Look at a couple things this idea might explain better. There's confusion over how the big bang originated. Since the initial Big Bang proposal, we've found quantum observations that indicate a vacuum energy ... we're riding a sea of possibilities.
Now if time is bidirectional, then a single quantum fluxuation in a void would not recombine instantly because energies created would be separated by time. Time in this example doesn't seem to need to be "thick", though the thickness would seem to determine the rate at which these initial energies would decay (if they're more diffused over a larger volume, then recombination would be slower).
When we measure the speed of light, we have no way of knowing whether an individual particle was emitted from the source and later detected or whether a particle traveling backwards through time left the detector and reached the source. Yes, it might sound funky but consider that even consciousness doesn't have a rigid method of determining flow of time and whether time flows backwards or forwards, time inverted physics would seem appear indentical to an observer though having some phenomenon could appear to have an unclear relationship between cause and effect. Either view would still see time flowing forwards.
Any equation of the form c^2 could truly use a value of +/-c. Time dialation could be described as
(speed of light)^2 = (velocity through space)^2 + (+/-velocity through time)^2
And if we measure the speed of light as m/s then if inverting time reversed direction then -m/-s is still the same as m/s.
We implicitly understand that travel through spacial dimensions isn't polarized but if we're going to see things as "spacetime" instead then why should motion through time not be similarly variable as well? It would only be possible to verify this if we could see a reversal in time between two systems, but that would require travelling faster than light speed (hence exactly why gravity could travel faster than the speed of light also, because it could move both directions through time). This would also seem to support a more steady state/continual expansion view of the universe as the Big Bang would not need be a novel, one time, unexplained event but a continual process distributed throughout space.
Yes, I've waded in knee deep but it doesn't seem difficult to go through some of the math behind the descriptions of the standard model and see if paradoxes are resolved by assuming time can flow either direction and quite possibly flows both directions. It might sound funky but either way a person would see a ball released first, and then fall afterwards. Why does time seem to pass faster as you get older or stop under anethesia etc.? Because we measure time relative to physical processes, a particle following a reverse path through time but with reversed physical characteristics would seem to only differ by having it's path affected by future events and not past ones. Cause and effect would be less clear and things like photons seeking out detectors, and spontaneous particle decay etc. would make more sense.
