Ancient power problem

[Quadhelix]

Project Arcturus wasn't reacting things together to generate power either, it was drawing it from a separate reality

Incorrect: it was drawing power from their reality, not someone else's:

"Trinity" (SGA 2x06)

ZELENKA: Project Arcturus was attempting to extract vacuum energy from our own space-time, making it potentially as powerful as the scope of the universe itself.

CALDWELL: It strikes me as something the Ancients would have tried first, even before ZeeP.Ms.

McKAY: And they may have, but extracting zero point energy from our own universe is ... well, it's, uh, definitely trickier.

In any case, the point that I was making is that the ZPM is more than just a bottle with a spigot: it actually does something to harness energy.

So if I need 2 Post-its and the guy in the cubicle next to me needs 18 and the lady at the front desk needs 148 then the supplies guy gets 168 Post-its, gives me 2, the guy next to me 18, and the lady at the front desk 148.

Atlantis' power-control system knows the Done Chair needs a certain amount of power, the Shields need a certain amount, and the Stardrive needs a certain amount. So it pulls the required amount of power from the ZPM, and sends some through the conduits to the Chair, some through the conduits to the Shield Emitters, and the rest through the conduits to the Stardrive.

Except that you still haven't explained how it controls where that energy goes. You say it sends some through one conduit and some through another, but how does it control how much energy goes into each conduit?

Basically, your post-it analogy is flawed because the City's systems cannot go to the ZPM and get a bucket of energy, nor can the ZPM go to the City's systems: there is a certain amount of power released by the ZPM, and a certain amount of power absorbed by the city's systems, but the ZPM cannot control how much power goes to which system.

The systems could, conceivably, control how much power they received by altering their resistance, but there would almost certainly be a minimum resistance for each system, so unless Atlantis's lightbulbs can set their resistance in the millions of ohms (for when they are powered by a ZPM) and then lower them into the hundreds (for when they are powered by, say, a Naquada Generator), there has to be some other method of control.

[Control_Chair]

Except that you still haven't explained how it controls where that energy goes. You say it sends some through one conduit and some through another, but how does it control how much energy goes into each conduit?

Basically, your post-it analogy is flawed because the City's systems cannot go to the ZPM and get a bucket of energy, nor can the ZPM go to the City's systems: there is a certain amount of power released by the ZPM, and a certain amount of power absorbed by the city's systems, but the ZPM cannot control how much power goes to which system.

The systems could, conceivably, control how much power they received by altering their resistance, but there would almost certainly be a minimum resistance for each system, so unless Atlantis's lightbulbs can set their resistance in the millions of ohms (for when they are powered by a ZPM) and then lower them into the hundreds (for when they are powered by, say, a Naquada Generator), there has to be some other method of control.

In Adrift didn't McKay say something about the city realising power wasn’t making it to the outer piers because of the damage caused to the cities power conduits by the Asuran satellite beam, so the city began drawing more power from the ZPM and began collapsing the shield to compensate. How the city would do this I am unsure (possibly by altering the resistance of the power conduits or by increasing power output from the ZPM).

[Duskofdead]

The main problem I always had with ZPM's was that they were introduced originally as some kind of "ultimate power source", at the very fringe limit of theoretical scientific understanding from the point of view of people like Carter or the smartest modern-day humans.

Yet, obviously, Ancients had technological capabilities which far exceeded their abilities to efficiently and reliably power all of it. Atlantis, for example, there's evidence all over the show that when the city is running "fully powered", I'm talking every little automatic sub-system, every active system, etc., it requires full use of whatever ZPM's are available and even then, drains them FAST.

In "The Siege", we know that even with (by Ancient standards) weak Wraith weaponry, a barrage on Atlantis's shield could completely drain a ZPM in three days.

I don't know about any of you but all of that put together, tells me that the power generation capacity of the Ancients fell quite a bit short of all the fancy technologies they were able to create, OR, they were over-perfectionists who added every bell and whistle to everything they ever created, making every device a vast power-hog that required way too much energy in order to perform its fundamental functions. Or, an out of universe commentary would be that the writers too heavily stunted the limits of ZPM power generation in order to create tense dramatic crises in the Atlantis storyline, because those things sure run out easy even being used only for critical functions that the Ancients apparently performed on a routine basis.

[sunrek]

Incorrect: it was drawing power from their reality, not someone else's:

You're right. I'm sorry about that.

In any case, the point that I was making is that the ZPM is more than just a bottle with a spigot: it actually does something to harness energy.

No, it only shows that Arcturus does something to harness the energy. If that's what ZPMs could do from the get-go, then they wouldn't have to have gone to all that trouble to invent Arcturus. No I don't know how ZPMs do it, but I wouldn't characterize them as Generators. Not Arcturus either for that matter.

Except that you still haven't explained how it controls where that energy goes. You say it sends some through one conduit and some through another, but how does it control how much energy goes into each conduit?

