Description The Lie of Intergalactic Travel presents the McDonald Constraint Closure Framework, a formal principle asserting that physical reality is defined not by mathematical possibility, but by constraint-supported realizability. The paper establishes that any physically valid system must satisfy a complete and self-consistent set of constraints—specifically source, containment, stability, evolution, and failure. These constraints must be simultaneously defined and mutually compatible; otherwise, the system is not merely incomplete, but non-realizable within known physics. Using this framework, the work rigorously evaluates intergalactic shortcut and warp-based travel concepts against established physical laws, including Special Relativity, General Relativity, thermodynamics, and quantum field constraints. A formal stress-energy analysis is performed, demonstrating that such proposals lack a valid, constraint-supported configuration. Numerical stress tests confirm that while equations can be populated with placeholder values, no physically justified source, containment mechanism, or stability condition exists to support them. The paper introduces a formal closure condition: Physical Realizability⟺⋂Ci≠∅\text{Physical Realizability} \Longleftrightarrow \bigcap C_i \neq \varnothingPhysical Realizability⟺⋂Ci=∅ and a corresponding failure condition where any missing or externally assumed constraint invalidates the system. The central conclusion is that intergalactic shortcut travel is not merely technologically infeasible, but physically undefined under current constraint space. The framework remains open to revision if and only if a complete, testable replacement constraint set is provided. This work reframes the boundary between theoretical description and physical reality, establishing that a system exists only when reality supplies the constraints required for its existence.