Suppose An isolated room. I somehow created a perfect vacuum (0 atm) inside the room, and placed an object inside it, will the object explode and all its molecules will be scattered throughout the room uniformly? If it is so, then a spacecraft travelling in deep space will explode? Then why the spacecraft remain undamaged.
I was thinking there are now particle in a vacuum, when introducing an object the molecule will diffuse throughout the volume.
Condensed matter doesn’t explode when placed in a vacuum, but it does tend to expand slightly (mediated by the bulk modulus) as the internal pressure drops from 1 atm to 0 atm. It also tends to evaporate/sublimate until the vapor pressure in the surroundings matches the equilibrium level. The driving force is the entropy increase when matter is distributed more evenly, as you indirectly refer to. (This process is occurring with all the objects around you, even in atmosphere. The rate depends exponentially on the homologous temperature and may be essentially undetectable for more refractive materials—but it is happening.)
The torque from uneven sublimation can cause an object in space (such as an icy comet, with water ice having a much higher homologous temperature that rock or metal) to rotate and come apart. This could be considered adjacent to explosive behavior.
Step 1: Explosion is when the materials inside a containing entity, are extremely densely packed, leading to an extremely high pressure difference. Why? The pressure difference is created, as for blowing into balloons, because the balloon membrane has a limiting maximum ability to stretch, beyond which, if stretch, it tends to prevent the stretching. This is because of the interparticle force of attraction between membrane particles, this will resist the entry of more air. If forcedly blown, the membrane is bound to burst because the outward force exerted by the air simply exceeds the inward force by membrane, which can neither expand.
Implosion is the exact opposite, due to which, for example, the submarines taken into great depth cannot contract in size despite inward force by water particles being terribly high. Imagine you take an inflated balloon to the Mariana Trench. As you go down, the balloon slowly shrinks, but if it could not contract in size, it would right away implode below a certain depth.
Thus explosion or implosion depends on two major factors: pressure difference and the resistance of the object to pressure (rigidity).
Step 2: If we place the same balloon in space, the outer pressure due to microgravity, is nearly zero. But the difference in pressure — is it high?
If the theory was true, earth would have exploded already. But it does not because the earth itself pulls everything towards itself. Even if we ignore the gravitational force of every particle / object in theoretically pure space, if you simply release it there without putting the high pressure difference, it won't explode, but only slightly expand.
But it can indeed explode. In your vacuum–exhausted room, the room is very rigid. Also there is no question of pressure difference in the way we look at balloons. In balloon, we have a membrane separating microgravity and high density matter. Here the membrane would be the surface particles, and the pressure difference would be higher than in balloon, but still it would implode into the vacuum because of 2 reasons: (i) the rigidity is higher than the balloon membrane, (ii) the balloon was filled with gas, exerting gas pressure due to "continuous collision between each and every gas particle". But is it same for the particles of our walls? Our walls were filled with minuscule air spaces during formation and same here. Our walls are solid, and the particles inside are not actively hitting each other with the same velocity as the gas in here (here means our case).
What about the object you placed inside? Whether it explodes, depends on the factors I have mentioned before Step 2.
BTW, here's a question for pondering: If the object you place be a hollow balloon (which you have somehow created), what will happen?
Remember, a very dense matter enclosed by a soft membrane in vacuum, will not explode, until it is the collisions of the matter (Kinetic Energy) that forces explosion. In real life, there would be very small expansion, but there would be no explosion.
The short answer is no. Any rigid body in a vacuum cannot explode, given that the rigid body is not hollow.
All atoms of a solid, non-hollow, rigid body are tightly bound together by covalent and intermolecular bonds, making a vacuum environment around them will not cause the strong covalent and intermolecular bonds to break and lose their structure. $0$ $atm$ pressure simply means that there is no force acting on the rigid body due to air molecules; the absence of this force can not break the intermolecular bonds.
However, if the given rigid body is hollow and has a weak, deformable surface, like a balloon or plastic bottle, and the cavity contains air or any gas with pressure $P>0$ $atm$, and if the external pressure drops to zero, the hollow body is most likely to explode, because internal pressure is more than that of the external pressure. (Think of it as someone is pressing it from inside and no one is pressing it from outside; the body will expand, and it will lose its lattice as the bonds made by the atoms inside it will break.).
A spacecraft is made of materials that can withstand the pressure difference of the vacuum while also maintaining an internal pressure for the astronauts.
The explosion of a hollow body just depends on what the external body is made of.
