Who can beat the Fifth Imperium?

[Vultur]

The Fifth Imperium of Humanity (from David Weber's books Mutineer's Moon, The Armageddon Inheritance, and Heirs of Empire, in case it's obscure) seems exceptionally powerful.

Who would be able to defeat them? God-level entities like Q and the Xeelee obviously could. Galactic scale civilizations like Star Wars probably could do so eventually by weight of numbers, if their weapons were powerful enough (I don't know if turbolasers would have a significant effect, and photon torpedoes would barely scratch them).

Some basic data for those who are unfamiliar:

The planetoid warships of the Imperium are the size of the Earth's moon (Utu-class) or slightly larger (Asgerd-class). They're FTL-capable, but at hundreds of times c, or a few thousand at best. They carry smaller non-FTL-capable warships. They have "gravitonic" missiles, which seem to be very powerful - they're definitely considered much more powerful than the Achuultani multi-gigaton antimatter weapons. (At the end of the series, a sun-destroying bomb is discovered).

Power of weapons:

Yet before the last Protector perished, he saw one great warship advance upon the Hoof [Iapetus]. Its missiles reached out—sublight missiles that took precise station on the charging moon before they flared to dreadful life. A surge of gravitonic fury raced out from them, even its backlash terrible enough to shake the wounded Earth to her core, triggering earthquakes, waking volcanoes. Yet that was but an echo of their power. Sixteen gravitonic warheads, each hundreds of times more powerful than anything Earth had boasted, flashed into destruction . . . and took the moon Iapetus with them.

... what happened to the real moon?"
"It was destroyed," his informant said calmly. "With the exception of sufficient of its original material to make up the negligible difference in diameter, it was dropped into your sun.

One warship can destroy Saturn's moon Iapetus. A single ship also destroys Earth's moon, but apparently by moving it into the sun rather than explosively. Also, the size figure for a Utu-class warship: 3202.795 kilometers in diameter. (The Asgerd ships are somewhat larger; I think about a quarter more massive.)

Speed, warp and sublight:
[quote="The Armageddon Inheritance", chapter ]which limits their [the Achuultani]best supralight speed to forty-eight lights; seven percent of what Dahak can turn out, six percent of what the Guard can turn out under Enchanach Drive, and two percent of what it can turn out in hyper[/quote]

"All ships, open the range," he snapped, and the Imperial Guard darted suddenly astern at sixty-five percent of light-speed.

Damage resistance: It's hard to find a good quote explaining the shields, but they're definitely capable of stopping multi-gigaton weapons (which is the biggest they're subjected to) in large numbers. They can be penetrated by a missile popping out of hyperspace between the shield and the ship, though.

Alarms screamed as a ten-thousand-megaton warhead exploded almost on top of Royal Birhat. The huge ship quivered as the furious plasma cloud carved an incandescent chasm twenty kilometers into her armored hull. Air exploded from the dreadful wound, blast doors slammed . . . and Birhat went right on fighting.
"Moderate damage to Quadrant Theta-Two," the sexy contralto said calmly. "Four fatalities. Point zero-four-two percent combat impairment."

So, a 10 gigaton weapon, even if it isn't blocked by the shield, is a minor injury.

[Dahak]

The Xeelee
The Time Lords

Just to name the usual suspects

[18-Till-I-Die]

It depends on what "beat" means here.

Theoretically the Galactic Empire or Civilization could just flood their territory with billions of cheap-as-shit ships till they drown in them. Either of those two could suffer immense casualties and a miniscule success rate in combat and still "win"--in as much as kill every 5th Imperium man, woman and child--by way of the fact both control the entire energy and material resources of their respective galaxies.

