Other universes that are undetectable are like other gods, about as likely as any other god.
Inflation theory wouldn't break the law of thermodynamics even if the universe expanded at 100 times the speed of light, because it is all there is, it is hence the laws of nature.
Multiverse theories are ten a penny and like most religions are impossible to prove.
Now this of course does not
violate the laws of physics as what applies to within the Universe does not apply to the Universe itself
It does apply to itself in so much as the Universe creates the laws under which all matter operates, it is not outside of itself, and neither is there any inconsistency in the fabric of space and time expanding at more than c, matter travelling through space and time now that is different kettle of albatrosses.
However if you can bend space and time with mass then it follows that you can travel at faster than c at least naively because a journey to say alpha centauri when travelling at the speed of light would take you 4.22 years or so, and those who remained on Earth would have passed through 200 years in their time frame when you arrived. So at least it would seem to those on Earth that you had travelled 4.22 light years in 200 years. And to you you had travelled 4.22 light years in 4.22 years.
Even so of course the energy required to accelerate a mass object beyond .9999999999999999999999999999...c is infinite, in other words mass objects may approach c but never attain or exceed it and photons always propagate at c and never propagate at less than c unless passing through a medium which refracts it. There's no anti particle to photons its anti particle is just itself, the photon has no rest mess and is a point particle that is infinitessimal in size.
Or to put it in maths gibberish:
Which means the speed of a photon is c and that any other propagation issues are undefined, or in fact undefinable.
Which means that f(x)=f'(x)
And hence time and space as relates to acceleration are proportional to the equation above.
or time is equal to space with a transformational rotation 90 degrees about it's axis.
An object in time in space:
In this animation, the vertical direction indicates time and the horizontal direction indicates distance, the dashed line is the spacetime trajectory ("world line") of an accelerating observer. The small dots are arbitrary events in spacetime that are stationary relative to each other. The events passing the two diagonal lines in the lower half of the picture (the past light cone of the observer) are those that are visible to the observer.
The slope of the world line (deviation from being vertical) gives the relative velocity to the observer. Note how the view of spacetime changes when the observer accelerates. In particular, absolute time is a concept not applicable in Lorentzian spacetime: events move up-and-down in the figure depending on the acceleration of the observer.