Quantum vacuum plasma thrusters as starship propulsion?

[Alchemist]

Last time I read something similar the next paragraph explained why this divider wouldn't work. Basically, one-way divider working with chaotic heat movement fastly heats to the point when it starts randomly opening and closing on its own

[Z-Man]

It's not a one way divider, just a selective one. I don't know whether such a thing exists. It still does not work as Maxwell's Demon, of course. What you put in is low entropy laser light, and what you neglect is going out is the high entropy radiation emitted by the atoms when they fall back into the ground state. So it's a fancy roundabout laser cooler, basically.

(Ignoring the other problems with the description. Like how an ideal gas would not cool down if you simply let it expand by removing the barrier, what you'd do instead is let it perform work by pushing the barrier first. That the excitation puts the gas out of thermal equilibrium, making temperature undefined and so the claim that temperature does not rise makes no sense.)

Edited April 16, 2014 by Z-Man

[Rakaydos]

I think I found it, but physics papers can be obtuse. Jump to section 2.

http://george.ph.utexas.edu/papers/Maxwelldemon.pdf

[Z-Man]

Yep: "Even in this extreme situation the second law holds as seen by taking into account the information that could be gathered by a photon detector, realizing the original scheme of Szilard." They don't claim the device IS Maxwell's Demon, they say it is similar, which is true.

[KASASpace]

A flywheel of mass m spinning with surface velocity v has total energy mv²/4. Maximum surface velocity for a steel flywheel is a little over 300m/s regardless of diameter. So a flywheel can only store about 25kJ/kg. Modern Li-poly battery holds more than 500kJ/kg. In other words, a modern battery is more than 20x better than a flywheel at storing energy. That's why you see a lot of remote controlled airplanes with batteries and none with flywheels. Oh, and there are commercial busses that run on batteries.

Please, stop arguing by posting various nonsense, when you don't know the physics or math to back it up. You really don't have any idea what you're talking about.

A flywheel stores energy more efficiently, not necessarily more energy.

I would suggest you pay attention, as that's your, I believe, second to third misunderstanding.

If by "various nonsense" you mean things that are obviously true, yet people with little to no understanding deny these things for no good reason (keep in mind, everything has a drawback, and so some things need to be done)

You're also forgetting, you don't necessarily have to be limited to 300m/s.

Also, I don't provide any mathematical proof because I'm trying to keep it easy on you, but even THAT'S not enough.

[K^2]

A flywheel stores energy more efficiently, not necessarily more energy.

I would suggest you pay attention, as that's your, I believe, second to third misunderstanding.

Batteries have higher capacity per weight and better conversion factor. I don't know what other measure of "efficiency" you have in mind, but these are the only things that matter to spacecraft applications, so you're wrong either way.

If by "various nonsense" you mean things that are obviously true, yet people with little to no understanding deny these things for no good reason (keep in mind, everything has a drawback, and so some things need to be done)

You're also forgetting, you don't necessarily have to be limited to 300m/s.

You still haven't demonstrated any knowledge, even as far as basic mechanics goes. 300m/s is a structural limitation. You can't go much faster.

Also, I don't provide any mathematical proof because I'm trying to keep it easy on you, but even THAT'S not enough.

Very funny. I have degrees in mathematics and physics. Why don't you try and impress me with your difficult mathematical proofs.

[N_las]

Also, I don't provide any mathematical proof because I'm trying to keep it easy on you, but even THAT'S not enough.

Please, don't go easy on K^2 . I would love to see 'any mathematical proof' from you. Your comments are are the only reason I read this thread, they are most entertaining.

So please, show us your calculations that demonstrate how using a quantum vaccum plasma thruster has advantages over any old ion thruster. I am really confused about that topic and would love to be enlightend by your insight.

[KASASpace]

Please, don't go easy on K^2 . I would love to see 'any mathematical proof' from you. Your comments are are the only reason I read this thread, they are most entertaining.

So please, show us your calculations that demonstrate how using a quantum vaccum plasma thruster has advantages over any old ion thruster. I am really confused about that topic and would love to be enlightend by your insight.

Did I ever say it provided any advantages?

No, I did not.

I said that it would have similar functions and uses, not any particular advantages.

Batteries have higher capacity per weight and better conversion factor. I don't know what other measure of "efficiency" you have in mind, but these are the only things that matter to spacecraft applications, so you're wrong either way.

Any particular source?

