A question about really big explosions

[Adrian Laguna]

Actually the way the shield goes down is important.
[snip list of things that have nothing to do with what made the shield go down]

Your argument and evidence don't match each other. If you were to change that first sentence to, "The way the shield handles the energy thrown at it is important." Then it would make sense.

[Wyrm]

Actually the way the shield goes down is important.
[snip list of things that have nothing to do with what made the shield go down]

Your argument and evidence don't match each other. If you were to change that first sentence to, "The way the shield handles the energy thrown at it is important." Then it would make sense.

Well, the bolded part is important too. But the point of a shield is to protect you against damage. Presumably, an intact, powered, well-functioning shield is going to do just that, in part by absorbing energy directed at the target and dissipating it harmlessly. This might be accomplished in several ways, depending on the shielding mechanism, such as a heavy-duty heat sink attached to the shield generator absorbing the excess heat, or the shield might act as its own heat sink, radiating heat outside itself (not inwardly), or by other mechanisms, by themselves or in combination.

But Silence's scenario has the shield failing in some unspecified manner in some unspecified timeframe after absorbing a lot of punishment over a relatively short period of time. This implies that the shield might not have enough time to dissipate the energy it absorbed normally, which implies an abnormal, and perhaps catastrophic, dissipation of this energy.

If the shield generator doesn't fail in a way that shunts the absorbed energy in a way that does not harm the city, then things can be... messy.

[The Silence and I]

But Silence's scenario has the shield failing in some unspecified manner in some unspecified timeframe after absorbing a lot of punishment over a relatively short period of time. This implies that the shield might not have enough time to dissipate the energy it absorbed normally, which implies an abnormal, and perhaps catastrophic, dissipation of this energy.

If the shield generator doesn't fail in a way that shunts the absorbed energy in a way that does not harm the city, then things can be... messy.

I'm sorry for the confusion, I pointed out in a post after the opening post that the shield generator does not do anything nasty. Neither does the shield. You may think of the shield itself as a physical material that reflects/absorbs and re radiates the energy directed at it and then vanishes without incident.

[drachefly]

Out of curiosity, what raised the question?

I'm writing a story where a situation much like this one comes up, and I wanted to be scientifically accurate within reason.

The capitol city of a planet is captured by the bad guys(TM), and the good guys(TM) come to save it. The time interval allows the bad guys to set up a theater shield which is 30 km high at its apex, preventing the orbiting fleet from saving the day. I needed to breach the shield, which has a capacity roughly around 30 GT under the circumstances of this particular bombardment, and it is important to the story what happens to the city below after it fails. Very important... :)

Well, then, decide whether you want the city to be destroyed or not, and based on that decide whether the energy is dissipated harmlessly, contained, or directed inward! Simple.

Want the shield to fail without destroying the city? A fairly foolproof way is to just have it mostly fail, so that it could not block hard radiation or heavy objects, but is still reflective to IR and hard against gasses.

In the usual sense, this shield is down hard - bombs could be dropped through it.
It isn't hard to see how shields could have varying degrees of effectiveness; and that this basic degree of effectiveness could be what the more powerful one is liable to 'break' into.