Who can beat the Fifth Imperium?

[lordofFNORD]

"It's true, Ger." Amesbury's weary face looked back from Hatcher's com screen. "It took some time to get a probe near enough to burn through their ships' energy emissions and confirm it, but we found it right enough. Dead center in their formation: Iapetus—the eighth moon of Saturn."
"I see." Hatcher wanted to curse, to revile God for letting this happen, but there was no point, and his voice was soft. "How bad is it?"
"It's the end, unless we can stop the bloody thing. This is no asteroid, Ger—it's a bleeding moon. Six times the mass of Ceres."
...(snipped some in between stuff)
"They're coming at us at upwards of five hundred kilometers per second—seven times faster than a 'fast' meteorite. I haven't bothered to calculate how many trillions of megatons that equates to, because it doesn't matter. That moon will punch through our shield like a bullet through butter, and they'll reach us in about six days. That's how long we've got to stop them."

Right then. Yay numbers. The relative velocity is "upwards of five hundred kilometers per second", but it will "punch through our shield like a bullet through butter", so for an order of magnitude, I'm just going to use those numbers. The total kinetic energy is .5(1.8*10^21)*(5*10^5)^2, mean the order of 10^33 joules (or an about a trillion teratons). This upper limit is well above the firepower of a conventional GE fleet, but well below that of a Death Star superlaser; in fact, given the apparent ability of the Alderaan shield to withstand a small fraction of the Death Star blast, it seems that Planetary shields, at least top of line versions at peak power.

However, this relies on semi-excited speech. And 500 kilometers/second seems awfully slow compared to the speeds of other ships in the universe. If it's supposed to be 500,000 kilometers/second (about .6c), then the kinetic energy is on the order of 10^38 J, which is around the same order as a Death Star blast.

[Luzifer's right hand]

And 500 kilometers/second seems awfully slow compared to the speeds of other ships in the universe. If it's supposed to be 500,000 kilometers/second (about .6c), then the kinetic energy is on the order of 10^38 J, which is around the same order as a Death Star blast.

The speed of light is about 299 792 kilometres per second...
The normal STL drives counter mass and inertia according to the technobabble in the books, you do not want to do those things with a weapon.

[lordofFNORD]

And 500 kilometers/second seems awfully slow compared to the speeds of other ships in the universe. If it's supposed to be 500,000 kilometers/second (about .6c), then the kinetic energy is on the order of 10^38 J, which is around the same order as a Death Star blast.

The speed of light is about 299 792 kilometres per second...
The normal STL drives counter mass and inertia according to the technobabble in the books, you do not want to do those things with a weapon.

Um. Right.
Not quite sure why I mentally tripled c.

[Stark]

Did you just base a load of numbers on dialogue, AFTER inflating them by 3 orders of magnitude? You disgust me.

Let's play the 'get the biggest number you can' game!

[lordofFNORD]

Did you just base a load of numbers on dialogue, AFTER inflating them by 3 orders of magnitude? You disgust me.

If dialogue is the only source of numbers you can get, it's better than guessing. And if a military officer says "such and such can penetrate our shields", there is no reason to disbelieve him.

And I gave both sets of numbers, with explanations for both. It just seemed weird to me that someone would be concerned about something moving at 500 km/s in a universe where battles take place at .6c.

[Luzifer's right hand]

Did you just base a load of numbers on dialogue, AFTER inflating them by 3 orders of magnitude? You disgust me.

Let's play the 'get the biggest number you can' game!

It is certainly not a line well suited for calculations, he even said that he did not bother with calculations.
I only posted to counter the assumption that the the shields could not be overwhelmed with a kinetic weapon.
Edited for clarification:
Weber even used "trillions of megatons" which is about as useless as billion when it comes to analysis.
10^12 or 10^18 take what you want...

[Connor MacLeod]

And I gave both sets of numbers, with explanations for both. It just seemed weird to me that someone would be concerned about something moving at 500 km/s in a universe where battles take place at .6c.