Batteries are lighter, yet flywheels can APPLY the energy they possess in a much more efficient manner, it's physical energy, which is more useful than electrical energy as well.

You still haven't demonstrated any knowledge, even as far as basic mechanics goes. 300m/s is a structural limitation. You can't go much faster.

Okay, how about some isogrid structural components to increase possible operational speed. Either that or some sort of honeycomb structure.....

Very funny. I have degrees in mathematics and physics. Why don't you try and impress me with your difficult mathematical proofs.

I never said they were difficult, I'm just saying you haven't shown much knowledge yourself.

Anyways, there is quite a common misconception about infinity..........

Believe it or not it has a numerical value.

[K^2]

Batteries are lighter, yet flywheels can APPLY the energy they possess in a much more efficient manner, it's physical energy, which is more useful than electrical energy as well.

Electric to mechanical can be over 97% efficient with brushless motors. Again. You just throw out random claims without ANY numbers to back them up.

Okay, how about some isogrid structural components to increase possible operational speed. Either that or some sort of honeycomb structure.....

You can typically get something like factor of 2x on streangth of the disk with that. You can probably get another increase with better materials. So maybe you can get 5x higher energy density by utilizing extremely expensive materials and manufacturing techniques. Cheapest LiPo batteries are still 4x better. Top of the line ones can be more than 10x better. And we're still making advances on these.

For the second time, if gyros were actually good at storing energy, that's what we'd be using in electric cars, RC planes, drones, and so on. But for some silly reason, people just keep using LiPo batteries for these. I wonder if it has anything to do with the above numbers.

I never said they were difficult, I'm just saying you haven't shown much knowledge yourself.

Anyways, there is quite a common misconception about infinity..........

Believe it or not it has a numerical value.

Suppose that was so. You are going to prove what, exactly, with that? I thought you were going to use mathematics to prove your points. About flywheels, or maybe QTs. Or maybe you can actually derrive something for warp drives.

But even your claim is absurd. Say it has numerical value. Call it x. Clearly, infinity + infinity is still infinity. So x + x = x. 2x = x. Divide both sides by x, which is a number according to you, and clearly not zero, so we can divide by it, and we get 2 = 1.

Now, there is a concept of extended reals. Here, infinity is part of the set. But it has special rules for binary operations so that you don't end up with the silliness above. It's very useful in measure theory. You could go as far as claiming that infinity as a number this way. Specifically, that infinity is an extended real number. But the fact that you claimed that it has a "numerical value," really underlines the fact that you don't get the concept.

[m4v]

I never said they were difficult, I'm just saying you haven't shown much knowledge yourself.

He did, you just quoted him calculating an estimate of the maximum energy a steel flywheel can store. So what are you trying to achieve? you're just rhetoric and not convincing at all.

[KASASpace]

Electric to mechanical can be over 97% efficient with brushless motors. Again. You just throw out random claims without ANY numbers to back them up.

Yes, but what if you needed that extra 3% for doing the appropriate work?

"can be"

Most ways probably aren't.

You can typically get something like factor of 2x on streangth of the disk with that. You can probably get another increase with better materials. So maybe you can get 5x higher energy density by utilizing extremely expensive materials and manufacturing techniques. Cheapest LiPo batteries are still 4x better. Top of the line ones can be more than 10x better. And we're still making advances on these.

For the second time, if gyros were actually good at storing energy, that's what we'd be using in electric cars, RC planes, drones, and so on. But for some silly reason, people just keep using LiPo batteries for these. I wonder if it has anything to do with the above numbers.

Flywheels, can apply a more useful type of energy.

Flywheels can also be used as inertial navigation at the same time.

And, since batteries are ONLY electrical, and ONLY energy storage, than it can be logically said that flywheels are a more useful choice on spacecraft, as you want to pack as much as you can into as many useful things as possible.

Suppose that was so. You are going to prove what, exactly, with that? I thought you were going to use mathematics to prove your points. About flywheels, or maybe QTs. Or maybe you can actually derrive something for warp drives.

But even your claim is absurd. Say it has numerical value. Call it x. Clearly, infinity + infinity is still infinity. So x + x = x. 2x = x. Divide both sides by x, which is a number according to you, and clearly not zero, so we can divide by it, and we get 2 = 1.

