[zchrykng]

Please enlighten us how purely theoretical mathematical constructs, that are impossible to test, help us understand anything about our universe.

[Erem]

Imaginary numbers are purely theoretical, but they turn out very helpful in almost every engineering discipline

[sigmoid10]

Imaginary numbers are a helpful tool for calculating things in our universe. All these holographic theories and their insights are based on a universe that behaves basically opposite to ours.

[Erem]

From Wikipedia, imaginary numbers...

> Originally coined in the 17th century by René Descartes[4] as a derogatory term and regarded as fictitious or useless, the concept gained wide acceptance following the work of Leonhard Euler in the 18th century, and Augustin-Louis Cauchy and Carl Friedrich Gauss in the early 19th century.

I think the jury is still out wrt utility of AdS spaces. They could be useless toys, or they could be in the Descartes phase rn.

[zchrykng]

Sure, let me know when any of these imaginary physics is useful for predicting anything that can be observed.

[Erem]

Not a physicist, but I think this paper used holographic principles to predict the minimum ratio of shear viscosity to volume density of entropy in fluids https://arxiv.org/pdf/hep-th/0405231

[dwroberts]

Lots of science is impossible to test practically for hundreds of years before it is actually experimentally verified

[zchrykng]

Not actually science until you can test it.