And what? You have no bloody idea about the engineering issues of actually moving Iapetus, or what compromises they may or may not have had to make. Just because a planetoid (which takes years to be built and is DESIGNED to the engines it has) can achieve a certain velocity (even here I should note you're ignoring the fact that their reactionless drives are NOT instantaneous!) doesn't mean they can do this in all cases. The stresses involved in propelling the moon may have limited the speed. Or maybe they could onyl attach a certain number of engines (or engines of a certain size) to the moon to propel it - you seem to assume the Achuultani would just have enough undamaged. Or the timeframe may have necessitated an imperfect job, or rushing it. Or fuel considerations may have been a limitation. Or anything

The point is, you made an unverified assumption that basically amounts to you arbitrarily inflating the figure, which is basically what Stark was mocking.

[Imperial Overlord]

However, this relies on semi-excited speech. And 500 kilometers/second seems awfully slow compared to the speeds of other ships in the universe. If it's supposed to be 500,000 kilometers/second (about .6c), then the kinetic energy is on the order of 10^38 J, which is around the same order as a Death Star blast.

I don't like to dog pile, but Jesus fucking Christ that's an ugly example of dishonesty and knowing shit about basic science.

[Stark]

His defence for massively inflating near-worthless dialogue? One thing goes .6c, so OBVIOUSLY everything goes .6c. Brilliant.

As Connor says, it boggles the fuck out of me that anyone could compare an improvised flying moon to a custom-designed space warship and pretend it makes sense that performance is the same, even when their own source says it isn't.

Remember, if the source doesn't give big enough numbers, just start inventing stuff!

[lordofFNORD]

One thing goes .6c, so OBVIOUSLY everything goes .6c. Brilliant.

3 orders of magnitude slower than ships that are ALSO the size of moons? Surely you can see why that might raise suspicions.

But fine, moving on. That figure is irrelevant anyway, because Luzifer's right hand informs us that the high speed drives reduce inertia.

The ~10^33 J value, given the officer's apparent confidence that Iapetus would penetrate their shields, gives us a decent order of magnitude upper limit on shield strength, at least for kinetic impacts.
Spoiler

I don't like to dog pile, but Jesus fucking Christ that's an ugly example of dishonesty and knowing shit about basic science.

What the fuck do you mean? The way I deviously concealed my reasoning by EXPLICITLY noting that I was diverging from the quoted source? Or the explicit disclaimer that "this relies on semi-excited speech"? You can stay it was a stupid counterfactual, as Stark et al. have, but dishonest?

The mass of Iapetus is 1.8x10^21 kg. .6c gives a Lorentz factor of 1/sqrt(1-.6^2) = 1/.8 = 1.25. So the total energy of Iapetus would be 1.25(1.8e21)c^2 and the kinetic energy would be .25(1.8e21)c^2 = 4.0x10^37. Since my previous calculation was order of magnitude (which I cleverly concealed by using the phrase "on the order of"), that fits.

[Imperial Overlord]

Spoiler

I don't like to dog pile, but Jesus fucking Christ that's an ugly example of dishonesty and knowing shit about basic science.

What the fuck do you mean? The way I deviously concealed my reasoning by EXPLICITLY noting that I was diverging from the quoted source? Or the explicit disclaimer that "this relies on semi-excited speech"? You can stay it was a stupid counterfactual, as Stark et al. have, but dishonest?

The mass of Iapetus is 1.8x10^21 kg. .6c gives a Lorentz factor of 1/sqrt(1-.6^2) = 1/.8 = 1.25. So the total energy of Iapetus would be 1.25(1.8e21)c^2 and the kinetic energy would be .25(1.8e21)c^2 = 4.0x10^37. Since my previous calculation was order of magnitude (which I cleverly concealed by using the phrase "on the order of"), that fits.

Oh please. What a stack of passive aggressive bullshit, "concealed" in a spoiler.

1) It's inherently dishonest to decide "hey, I don't like the figures given so I'm going to increase them by three orders of magnitude and pretend that's reasonable, because a jury rigged moon can fly just like a custom built ftl battlestation." That you're outraged that you're called on it is hilarious.

2) 500,000 km/s isn't .6 C. It's in fact about 1.66 C. You should have some fucking idea what C is before you attempt argue anything involving it, let alone doing math involving it.

[Lord of the Abyss]

And I gave both sets of numbers, with explanations for both. It just seemed weird to me that someone would be concerned about something moving at 500 km/s in a universe where battles take place at .6c.

