What use are theater shields

[Mr. Oragahn]

Absolutely, and funny enough, in Star Wars they're quite relevant against vast deployment of mechanized forces.

[Praeothmin]

In the movie, they only moved at a few meters per second tops. At that speed, it would take a full minute to cover their own length.

Now, I'm not the best at math, but wouldn't a 20 meter long machine doing, let's say, 2 meters per second, need only 10 seconds to cover it's own length, and not a full minute?

In short, in my opponion theather shields probably work because a sane military (esp. one that belongs to a civilized bunch) generally won't blow up a chunk of planet to get below them.

Except if the planet is a remote one that no one uses, and the military in question has already established that it doesn't care about keeping worlds intact when it previously built a whole, moon-sized battlestation with the specific goal of exploding planets... :)

[Roondar]

In short, in my opponion theather shields probably work because a sane military (esp. one that belongs to a civilized bunch) generally won't blow up a chunk of planet to get below them.

Except if the planet is a remote one that no one uses, and the military in question has already established that it doesn't care about keeping worlds intact when it previously built a whole, moon-sized battlestation with the specific goal of exploding planets... :)

Ah, but I was writing about the generic case (like the OP), not the Hoth example per se.

Thus, my point stands - theather shields are quite useful and not a waste to install. Villanous planet destroying* boogeymen as enemies excepted, of course!

*) Lucky for the poor people on Hoth the boogeymen didn't have said moon with them at the time due to 'minor technical difficulties' and the rest of their ships can't do anything close to what it did in any reasonable amount of time ;)

[Praeothmin]

Well, I thought we were talking specifically about SW, but yes, theater shields are a viable option...

[Mr. Oragahn]

In the movie, they only moved at a few meters per second tops. At that speed, it would take a full minute to cover their own length.

Now, I'm not the best at math, but wouldn't a 20 meter long machine doing, let's say, 2 meters per second, need only 10 seconds to cover it's own length, and not a full minute?

Right. Fucked up using the frames. :/

[Praeothmin]

And my math teacher said I couldn't do divisions... :)

[Lucky]

I doubt that any target worth attacking by ships - even if these ships are runabouts - would be built by bricks and/or concrete. Besides, based on size comparation, Runabout torpedoes are most likely in single-digit to double-digit megatons, which is about most one can expect larger theater shields to be useful against.

We see the Star Fleet Academy get trashed twice, and both times I don't recall any signs they used super material, or any sign of large explosions.

You aren't going to use super materials if they are expensive/rare, and aren't going to provide better protection then something like common iron and carbon can provide.

[Lucky]

The better thing to do would be to gauge distance based on known height and visual size. There are formulas for that but I don't know them. Still, for structures that are about 22 meters highs to appear like mere pimpricks and require super duper googles to get spotted, they had to be very far.

http://www.starwars.com/databank/vehicle/atat/
StarWars.com says AT-AT are 15.5 meters tall. Where are you getting your figures from?

http://www.youtube.com/watch?v=C6uQ1ROQm0k
The problem is that we don't know if those are AT-AT appearing at 7:11. They could be AT-ST which we know were deployed at Hoth?

At 7:46 we see the AT-AT climbing up a hill that is taller then they are so we can't have seen them at 7:11. It makes it seem like the Rebel base was at the top of a hill rather then a valley like it is often shown in the EU. It makes you wonder what the guy with the binoculars was really see.

Then, wookieepedia's page claims a silly max speed, like 60 km/h. Yeah, whatever. That's over 16 m/s. Bollocks. Over 3/4s of the AT-AT's length. They'd need to be very agile to cover such a distance that fast, but they're not. Besides, this is ice and snow, so they'd rather have to be careful.

I thought I heard 90 somewhere as the top speed, not that it matters as you say.

In the movie, they only moved at a few meters per second tops. At that speed, it would take a full minute to cover their own length.
Well, if you want to do some maths, now...

