Perception and…branes!
These are the golden lions of Goryachii Klyuch, Krasnodar Krai, Russia, a town built around a balneotherapy health resort going back to 1864. Balneotherapy is a “method of treating diseases by bathing…Since ancient times, humans have used hot springs, public baths and thermal medicine for therapeutic effects.” The arch was built on its fiftieth anniversary in 1914 and originally had gates—an entrance to the resort park. The golden lions were installed in the 1950s to symbolize the victory of health over illness—notice the lions have defeated boars which represent ailment.
Some believe that if you walk through the arch with your eyes closed, you enter an alternate dimension.
The Incredible Bulk
There may be more dimensions, as in physical or time dimensions, as well as alternate universes.
Our universe might be a membrane—a surface—embedded within something much bigger: the braneworld.
The larger containing universe, or “multiverse” if you prefer, would have more dimensions. Our brane is just a 4-D (3 space dimensions + 1 time dimension) slice or perhaps an object “flying” around in the larger universe: “much like a strand of filmy seaweed floating in the ocean.”1https://phys.org/news/2006-05-scientists-fourth-dimension-space.html
The larger higher-dimensional space-time is called the bulk.
The bulk might be 5-dimensional, or it could have even more. We apparently cannot perceive the other dimensions in the bulk outside our brane. Or it could be that we experience 5-D, but the fifth dimension is so small in a strongly curved bulk, that it just seems 4-D.2P. Eleftherios, “Brane Cosmology.” Lect.Notes Phys. 592 (2002) 458. https://arxiv.org/abs/hep-th/0202044v2
What’s also freaky is that “other branes may be moving through this bulk. Interactions with the bulk, and possibly with other branes, can influence our brane…”3“Brane cosmology.” Wikipedia, The Free Encyclopedia, 18 Aug. 2022 https://en.wikipedia.org/wiki/Brane_cosmology These other branes could be parallel universes.
But why would scientists come up with this? Well it could solve some issues: “One of the appealing features of the brane world is that it can explain why gravity is much weaker than the other forces, with the nongravitational forces being localized to the brane and the gravitational force not limited to the brane.”4https://www.oxfordreference.com/view/10.1093/oi/authority.20110803095524666 And it can be connected to String Theory.
When Worlds Collide
If the bulk is an empty spacetime, and there are multiple branes (ours being one of them) moving around, they could collide. It’s possible that the Big Bang was one of those brane collisions.5D. Langlois, “Brane cosmology: an introduction.” Prog.Theor.Phys.Suppl.148:181-212,2003. https://arxiv.org/abs/hep-th/0202044v2 It’s also possible that universe-collision Big Bang events happen repeatedly for eternity—no start and no end.6Z. Merali, “Will Our Universe Collide With a Neighboring One?” Discover Magazine, 2009. https://www.discovermagazine.com/the-sciences/will-our-universe-collide-with-a-neighboring-one
Each brane could have a different cosmological constant. And if a brane with a lower constant collides with our brane it could destroy us. A “wall” would form between the two branes, and depending on tension, the wall would fly through, “eating” everything in its path at almost the speed of light and killing anybody who hit the wall.6Z. Merali, “Will Our Universe Collide With a Neighboring One?” Discover Magazine, 2009. https://www.discovermagazine.com/the-sciences/will-our-universe-collide-with-a-neighboring-one
It makes one wonder: how would this look to us humans if the wall was slow enough for us to have a chance to perceive anything before getting annihilated? And what about nonlethal distant reactions between branes—one would think that could cause some things to our 4-D that we would perceive as very strange. But probably only if it was a sudden change out of the ordinary that challenged the perception we evolved and grew up with and was a large enough anomaly to not just get ignored by our brains.
Multiverse fiction has become massively mainstream lately, such as with Marvel films like Doctor Strange in the Multiverse of Madness and the upcoming Ant-Man and the Wasp: Quantumania. But those visual depictions of multiverse interactions, at least so far, assume universes similar enough that a character could actually somehow still exist and have their sensory and perception faculties working in them. Environments like the “Mirror Dimension” show fun intersecting worlds type of things that are sometimes similar to Inception, but they’re very much movie magic visualizations—and essentially limited to 2-D—that I doubt would give us insight to a real experience of intermingling branes.
On the other hand, since our perception is largely a construction and/or an interface to the world, brane interactions could show up to us in whatever way we can handle including being influenced by Marvel movies.
Regardless of crashing into each other, the very motion of our brane through the gravitational field of other branes in the bulk could cause our cosmic evolution.2P. Eleftherios, “Brane Cosmology.” Lect.Notes Phys. 592 (2002) 458. https://arxiv.org/abs/hep-th/0202044v2 And our world could be under the influence of simulated “mirage” matter, which could be part of dark matter, the hypothetical and mysterious invisible stuff populating our universe.7A. Kehagias & E. Kiritsis, “Mirage Cosmology.” JHEP 9911 (1999) 022. https://arxiv.org/abs/hep-th/9910174v4