And what? You have no bloody idea about the engineering issues of actually moving Iapetus, or what compromises they may or may not have had to make. Just because a planetoid (which takes years to be built and is DESIGNED to the engines it has) can achieve a certain velocity (even here I should note you're ignoring the fact that their reactionless drives are NOT instantaneous!) doesn't mean they can do this in all cases. The stresses involved in propelling the moon may have limited the speed. Or maybe they could onyl attach a certain number of engines (or engines of a certain size) to the moon to propel it - you seem to assume the Achuultani would just have enough undamaged. Or the timeframe may have necessitated an imperfect job, or rushing it. Or fuel considerations may have been a limitation. Or anything

In the interests of completeness, the full quote including the part he snipped. Note the bolded.

"It's true, Ger." Amesbury's weary face looked back from Hatcher's com screen. "It took some time to get a probe near enough to burn through their ships' energy emissions and confirm it, but we found it right enough. Dead center in their formation: Iapetus—the eighth moon of Saturn."
"I see." Hatcher wanted to curse, to revile God for letting this happen, but there was no point, and his voice was soft. "How bad is it?"
"It's the end, unless we can stop the bloody thing. This is no asteroid, Ger—it's a bleeding moon. Six times the mass of Ceres."
"Moving how fast?"
"Fast enough to see us off," Amesbury replied grimly. "They could have done that simply by dropping it into Sol's gravity well and letting it fall 'downhill' to us, but we'd've had too much time. They've put shields on it, but if we could pop a few hyper missiles through them, we might be able to blow the bugger apart before it reaches us. That's why they're bringing it in under power; they don't want to expose it to our fire any longer than they have to.
"Their drives are much slower than ours are, but they've got the ruddy gravity well to work with, too. I don't know how they did it—even if they hadn't been picking off our sensor arrays, we were watching the asteroids, not the outer-system moons—but I reckon they started out with a very low initial acceleration. Only they're coming from Saturn, Ger. I don't know when they actually started, but we're just past opposition, which means we're over one-and-a-half billion kilometers apart on a straight line. But they're not on a straight-line course . . . and they've been accelerating all the way.
"They're coming at us at upwards of five hundred kilometers per second—seven times faster than a 'fast' meteorite. I haven't bothered to calculate how many trillions of megatons that equates to, because it doesn't matter. That moon will punch through our shield like a bullet through butter, and they'll reach us in about six days. That's how long we've got to stop them."

So they don't HAVE drives that are as good as the Imperium's, and they weren't accelerating that fast by in-universe standards anyway. So yes, compromises were made.

I'd also like to point out that Fourth Empire/Fifth Imperium technology is better than the Fourth Imperium shields in question, so I'm not sure how relevant all this is.

"In general, their progress may be thought of as coupling miniaturization with vast increases in power. A warship of Dahak's mass, for example, built with the technology we have so far encountered—which, I ask you to bear in mind, represents an essentially civilian attempt to create a military unit—would possess something on the order of twenty times his combat capability."

[consequences]

'Combat capability' is vague as hell. Increasing a couple of important areas by 100% can easily get you into that range, especially when your are talking about something that shoots twice as fast hitting twice as hard while sitting behind a shield that's twice as tough. On an even vaguer note, 4th Imp ships could manage to fight just on their fusion plants, with the Core tap being primarily needed for ftl travel(and yes, I realize that they specifically made a Core tap to power Earth's defenses), while the 4th Empire tends to more actively use them to meet their power requirements, and has more powerful Core taps to boot. Man, I would wish for more hard numbers, but knowing Weber, they'd be quite silly.

[Andras]

Civilization:

A Sunbeam will put paid to any planetoid that showd up in a system with one (76million gt/second)

The Dauntless and her sisterships runs a time-averaged 5.8 teratons/second, with 60% of that is saved up and discharged every 30 seconds in the form of primary beams (24 beams each of 4.4 teratons)

Maulers run 147gt/sec w/o primarys

The Supermauler's primary puts out 1.76 million gigatons

It's possible they could open a hyperspacial tube directly inside a 5th Imperium planetoid and deliver a negabomb via that tube.

