▁has ▁volunte ered ▁to ▁serve ▁in ▁the ▁Soviet ▁army ▁on ▁the ▁first ▁day ▁of ▁Naz i ▁Germany ' s ▁invasion ▁of ▁the ▁Soviet ▁Union ▁in ▁World ▁War ▁II , ▁ 2 2 ▁June ▁ 1 9 4 1 . ▁After ▁a ▁short ▁training ▁course , ▁he ▁joined ▁an ▁anti - t ank ▁art illery ▁unit ▁and ▁fought ▁in ▁it ▁until ▁the ▁end ▁of ▁the ▁war . ▁ ▁He ▁returned ▁to ▁Kaz an ▁University ▁in ▁ 1 9 4 6 , ▁to ▁work ▁on ▁the ▁phenomen on ▁of ▁electron ▁param agnet ic ▁reson ance ▁( E PR ), ▁newly ▁discovered ▁by ▁Z av ois ky . ▁In ▁ 1 9 4 8 , ▁he ▁demonstrated ▁the ▁so - called ▁hyper f ine ▁interaction ▁in ▁E PR , ▁that ▁is ▁splitting ▁of ▁the ▁reson ance ▁signal ▁due ▁to ▁elect romagnet ic ▁interaction ▁between ▁the ▁sp ins ▁of ▁the ▁reson ance ▁electron ▁and ▁a ▁nearby ▁nucle us . ▁This ▁finding ▁had ▁great ▁practical ▁impact ▁as ▁it ▁allowed ▁detection ▁of ▁nuc lei ▁through ▁reson ance ▁absor ption ▁by ▁electrons . ▁Although ▁Z av ois ky ▁left ▁the ▁group ▁in ▁ 1 9 4 7 ▁to ▁work ▁in ▁nuclear ▁physics ▁in ▁Moscow , ▁he ▁continued ▁generating ▁new ▁ideas ▁in ▁the ▁area ▁of ▁electron ▁reson ance . ▁In ▁particular , ▁he ▁suggested ▁that ▁the ▁E PR ▁phen omena ▁could ▁be ▁extended ▁from ▁the ▁radio ▁to ▁the ▁sound ▁waves . ▁This ▁idea ▁was ▁theoret ically ▁developed ▁by ▁Alt sh uler ▁in ▁ 1 9 5 2 , ▁and ▁resulted ▁in