# Vacuum as the low energy limit of....

• oquen
In summary, the physical vacuum is a state with no "physical particles" and is the ground state of the field. It can be considered as a condensed matter system in its low energy limit and Lorentz invariance is a temporary symmetry at low energies. The vacuum is also a low energy limit of a quantum gravity theory and can have new dynamics and degrees of freedom when cooled.
oquen
It is said that the physical vacuum, is by definition a state with no "physical particles" -- more precisely, it is the ground state (state of lowest energy) of the field.

Is there any beyond standard model where the vacuum is a lower energy limit of another theory or stuff... like the holographic principle or event horizon of a black hole?

Or is it correct to say that the vacuum is low energy limit of a quantum gravity stuff?

Or the idea that the vacuum Lorentz invariance is a kind of temporary symmetry much like when you raise the temperature of certain object it becomes magnetized (or unmagnetized).. or the vacuum like surface of boiling water.. when you cool it.. you get new dynamics or new degrees of freedom?

Yes, vacuum can be considered as a condensed matter system in its ground state (low energy limit) .
Yes, Lorentz invariance is a low energy symmetry(temporary).
Effective theory(possesing Lorentz symmetry) is valid only at low energies/small frequencies and large distances.

Easy to read here in details:
Quantum Field Theory and Condensed Matter Physics: making the vacuum concrete
https://www2.physics.ox.ac.uk/sites...8-05/making_the_vacuum_concrete_pdf_67668.pdf

Demystifier

## 1. What is vacuum as the low energy limit of a physical system?

Vacuum, in the context of physics, refers to the absence of matter and energy in a given space. It is considered the lowest possible energy state of a physical system, meaning that no energy is present and all matter is removed.

## 2. How is vacuum related to the concept of energy?

In physics, energy is defined as the ability to do work or cause change. In a vacuum, there is no matter or energy present, making it the lowest possible energy state. This is why vacuum is often referred to as the low energy limit of a physical system.

## 3. Why is vacuum considered the lowest energy state?

Vacuum is considered the lowest energy state because it is the state of minimum energy. In other words, it is the state in which there is no energy present and all matter is removed, resulting in the lowest possible energy level for a physical system.

## 4. How does vacuum behave at the quantum level?

At the quantum level, vacuum is not truly empty. Instead, it is filled with virtual particles that constantly appear and disappear. These particles have a very short lifespan and do not violate the laws of energy conservation.

## 5. How is vacuum used in scientific research?

Vacuum is an essential tool in scientific research, particularly in fields like particle physics, where it is used to study the behavior of particles and their interactions without any interference from external factors. It is also used in many industrial processes, such as in the production of microchips and electronic devices.

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