Okay. You're a thinker instead of a critic. I'm impressed. Let's unpack some of those ideas and compare the way we look at them.
So essentially my issue with a multiverse is that every trip back or forward in time would really either result in an alternate parallel universe, or an outright jump to an already existing parallel universe.
In one context I see what you're saying, and it's a valid point that we can come back to later, but that's not the context I was trying to illustrate on the show. Not sure if you're on The Paracast Plus commercial free version or not, but I can track down the time if you need it.
My suggestion was that in a multiverse model there is no time travel in the usual context and no new timeline needs to be created in the process. What is happening is that there are two separate roughly parallel universes that have evolved from a different starting point relative to each other within the larger frame of reference. So for travellers from the more evolved universe coming here, it would appear to them from a subjective perspective, like going back in time.
In this model, backward and forward "time travel" only requires two universes. The limitation is that unlike the typical sci-fi type time travel stories, there is no option to "dial-in" a particular point in time. That would require that there be a corresponding separate universe for each point in time. Given that the universe on the grandest scale is infinite, it's not philosophically impossible, but I tend to share your sentiment that it seems unlikely, especially if our universe is a construct that was created within the larger universe.
The energy supplying these alternate realities would have to come from somewhere and if someone were to go all time travel crazy and bounce around like Dr. Who, you would be generating so many realities as to be absurd, each with an origin focused around one traveling individual. It seems like an unlikely overly complicated model for an otherwise well structured universe.
A valid point within the "simulated universe" model as mentioned above. However only two universes are required to produce the effect, and several don't seem unreasonable as a possibility. Our own minuscule efforts to model universes include several versions already, and I imagine they're all stored within a series of folders on some supercomputer.
It would also render time travel pointless. You aren’t witnessing or affecting events in your own timeline of origin. As soon as that became clear “time” travel would come to a quick end.
The multiverse model wouldn't necessarily render travel between universes pointless. Perhaps there are certain resources available in a less evolved universe that aren't available anymore in the more evolved one. Plus the opportunity to study a parallel timeline could give those in the more evolved universe clues to missing pieces in their own past. It would be amazing. Far from pointless IMO.
But as you correctly point out, it wouldn't really be "time travel". That is simply an illusion, and that is one of my major points. Because it
could be an illusion we shouldn't decide to be so sure that it's
really time travel, or else our worldview could be all messed up, and that's why I don't buy into the idea of "time travel" in the typical sci-fi sense ( other than to agree with the
Vulcan Science Directorate )
It would also go against the idea of the Mandela effect, which I have a fond place for (so this bit of bias can be ignored). Anyone from any alternate timeline would have no reason to have any memory spillage from the other lines, as your duplicate never experienced the events you did after the timeline split.
I too find the Mandela Effect quite interesting. I remember both scenarios. I definitely recall Mandela dying in jail along with all the news and mourning crowds. I also remember thinking: "WTF, is this some sort of impostor?" When he got released. Have you run across the bit where the actor who played Jaws in the James Bond movie said before he died that he remembered dolly with braces?
Anyway, no need to be disappointed if multiverses are the case. The Mandela effect is safe. All that would need to happen is for there to be a parallel universe that started at the same moment as ours and evolved almost, but not exactly the same, and for someone to be transported from one to the other. Perhaps the mechanism of transport are abductions, or perhaps they're "portals". Or maybe the overlord of the great OS decides to simply cut and paste someone out of one and into another. We get exactly the same effect.
A block model makes sense from a higher dimensional sense. Where from the perspective of a higher dimension everything down here is a convoluted mash of stringy matter extending forward and backward in time. It’s not so much that the universe is some physical “block” paperweight sitting on some diety’s desk, but more that the nature of time and it’s interaction with our 3 dimensions would be perceptible as a whole.
To connect it with the simulated universe theory (in which case, we might be a paperweight) time becomes a very complicated equation, and our reality is just a representation of that equation moving toward solution.
