Is the vacuum the same as a quantum vacuum?

In summary: So fluctuations in the vacuum state correspond to fluctuations in energy.In summary, the vacuum is a state of nothingness that surrounds every particle in quantum mechanics. It is the discontinuity of the body density, and serious difficulties of comprehension appear when we try to describe it by using quantum treatment. However, these difficulties are just an adjustment of our comprehension of things, and if we consider a zone of 0 energy for a short time, Heisenberg's equation implies that it has an infinity value of energy. The vacuum state is also observed in laboratory, and is related to the Casimir effect. Finally, it is still an open question as to what the difference between the quantum field and vacuum
  • #1
is the vacuum the same as a quantum vacuum? Minor question but just wondering.
 
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  • #2


define "the vacuum"
 
  • #3


I must say I'm Sorry for my weak English.
What is Vaccum?, me I do not know, and doubt if anybody knows.
But, when we say quantum vacuum we mean that sheild of nothing surroundin every particle,; it is the discontinuoty of the body density.
Serious difficulties of comprehension appear when we try to describe that by quantum treatement, because in fact when we describe a vacuum in QM we make it very crowded, and very energytic which appear like a contradiction.But it is not, ther is just some adjusment of our comprhension of things which has to be adapted.If we consider a zone of 0 enrgy, for a short time Heisenbergs implyes that it shoul have infinity value of energy ,
this folows immediatly by the application of incertitude relation. I think it just( gives us more raison to adjyst our definition of vaccum,
I think the othor vacuum which is not QM, is the one describe in GR by the density fonction, where we estimate the energy of the universe by adding the energy of radiation, the energy of mass, and the energy of vaccum. This en,ergy of vacuum implyes the addition of a constanc in the einsteins equation noted ( lambda), that is why we name the present model (lambda)cdm = means cold dark matter ( + the constant lambda, which is due to the vacuum energy)
measurment by time are progressing in the favor of a plate universe ( not spherical or heberbolic) which means that there is truly this vacuum enerhy and it is even estimated in pourcentage of the total universal mass, but whar is it,how to explain it?, I think that is still the subject of reseaches - as far as I know-,
Experimntally concerning the Qm vaccum, we find the Casimir effect, observed in laboratory; two objects distant of 1 micrometre, infuelece each othor by a force proportionnel to the surface of the subjects. This force is due to the vacuum betueen the objects.
Finally befor to answer QM vaccum= vacuum or not, we have to firt knowwhat is vaccum, and we have to know sufficient about the QM vaccuum.
 
  • #4


i guess another question I would ask is what is the difference between the quantum field and the vacuum?
 
  • #5


redhedkangaro said:
i guess another question I would ask is what is the difference between the quantum field and the vacuum?
I think you seem to be using terms in ways that aren't quite in line with standard usage. Until you get some of the standard relationships between concepts a little more straight in your head, you will get answers to the questions that people think you might have asked, or that they think you ought to have asked. Keep at it! You probably need to do some more reading in parallel with asking questions on Physics Forums. When I get confused, I often try to read a different book on QFT, because it's often quite illuminating when you notice differences between presentations.

When considering quantum field theory at an elementary level, people often just say that the vacuum state of a quantum field is the lowest energy state. However, just as important is the invariance of the vacuum state of a quantum field under Lorentz transformations and under translations --- so the quantum field vacuum state looks the same to you no matter what constant velocity you're going and no matter where you are. Don't accelerate, however, because then the vacuum state of a quantum field does look different.

The vacuum state looks very similar to a thermal state insofar as there are fluctuations, but a thermal state is different because there is a special observer who sees the thermal state as moving at the same constant velocity, where all other observers see it as moving relative to them. Thermal states are invariant under translations, however, just like the vacuum state; that is, they look the same wherever you are.

It's famously the case that the vacuum state of quantum field looks like a thermal state to an accelerating observer, which is known as the Unruh effect. There are some tricky details, but this more-or-less means that you can reasonably think of the vacuum state of a quantum field as very similar to a thermal state of the same quantum field, with the distinction that the vacuum state and a thermal state have different properties under Lorentz transformations. Speaking loosely in terms of concepts from general relativity, by changing to an accelerating frame of reference you can turn the vacuum state into a thermal state.

All the above is fairly conventional. For quantum field theory it's also possible to think of Planck's constant as a measure of fluctuations in the vacuum state, just as temperature is a measure of fluctuations in thermal states. Sadly, we don't know how to reduce Planck's constant the way we can reduce the temperature when we want to make our measurements more precise. Don't put what this last paragraph says in a term paper, however, even though you can find mathematics supporting it in a published paper of mine.

Enjoy!
 
  • #6


I think you're talking about concepts which arise in SSB (spontaneous symmetry breaking). In general, the classical vacuum is not the same as the quantum vacuum, because loop corrections affect the construction of the quantum action, so that the ground state is modified a little.
 

1. What is a vacuum?

A vacuum is a space that is completely empty of any matter or particles.

2. What is a quantum vacuum?

A quantum vacuum, also known as a zero-point field, is the lowest possible energy state of a quantum mechanical system. It is not completely empty, as it contains small amounts of energy and particles that constantly fluctuate in and out of existence.

3. Is the vacuum the same as a quantum vacuum?

No, the vacuum and the quantum vacuum are not the same. While both refer to empty space, the quantum vacuum contains energy and particles that the vacuum does not.

4. How is the quantum vacuum related to quantum mechanics?

In quantum mechanics, particles are described as waves that exist in a field of energy. This energy field is the quantum vacuum, which is constantly fluctuating and interacting with particles in the universe.

5. What is the significance of the quantum vacuum?

The quantum vacuum plays a crucial role in many phenomena, such as the Casimir effect and the Lamb shift, and is also important in understanding the behavior of particles on a quantum level. It is also being studied for potential applications in technology, such as quantum computing.

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