In string theory, do fundamental gravitational strings interact with each other constantly, or can they interact and then cease to interact?

  • 3
    $\begingroup$ This is similar to asking whether two electrons interact constantly. It’s not specific to string theory or gravity. $\endgroup$
    – G. Smith
    Oct 25, 2020 at 20:54
  • $\begingroup$ Are the two electrons constantly interacting? $\endgroup$ Oct 25, 2020 at 21:06
  • $\begingroup$ I agree with @G. Smith. The coupling constant of the electromagnetic interaction between two electrons depends on the energy of those electrons. In string theory the situation is the same, except that the coupling constant of a fundamental string depends on the value of a dynamical scalar field (the dilaton) of the theory, and also on the energy of the strings (as usual from QFT). $\endgroup$ Oct 25, 2020 at 22:33

2 Answers 2


It depends. Since the dilaton field is dynamical and since the dilaton field determines the strength of interaction of strings, one can imagine a scenario and compactification or 2d matter CFT more generally where the dilation runs off to minus infinity, in which case all fundamental strings will stop interacting.

The generic situation however is that when fundamental strings are a good description they interact constantly

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – rob
    Jan 1, 2021 at 14:47

You can define a ground state in which all the possible gravitational radiation is radiated. There is no such thing as a fundamental gravitational string.


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