# Empirical studies

There have been some empirical studies in various fields where the observers attempted to fit the data to multi-dimensional time models. Two of these are mentioned briefly here now.

**Fig. 12.1 ****Conclusions from Tegmark [1997]: UE = unstable elliptic, U = unstable,**

*T = tachyonic, S = too simple, UH = unstable ultrahyperbolic,*** M ^{4} = **

*Minkowski spacetime (our local spacetime).*

# Tifft’s analysis of red shifts

The astrophysicist W. G. Tifft measured the red shift of distant galaxies and believed that there were some unusual patterns in the data. He attempted to fit this data with a model of three-dimensional time [Tifft, 1996]. Subsequent independent observation did not verify Tifft’s data so his model is no longer viable.

# The two-dimensional arrow of biological time

Recent studies by Bailly and collaborators on multiple biological rhythms such as heart beat, circadian rhythms, and so on, came to the conclusion that biological time should not be invariably modelled by a linear concept of time but could be better understood in terms of a two-dimensional time ‘parameter’. One of these dimensions would represent the ordinary ‘flow’ of linear time whilst the other would be cyclic, ‘rotating’ around the other time [Bailly *et al.,* 2011].