Do you know? There is a solid that is lighter than air, with a density as low as 0.001g/cm³, and it is called "solid smoke". It is called aerogel. It wasn't until nanotechnology developed that this wonder material truly came into the public's view, especially its excellent heat insulation properties! 
The Mars rover of NASA is equipped with an insulating layer made of aerogel. On Mars, the temperature drops so low at night that it can cause things to freeze. However, this thin layer can protect the sophisticated instruments from malfunctioning. 
The structure of aerogel is extremely special. Its porosity is over 99%, and the interior is filled with nanoscale pores, which trap stationary air and block heat conduction. There are several types of aerogels: the silicon-based ones are excellent for heat insulation, the carbon-based ones are highly conductive and suitable for energy storage, and the polymer-based ones have good flexibility and can be used to make flexible devices. 
Not only is it lightweight, but it can also withstand pressures thousands of times its own weight. Its specific surface area can reach over 1000 m²/g, and its adsorption capacity is extremely strong. 
Now it is gradually transforming various industries: In construction, coatings and panels with aerogel are being added, with a 2mm thickness being equivalent to the insulation capacity of 50mm rock wool. This technology is being promoted in many European countries. For new energy vehicles, it is used as a heat insulation material for batteries, which can enhance safety and lifespan. In the petrochemical industry, it is used as an insulation material for high-temperature pipelines, achieving remarkable energy-saving effects. 
The research team from Southeast University has also developed an even more remarkable layered structure double oxide nanofiber aerogel. Its density is as low as 8mg/cm³, and its thermal conductivity is only 7mW/(m·K). It remains stable at extreme temperatures ranging from -196 to 1300°C and can also absorb sound, reduce noise and catalyze reactions. It has great potential for application in the fields of aerospace and automobiles in the future. 
However, aerogels also have challenges, such as their high brittleness and high cost. But scientists are developing atmospheric drying technology to reduce costs. Which industry do you think aerogels are most likely to first transform? Please feel free to share your opinions in the comment section!