I always forget about option 1. But even that they would have solved after a couple fuck ups so its not really an option.

Here's how reality is structured:

So we live in a timeline, which is like a film reel of static universes, that begins with a singularity, expands until a certain size is reached, then collapses back into a singularity again, our timeline has a "b-side" which is an "anti-timeline" on the opposite side from our own, whereas one is the "positive" and filled with matter and energy and etc., the other half is the "negative", which is comprised of the "anti-" version of everything (for example, "matter" on one side = "anti-matter" on the other).

Now, you may ask the question ""opposite side"? opposite of what?".

The opposite side of the core of our multiverse, like an atom has a nucleus, a solar system has a sun, and an egg has a yolk, our timeline/anti-timeline is structured around a "core" that determines the natural properties of the timelines which surround it, there is one timeline for every possible set of "frames" (configurations of matter/energy) that could occur within the natural properties out multiverse's core imbues them with, there are so many that they essentially form an "eggshell" for the "yolk" that is the core.

It's worth noting that the timelines do not go around it in a circle, but instead in a ellipse, therefore "egg" is a better approximation of the designated shape than "ball", also the furthest points from the core are the singularities, while the closest point's to the core are the "frames" in which our universe has reached it's maximum-size in the timeline and anti-timeline.

There are also a lot of "multiverses" aside from our own, each with their own set of natural laws, and one timeline for every possible sequence of configurations of matter and energy that could occur in them between their universes expanding from a singularity, and collapsing back into one to set off the "anti-" version of the same timeline on it's "b-side".

The sum of all these multiverses is the "omniverse", basically the "master folder", in which we get the first "sub-folder" for "natural properties" (the multiverses, whose properties are determined by their cores), and under them are the "sub-folders" for "set of configurations of matter and energy" (timelines, which are arranged around the core like a shell, and have an ""a-side"/""positive" and "b-side"/"negative" to them)

Just as there is one timeline for every possible sequence of matter/energy configurations, there is also one multiverse for every configuration of natural properties.

So, what about time travel to the past? Well, the multiverse has "one timeline for every possible series of configurations of matter/energy", right? Well, the timelines where people disappear out of the timeline due to travelling to the past and timelines where someone appears due to travelling back from the future, are all present.

This is different from the more anthropocentric version of the "multiverse time traveler", where "travelling to the past creates a new future which diverges from the timeline's past", in that it's TRULY a set of PARALLEL timelines, the timelines never diverge from one another, there's no "branching out", rather, they run in full parallel to each other, from beginning with a singularity, to ending up collapsing back into one, most timelines are going to be mostly identical, with only minor changes near the end of the line.

Also, these timelines are never created, nor destroyed, instead, they are all always existing, fully-formed, from beginning to end, and the time-traveler is merely a experiencing being a part of something he always was a component in.

Basically, time-travel is already incorporated into any multiverse with properties which allows for it. and out multiverse explicitly has properties that permit it to happen.

An infinite number of people, have already made an infinite number of trips into the past, popping out of one timeline, and popping into another.

Also, time travel to the past of one timeline causes whatever is inhabiting the space of the destination to switch places with whatever has set off into that space, thus preventing super-positioning, where two particles occupy the same space at the same size, meaning that if you time travel into a rock, the parts of the rock that you are inserting yourself over will travel to the part of your future to occupy the space that you left open when you left, to an observer of you taking your trip back, it might even appear as if you and your clothes had been petrified.

So you see, there's a reason we never get time travelers showing up to our "welcome back!" parties, because they are attending those parties in another timeline, not ours, from their perspective, they had made it and are enjoying the festivities, from ours, it's just a major letdown where no-one shows up.

Also, the issue of how simply travelling back in time alone has the difficulties of making us show up somewhere in outer space can be overcome with supercomputer calculations which can determine the spot we'd need to show up in, at least close enough to our intended destination that some basic space travel can take us where we need to go before we run out of necessities.

As for method, I suggest we start looking at warp technology, finding ways to mess with the fabric of space-time is the key to finding out the practical question concerning "how" we would accomplish this, first by finding out how to generate the energy and particles that we need, then finding out new answers to the facts regarding making the journey possible, not all of physics is mapped out, it was only relatively recently that we discovered why the sky was dark out at night.

Hi Trevor. It's me/us from the future. BUY WET WIPES.