[pujjad]

In a world with two time dimensions there would be no such thing as causality: with a, b \in R^2 (the field of real numbers), a<b doesn't make sense, because two events can have the same distance from (0,0) but different angle \phi (modulo orientation of chosen frame of reference), and therefore I wouldn't be able to distinguish between past and future events in general. Causality breaks down.

Propagating along a 1D trajectory (ie flow of time) would then be along a 2D "trajectory" through which I would experience indefinitively many events at once, unclear which one impacts on which others. But clearly I perceive me writing this post "right now", and am about to push the send button..

[mjan22640]

When you observe a particle, you see it in a superposition of a indefinite number of states.

A photon moves at the speed of light, it does not experience the flow of time because of that, its whole lifetime is an instant from its point of view, and it "sees" the universe in the superposition of the states the universe goes through.

Similarly, the indefinite number of states of the particle could be observing a development in a time dimension in which the time does not flow for the observer.

They say, one man's instant, another man's eternity...

[_zywo]

Relativity already has the inability to distinguish between past and future states built in: https://en.wikipedia.org/wiki/Relativity_of_simultaneity

I have no idea how 2D time would work, though.

[halter73]

It's possible to distinguish between past in future states if they exist in the same light cone. It says this in the wiki you linked to

> However, if the events are causally connected, precedence order is preserved in all frames of reference.

[humbleguy]

Can't tell if trolling or not...

[pujjad]

It's an argument pro two-time scales and against two dimensional time just by looking at what math says about partially ordered sets. R^2 is clearly not partially ordered as opposed to R^1.