Death's End discussion

I want to preface my post by saying that I consider this trilogy by Liu Cixin to be the most significant SF work since Azimov. So I'm really nitpicking on a speck of dust that only stands out because the rest is like a perfectly pristine mirror surface.

BUT. To me it makes no sense that 3D objects can subsist and survive in the 4th dimension. In the story, people are able to move in a certain direction in the 4th dimension to access the interior of 3D objects. Micro asteroids are able to strike the interior of spaceships without breaching the hull.

IF that is the case, then the air in the spaceships would also be able to escape into space through that same direction in the 4th dimension. Our blood would simply seep out of our veins through that same direction. Our clothes would flow into our body as we move. Our own organs would flow into each other! There is no way we would survive an incursion into the 4th dimension.

At a smaller scale, organic cells that have evolved to have structural integrity in three dimension have no reason to have structural integrity in the 4th dimension. Picture a little 2D character made out of threads on a flat table. Now lift that character up into the air. Yeah, we would suffer the same fate going from 3D to 4D.

More fundamentally, even electrons would reorganize around the atomic nuclei in order to find new lower energy orbitals in that 4th dimension. The properties of all materials would completely change, probably releasing enormous amounts of energy in the process. It's possible Constantinople would have been turned into a smoking crater 200km across.

[/Nerd-Rant]

All the 2D-3D-4D business I just termed as abstract because some concepts didn't really made sense.

*Spoilers-
Like an expanding 2D plane at the end might touch all the planets but that won't cover all the specks of dust and other things. I would have preferred an expanding sphere which still has a 2D surface.

Coming to your point, viewing 4D felt really weird to me, there was question of 'coastline paradox' since we were seeing inside of things.

Let's just assume all 3D objects have some weak force holding them together, no one is trying to pick up the thread kept on the table.