More dimensions and universes: exotic theories

Transcription

1 More dimensions and universes: exotic theories Szydagis Above right: Rod Serling of The Twilight Zone 1 / 8

2 2 / 8 A new spatial dimension There is length, width, height (time is not spatial ). What if there is a fourth one we cannot perceive? A hot topic especially in the 19 th century, in context of an explanation for the paranormal (psychic mediums) Theories of Everything like supersymmetry and string theory call for many additional dimensions (11 total) to unify the 4 forces and the laws of physics successfully Not necessarily large and straight. Can be small, curved 2D analogy: if we were all perfectly flat, we would not be able to visualize/imagine the third dimension Demos: point, line, square, cube, hypercube, hose. Shadows, folding (tesseract), angles, cross-sections Strange effects: locked room, reversal, all-seeing

3 3 / 8 Wormholes: cosmic shortcuts? The curvature of the universe is NOT NECESSARILY embedded within an extra ( higher ) dimension: space-time can be curved without one (GR) But if it is, then one might be able to cut through this hyperspace to reach another point in space and/or time (or another universe!) Einstein-Rosen bridge, wormhole Catch: negative mass to hold open throat. Otherwise only tachyons can make it through (Dark energy won t help) Diagram from Hyperspace by Michio Kaku DEMO: Sheet of paper analogy (too bad need faster than light)

4 Say no to Bang? 4 / 8 There was no Big Bang: our universe is a result of a collision between two branes in a higher dimension Heated up cold, dead space, resulting in high (key: but not infinite) temperature & density. Rest of story same CMB polarization and primordial gravitational wave spectrum should be able to distinguish between this ekpyrotic model and the Big Bang with inflation Klein-Alfvén cosmology (currently a dead theory): plasma physics and electromagnetism much more important for formation of large-scale structure (galaxy clusters) than gravity. A segmented universe Equal amounts of matter and antimatter in universe Annihilation causes explosions, repulsion (expansion) CMB, gamma-ray background inconsistent with this

5 Multiverse #1 5/8 In the model of eternal inflation: causally disjoint, physically separated bubble universes exist Each with a different set of (some) physical laws and constants, expansion rates Multiple Big Bang(s) may be quantum fluctuations in distinct regions (points) Full multiverse is infinite in extent (but each universe its own space-time, has own set of dimensions with #=?) and uncreated Anthropic principle: The only reason our universe is the way it is (supportive of sentient life) is because if it were otherwise, then we would not be here to ask! Other universes devoid of life Some get crunched, others ripped. Life probably RARE!! Olena Shmahalo / Quanta Magazine Important to have evidence Olena Shmahalo/Quanta Magazine; source: S.M. Freeney et al., Physical Review Letters

6 Multiverse #2 Parallel universes (each with same basic set of dimensions, common misconception) occupying the same space at same time unseen in superspace Instead of distinct laws of physics, same, and maybe with copies of all of us often, each slightly different A possible consequence/interpretation of quantum mechanics. Created by historical forks in road (any, at subatomic level, not just major events). If time travel possible, might result in parallel timeline Communication & travel likely not possible (as with Multiverse version #1). Impossible model to prove? Common theme in science fiction literature, media Suspicious real-life stories are most likely all hoaxes 6 / 8 Like TV show Sliders. Ghostly overlay

7 Cyclical cosmological model Only one universe, but oscillatory. But remember: no time outside of it. (Can define a meta-time ) Big Crunch followed by Bang, on & on, forever One iteration not necessarily same as next. Time does not reverse in collapse. Each cycle random Universe born from black hole of other ( larger ) What if that other=ours: an ontological paradox! 7 / 8 w/ dark energy kind of messes up the Crunch (but still doable) Source -

8 8 / 8