What does a negative potential energy mean?

[Kiley]

A consequence of Coulomb's law is that oppositely charged particles have a negative potential energy. I'm having trouble undsrstanding how anything can have a negative potential energy and what consequences that has. Does it just mean the change in potential energy is negative or is it a matter of direction?

 

[Orodruin]

With the usual definition of having zero potential at infinity, it means that a particle has less potential energy than it would at infinity, nothing more and nothing less.

 

[Dale]

I'm having trouble undsrstanding how anything can have a negative potential energy and what consequences that has.

It means that it takes energy to move the charge to the reference location

 

[Janus]

Potential energy is measured with respect to some reference which is considered as being 0. In many cases it is most convenient to have this reference located at infinity. Thus the potential energy measured anywhere closer than an infinite distance has a lower than 0 potential energy and has a negative value assigned to it. In principle this is no different than -30° C being a lower temp than 0° C