[Connor MacLeod]

'Combat capability' is vague as hell. Increasing a couple of important areas by 100% can easily get you into that range, especially when your are talking about something that shoots twice as fast hitting twice as hard while sitting behind a shield that's twice as tough. On an even vaguer note, 4th Imp ships could manage to fight just on their fusion plants, with the Core tap being primarily needed for ftl travel(and yes, I realize that they specifically made a Core tap to power Earth's defenses), while the 4th Empire tends to more actively use them to meet their power requirements, and has more powerful Core taps to boot. Man, I would wish for more hard numbers, but knowing Weber, they'd be quite silly.

Interesting that you brought up the Core tap used to power earth, because they expected a partial mass-extinction event in a "worst case" scenario (if they lost control of it.) Given that they were still using human interaction to "control" said tap (even considering these are "enhanced" 5th Imperium people, they're still not going to be incredibly fast (IE I doubt we're dealign with microsecond or nanosecond "reaction" times to help control the reactor, so that limits just how much energy could be "lost" if we assuem the worst case scenario refered to a "temporary" loss of control. Its worth noting that even the 4th Imperium personnel on the plant never once considered a result worse than a "mass-extinction" event. as well.

And the Core tap, I should further add, were expected to complement the existing power generation on Earth (which was as I recall fusion plants.)

On the offensive side of things, ,we know that Planetoids typically throw "thousands" of missiles each (and have endured the aforementioned "millions" of missile salvos in larger scale battles.) And the fact that antimatter missile are definitively in the gigaton range (expressly stated in ARmageddon inheritance) also puts limits (it also sets a general limit on gravitonic warheads since they reasonably cannot be expected to be VASTLY more powerful than antimatter warheads, otherwise there would be no point in using them in combat, their technobabble damage elements aside.)

If one wants to determine limits on planetoid shielding, I'd suggest that we can infer it fits somewhere between Anu's facility in Mutineer's Moon (the lower limit) and the planetary shield around Earth (upper limit, and a rather generous one at that.) You could probably scale up/scale down in terms of size/volume.

[Luzifer's right hand]

If one wants to determine limits on planetoid shielding, I'd suggest that we can infer it fits somewhere between Anu's facility in Mutineer's Moon (the lower limit) and the planetary shield around Earth (upper limit, and a rather generous one at that.) You could probably scale up/scale down in terms of size/volume.

There is that though.

Oh, we could, but planetary shields aren't like warship shields. Not on habitable planets, anyway. Shield density is a function of shield area; after a point, you can't make it any denser, no matter how much power you put into it. To maintain sufficient density to stop really large kinetic weapons, our shield is going to have to contract well into the mesosphere. We can stop most smaller weapons from outside atmosphere, but not the big bastards, and we can't count on avoiding heavy kinetic attack. In fact, that's exactly what we're likely to be under if we do need to launch from planetary bases."

It might be possible that planetoid size is the ideal shield size.
Although in the light of the system shield in the Bia system the Empire seems to have solved those problems.

[Connor MacLeod]

If one wants to determine limits on planetoid shielding, I'd suggest that we can infer it fits somewhere between Anu's facility in Mutineer's Moon (the lower limit) and the planetary shield around Earth (upper limit, and a rather generous one at that.) You could probably scale up/scale down in terms of size/volume.

There is that though.

Oh, we could, but planetary shields aren't like warship shields. Not on habitable planets, anyway. Shield density is a function of shield area; after a point, you can't make it any denser, no matter how much power you put into it. To maintain sufficient density to stop really large kinetic weapons, our shield is going to have to contract well into the mesosphere. We can stop most smaller weapons from outside atmosphere, but not the big bastards, and we can't count on avoiding heavy kinetic attack. In fact, that's exactly what we're likely to be under if we do need to launch from planetary bases."

It might be possible that planetoid size is the ideal shield size.
Although in the light of the system shield in the Bia system the Empire seems to have solved those problems.

If you bothered to quote the entire bit, you'd realize that portion was derived from a discussion as to the problems of deploying hypermissiles on a habitable planet and the problems atmosphere created (hence the distinction between habitable planets and uninhhabitable ones.)

