  In topological physics, it is commonly understood that the existence of the
boundary states of a topological system is inherently dictated by its bulk. A
classic example is that the surface Fermi arc states of a Weyl system are
determined by the chiral charges of Weyl points within the bulk. Contrasting
with this established perspective, here, we theoretically and experimentally
discover a family of topological chiral bulk states extending over photonic
Weyl metamaterial waveguides, solely induced by the waveguide boundaries,
independently of the waveguide width. Notably, these bulk states showcase
discrete momenta and function as wormhole tunnels that connect Fermi-arc
surface states living in different two dimensional spaces via a third
dimension. Our work offers a magneticfield-free mechanism for robust chiral
bulk transport of waves and highlights the boundaries as a new degree of
freedom to regulate bulk Weyl quasiparticles.
