How would you destroy a traversable wormhole?

[Velthuijsen]

You mean a Visser wormhole when you say a cube of exotic matter?
That is the exotic matter is a framework around the wormhole itself?
Or do you mean a more traditional wormhole where large negative masses are placed inside both exits?

The second option is easy (compared to the first one), just move out the mass on your side and the wormhole will collapse.

The first is a bigger problem seeing that a Visser wormhole needs string density materials as framework. Trying to blow that up is just adds material to it.
However you can destabilize it by pumping enough mass through it if both exits are in rest relative to the systems they connect (and not each other). The mass sent through the wormhole would compensate for the difference in speed by adding/substracting from the wormhole itself. Now all that is needed is enough mass (I suggest asteroids accelerated to close to c, seeing that you need quite a bit of mass) that one exit pulls free from the exotic matter that keeps it open, causing the wormhole to collapse.
Most likely there is one side effect, the exotic matter turning itself into a lot of exotic particles and EM-radiation due to the wormhole being the only thing that kept it stable and we are talking solarmasses worth of energy here.

[Winston Blake]

You mean a Visser wormhole when you say a cube of exotic matter? That is the exotic matter is a framework around the wormhole itself?

Yep.

The first is a bigger problem seeing that a Visser wormhole needs string density materials as framework. Trying to blow that up is just adds material to it.

However you can destabilize it by pumping enough mass through it if both exits are in rest relative to the systems they connect (and not each other). The mass sent through the wormhole would compensate for the difference in speed by adding/substracting from the wormhole itself. Now all that is needed is enough mass (I suggest asteroids accelerated to close to c, seeing that you need quite a bit of mass) that one exit pulls free from the exotic matter that keeps it open, causing the wormhole to collapse.

Hmmm, so hitting it with near-c asteroids is near the lower limit? I guess a satchel charge of nukes won't be much good at all. Thanks for the info.

Most likely there is one side effect, the exotic matter turning itself into a lot of exotic particles and EM-radiation due to the wormhole being the only thing that kept it stable and we are talking solarmasses worth of energy here.

Sooo, we're talking about a yield of hundreds of supernovas? Damn, now I know what Degan meant by the radiation burst being the bigger worry.

[Kuroneko]

It's very loose logic. According to Visser himself, there exist wormhole geometries with arbitrarily small violations of the averaged null energy condition even for a fixed throat radius, and small amount of exotic matter would be correspondingly more sensitive to minor perturbations--of course, that's a bit different from requiring the wormhole to be capable of transporting a given mass without collapsing. I don't think anyone can answer the OP's question with any certainty. For story purposes, it would not be unreasonable to assume that a wormhole's "toughness" is a parameter independent of its size at least up to some range of variation, similarly to how objects of similar size and mass can have vastly different material toughness.

I'm not familiar with Visser's "cubic" construction and unaware of any limit results on that type of wormhole in particular. However, exotic matter is fairly easily destroyed by adding matter to it. It then becomes a question a question of how much exotic matter is there and how much the destructive attempt can provide. Of course, it's also possible for the exotic matter to react unfavorably to normal matter in the first place, which would hasten its destruction.

[Velthuijsen]

Hmmm, so hitting it with near-c asteroids is near the lower limit? I guess a satchel charge of nukes won't be much good at all. Thanks for the info.

It is not hitting it with asteroids but sending them through the wormhole, this should 'steal' some of the massenergy it consists of. The reason for the high speeds is to create pseudomass so that more is 'stolen' from the wormhole. Do this enough times and the wormhole will collapse.

Sooo, we're talking about a yield of hundreds of supernovas? Damn, now I know what Degan meant by the radiation burst being the bigger worry.

This is a possible interpretation of when the string used to keep the wormhole open starts to break up. This is because you need a lot of (exotic) matter to make the string of a classic Visser wormhole.

Kuroneko is correct that Visser and others have taken the idea and worked out how to use less exotic materials but from what I've read (not the actual papers) it still takes (normal) mass and energy in the same order of magnitude and possibly more since the wormhole itself is deformed.

[Admiral Valdemar]

So I take it that dusting the thing with AM would likely make it corrode faster than interacting with stellar hydrogen.