Here goes:
If the AT-AT are 15.5 meters high that means they are about 17.7142858 meters long going by this picture: http://images.wikia.com/starwars/images ... T_egvv.jpg

I will just round up to 18 meters to simplify things, and I'm likely still lowballing the length a tiny bit.

18*60= 1080 meters per hour or 1.08 kilometers per hour

If we use your 22 meter length:

22*60= 1320 per hour or 1.32 kilometers per hour

If we assume the AT-AT at Hoth had been traveling their length every 10 seconds:

18*6= 108*60= 6,480 meters per hour, or 6.48 kilometers per hour

22*6= 132*60= 7920 meters per hour, or 7.92 kilometers per hour

These results seem to be unreasonable, given what we see before and during the battle of Hoth since humans can easily out run the AT-AT. A human tends to have a top speed of something like 24 kilometers per hour in good conditions(not on snow) right?

Since the Rebels couldn't have been standing in those trenches for very long given the weather I have a hard time believing the Rebel's shield had a radius much larger then a couple kilometers given the slow speed the AT-AT moved at.

They work in the Tok'ra and the Jaffa. Dakara is well known to them, and the ruins is actually a fairly small area around the temple. There's no real need to aim when firing a 1.2 GT device at the ground.

CARTER: How much time do we have before Baal's fleet reaches Dakara?

O'NEILL: Why?

CARTER: Baal didn't say exactly where the device was, did he?

O'NEILL: No. He said it was hidden.

CARTER: Well, chances are it's in the ruins, but we can't be sure. I mean, short of blowing up the entire planet, we can't be a hundred percent positive we've destroyed it -- and if it's protected by a shield, even our biggest naqahdah-enhanced nuke might not do it.

For all they knew what they are looking for is at the center of the planet. They think it is likely in the ruins, but don't know, and on top of that they don't know what they are looking for.

The shield is extremely efficient and strong. The city was not designed as a starship, but they strapped a shield system on it that's simply the best out there.

Only if considerably stressed.

Only if considerably stressed is what would be expected from combat. Atlantis's shield was designed to let it travel safely through space, and help it deal with the rare negative space wedgie. I seem to recall the shield stopping at the surface of the water for example, and things being able to travel under it. Atlantis's shield is great so long as you have a steady supply of ZPM and the threat is direct.

The way the shield is used in the series only works because the Wraith want Atlantis in tact.

Well since covering a whole planet would be an upper end, it's safer and more reasonnable to consider it a theater shield.

But how much area was the shield powered by the volcano covering, and what was it covering?

In theory, I think only Halla, once turned into a Replanet, would be capable of complete planetary shielding.

In theory a lot of stuff could be done, but like most of that stuff it wasn't.

Obviously, if it were a theater shield, it would be built in order to prevent such problems. Most likely it will offer a very good area of protection so even a high seismic event, like a distant low gigaton explosion, wouldn't be hurting the base.

You can start earthquakes and cause volcanos to erupt by hitting the opposite side of the planet hard enough.

What was under the shield? It sounds like the Wraith wanted it in tact.

Depends on what you want in the form of a shield. It will pulverize any missile and solid projectile. I'm not sure how it would react to projectiles thrown at fractions of c, and there's no evidence that it would block particle beams.
It's not a complete shield, but if you look at modern defense systems, very few are polyvalent. The vast majority are only geared at stopping one kind of weapon.
Even some types of armour do well against kinetics, but are quite shitty against heat.

Fair enough, but why was the time dilation field built?

It's hinted at being an after effect of the time dilation field of this santuary, although we've seen other time dilated areas where there's no such effect at all.

That's not what I was asking, but I see how someone could make that mistake.

The effect was caused by the warping of space used to alter the flow of time inside the field.

Wasn't every other time dilation field planetary, or even solar system sized? That might have something to do with the differences.

It's not as good as those polyvalent generic SF shields the Lanteans use, that's why.

