I have no business asking this question since I am not a string scientist but I like to follow science news in phys.org and I read an article dated today Gravitational waves provide dose of reality about extra dimensions. This is based on the paper Limits on the number of spacetime dimensions from GW170817.

The article assuming I read it correctly which is a bit of a stretch on my part reports that at least in the "theory" referred to in the article the experimental evidence suggests no leakage is seen. They don't really say what the name of the theory is which is what prompted me to ask. But this was the first time someone was able to catch both the gravitational wave and the light wave from the same event.

Does this result also apply to the theories of string theory since they demand extra dimensions to exist ?

Sorry I worded the question a little differently in the title but I was haveing trouble making it fit.

  • $\begingroup$ I'm pretty sure testing the holographic principle can test string theory. May you provide a link to the phys.org article please? $\endgroup$ – N. Steinle Sep 14 '18 at 19:16
  • $\begingroup$ phys.org/news/… I am not sure if this will work $\endgroup$ – Sedumjoy Sep 14 '18 at 19:19
  • $\begingroup$ ....so the extra dimensions of string theory must obey the rules of the "holographic principle " and leakage is a physical characteristic that does not apply in this case? the article gives so little detail and that is why i posted to get a little more info $\endgroup$ – Sedumjoy Sep 14 '18 at 19:23
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    $\begingroup$ One thing to keep in mind is that the paper linked discusses leakage into non-compactified extra dimensions. String theories tend to use compactified extra dimensions AFAIK. I don't really understand the implications to string theory though. $\endgroup$ – enumaris Sep 14 '18 at 20:00

Does this result also apply to the theories of string theory since they demand extra dimensions to exist ?

You find the answer on page 5 of the paper: "We stress that our results do not hold for extra-dimensional theories with compact extra dimensions (e.g. string theory".

In other words, they only constrain the number of non-compact spacetime dimensions. The extra dimensions (beyond the 4d non-compact spacetime dimensions) in string theory will be compactified, and at a length scale which is way too small to have an effect in their analysis.

  • $\begingroup$ Ahh...yes ...I see the rest! Would you guess the answer to the question is "perhaps" since the scale of "compactification" is not known or is it known and is too minute to ever observe? $\endgroup$ – Sedumjoy Sep 14 '18 at 20:14

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