As you approach c time slows. Relative to an observer. But it is an actual thing. A material thing can be seen to have not aged as the observer did, right? Well if time slows then an atom cannot vibrate at the same frequency as 'normal'. It must be slowed. An atom vibrating at an unnaturally slow rate would be what? A different material atom? An atom in a different state? Could materials retain their integrity under such conditions?