A fractal model for time could still work with higher dimensions, might give the illusion of alternate timelines for time travelers, who accidentally visit non-dominant branches. Perhaps the Mandela effect is a result of these non-dominant branches. As fractal time beings we would have some possible seepage of memory from non-dominant, dead-end branches that still exist within the pattern of our primary time pattern. It may even be the result of time travelers going back and altering the dominant formation of the pattern, but ultimately they would never be able to change the events of history as they recall it as their leap back is already a part of the dominant pattern they are traveling from.
The idea of "higher" and "lower" spatial dimensions is in and of itself logically incoherent. To really understand why requires it to be grasped entirely on an abstract comprehension level. Mathematical expressions and references to them can't get you there, though they might help a math-head see where the breakdown is. I can try to explain it in words, but it's still not easy for some people to get, especially those with
Aphantasia.
First, it's important to note that people wrongly assume that time is a fourth spatial dimension ( which it's not ). Within spacetime geometry, the word "dimension" with respect to time, is synonymous with "aspect" rather than "spatial dimension".
Read closely and you'll see the difference, but those who don't get that, have interpreted the "dimensional" aspect to suit their own notions.
The next thing is to come to the realization that the
nature of spatial dimensions is existentially a codependent hierarchy. In other words there can be no second dimension without a first, and no third without a first
and second. So for example, there
can be no "third dimension" that is somehow separated from it's 2D foundation and hanging "up there" over those in Carl Sagan's Flatland. The base of any 3D object such as a skyscraper would be clearly defined by the shape of it's foundation on the ground, just like everything else, which means that logically, there is another rule that must be the case, which is that in any given spatial construct all its dimensions must exist simultaneously everywhere.
Extrapolating that into any hypothetical spatial dimension beyond 3D means that any 4D ( not to be confused with 3D + T ) skyscraper would also have to be firmly rooted in 3D space. It would not be possible for there to be some single "higher" spatial dimension that other 3D things could "come out of" into the "lower" 3D realm. Any such "dimension" would clearly require it's own separate 3D construct for there to be separate 3D things in it. However it would be possible for another 3D construct ( spatial universe ) to exist, that things could be transported to and from, giving the illusion of them coming from another "dimension", in the generic sense like "another mysterious place".
Once ( if ) you get all that, then it simplifies the whole "dimensional" problem a lot and eliminates the sort of concerns you have.
It may sound a little like I’m talking about branching or parallel timelines in slightly alternate terms but it really is a dramatically different model. It might help to think of it this way: The people in separate or branching time lines have their own experiences and completely different futures. The people in a fractal time model experience a number of variations but ultimately share one perceptual experience and have one shared inevitable future. Our free will is simply a part of the complicated math that forms that shared pattern.
Like I said on the show, math is at best a description or representation, not reality itself, and just like other abstract representations such as artwork, it can create nonexistent impossible scenarios ( like Escher's impossible staircase ). Math-heads however, seem to think that math=reality. I'm sorry to say that it doesn't.
For example if we convert Escher's impossible stairs into a set of mathematical coordinates that correspond to the positions of the materials that a real-world staircase would require, it turns out that such a staircase cannot actually be built. I've had math-heads tell me that I don't know what I'm talking about, but it's true. They're so blind to the difference between abstract representation and reality itself that they just don't get it. Interestingly some have actually attempted to build Escher's impossible stairs. You can look it up, Better be careful trying to climb them though
The point here is that there is a certain
conceptual grasping of why these things are impossible that isn't explainable in simple words or math. You just need to "get it". What I've tried to do is point the way to that understanding. I hope I succeeded.
So to sum up, the problems you pointed out appear to have been adequately addressed, but if you see any holes please let me know. In the meantime, we haven't even touched on the problems with time travel in the context of block universes. I don't have the time now to write about that, but if you get what I was saying above, you're already half ways there.
Good discussion so far