Why wasn't Earth destroyed in ID4?

[Batman]

Enough nukes probably could, but that relies on them A) having that many nukes handy and available where they were and B) willing to live with the radiation later

I can't remember what they said about the USA's nuclear silos if anything, so not sure about (A). For (B), I think they were prepared - they did do the whole thing about "using nukes on American soil" before trying the stealth bombers on one of the ships. Granted a 32MT nuke means a lot more collateral damage and radiation but my impression was that they were desperate enough to nukes - therefore why not use a proper one?

The fact that they don't have them, perhaps? MT range nukes (leave alone double-digit MT ones) are largely a thing of the early 60s (if the US ever had the latter to begin with outside test warheads). Nuclear warheads these days are firmly in the triple-figure kiloton range tops.

[Baal]

Enough nukes probably could, but that relies on them A) having that many nukes handy and available where they were and B) willing to live with the radiation later

I can't remember what they said about the USA's nuclear silos if anything, so not sure about (A). For (B), I think they were prepared - they did do the whole thing about "using nukes on American soil" before trying the stealth bombers on one of the ships. Granted a 32MT nuke means a lot more collateral damage and radiation but my impression was that they were desperate enough to nukes - therefore why not use a proper one?

The fact that they don't have them, perhaps? MT range nukes (leave alone double-digit MT ones) are largely a thing of the early 60s (if the US ever had the latter to begin with outside test warheads). Nuclear warheads these days are firmly in the triple-figure kiloton range tops.

The US military does have some left but as a rule smaller nukes are better. Three smaller nukes in a cluster will more effectively destroy a target than one really large nuke.

[Batman]

SNIPPY for length
The US military does have some left

Chances are those are single-figure MT freefalls. Low end single figure.

but as a rule smaller nukes are better. Three smaller nukes in a cluster will more effectively destroy a target than one really large nuke.

Hogwash. Either a target can withstand a given energy input or it can't. Wether that input comes from one large or several small warheads is irrelevant.
The reason for the move to smaller warheads was that thanks to improved targeting nukes no longer needed the larger warheads to ACHIEVE said energy input, and that since there's several warheads for the same payload, they can hit several separate targets.

[Baal]

SNIPPY for length
The US military does have some left

Chances are those are single-figure MT freefalls. Low end single figure.

but as a rule smaller nukes are better. Three smaller nukes in a cluster will more effectively destroy a target than one really large nuke.

Hogwash. Either a target can withstand a given energy input or it can't. Wether that input comes from one large or several small warheads is irrelevant.
The reason for the move to smaller warheads was that thanks to improved targeting nukes no longer needed the larger warheads to ACHIEVE said energy input, and that since there's several warheads for the same payload, they can hit several separate targets.

You miss my point. Very rarely do targets need direct hits to take out.

Simple physics dictates that several small nukes work better than one large nuke.

There is an inverse square or inverse cube formula that determines how much energy from a nuke hits a specific spot whena bomb is dropped. The further you are from ground zero obviously the less the energy that reaches you. Because of the inverse relationship between range and damage it quickly works out that three spread out nukes do more damage to a given area than one single nuke. Sure the one single larger nuke will do more damage at ground zero than any one of the smaller nukes but very few targets are strong enough for this to be an issue. A vast majority of the time when you drop a nuke you want decent damage over a large area.

A single big nuke does a massive amount of overkill damage at ground zero then greatly diminishing damage at longer and longer range. 3 smaller nukes in a triangle pattern do each less but still more than enough damage at each ground zero and since there are three of them they cover a larger overall area with their damage radius.

[Batman]

You miss my point. Very rarely do targets need direct hits to take out.
Simple physics dictates that several small nukes work better than one large nuke.

The term 'No' comes to mind.

There is an inverse square or inverse cube formula that determines how much energy from a nuke hits a specific spot whena bomb is dropped. The further you are from ground zero obviously the less the energy that reaches you. Because of the inverse relationship between range and damage it quickly works out that three spread out nukes do more damage to a given area than one single nuke.

If you actually understood the math involved it would be obvious to you that no, it doesn't.

Sure the one single larger nuke will do more damage at ground zero than any one of the smaller nukes but very few targets are strong enough for this to be an issue.

Technically correct for current real-world targets and completely irrelevant at the same time.

A vast majority of the time when you drop a nuke you want decent damage over a large area.

As a matter of fact no you don't. I hate to tell you but counter-value strikes went out of fashion 40 years ago.

A single big nuke does a massive amount of overkill damage at ground zero then greatly diminishing damage at longer and longer range. 3 smaller nukes in a triangle pattern do each less but still more than enough damage at each ground zero and since there are three of them they cover a larger overall area with their damage radius.

Too bad area-affect isn't going to achieve what nukes are supposed to do today and have been for the past 35 years...

[Baal]

You have any evidence or you just talking out of your ass?

[Winston Blake]

Of course, the next question is: why should being behind the Moon protect the mothership from being nuked? If they've got missiles that could kill it if it was near-but-not-behind the Moon, then shouldn't those missile have been able to curve around to hit something on the far side?

Wouldn't an ICBM's MIRVs splitting apart be a bit of a problem?

Also, it took Apollo 11 four days (IIRC) to get to the moon. I don't know if an ICBM or whatever would be any faster (or if they could even get there in the first place) but maybe they figured they didn't have the time.

Additionally, they might have sent fighters to take out the various rocket bases on the planet (as they did with Will Smith's MCAS...El Dorado IIRC). Which would make things more difficult for reaching the moon (or behind the moon, wherever the thing was).

Finally, wasn't the mothership shielded too? If they couldn't nuke a city destroyer, why would they have any better luck against the mothership?

Previously in the thread it was established that they had the ability to nuke the mothership, but couldn't because it was hiding behind the Moon:

IIRC, it's stated both in the movie and in the novelization that attempts to nuke the mothership in orbit would fail because it was hiding behind the moon...which means at the very least it was beyond the moon's orbit.

So they somehow had the ability to hit something near the Moon, yet not if it's hiding behind it. This is despite the fact that missiles don't need to fly in a straight line, hence my question.

[Winston Blake]

The US military does have some left but as a rule smaller nukes are better. Three smaller nukes in a cluster will more effectively destroy a target than one really large nuke.

I think the confusion here is coming from a misunderstanding of the word 'target'. Seems like Baal was talking about a target colloquially, as in a target area, whereas Batman has understandably taken Baal's statement to more specifically mean a point target.

Tp Baal: it's clear that Batman understands the area damage purpose of MIRVs. This is not in dispute.

To Batman: the little factoid above is just that, a piece of trivia. I don't think Baal intended it to be relevant to killing ID4 ships, he was just tossing it out to follow through with his nitpick that, yes, the U.S. does still have megaton-range nukes.

The biggest nuke still in the American stockpile is the B53 at 9 Mt. So while Batman is right that monsters like the 32 Mt warhead proposed earlier in the thread would not have been feasible, and also right that the biggest is single-digit megatons, it is actually high-end single-digit. That's all there is to it.

[Lost Soal]

Previously in the thread it was established that they had the ability to nuke the mothership, but couldn't because it was hiding behind the Moon:

IIRC, it's stated both in the movie and in the novelization that attempts to nuke the mothership in orbit would fail because it was hiding behind the moon...which means at the very least it was beyond the moon's orbit.

Except it wasn't hiding behind the moon. It was on Film4 last night so I caught the end of it. The mothership had a direct line of sight between itself and Earth. The whole ship was visible to Geff and Will and the Moon wasn't even in shot.