Future submarines will be made of materials allowing subs to stay invisible for enemy radars, Scientific Head of the Krylov State Research Center Valery Polovinkin told TASS on Thursday on the eve of Russia’s Navy Day.According to the scientist, the submarines’ sheathing will be made of the so-called meta-materials that will be able both to trace impacts and resist them."If the submarine’s sheathing is made of this material, any locator or acoustic signal will simply skirt it, spreading farther. Physically, such an invincible submarine can be developed," the expert said.The submarines’ dimensions will be gradually decreasing and their division into strategic and multipurpose ships will become notional."The submarine’s affiliation with a particular class will be determined by the weapons mounted on it at the current moment. As weapons are improved, this difference will gradually disappear," he noted.Meta-materials are composite materials specially structured to get new properties.