Basically, your post-it analogy is flawed because the City's systems cannot go to the ZPM and get a bucket of energy, nor can the ZPM go to the City's systems: there is a certain amount of power released by the ZPM, and a certain amount of power absorbed by the city's systems, but the ZPM cannot control how much power goes to which system.

The systems could, conceivably, control how much power they received by altering their resistance, but there would almost certainly be a minimum resistance for each system, so unless Atlantis's lightbulbs can set their resistance in the millions of ohms (for when they are powered by a ZPM) and then lower them into the hundreds (for when they are powered by, say, a Naquada Generator), there has to be some other method of control.

[/QUOTE]

Why are you assuming that the whole of Atlantis is on one serial circuit? The Ancients would have known better than that. Why can't the Stardrive be on one circuit which handles the massive power requirements of the city's engines, and the mood-lighting is on a separate circuit that only pumps through enough power to illuminate the city. And for a race as advanced as the Ancients, it's not too much of a stretch to think that each pier, building, and system has its own sub-system to control how much power is sent through each circuit.

Anyway, I'm saying the ZPM only releases power as it's needed (they don't deplete when not in use or only powering a small EM field), and the power is sent only to where it needs to go. The Ancients may not have been all that smart when it came to tactics, but they could have developed a smart power-distribution system.

[lordofseas]

I don't think the ZPM controls the output of the energy, I believe that the Hub or the station that its placed in does.

[Quadhelix]

In Adrift didn't McKay say something about the city realising power wasn’t making it to the outer piers because of the damage caused to the cities power conduits by the Asuran satellite beam, so the city began drawing more power from the ZPM and began collapsing the shield to compensate. How the city would do this I am unsure (possibly by altering the resistance of the power conduits or by increasing power output from the ZPM).

This makes sense in the "Resistors paradigm": the amount of power received by any particular device is the square of the current flowing through it divided by its resistance. In other words, to keep power output constant, you have to keep current constant.

If the power conduits are damaged (raising their resistance), then the amount of current is going to drop. This means that the ZPM is going to have to increases its output somehow, either by increasing its voltage or by lowing its own internal resistance. Now, for that particular branch of the circuit, this balances out. Unfortunately, there are other circuits in parallel with the damaged circuit, and these circuits now have a higher voltage across them.

Thus, in order to restrict the flow of current, the "regulatory resistors" are going to have to increase their resistance. However, for a given resistance, current increases proportionally to the voltage, while power consumption increases proportionally to the square (the equations are I=V/R and P=[V^2]/R). What this means is that, if you increases the voltage while maintaining a constant current, power consumption is still going to increase.

Yet, obviously, Ancients had technological capabilities which far exceeded their abilities to efficiently and reliably power all of it. Atlantis, for example, there's evidence all over the show that when the city is running "fully powered", I'm talking every little automatic sub-system, every active system, etc., it requires full use of whatever ZPM's are available and even then, drains them FAST.

A. How fast is "fast"? A month? A year? A week?

B. All that this means is that 1) the Ancients didn't leave every single gadget running and/or 2) the Ancients could build new ZPMs fast enough to replace the old ones as they were depleted.

No, it only shows that Arcturus does something to harness the energy. If that's what ZPMs could do from the get-go, then they wouldn't have to have gone to all that trouble to invent Arcturus.

Actually, yes, ZPMs do actively tap ZPE. The difference between a ZPM and Project Arcturus is that a ZPM is limited to a "pocket universe," while Arcturus has the entire universe at its disposal

That is why they tried to develop Project Arcturus.



BTW, note this quote:

McKAY: A Zero Point Module is an artificially created region of subspace time. It's kind of like a miniature universe in a bottle.

ZELENKA: It extracts vacuum energy from this artificial region of subspace time until it reaches maximum entropy.

Why are you assuming that the whole of Atlantis is on one serial circuit?

I'm actually assuming that they are on parallel circuits with a common voltage source (the ZPM).

Because the circuits are in parallel, they have the same voltage across them. This means that the power drawn by a given circuit will be (V^2)/R, where R is the resistance of that circuit. Now, unless the stardive has less resistance than the lightbulbs, the circuit containing the lightbulbs is going to have to have a fairly large resistor to keep the lights from hogging all the power that should be going to the stardrive, shields, etc.

However, because that resistor is in series with the lightbulbs, we have to use P=(I^2)*R to determine how much power the resistor gets relative to the lights. If the lights are in series with one another, then the current flowing through the resistor is the same as the current flowing through each light, and since the resistor has a higher resistance than all the lights put together, it is going to use most of the power being drawn by that circuit.

If, however, the lights are in parallel with one another, then the amount of current flowing through the resistor is going to be the current flowing through each light multiplied by the number of lights. In other words, the resistor is still going to be using huge amounts of power relative to the lights, though probably not so much power compared to the stardrive.