Now, there is a concept of extended reals. Here, infinity is part of the set. But it has special rules for binary operations so that you don't end up with the silliness above. It's very useful in measure theory. You could go as far as claiming that infinity as a number this way. Specifically, that infinity is an extended real number. But the fact that you claimed that it has a "numerical value," really underlines the fact that you don't get the concept.

Okay, okay.

Let's say we had a number, x.

No matter what you use for x, the formula below always applies:

x+(-)x = 0

Now, if we derive that:

x+(x+1)+(x+2)+(x+3)+(-)x+(-)(x+1)+(-)(x+2)+(-)(x+3) = 0

All numbers, all REAL numbers, when added together, give you the numerical value zero.

Now, we can also see how infinity and zero are related:

anything times infinity gives you infinity,

and anything times zero gives you zero.

As such, infinity is either, A) zero, or in need of new definition

[KASASpace]

He did, you just quoted him calculating an estimate of the maximum energy a steel flywheel can store. So what are you trying to achieve? you're just rhetoric and not convincing at all.

Oh really?

Okay, how about this:

The kinetic energy of a 1,000 gram (1kg) "flywheel" moving at 300 m/s is 90000000 Joules.

Now, since that is effectively "work", we can get the power, 90000000 J/per sec is effectively 90000000 Watts, or 90,000 kilowatts. That's not very close to what we need, but 1,000 kg is not the limit, not to mention.

Plus, if diameter and thickness do not matter, than you can make them more efficient by using more dense materials, if not equally efficient.

[Accelerando]

Oh my God, just stop already. Reading your posts is like a childrens' practice version of attempting to decipher the Time Cube.

[K^2]

Yes, but what if you needed that extra 3% for doing the appropriate work?

They you bring 3% more battery, and your ship is still 20x lighter. Are you really struggling with that concept?

Flywheels, can apply a more useful type of energy.

Again, electrical energy is converted into the same type of energy at a 3% loss. Heck, make it 10% loss. You want 50% loss? I'll give you that. Battery is still a more efficient storage. Again, if this weren't true, we'd actually be using flywheels for storage. We don't. Anywhere. Ever. Not since Lithium batteries became a thing. Have you ever seen a cellphone with a flywheel? Or a laptop? Or a satellite? Or a mass-produced car? Anything? Come on. Use your brain, please.

Okay, okay.

Let's say we had a number, x.

No matter what you use for x, the formula below always applies:

x+(-)x = 0

Now, if we derive that:

x+(x+1)+(x+2)+(x+3)+(-)x+(-)(x+1)+(-)(x+2)+(-)(x+3) = 0

All numbers, all REAL numbers, when added together, give you the numerical value zero.

First of all, so far you've been working with integers, not reals. There is an uncountable number of reals. You can't organize them into any manner of adding them together. What you've said applies to integers.

Except, it just doesn't work that way. Consider the following way of adding all integers together.

(0 + 1) + (-1 + 2) + (-2 + 3) + (-3 + 4) + ...

Absolutely any integer will show up in one of these brackets. So by adding all of these numbers together, we add up all the integers. Except, each bracket adds up to 1. Exactly one, no matter how far out you go. So the above is just 1 + 1 + 1 + ... What does that add up to? Well, certainly not zero. Certainly not anything negative, either. Unless... What if I add them up like this?

(0 + (-1)) + (1 + (-2)) + (2 + (-3)) + ...

Same thing as above, except this is -1 - 1 - 1... Which is certainly not positive. But not zero, either.

Moral? To find a sum of infinite series, you really need to understand what an infinite series is, and how it is defined via limits.

Now, we can also see how infinity and zero are related:

anything times infinity gives you infinity,

and anything times zero gives you zero.

As such, infinity is either, A) zero, or in need of new definition

Or it simply isn't a number. Which is the real case. You cannot multiply by infinity. You cannot add to infinity. You cannot perform any mathematical operation on infinity, because infinity is not a Real Number. Like I've pointed out, there are other algebras with slightly different definitions. And there are even some really creative ones where you can actually add infinities, but this has absolutely nothing to do with any mathematics you are familiar with. What you understand as numbers are Real Numbers. And what you understand as addition and multiplications are the binary operations on the Field of Real Numbers. These things are strictly defined in mathematics. People have thought really hard about some of the things you've brought up, and solved these issues over 100 years ago. And if you end up studying real mathematics, you will learn about all of this.

[KASASpace]

Oh my God, just stop already. Reading your posts is like a childrens' practice version of attempting to decipher the Time Cube.