To put it briefly, planetoids (and uninhabited planets) with shields have no atmosphere, thus you can deploy hypermissiles for targeting (prior to launch) behind the shield (which protects them from interception.) To do this on a habitable planet, you have to extend the shield beyond the atmosphere enough that the hyper missiles can engage. But that means the shield's "density" (which here I laugh, because Weber yet again fucked the details of what he's trying to explain up - density is related to volume, not area) decreases because it has to encompass a larger area (or rather, volume. Though Weber might have meant intensity rather than density), which decreases the ability of the shield to deflect large impacts (though this also fails to account for the impactor's own surface area/volume, which will play a role in stopping it.)

This also means (and as they state even in your quote) that if they reduce the surface area (or volume) of the shield the density goes up and they can stop projectiles. But now their shields would be in the mesosphere (IE inside the atmosphere) and they couldn't launch hypermissile without deploying them outside the shield (and they would be vulnerable to interception then)

Basically (and what they also say in the novel) is that its about tradeoffs. They went with big fuckoff huuge missile launchers that enclosed the hyper field instead of sacrificing missile capability or protection.
It does NOT mean the planetary shields were inherently weaker than planetoid shields. The "difference" mentioned was purely WRT to missile launching.

[Luzifer's right hand]

If you bothered to quote the entire bit, you'd realize that portion was derived from a discussion as to the problems of deploying hypermissiles on a habitable planet and the problems atmosphere created (hence the distinction between habitable planets and uninhhabitable ones.)

To put it briefly, planetoids (and uninhabited planets) with shields have no atmosphere, thus you can deploy hypermissiles for targeting (prior to launch) behind the shield (which protects them from interception.) To do this on a habitable planet, you have to extend the shield beyond the atmosphere enough that the hyper missiles can engage. But that means the shield's "density" (which here I laugh, because Weber yet again fucked the details of what he's trying to explain up - density is related to volume, not area) decreases because it has to encompass a larger area (or rather, volume. Though Weber might have meant intensity rather than density), which decreases the ability of the shield to deflect large impacts (though this also fails to account for the impactor's own surface area/volume, which will play a role in stopping it.)

This also means (and as they state even in your quote) that if they reduce the surface area (or volume) of the shield the density goes up and they can stop projectiles. But now their shields would be in the mesosphere (IE inside the atmosphere) and they couldn't launch hypermissile without deploying them outside the shield (and they would be vulnerable to interception then)

Basically (and what they also say in the novel) is that its about tradeoffs. They went with big fuckoff huuge missile launchers that enclosed the hyper field instead of sacrificing missile capability or protection.
It does NOT mean the planetary shields were inherently weaker than planetoid shields. The "difference" mentioned was purely WRT to missile launching.

That talk about the hyper missiles is all nice and fine but completely irrelevant. What's clearly stated is that by reducing the size of the planetary shield it can take more powerful impactors.
The planetary shield generators and the planetary core tap were built with rather limited resources after all and nothing in the books suggest that those things are anything but minuscule compared to the size of planetoids.
Of course that does not make it certain that planetoid shields are stronger than planetary shields but it's certainly possible.

[Connor MacLeod]

That talk about the hyper missiles is all nice and fine but completely irrelevant. What's clearly stated is that by reducing the size of the planetary shield it can take more powerful impactors.

ACtually it does, since the only "difference" between Planetary shields on a habitable planet and those on a planetoid involved the discussion of hypermissiles. Its all about "context", and the context had nothing to do with the absolute strength of planetary shields re: to planetoid shields.

The planetary shield generators and the planetary core tap were built with rather limited resources after all and nothing in the books suggest that those things are anything but minuscule compared to the size of planetoids.
Of course that does not make it certain that planetoid shields are stronger than planetary shields but it's certainly possible.

There's no evidence to suggest planetoid shields are stronger than planetary shields or that these "miniscule resources" you claim somehow made them dramatically weaker. Or that the core tap was less powerful. Unless you can actually come UP with such evidence we have no reason to treat them differently.

[Luzifer's right hand]

ACtually it does, since the only "difference" between Planetary shields on a habitable planet and those on a planetoid involved the discussion of hypermissiles. Its all about "context", and the context had nothing to do with the absolute strength of planetary shields re: to planetoid shields.

It does not as the only relevant point is.

shield density is a function of shield area; after a point, you can't make it any denser, no matter how much power you put into it. To maintain sufficient density to stop really large kinetic weapons, our shield is going to have to contract well into the mesosphere

The planetary shields protects better when it is smaller, one could claim that it is at is maximum strength when it is contracted into the mesosphere or one could claim it would be even more effective if contracted even further. There is no evidence which supports either idea.

