
How do we look for potential similarities between wormholes and entanglement? We know how to entangle particles by experiment. And scientists have been doing this for some time. So we can try to build a special kind of quantum system: one that can be described by the same physics we use for wormholes. If we could build such a system in the lab, it would behave like a wormhole, which would support the idea that entanglement and wormholes are two sides of the same coin.
In a quantum computer, the basic components can be placed in various quantum states for running quantum experiments. So it looks like they provide an opportunity to test the relationship between wormholes and entanglement.
This may be why there are reports that physicists have used quantum computers to generate a wormhole. But this does not seem to be the case in reality, although understanding why is not simple.
03Not a wormhole
What physicists do is organize the basic components of a quantum computer into specific quantum states. They are then able to transfer information from one part of the computer to another through a quantum system.
Quantum systems, and the way information is transferred, can be described by a specific model in physics. According to this model, the information transfer that takes place inside a computer is very similar to the way something passes through a wormhole.
However, the model being used has at least two limitations.
First, it seems to make unrealistic assumptions about the physics of our world. In particular, it assumes that spacetime - the structure of the universe - has certain properties that it may not have.
Second, the model has been simplified to describe a simple system that can be implemented with a quantum computer. This simplified model may not be physically accurate.
So while we can use a particular model to describe what happens inside a computer as if it were a wormhole, it is unclear whether this model represents the world as we know it.
04Experiments and simulations
Some commentators have given different reasons to doubt the existence of wormholes: it is just a simulation. As one said, considering this system as a wormhole "is like claiming that playing a video game portal requires creating an actual wormhole because it depicts something similar to the theoretical concept on the screen".
We do have to be careful about extrapolating reality from simulations. However, the quantum aspect of this simulation makes it more like an experiment than a normal simulation you might run on your everyday computer.
Thus, this simulation seems to tell us something reasonably about the quantum system it is simulating. The problem remains, however, that we can only interpret the system as a wormhole in a specific, potentially unrealistic physical model.
05No wormholes, but still impressive
Therefore, we should probably doubt that any wormholes have been created. Nonetheless, there are still reasons to be impressed.
First, the team used machine learning techniques to simplify the model they used to simulate it in a useful way. Using machine learning to produce simplified models is great, and we should expect to see more use of machine learning like this in the future.
It is also important that quantum computers are used to run such controversial quantum experiments. This is perfectly doable, and it opens the way for further experiments. This could open up an experimental paradigm that could be used to make progress in physics.
There is also a possibility - albeit a small one - that some aspects of the model used to describe quantum systems will prove to be correct. This could lead to the discovery of a relationship between quantum entanglement and wormholes in the future.
Reference link：
https://theconversation.com/did-physicists-make-a-wormhole-in-the-lab-not-quite-but-a-new-experiment-hints-at-the-future-of-quantum-simulations-195816