If you mean like, conquer them, force on force, not a whole lot. They're pretty far advanced as sci-fi galactic powers go. Again, the Galactic Empire, Civilization, people like that who control whole galaxies could take them on by simply having MOAR of everything even if their ships are many times more powerful and durable. The folks from the Starfire novels, iirc, had the capacity to cause extention level events with fighter shoals launching heavy antimatter missiles...i'd say that's pretty fucking impressive, but they're bound by a hediously clumsy FTL system dependant on chokepoints that would fuck up any genuine long range advancement. But the sheer fact that a few thousand fighters with antimatter missiles can literally BDZ a planet gives them a rough parity at minimum in terms of firepower.

Obviously people like the Timelords or the Xeelee would rape them furiously but considering any of those three bastions of wank could raep the Galactic Empire and Civilization combined that's a rather obvious statement.

If you're looking for people like Star Trek, B5, Stargate tho...no. Nuh-uh.

[NecronLord]

Along with those, there's a whole pile of other sci-fi uber races you could name, Daleks, etc.

Probably the Imperium of Man and the Galactic Empire, too.

[18-Till-I-Die]

Ghetto edit:

Civilization is the primary protagonist force from the Lensmen series by Doc Smith, they're basically a less technologically sophisticated version of the Galactic Empire with vastly superior propulsion systems and WMDs.

Forgot to mention that.

[open_sketchbook]

I'd say the Imperium of Man could do these guys in through numbers, and in addition they do have a significant weakness in that their shields are nice and open to missiles going under them through hyperspace; presumably, warp missiles (the kind that go around shields) and teleporters could be used mercilessly against them, and if their crew density is as low as indicated an imperial cruiser could more than likely board, take and destroy from the inside.

[NecronLord]

if their crew density is as low as indicated an imperial cruiser could more than likely board, take and destroy from the inside.

They sound more like the kind of setting that has realistic boarding defences; when you tried that, the AG would just go up to ten thousand G and you'd die.

[Xon]

if their crew density is as low as indicated an imperial cruiser could more than likely board, take and destroy from the inside.

5th Imperium planetiods could lose entire battalions of IoM troups in the corridors before they got anywhere important. Those planetiods are just that stupidly big. And thier internals can survive multi-gigaton anti-matter weapons going off inside them (normally there is a safety system shunts it on a one-way trip into hyperspace).

They sound more like the kind of setting that has realistic boarding defences; when you tried that, the AG would just go up to ten thousand G and you'd die.

They use tubs where the occupants are accelerated at tens of thousands of gees to move around the 'ship'. Simply not having the implants which activate those means you arent getting around a moon sized object quickly. They can produce arbitary hyper-translation fields which send stuff into hyperspace. Said hyperspace will instantly vaporise a moon sized planetiod without an intact and active drive field up.

[eyl]

I'd say the Imperium of Man could do these guys in through numbers, and in addition they do have a significant weakness in that their shields are nice and open to missiles going under them through hyperspace; presumably, warp missiles (the kind that go around shields) and teleporters could be used mercilessly against them, and if their crew density is as low as indicated an imperial cruiser could more than likely board, take and destroy from the inside.

YOu'd need to flood them with missiles for that; hyperspace in the Dahakverse is divided into "bands", and their shields can block some of them (I'm not sure why they can't block all of the bands at once; possibly it's because that would block their own missiles).

[consequences]

Civilization would cockslap them, they've never exhibited the ability to hit ftl targets in realspace, and the Grand fleet gets to be orders of magnitude larger than the Great Visit. then there's the whole telepathic uberbeings which will damned well cheat if they have to.

The Galactic Empire can do it, it'll just cost out the ass. They'll be aided in the longterm by the fact that the Fifth Imperium's survey and recon techniques are possibly the worst in the history of science fiction(actually probably the second worst after the Starfire-verse Arachnids)

[Count Chocula]

Yah, I'd say the Lensman civilization could beat the remnants, but not when the Fifth Imperium was at its peak. The battle moons used in Weber's series were The Emperor's Personal Fleet, and they wiped out IIRC a two million ship invasion fleet, which had ships ranging from a few km to 60km in size.

The Fifth Imperium at its peak would have spanked the Galactic Empire and maybe the Lensman civilization. Heck, I bet the Imperium leftovers after the Achuultani incursion were driven off could spank the New Republic.