Warped space/time will always be better then a wall that can be punched through. It wouldn't matter how much force was applied to the outside unlike the shields used.

But what it means is that if they were to weaponize it, they could have time dilation fields be shaped to literally turn planets to bits.

That sounds like what we see when Star Trek ships hit things like planets with the navigational deflector is turned on.

[Lucky]

One very valid use for theather shields would be to stop anything smaller than said capital ships and huge weapons from being a threat. If it would be akin to a Star Trek forcefield you could effectively stop infantry and most small craft without them being able to do anything about it.

Just two thing:
1) We are talking about shields meant to defend against capital ships.

2) Those weak fighter weapons are often portrayed as being able to damage those gigaton throwing capital ships.

3) Star Trek covers entire planets in shields, and has the problem of fleet battles that happen near planets turning the nearby planets into asteroid fields.

A second point here, which is often forgotten about, is that the attackers may not actually want to blow up/irradiate/otherwise destroy the surrounding land. Most modern day attacks are not done with nukes either ;)

And then we have situations like Hoth where the entire planet could be turned into an asteroid field to kill the rebels, and it is likely no one would care because it is nigh useless.

I know that the argument is that the situation is not comparable because in Sci-Fi stories there are usually multiple planets so losing part/all of one is no big deal, but I don't buy it. 99% of military actions do not have the goal of random destruction, but getting rid of opposition or getting access to resources. Bombing worlds into the stone age and further won't make the natives any friendlier (see Babylon 5 and the Narn for one example), nor will it get you anything worthwhile to own.

The way you hear some (sarcasm)fans(/sarcasm) talk you would think some settings would consider having to do terraforming on a planet mildly annoying, and their (sarcasm)advanced(/sarcasm) technology would make it easy

The point of General Order 24(Star Trek), Base Delta Zero(Star Wars), and Extremis(40K) is to leave no survivors because you want what is on the planet dead.

Keep in mind every setting has it's Hoth. The one or more time when they can just unload on a planet with almost nothing holding them back.

In short, in my opponion theather shields probably work because a sane military (esp. one that belongs to a civilized bunch) generally won't blow up a chunk of planet to get below them.

We aren't talking about what generally happens in sane settings.

[Lucky]

Well, I thought we were talking specifically about SW, but yes, theater shields are a viable option...

The Hoth shield is just a well known example of shields that are designed to hold off capital ship, but are to small to hold off the attackers if they can fire even one gigaton shot do to the often neglected secondary effects of explosions.

[Praeothmin]

But since we know SW does not have GT weapons, then the Hoth shield makes sense... :)

Also, about the AT-AT's height, there was some scaling done I believe at SB.com or ADN, and maybe even here, and the general consensus was that they could not be 15 meters tall when compared to Luke, they had to be about 20 meters tall...



IIRC, of course...



Too lazy to do research...


And here, they say length of 20 meters with height of 22.5 meters...
At the bottom of the article, it also explains the confusion for the measures...

[Mr. Oragahn]

http://www.starwars.com/databank/vehicle/atat/
StarWars.com says AT-AT are 15.5 meters tall. Where are you getting your figures from?

They still have that one?!
Damn.

http://www.youtube.com/watch?v=C6uQ1ROQm0k
The problem is that we don't know if those are AT-AT appearing at 7:11. They could be AT-ST which we know were deployed at Hoth?

At 7:46 we see the AT-AT climbing up a hill that is taller then they are so we can't have seen them at 7:11. It makes it seem like the Rebel base was at the top of a hill rather then a valley like it is often shown in the EU. It makes you wonder what the guy with the binoculars was really see.

Then, wookieepedia's page claims a silly max speed, like 60 km/h. Yeah, whatever. That's over 16 m/s. Bollocks. Over 3/4s of the AT-AT's length. They'd need to be very agile to cover such a distance that fast, but they're not. Besides, this is ice and snow, so they'd rather have to be careful.

I thought I heard 90 somewhere as the top speed, not that it matters as you say.

