Free space problem in matter We know that atom is ninety nine percent empty and all matter is made up of matter then why matter is mostly empty ? 
 A: The atom isn't empty. It's full of very strong fields. Try to squeeze the atoms of a solid together as hard as you can. Does that feel like empty space to you? It's like a super-strong version of the force that repels two permanent magnets when equal poles are facing each other. In modern physics we don't make a distinction between these fields and matter. Matter is the fields. The notion of an "empty atom" was developed at a time when this identity was not fully understood. It was based on experiments by scientists in Rutherford's laboratory who observed that alpha particles (helium nuclei) can be shot trough thin foils of metal. This indicated that most of the space between the densest parts of atoms was empty. In reality, of course, the alpha particles simply don't care about the electrons that are in that space since they are much heavier. It's like shooting a canon ball trough rain... it won't slow down much, either. That doesn't mean the rain is not there, it simply means that canon balls are not a good method to check for rain. 