Anyway, I'm saying the ZPM only releases power as it's needed (they don't deplete when not in use or only powering a small EM field), and the power is sent only to where it needs to go. The Ancients may not have been all that smart when it came to tactics, but they could have developed a smart power-distribution system.

Right, but like I was saying, the only way to control where that power is going to go is by adding in resistors that "block" too much current from traveling down circuits that require only small amounts of power.

However, due to the nature of the circuits, these resistors will use the lion's share of the power being drawn by that circuit.

[sunrek]

Right, but like I was saying, the only way to control where that power is going to go is by adding in resistors that "block" too much current from traveling down circuits that require only small amounts of power.

Or not sending power down the conduits that aren't using them. If the Shield isn't up, why send power to the Shield generators? All the lights on the East Pier are off except the ones in Tower Two? Only send enough power through the East Pier Lighting circuit to power the lights, and only send it through the conduit that goes to Tower Two. If the only thing in the whole city that is turned is a 80-watt lamp in East Pier's Tower Two, shut down power-distribution to everywhere but there, and only send enough power through the conduit to power the lamp. The only drain on the ZPM is however much it needs to keep that lamp lit (plus whatever systems comprise the power-distribution system). Think of it like flipping off the Circuit Breakers instead of switching off the lights. Only thing that needs to be on while you're away is the refrigerator? Kill everything except the breaker that the fridge is on.

[Quadhelix]

Or not sending power down the conduits that aren't using them. If the Shield isn't up, why send power to the Shield generators? All the lights on the East Pier are off except the ones in Tower Two?

This is all rather obvious. In fact, I was taking this as given in my previous arguments: the systems that don't need any power are not going to be connected to the ZPM.

Only send enough power through the East Pier Lighting circuit to power the lights, and only send it through the conduit that goes to Tower Two. If the only thing in the whole city that is turned is a 80-watt lamp in East Pier's Tower Two, shut down power-distribution to everywhere but there, and only send enough power through the conduit to power the lamp. The only drain on the ZPM is however much it needs to keep that lamp lit (plus whatever systems comprise the power-distribution system).

That is all well and good when the only thing running in the City is 80-watt lamps.

However, what you keep failing to address is what happens when you want to run an 80-watt lamp and, for example, the shields. One of them is going to draw more power than the other - and if you just connect the two in parallel, it's probably going to be the lamp. That is why you need the resistors.

[sunrek]

One of them is going to draw more power than the other - and if you just connect the two in parallel, it's probably going to be the lamp. That is why you need the resistors.

Is this true if they are on separate circuits?

[Quadhelix]

Is this true if they are on separate circuits?

This is true only if they are on separate circuits.

This is because both circuits have the same voltage source: the ZPM. Since the two circuits share a voltage source, they have the same voltage across them, which means that the circuit with the lower resistance is going to receive more current.

However, the power drawn by a circuit is the voltage across that circuit multiplied by the current flowing through it. Therefore, because the two voltages are the same, the circuit with the higher current will draw more power.

[sunrek]

In my house most of the circuits are 110 volts. For a few things, like the dryer, there are circuits with 220 volts. They share a voltage source (the power-line coming into my house). When my dryer is running, the circuit the lights in my living room are on doesn't suddenly become a 220 circuit, and it doesn't need an adaptive resistor to do that.

[Quadhelix]

In my house most of the circuits are 110 volts. For a few things, like the dryer, there are circuits with 220 volts. They share a voltage source (the power-line coming into my house). When my dryer is running, the circuit the lights in my living room are on doesn't suddenly become a 220 circuit, and it doesn't need an adaptive resistor to do that.

Okay, first, that is AC, which is an entirely different kettle of fish than DC.

Part of the issue is that the power lines actually have very, very high voltage (>100,000 volts). When it gets to your house, it converted to low voltages by a transformer. The 120-volt circuits are connected to a different transformer than the 220-volt circuits, so actually, they don't have the same voltage source.

[Duskofdead]

A. How fast is "fast"? A month? A year? A week?

B. All that this means is that 1) the Ancients didn't leave every single gadget running and/or 2) the Ancients could build new ZPMs fast enough to replace the old ones as they were depleted.

For the first question-- how many times has Rodney flipped out yelling that if they don't shut something down the ZPM is going to be completely drained in minutes/hours?

It's been frequent, IIRC. Sometimes even just single devices or functions have threatened to totally drain a ZPM.

