3
votes
3answers
265 views

Why must the excitation of closed strings in String Theory be spin-2?

In String Theory it is predicted that as a result of the closed strings we have spin-2 gravitons. 1) How do we know there must be an excitation of spin-2 particles? 2) Why does a spin-2 particle ...
3
votes
1answer
350 views

Why are there Gravitons among the modes of oscillation in String Theory?

Why are gravitons present among the modes of oscillation of the 'strings' in String Theory?