90 km/h really is silly. That's 25 meters per second. More than their length.

If the AT-AT are 15.5 meters high that means they are about 17.7142858 meters long going by this picture: http://images.wikia.com/starwars/images ... T_egvv.jpg

I will just round up to 18 meters to simplify things, and I'm likely still lowballing the length a tiny bit.

18*60= 1080 meters per hour or 1.08 kilometers per hour

If we use your 22 meter length:

22*60= 1320 per hour or 1.32 kilometers per hour

If we assume the AT-AT at Hoth had been traveling their length every 10 seconds:

18*6= 108*60= 6,480 meters per hour, or 6.48 kilometers per hour

22*6= 132*60= 7920 meters per hour, or 7.92 kilometers per hour

These results seem to be unreasonable, given what we see before and during the battle of Hoth since humans can easily out run the AT-AT. A human tends to have a top speed of something like 24 kilometers per hour in good conditions(not on snow) right?

Since the Rebels couldn't have been standing in those trenches for very long given the weather I have a hard time believing the Rebel's shield had a radius much larger then a couple kilometers given the slow speed the AT-AT moved at.

We don't know. A thing that is clear is that when there's little wind, you can survive much longer outside, on the permafrost. Plus we don't know how long the walkers had been walking. The movie is full of cuts. The thing is, the rebel troopers had no need to leave the base until the enemy would soon be in range.
The rebels were far more concerned about leaving the planet. We see that as they didn't use more than their speeders for forward defense.
So I see no problem in accepting the large radius figure, especially since nothing contradicts it, really.

They work in the Tok'ra and the Jaffa. Dakara is well known to them, and the ruins is actually a fairly small area around the temple. There's no real need to aim when firing a 1.2 GT device at the ground.

CARTER: How much time do we have before Baal's fleet reaches Dakara?

O'NEILL: Why?

CARTER: Baal didn't say exactly where the device was, did he?

O'NEILL: No. He said it was hidden.

CARTER: Well, chances are it's in the ruins, but we can't be sure. I mean, short of blowing up the entire planet, we can't be a hundred percent positive we've destroyed it -- and if it's protected by a shield, even our biggest naqahdah-enhanced nuke might not do it.

For all they knew what they are looking for is at the center of the planet. They think it is likely in the ruins, but don't know, and on top of that they don't know what they are looking for.

All the dialogue says is that Carter considered that if the thing they were looking for was protected by a shield -which is a very clear statement- then it was possible that their best nuke might not get through such a defense.
Of course, in the absolute, since they couldn't know where the thing was on the planet, the only way to be sure to destroy it would have been to pulverized the whole planet, Death Star style. But that's just a way to see something obvious. It's not related to the statement about the shield.
Regarding the shield, it is impossible to tell if Carter was thinking of an Ancient made shield, or one put in place by Anubis.
So let's toss that one, since we can't guess more.

The shield is extremely efficient and strong. The city was not designed as a starship, but they strapped a shield system on it that's simply the best out there.

Only if considerably stressed.

Only if considerably stressed is what would be expected from combat. Atlantis's shield was designed to let it travel safely through space, and help it deal with the rare negative space wedgie. I seem to recall the shield stopping at the surface of the water for example, and things being able to travel under it. Atlantis's shield is great so long as you have a steady supply of ZPM and the threat is direct.

The way the shield is used in the series only works because the Wraith want Atlantis in tact.

The shield certainly can go through water at will, but in general it will be used to keep water at bay. It can fully cover the city.
Schematic views throughout the show prove that, as well as the times when we saw the city fly or fall.

What's about the steady supply of ZPMs?
It's just like saying any shield is good as long there's energy in the capacitors or fuel for the reactor.
What matters is how long a shield can last outside of resupply and how much it can take.
At best, a shield like that can be used with 3 ZPMs, so it can last quite some time, and we know it's damn powerful. One thing that's generally overlooked is some basic tactics the Wraith could have used during the war and the siege to get the shield down, like spamming rocks on the city. We saw them use asteroids as triggers against the proxy fuses of the gigaton mines placed in orbit of Lantea I.

