A tunnel is a type of passage that sometimes goes through things, or sometimes goes under things.
Tunnels are really helpful for travelers. They allow people to keep going the direction they were originally headed without having to take lengthy detours. Tunnels are also an excellent resource for prison inmates who happened to be traveling towards freedom, and didn't feel like taking the long route of parole.
Those wishing to a travel in a straight line directly from one side of the Earth to the other (bypassing the barrier created by the Earth's circumference) can do so using a tunnel. Creating this passage would require a vertical decent using a tunnel boring machine............which unfortunately - does not make bottomless pits.
This is when an excited particle moves through a thickness in the barrier of spacetime.
Curvature causes barriers and sometime the barrier can be breached through tunneling.
- A tunnel is not a bottomless pit.
- A tunnel does not need to have two openings, but it helps.
- There is no light at the end of the tunnel.