If that is how you perceive the universe.....

[Dust]

K^2 - "Truly, you have a dizzying intellect."

KASASpace - "Wait till I get going!"

[m4v]

The kinetic energy of a 1,000 gram (1kg) "flywheel" moving at 300 m/s is 90000000 Joules.

Joules is kg*(m/s)^2, not g*(m/s)^2 so you got that simple math wrong, I also think that the kinetic energy formula for a non-rotating mass has a 1/2 somewhere.

Really, I know some forum members are finding this entertaining but this is sad.

[KASASpace]

They you bring 3% more battery, and your ship is still 20x lighter. Are you really struggling with that concept?

Again, electrical energy is converted into the same type of energy at a 3% loss. Heck, make it 10% loss. You want 50% loss? I'll give you that. Battery is still a more efficient storage. Again, if this weren't true, we'd actually be using flywheels for storage. We don't. Anywhere. Ever. Not since Lithium batteries became a thing. Have you ever seen a cellphone with a flywheel? Or a laptop? Or a satellite? Or a mass-produced car? Anything? Come on. Use your brain, please.

They don't use them because they are heavy, they have to be. This matters little once in space, especially if power is your only resource.

It's smaller and lighter, but it also has it's own fair share of problems:

What if the circuit the battery runs shorts out?

The battery will not provide more useable power, but the flywheel will keep on spinning.

Or what if the battery was built incorrectly?

Than its chemical composition will mess with EVERYTHING.

Or what if it leaks?

Believe it or not, it happens. Everything will have chemicals over it, and the battery becomes dead weight.

First of all, so far you've been working with integers, not reals. There is an uncountable number of reals. You can't organize them into any manner of adding them together. What you've said applies to integers.

Except, it just doesn't work that way. Consider the following way of adding all integers together.

(0 + 1) + (-1 + 2) + (-2 + 3) + (-3 + 4) + ...

Absolutely any integer will show up in one of these brackets. So by adding all of these numbers together, we add up all the integers. Except, each bracket adds up to 1. Exactly one, no matter how far out you go. So the above is just 1 + 1 + 1 + ... What does that add up to? Well, certainly not zero. Certainly not anything negative, either. Unless... What if I add them up like this?

(0 + (-1)) + (1 + (-2)) + (2 + (-3)) + ...

Same thing as above, except this is -1 - 1 - 1... Which is certainly not positive. But not zero, either.

Moral? To find a sum of infinite series, you really need to understand what an infinite series is, and how it is defined via limits.

Or it simply isn't a number. Which is the real case. You cannot multiply by infinity. You cannot add to infinity. You cannot perform any mathematical operation on infinity, because infinity is not a Real Number. Like I've pointed out, there are other algebras with slightly different definitions. And there are even some really creative ones where you can actually add infinities, but this has absolutely nothing to do with any mathematics you are familiar with. What you understand as numbers are Real Numbers. And what you understand as addition and multiplications are the binary operations on the Field of Real Numbers. These things are strictly defined in mathematics. People have thought really hard about some of the things you've brought up, and solved these issues over 100 years ago. And if you end up studying real mathematics, you will learn about all of this.

So, your point is it actually IS too difficult for you. Got it.

After all, you didn't understand it.......

AT ALL

And you know what?

I won't even bother to explain it to you, as you will probably never grasp such a simple concept.

[KASASpace]

Joules is kg*(m/s)^2, not g*(m/s)^2 so you got that simple math wrong, I also think that the kinetic energy formula for a non-rotating mass has a 1/2 somewhere.

Really, I know some forum members are finding this entertaining but this is sad.

You know what, I'm tired.

When I'm tired I can't do mathematical equations as effectively, and only when some thing are good can I do so.

You want what I meant, then?

1,000 kg

300 m/s

The power is 500*300*300, or effectively just 45,000,000 Joules, or Watts when over time.

45,000 kilowatts, per 1,000 kg.

Either way, density can be modified by using such things as depleted uranium, and thus changing energy density as well.

[TheGatesofLogic]

Stop making a fool of yourself, firstly you did the math wrong again. The energy stored in a fly wheel of 1000 kg with a surface velocity of 300 m/s is 22500000 joules, not 45000000 Joules, secondly your proposed amount of power is the amount of power one could supply FOR A SINGLE SECOND. No Longer. Power is a rate of energy transfer, not a stored potential of some kind as you seem to think, thus you cannot define a power density because it doesn't make any sense to do so. Thirdly, you contradicted yourself in saying that infinity has a real numerical representation, which of course it cannot or else a thousand years worth of revolutionary mathematicians have all been wrong, and the world we live in doesn't actually exist.