For B., yes, obviously the Ancients didn't leave every system at full power 24/7. But I still think that there is a contradiction in the show where the Ancients are supposed to be at the verge of infinite knowledge of the workings of the universe, and near maximum technological progression (only the Asgard even approached their level of technology, not including the Ori, who are basically the "same race" as the Ancients) would basically rely on these "batties" which would have had to have been spammed en masse and replaced like copper tops going by the limits of ZPM energy output we have seen written into the show. Again, like I said before I think this is a matter of the writers conveniently making the ZPM limited to keep tension and crisis possible in Atlantis (otherwise just connect the ZPM to Atlantis/Daedalus and you're gold, basically) but I do believe that the inconsistency does exist where ZPM's are treated (even by Asurans somewhat) as important resources created in relatively small numbers which then various episodes treat like insufficient power sources that get drained at the drop of a hat.

I think if ZPM's were the ultimate power source the Ancients came up with, they should for all intents and purposes replace generators as a more "permanent" power source, rather than something that gets drained every so many hours/days. Seems like an inefficient system.

And yeah this is all subjective interpretation based on the different impressions we've been given of ZPM's in the show. I don't get into the technical side of how they're supposed to work or how theoretically they work because I think it's pointless and we'll never know. They'll be as powerful or limited as the writers make them and operate according to whatever rules writers make up.

[Quadhelix]

For the first question-- how many times has Rodney flipped out yelling that if they don't shut something down the ZPM is going to be completely drained in minutes/hours?

No clue, but without specific examples, we can't really evaluate the situations.

It's been frequent, IIRC. Sometimes even just single devices or functions have threatened to totally drain a ZPM.

Yes, but those tend to be the exception rather than the rule (e.g., the Miller Spacetime Bridge).

It should also be noted that Atlantis has, for the most part, been running off a single ZPM when it was designed to run off of three. While this might have increased the rate of depletion linearly, it is also possible that functions that could nearly deplete a single ZPM would "barely register" on three.

But I still think that there is a contradiction in the show where the Ancients are supposed to be at the verge of infinite knowledge of the workings of the universe, and near maximum technological progression (only the Asgard even approached their level of technology, not including the Ori, who are basically the "same race" as the Ancients) would basically rely on these "batties" which would have had to have been spammed en masse and replaced like copper tops going by the limits of ZPM energy output we have seen written into the show.

Well, it is possible that ZPMs, as "limited" as their output is, are simply the best possible power source, barring, perhaps, actual ZPE extraction from normal spacetime.

I think if ZPM's were the ultimate power source the Ancients came up with, they should for all intents and purposes replace generators as a more "permanent" power source, rather than something that gets drained every so many hours/days. Seems like an inefficient system.

The problem with this is that any generator is going to require fuel. The theoretical limit of the amount of energy (E) that can be extract from a mass (m) of fuel is E=m*(c^2). Thus, by the following set of calculations...

Spoiler:

A lightning strike apparently carries about 5*10^8 J of energy. Based on "The Eye," if we assume that it takes a lightning strike every five seconds to power the shields, it would take 6,307,200 lightning strikes (or 3*10^15 J) to power the shield for one year. Multiply that by 3,000 years and we find that a single ZPM should have an output of somewhere around 9*10^18 J.

Using E=m*(c^2) to calculate how much mass would have to be put into a matter/anti-matter reaction to get the same output, we find that the combined mass of the matter and anti-matter would have to be 105 kg. Additionally, most of the output of the matter/anti-matter reaction is going to be lost as neutrinos, so you presumably need even more matter and anti-matter to match the output of one ZPM.

On top of this, the calculations above don't even take into account the extra drain on the shield due to water pressure, so it is quite possible that the ZPMs' effective output is much higher.

...we find that even if there was no extra strain on the shield from being submerged, it would still take 105 kg (that is about 230 lb.) of our hypothetical 100% efficient fuel to match the energy that can be harnessed by one ZPM.


Thus, the choice is is not whether to use a ZPM or a generator, but rather rather whether to use a ZPM or a generator plus well over 200 lbs. of fuel.

[Duskofdead]

Wow okay WAY too technical.

My point was merely this: I think the ZPM's are touted to be ultimate in some cases, then made too limited in others. It was a writing contradiction (IMHO) which had to do with keeping dramatic tension more than hard thoroughly thought out mechanics of how ZPM's worked in the Ancients' civilization.

I think the fact that in "Before I Sleep" the Ancient scientist leaves Weir with the same three ZPM's that presumably were already "plugged in" for a 10,000 year powering of the shield implies both that the power potential is enormous and also that the Ancients didn't simply have hundreds or thousands of these things laying around spare in storage. In fact I'd go further and speculate that the Ancients did not anticipate have to frequently replace ZPM's-- or ever. (Who thinks about replacing a power source that can potentially last centuries or millenia?) Otherwise it gets dicey explaining Atlantis not having extras given that it was the last great holdout of the Ancient empire (and under siege, no less.) I reject the supposition a few have made that they mass evacuated tons of tech and a bunch of ZPM's to Earth since we know they "absorbed" themselves into Earth civilization of that time and Earth didn't have tons of spare ZPM's laying around.