Is the vacuum state insulated, can an absolute vacuum be absolutely insulated

The upstairs is too cumbersome and to the point, so I'll do it. Your question is incomplete, and I have two understandings:

1. If the food is filled in an ordinary bottle, and then the inside of the bottle is pumped into a vacuum, then it doesn't matter whether it is kept warm or not, because the heat at that time will be lost through the conduction of the bottle wall, and it has nothing to do with the vacuum.

2. If there is a sandwich on the outer wall and the sandwich is vacuumed, then it can be insulated. There are three ways in which heat is transferred: convection, conduction, and thermal radiation.

When vacuumed, the main heat dissipation mode of the food in the bottle: the conduction path disappears, and the food will cool very slowly. Of course, some of the heat is lost back through the conduction through the bottle wall, but very little at that time.

Do you understand? --Department of Physics.

There are three ways in which heat can be transferred:

Convection, conduction, thermal radiation.

Convection: For objects in liquids or gases, liquids (gases) are the medium through which convective heat is transferred. In vacuum, there is no convective heat transfer.

Conduction: It needs to be in contact with other objects, and if it is an object suspended in a vacuum, it will not be conducted.

Radiation: Objects below absolute zero will radiate energy outward, generally in the form of infrared radiation, and the mercury on the thermos bottle upstairs plays the role of reflecting infrared rays.

All else being equal, an object in a vacuum will be cooler than in air because there is one less heat transfer pathway.

The modes of heat transfer are: conduction, convection, and radiation.

There is no medium in the vacuum, and of course there is no conduction and convection, but radiation can exist, so the vacuum is still not completely insulated.

Absolute vacuum andAbsolute zeroThe same only exists in the imagination, so there is no absolute vacuum that can be absolutely insulated.

Neither of these situations is non-existent. Absolute temperature.

It's 0k, which is Celsius.

Because nothing in nature can reach such a low temperature, this is just a critical value. In vacuum, it can also be understood as the temperature in the universe, that is, the cosmic microwave background radiation.

The temperature is 3k.

Thermal insulation materials are divided into three categories: porous materials, heat-reflective materials and vacuum materials. The former uses pores that are lacking in the material itself to insulate due to the air or inert gas in the voids.

The thermal conductivity is very low, such as foam materials, fiber materials, etc.; Heat-reflective materials have a high reflectivity and can reflect heat, such as gold, silver, nickel, and aluminum foil.

or metallized polyester, polyimide film, etc.

Vacuum insulation materials use the internal vacuum of the material to achieve convection barrier to heat insulation. The aerospace industry has strict requirements for the weight and volume of the thermal insulation materials used, and often requires it to have sound insulation, vibration damping, corrosion protection and other properties. The need for thermal insulation varies from aircraft to aircraft.

Foam, ultra-fine glass wool, high silica cotton, and vacuum heat insulation boards are commonly used in the cockpit and cockpit of aircraft to insulate heat.

The thermal insulation material used for the head of the missile was phenolic foam in the early days, and with the application of polyurethane foam with good temperature resistance, a single thermal insulation material was developed into a sandwich structure. The heat insulation method of the air core of the missile instrument compartment is to coat a layer of foaming paint several millimeters thick on the outer skin of the cabin, which is used as an anti-corrosion coating at room temperature, and when the pneumatic heating reaches more than 200 °C, it will be evenly foamed and play a role in heat insulation.

Artificial Earth satellites are at high temperatures. In the low-temperature alternating environment, multi-layer thermal insulation materials with high reflective properties must be used, which are generally composed of dozens of layers of aluminized film, aluminized polyester film, and aluminized polyimide film. In addition, the development of surface insulation tiles successfully solved the space shuttle.

At the same time, it also marks a higher level of the development of thermal insulation materials.

Heat conduction requires direct contact, for example, if you put ice cubes on your body, the ice cubes will be in direct contact with you. Because the temperature is different, the heat of your ** is taken away by the ice. For example, if you leave the ice cube by one centimeter, you can still feel the coolness, because the ice cube contacts with the air and takes away the heat of the air, and the air becomes cooler, and the air contacts with your ** and takes away the heat of your **.

But vacuum is different. For example, if A and B are not in contact and there is a vacuum in between, it means that heat cannot be conducted directly between A and B, nor indirectly through A-vacuum-B. So you can insulate the heat.

Of course, heat is not completely impossible to conduct in a vacuum, and heat radiation is fine, but the efficiency is very low.

Because vacuum does not have the conditions to transfer heat, there are three basic ways in which heat is transferred: conduction, convection, and radiation.

Heat conduction, if there is a continuous temperature difference between the two parts of the object, the heat will automatically flow from the high temperature part to the low temperature part until the temperature of the whole part of the object is equal, this heat transfer method is called heat conduction, also known as heat conduction, in the solid and most liquids of bad conductors, heat burial conduction is caused by the momentum transfer of individual molecules; In gases, heat conduction is caused by the irregular movement of molecules. Convective heat transfer refers to the heat exchange caused by the relative displacement of particles in the fluid, and the convective heat transfer only occurs in the fluid, so it is closely related to the flow condition of the fluid. Radiative heat transfer, the transmission of electromagnetic waves in space due to the cause of heat bending blindness, is called heat radiation god town.

Vacuum cannot conduct heat, but thermal radiation can propagate heat, which is the irregular movement of material molecules, which we can understand as a billiard model The faster the molecules move, the hotter the object will be.

If there is no matter in the vacuum, there is no molecular movement, so it cannot propagate heat Thermal radiation is an electromagnetic wave, and light is also an electromagnetic wave, and it travels the fastest in a vacuum, and there will be deceleration in other media, but this is not heat, this is energy.

The meaning of vacuum refers to the state of gas with a pressure below one atmosphere in a given space and is a physical phenomenon. In the "void", sound cannot be transmitted because there is no medium, but the transmission of electromagnetic waves is not affected by the vacuum.

In vacuum technology, vacuum is for the atmosphere, and when part of the matter in a specific space is expelled so that its pressure is less than one standard atmosphere, then we call this space a vacuum or vacuum state.