The history of the dream of star-flight is built on the bones of the hope of faster-than-light travel.
– Space, time: when, where? (Olympus Mons, Dustbunny Press)
The absolute limit of things that can influence – or can be influenced – by an observer is defined in relativity by the speed of light. This luminal limit, “c”, is something any observer, wherever they are in spacetime, should agree on.
Mixing faster than light (FtL) travel into a universe with these rules means that causes and effects get muddled up for at least some observers, and causality is a casualty. Anything else implies a special frame of reference that gets to define the ‘real’ order of events. This kind of privileged frame is firmly excluded in special relativity. Any FtL system is also a time machine, by exceeding the causal limit characterised by c. Time machines permit paradox. Paradox is the bane of causality. Relativity, FtL, causality: as the saying goes – pick two.
Relativity is looking healthy. Its description of spacetime has (so far) taken every theoretical and experimental challenge with only cosmetic updates. It does allow spacetime to be messed with: permitting black holes, wormholes, higher dimensions, gravity waves and all that cosmological goodness. And some of those tricks can look like Ftl systems.
Beings may point to wormholes when thinking about the Tree. The vast (potentially trans-universal) distances observed between edgemouths doesn’t seem to be a formal requirement of wormholes themselves, however. Attempted solutions to this apparent discrepancy include:
- Links between node on the Tree – Edges – are primordial and naturally occurring. They are so rare, in a universe so vast, that we should only expect to find them, on average, at a rate of one (or less) per Hubble volume.
- Strong causality projection isn’t a cop-out but a feature of the very fabric of things. Points connected by wormholes cannot share a causality sphere. On this view if you could travel between two vertices through “flat” spacetime at slower-than-light speeds before the end of the universe, an edge between them would be invalid under causality protection and unphysical, so impossible.
- A related point of view is that the act of making the wormholes creates the other spaces: the edge-mouth and the universe-as-vertex it opens ‘into’. Some beings find this idea distressingly recursive, but it does appear to be formally equivalent to the view above.
The luminal limit and the scale of our cosmos is such that travelling slower than light (StL) imposes energy requirements and travel times that are serious barriers to limited beings with aspirations of seeing far-off worlds up-close. The Worlds Tree appears to be consistent with relativity, causality and a kind of FtL. You can visit alien worlds that are simultaneously unimaginably distant and ‘easily’ reached. This is done by traversing Edges and the conventional spaces in-Vertex.
The systems in the Tree are each other’s hyperspaces.
© 2024 Ben Ridley / NeurOnToSomething is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Brane Connectome Project : tales from the Worlds Tree
Our empty universe? A single node, a point, a Vertex. Between the Vertices, a network of links, of Edges. Vertices and edges forming a multi-universal topology, a hyper-graph. The worlds tree. The brane connectome.
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