By Steven Henderson One of the major hurdles in developing models for faster-than-light (FTL) travel is establishing consistency with the notion of causality in physics - that cause must always precede effect. Any FTL mechanism that allows influencing the past or introducing temporal paradoxes runs into fundamental problems. In this article, I propose a new approach for achieving FTL without violating causality that applies concepts from bosonic string theory and the idea of pocket dimensions. The core idea is that by utilizing pocket dimensions isolated from our observable spacetime, travelers could effectively circumvent normal spacetime to reach distant destinations in an instant from their reference frame, without permitting direct causal connections backwards in time. Causality Constraints on FTL Let's first briefly review why FTL poses issues for causality under standard physics models. Allowing objects to surpass light speed enables closed timelike curves where an object's worldline forms a loop, potentially reaching its past. It also permits sending signals backwards in time from some reference frames. Both introduce intolerable paradoxes like changing one's past actions. Practical FTL requires constraining causes and effects to normal ordered sequences, avoiding direct manipulation of past events or introducing contradictory causal chains. But how can we enable faster-than-light transit locally while still respecting the overarching causal structure of spacetime? The Role of Compactified Dimensions This is where the geometry of string theory becomes potentially important. Bosonic string theory describes strings that vibrate in 26 total dimensions - our familiar 4 dimensions plus 22 additional compactified spatial dimensions curled up too small to perceive. Could these compactified dimensions allow shortcuts? What if a pocket dimension independent of our observable spacetime could be accessed via an "entry" and "exit" connected by a folded higher dimensional geometry? Travelers transiting this closed folded passage would then emerge at distant locations without directly traversing intervening space. Critically, if conditions inside the pocket dimension enforced its own non-contradictory physics such as preventing closed loops or retrocausality, then in principle it could mediate FTL connections without disrupting causality in our external spacetime. Effectively, it serves as an isolated "wormhole" bypass for FTL that avoids paradoxes. Maintaining Physical Consistency Of course, this raises formidable theoretical challenges - precisely constraining the geometries and dynamics within these higher-dimensional pocket realms would require a self-consistent and rigorously formulated model. Some possibilities include: - String vibrational modes sculpt compactified dimensions in a topologically consistent way - Quantum gravity effects maintain an orderly closed structure without singularities or closed timelike curves emerging over time - Boundary conditions isolate influences between the pocket and external spacetime - Quantum entanglement between strings penetrating our brane and the pocket realm transmits signals FTL indirectly Much work lies ahead to flesh out detailed mechanisms and establish that no logical inconsistencies could arise from small perturbations or interactions over long periods. But the idea potentially leverages our emerging understanding of string and quantum gravity to achieve localized FTL while still respecting integrity of causality on the largest scales. It remains an avenue worth serious consideration and ongoing theoretical development. In conclusion, applying principles of bosonic string theory and envisioning tailored pocket dimensions could open up a novel path towards physically realizable faster-than-light travel fully aligned with causality. While hurdles clearly exist, the approach warrants further exploration as an intriguing potential resolution to longstanding difficulties reconciling FTL with modern physics. Continued refinement may help assess its ultimate viability or point towards other promising solutions.

By Steven Henderson One of the major hurdles in developing models for faster-than-light (FTL) travel is establishing consistency with the notion of causality in physics - that cause must always precede effect. Any FTL mechanism that allows influencing the past or introducing temporal paradoxes runs into fundamental problems. In this article, I propose a new approach for achieving FTL without violating causality that applies concepts from bosonic string theory and the idea of pocket dimensions. The core idea is that by utilizing pocket dimensions isolated from our observable spacetime, travelers could effectively circumvent normal spacetime to reach distant destinations in an instant from their reference frame, without permitting direct causal connections backwards in time. Causality Constraints on FTL Let's first briefly review why FTL poses issues for causality under standard physics models. Allowing objects to surpass light speed enables closed timelike curves where an object's worldline forms a loop, potentially reaching its past. It also permits sending signals backwards in time from some reference frames. Both introduce intolerable paradoxes like changing one's past actions. Practical FTL requires constraining causes and effects to normal ordered sequences, avoiding direct manipulation of past events or introducing contradictory causal chains. But how can we enable faster-than-light transit locally while still respecting the overarching causal structure of spacetime? The Role of Compactified Dimensions This is where the geometry of string theory becomes potentially important. Bosonic string theory describes strings that vibrate in 26 total dimensions - our familiar 4 dimensions plus 22 additional compactified spatial dimensions curled up too small to perceive. Could these compactified dimensions allow shortcuts? What if a pocket dimension independent of our observable spacetime could be accessed via an "entry" and "exit" connected by a folded higher dimensional geometry? Travelers transiting this closed folded passage would then emerge at distant locations without directly traversing intervening space. Critically, if conditions inside the pocket dimension enforced its own non-contradictory physics such as preventing closed loops or retrocausality, then in principle it could mediate FTL connections without disrupting causality in our external spacetime. Effectively, it serves as an isolated "wormhole" bypass for FTL that avoids paradoxes. Maintaining Physical Consistency Of course, this raises formidable theoretical challenges - precisely constraining the geometries and dynamics within these higher-dimensional pocket realms would require a self-consistent and rigorously formulated model. Some possibilities include: - String vibrational modes sculpt compactified dimensions in a topologically consistent way - Quantum gravity effects maintain an orderly closed structure without singularities or closed timelike curves emerging over time - Boundary conditions isolate influences between the pocket and external spacetime - Quantum entanglement between strings penetrating our brane and the pocket realm transmits signals FTL indirectly Much work lies ahead to flesh out detailed mechanisms and establish that no logical inconsistencies could arise from small perturbations or interactions over long periods. But the idea potentially leverages our emerging understanding of string and quantum gravity to achieve localized FTL while still respecting integrity of causality on the largest scales. It remains an avenue worth serious consideration and ongoing theoretical development. In conclusion, applying principles of bosonic string theory and envisioning tailored pocket dimensions could open up a novel path towards physically realizable faster-than-light travel fully aligned with causality. While hurdles clearly exist, the approach warrants further exploration as an intriguing potential resolution to longstanding difficulties reconciling FTL with modern physics. Continued refinement may help assess its ultimate viability or point towards other promising solutions.