[consequences]

The Fifth Imperium has never yet been at its peak(or at least they'd better hope so, because they're completely screwed against the Master Computer of the Aku'Ultan if so). The Fourth Empire, with 5000 systems and just short of a million planetoids does have a much better probability of victory. It would still take them a bare minimum of 20 years to win, presuming they get portals from each and every one of their worlds to the center of the SW galaxy, perfect intel on where to go, and an additional 50 million or more ftl platforms in order to hit every target of any consequence in one go.

They would still lose horrifically to Civilization. Way back in Galactic Patrol their ships were around 500 times faster than those of the Fourth Empire. By the time of Children of the Lens, they have 65 billion inhabited worlds at a bare minimum, and are still expanding in two galaxies with essentially half of the First locked down, and an undefined chunk of the Second.

[dragon]

One major limiting factor for the Dahak verse is their slow ftl drives if they ever get around that then they become a major contender. Hum Asgard hyperdrives on a planetoid

[White Haven]

Y'mean the FOURTH, Choccy. The Fifth we never see get beyond a relative handful of planetoids, albeit more advanced ones than the old Fourth Imperium. Now the Fourth Imperium or Empire might be another story...especially the latter. The Fifth is 'quality over quantity' taken to an extreme. Both of the Fourths are 'Quantities of quality, eat it bitch' militaries, and as such that puts them on a whole new level of dangerous.

[Lord of the Abyss]

I'm surprised it hasn't been mentioned yet, but the Culture could. They have too many things the Imperium couldn't defend against, and more sheer power.

[Count Chocula]

Serves me right for doing this from memory at work, and not going home to pull the books off my shelf.

FOURTH Imperium! and the second time today I earned my sig line.

[Solauren]

Just drop off a few dozen Replicators from Stargate on one of there ships, and sit back.

They won't just beat them, they'll eat them.

[fgalkin]

I'm surprised it hasn't been mentioned yet, but the Culture could. They have too many things the Imperium couldn't defend against, and more sheer power.

Many of the high-level Involveds could do it, easily. Hell, maybe even something like the Affront would be a match for them.

Have a very nice day.
-fgalkin

[Vehrec]

Forerunners from Halo could probably pull it off, but they probably wouldn't be willing fight a war to extinction. Their main advantages are production speed and firepower-their fleets contained star busters and a 3/4 finished Halo was 'a few more days' from completion. While somewhat difficult to calculate in terms of size, that is still a very impressive production rate for just one 'Forge'.

They could probably out-planetoid the planetoids, if they wanted to.

[18-Till-I-Die]

I don't think the Forerunners have the power required. The Planetoids were in effect larger, more resource efficient Death Stars. Multi-gigaton weapons barely cause any real damage to them, certainly not enough to slow them effectively and never even destroy them and we've never seen--to my knowledge--the Forerunners or the Covenant employ weaponry that went beyond gigatons in terms of yeild.

I would think that, the Culture could probably take on the 5th Imperium, i'm personally not sure about their chances against the 4th Imperium however. You know, effectors only go so far, at a certain point having half your ship vanish into hyperspace will prevent you from continuing combat operations effectively.

[Lord of the Abyss]

I would think that, the Culture could probably take on the 5th Imperium, i'm personally not sure about their chances against the 4th Imperium however. You know, effectors only go so far, at a certain point having half your ship vanish into hyperspace will prevent you from continuing combat operations effectively.

Thing is, IIRC they can do things like hover in hyperspace and affect targets light years away. And the Imperium has no way to trace the effectors to source, or to reach them in Culture-version hyperspace even if they could. And then there's tricks like using a displacer to drop some CAM next to the core tap - BOOM ! goes the planetoid.

It's the classic problem of pitting funky, universe-specific technology against other universes; the other universe may just not have the right defenses to deal with it. And in the case of the Culture, it has a lot of really good "funky technology"; more and better than the Imperium does.