Well since covering a whole planet would be an upper end, it's safer and more reasonnable to consider it a theater shield.

But how much area was the shield powered by the volcano covering, and what was it covering?

The area, we can't tell, but quite obviously the Lantean base plus the volcano itself, which was quite large.

Obviously, if it were a theater shield, it would be built in order to prevent such problems. Most likely it will offer a very good area of protection so even a high seismic event, like a distant low gigaton explosion, wouldn't be hurting the base.

You can start earthquakes and cause volcanos to erupt by hitting the opposite side of the planet hard enough.

Sure, but then how much energy would you need to input? What evidence do you use?

And the system itself was using energy from the mantle. If any pressure would happen, Lanteans could use it to power the shield. Not to say that they would have, at least, one Aurora-class ship to defend this outpost.
It is not negligible.

What was under the shield? It sounds like the Wraith wanted it in tact.

There's no indication that the Wraith wanted to capture anything. We can't tell. One thing that is sure is that no matter their goal, the only way they had to infiltrate the base was to get the shield down, which they could only achieve by brute force. Which would require quite a lot of firepower since the engine down in the caldera could pile up enough pressure so that if all were to blow up, the blast would be between 70 and 240 gigatons.

In theory, I think only Halla, once turned into a Replanet, would be capable of complete planetary shielding.

In theory a lot of stuff could be done, but like most of that stuff it wasn't.

That, you don't know.
Replicators can erect shields when they reach a scale where there's enough of them to make a ship.
I think it's a rather very safe assumption that they could erect a planetary shield to cover an area like the entire planet.
It's not like they'd absolutely need it. Any attack on them would have to be capable of being superior to high multi-GT attacks otherwise they'd most likely feed from the energy.
That would allow them quite some time to decide to raise a shield, even if it would be a patchwork of all shields that would be cast from the equivalent mass of cruisers.

Depends on what you want in the form of a shield. It will pulverize any missile and solid projectile. I'm not sure how it would react to projectiles thrown at fractions of c, and there's no evidence that it would block particle beams.
It's not a complete shield, but if you look at modern defense systems, very few are polyvalent. The vast majority are only geared at stopping one kind of weapon.
Even some types of armour do well against kinetics, but are quite shitty against heat.

Fair enough, but why was the time dilation field built?

For a sanctuary where you could focus on reaching the pre-ascension state and actually ascend.
Some humans had reached that stage, and had developped a wide variety of powers, but they had also collectively given life to some immaterial thing which was terrorizing them, so they actually were stuck and couldn't focus properly.
With the help of Sheppard, they somehow realized that the creature was out of their own mind, and so they could make it go away once they knew where it came from.

It's hinted at being an after effect of the time dilation field of this santuary, although we've seen other time dilated areas where there's no such effect at all.

That's not what I was asking, but I see how someone could make that mistake.
The effect was caused by the warping of space used to alter the flow of time inside the field.
Wasn't every other time dilation field planetary, or even solar system sized? That might have something to do with the differences.

Not always. The time dilation field seen in The Quest, put in place by Morgan LeFay, were only covering a small area around a cave.
The Asgards had a small TD device which they could use to focus a TD field towards a stargate.

The temporal shearing associated to the TF field of the sanctuary was an unique effect. All other fields may have a zone of transition, although some clearly don't but may negate such shearing since we see none.

It's not as good as those polyvalent generic SF shields the Lanteans use, that's why.

Warped space/time will always be better then a wall that can be punched through. It wouldn't matter how much force was applied to the outside unlike the shields used.

It would fail at stopping particles. It would only accelerate or delay their arrival inside the field. The very fact that light goes through is proof of that (although that's probably a part of TV SF that's overlooked, since there would be severe distorsion effects related to vision and light in proximity to such fields I think).