(ninja'd and edited)

please stop embarrassing yourself

Edited April 17, 2014 by TheGatesofLogic

[Accelerando]

If that is how you perceive the universe.....

This has nothing to do with how I perceive the universe, or very little to do with it at least. It has everything to do with the fact that you are humiliating yourself by your sheer refusal to bow to anyone else's analysis. You keep talking this inane rubbish about "giving the other opinion a chance" or "showing the other side of the argument" yet every time you are shown to be wrong, you do no research to verify either the other poster's or your own opinion, and keep coming back with the exact same "analysis", or dive deeper into your own misconceptions.

Batteries have a massive energy storage density advantage, on the order of double digits, over flywheels; and electromechanical systems can convert energy at 97% efficiency? Balls to that, you say! There must be a flaw, and it probably lies somewhere in the 3% of energy wasted out of the 97% * 20 times advantage that batteries have over flywheels! Or else K^2's evidence could be wrong! In other words, for you, no matter what proof anyone else offers, the only true base against which any claim can be argued against is your own imagined body of evidence.

Rubbish!

You are not making analyses. You are a making yourself a village clown!

[m4v]

You know what, I'm tired.

When I'm tired I can't do mathematical equations as effectively, and only when some thing are good can I do so.

And you know what?, I think you're just trolling. Nobody with some practice in physics would have missed that the result of that simple formula was 3 orders of magnitude off. You deliberately did that wrong so you can bait more people into this pointless discussion, I will not continue entertaining you.

[K^2]

They don't use them because they are heavy, they have to be. This matters little once in space, especially if power is your only resource.

Energy stored in the flywheel is mv²/4, as we've established. Kinetic energy of a ship traveling at v is mv²/2. So if we convert 100% of energy in a flywheel into kinetic energy, we get v/sqrt(2). That's about 210m/s for the flywheel we've been talking about. Make it twice as heavy to store twice as much energy, and you end up wasting twice as much energy to accelerate it. And we haven't even talked about mass of the ship here.

Flywheel has no practical applications as energy storage system. Again, if it did, there would be actual applications. There aren't.

It's smaller and lighter, but it also has it's own fair share of problems:

What if the circuit the battery runs shorts out?

The battery will not provide more useable power, but the flywheel will keep on spinning.

Unless bearings get busted.

Or what if the battery was built incorrectly?

Than its chemical composition will mess with EVERYTHING.

If the flywheel is built incorrectly, you won't be able to even spin it up.

Or what if it leaks?

Believe it or not, it happens. Everything will have chemicals over it, and the battery becomes dead weight.

And if a flywheel develops a crack, it explodes.

Actually, practice shows that electrical systems are less likely to fail than mechanical ones. That's why we use them for just about everything now.

So, your point is it actually IS too difficult for you. Got it.

After all, you didn't understand it.......

AT ALL

And you know what?

I won't even bother to explain it to you, as you will probably never grasp such a simple concept.

NO! YOU!!!!

See? I can do that too. Except it really does nothing except make you look both incompetent, and unwilling to even try and understand why you are wrong. But sure, have fun with this. I've been finding this whole thing immensely entertaining myself.

[N_las]

Either way, density can be modified by using such things as depleted uranium, and thus changing energy density as well.

The Energy in a flywheel will always be proportional to its mass. The energy density is a measure for stored energy per mass. So increasing the density of the flywheel by using depleted uranium doesn't effect the energy density at all. Using material with double the density allows for double the energy storage, but it will also double the mass. Hence the energy density isn't dependent on the density of the material.

[78stonewobble]

Hmm, the only place I know of that flywheels are used to provide power is in a supercomputer (not all, just one I heard off). Apparently conventional backup systems are not able to proved enough power quickly enough to continue running the thing. They still have backup systems, that take over in a power outtage, but thats after a shutdown and reboot, giving the emergency power enough time to kick in.

http://en.wikipedia.org/wiki/Titan_(supercomputer)#Hardware

Offcourse... Weight and room isn't as much of an issue in such a place compaired to a space vehicle.

Edited April 17, 2014 by 78stonewobble