[NecronLord]

You know, effectors only go so far, at a certain point having half your ship vanish into hyperspace will prevent you from continuing combat operations effectively.

Why would a culture ship even engage from normal space to let them do that?

[lordofFNORD]

I'd put my money on the Galactic Empire, at least if they can pull off a solid mobilization. I don't see a good upper-end quantitative data on Imperium capabilities, but the GE can throw orders of magnitude more firepower at them than they appear to withstand above.

The gravitational binding energy of Iapetus is ~10^26 J, which is only two orders of magnitude above Saxton's conservative estimate for BDZ. A few seconds of concentrated fire from an Executor-class dreadnought could probably take it apart. Based on ICS, a Venator should have a firepower of ~10^24 W, or around 100k of those 10 GTon bombs per second. An Imperator shouldn't be any less. Compared to Imperium ships, GE ships are tiny, but they still pack a hell of a punch.

And planetary shields, even the small, black-market version on Hoth, could hold up to that kind of firepower. Though who knows how they'd deal with "gravitonic" missiles, given the weird gravity/shield interactions we see in NJO.

The Empire would have a enormous strategic advantage, in terms of mobility. In fact, if the Imperium tried to invade the appear, it would apparently take them decades or longer to even reach the Core, if I'm reading you right. Giving the Galactic Empire decades of preparation would be bad. In tactical, sublight movement, the Imperium seems to have a significant edge, if they can "dart suddenly" at .64c. That could prove troublesome for the GE, though at least they're shooting at large targets.

[Xon]

I'd put my money on the Galactic Empire, at least if they can pull off a solid mobilization. I don't see a good upper-end quantitative data on Imperium capabilities, but the GE can throw orders of magnitude more firepower at them than they appear to withstand above.

The GE's biggest advantage is the 5th Imperium FTL tops out at 3-5 thousand times the speed of light. The 5th Imperium ship's are composed of Weber foam and actually take more damage than you would expect, but they are still Moon sized targets.

The gravitational binding energy of Iapetus is ~10^26 J, which is only two orders of magnitude above Saxton's conservative estimate for BDZ. A few seconds of concentrated fire from an Executor-class dreadnought could probably take it apart. Based on ICS, a Venator should have a firepower of ~10^24 W, or around 100k of those 10 GTon bombs per second. An Imperator shouldn't be any less. Compared to Imperium ships, GE ships are tiny, but they still pack a hell of a punch.

Iapetus wasn't vaporised. It was eaten by ~16 blackholes with multi-km event horizens which then dumped into hyperspace(and likely exploded in a burst of hawking radiation) in or out of existance femtoseconds after doing so.

Planetiods can vaporise Earth, but it is thier "gravitonic" missiles which are thier true killers.

And planetary shields, even the small, black-market version on Hoth, could hold up to that kind of firepower. Though who knows how they'd deal with "gravitonic" missiles, given the weird gravity/shield interactions we see in NJO.

Provided the missile doesnt go splat against something, the answer is the planet(and target) is utterly screwed. This are some truely massive blackholes that are generated, and it is only Act Of Plot technology which makes them go away before they utterly trash the solar system they are used in.

The Empire would have a enormous strategic advantage, in terms of mobility. In fact, if the Imperium tried to invade the appear, it would apparently take them decades or longer to even reach the Core, if I'm reading you right. Giving the Galactic Empire decades of preparation would be bad. In tactical, sublight movement, the Imperium seems to have a significant edge, if they can "dart suddenly" at .64c. That could prove troublesome for the GE, though at least they're shooting at large targets.

Planetiods have interialess 0.7c drives and STL missiles are interialess 0.9c sublight weapons. Hypermissiles have 'only' been clocked at a few thousand times the speed of light.

[Ender]

I'm surprised it hasn't been mentioned yet, but the Culture could. They have too many things the Imperium couldn't defend against, and more sheer power.

Actually, I recall a thread here from way back where it was determined that a GSV vs a Planetoid would end in a draw as neither ship could hit each other.