There's no evidence to suggest planetoid shields are stronger than planetary shields or that these "miniscule resources" you claim somehow made them dramatically weaker. Or that the core tap was less powerful. Unless you can actually come UP with such evidence we have no reason to treat them differently.

You just assume the planetary shields are the upper limit without any evidence for it too.
Upper and lower limits are nice and fine but to take something as upper limit just for the hell of it is rather pointless.
The plain truth is that there is not enough evidence. To say it's impossible to say for certain is an acceptable outcome for me.
I know it is not good enough for you and I respect that though.

[Xon]

And the fact that antimatter missile are definitively in the gigaton range (expressly stated in ARmageddon inheritance) also puts limits (it also sets a general limit on gravitonic warheads since they reasonably cannot be expected to be VASTLY more powerful than antimatter warheads, otherwise there would be no point in using them in combat, their technobabble damage elements aside.)

The anti-matter warheads where explicitly stated to being phased out as the gravitonic warheads where the real skip killers of the 4th Imperium. The 5th Imperium just didn't have enough ammo so where using anything which made a bang when defending Earth

And given the size of the planetiod, ICBM sized missiles can easily be stored in great numbers. The launcher's are still on the surface however.

[kinnison]

Civilization:

A Sunbeam will put paid to any planetoid that showd up in a system with one (76million gt/second)

The Dauntless and her sisterships runs a time-averaged 5.8 teratons/second, with 60% of that is saved up and discharged every 30 seconds in the form of primary beams (24 beams each of 4.4 teratons)

Maulers run 147gt/sec w/o primarys

The Supermauler's primary puts out 1.76 million gigatons

It's possible they could open a hyperspacial tube directly inside a 5th Imperium planetoid and deliver a negabomb via that tube.

Very interesting. I can calculate the time-averaged power figures myself; but where do you get the weapon discharge energy figures from?

No fair, anyway, pitting 5th Imp against Civilisation; the latter is probably in the top 10 of fictional civilisations. The Skylark crew are higher - so are the Culture, the Assassins, possibly the Tar-Aiym and definitely the Xeelee. Possibly, also, the Greater Archailects of Orion's Arm and the dwellers in Vinge's Transcend, but both those are difficult to quantify. After all, what can a baseline human imagine of the capabilities of something with 1E28 times his thinking power?

[Andras]

Kinnison, check out pages 2-4 of this thread

[Teleros]

For those still talking about Lensman firepower...

Each of the original Dauntless's cosmic energy intake screens could furnish the ship with 4.54e19W (10.8GT) - see below. With 200 of them, this works out as 9.08e21W (2.17TT). Note this doesn't include the accumulator cells etc (but then, we don't know how many accumulator cells there were, so giving a total figure is going to be... difficult). Most ships at the time had 2-3 intake screens by comparison, although they may have had additional accumulator cells to make up the difference.

Thus, the atomic motors which served as exciters had a maximum power of four hundred pounds per hour; that is, each exciter could transform that amount of matter into pure energy and employ the output usefully in energising the intake screen to which it was connected. Each screen, operating normally on a hundred thousand to one ratio, would then furnish its receptor on the ship with energy equivalent to the annihilation of four million pounds per hour of material substance.

1. Exciters for the intake screens convert 400lb per hour of matter into useable energy and use this to power the intake screens (4.54e15W).
2. Intake screens operate in galactic space on a 100,000:1 ratio - thus 4.54e19W. Okay, so it should actually be 4.54e20W, but then Doc Smith said "four million" instead of "forty million" (and in the same paragraph no less ), and I'm not prepared to say I know which figure he meant to use .

Possibly, also, the Greater Archailects of Orion's Arm and the dwellers in Vinge's Transcend, but both those are difficult to quantify.

So is the Skylark series if we're honest, simply because the physics works so differently: a guy in a "fourth order" shield can pretty much ignore such trivial weapons as a Death Star superlaser, relativistic planet or black hole (I kid you not), at least until his shields' power supply ran out.


Edit: Note that I'm sticking purely to the original 7 Lensman books for my analyses. No GURPS figures were used in the above .