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Topic: Thoughts about the Ur-Quan... (Read 32127 times)
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Art
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I remember that episode =p
Ahh..the Simpsons...Teaching Kids for 13+ years =p
This is a crazy thought.
Ignore the impossibility of about 90% of Star Trek universe..
Cylinder heated to above 100C...steam produced at bottom, rises to top, pushing turbine at half way, when it reaches top, it is teleported to bottom, and it starts over again.
I don't know how much energy would be used for the heating and the teleporters, I'm assuming (for the purpose of arguement) that they are small enough to be under the energy produced by the steam.
That would be a perpetual motion engine, provided the steam is produced in the first place, no? =p
There's no such thing as a teleporter. If there were, it would use up a huge amount of energy, depending on how it worked; no matter how it worked, it would have to use at least enough energy to negate any energy gains from your machine. In real life, magically jumping things from one place to another at no cost to cheat the Second Law of Thermodynamics doesn't work.
I'm not a scientist by training, but my reading has been wide enough (including multiple articles dealing with this very concept) to make it pretty clear that the Second Law of Thermodynamics (entropy constantly increases) is as near universal as any scientific law can be; every single observation made by scientists shows it to be true, and every single machine ever made has to work with it in mind. Certainly it's only a law of probability, not a deterministic law like other scientific laws, but it's a form of probability that always seems to hold -- it's always more probable that things go from order to randomness than vice versa. Any ordinary event that obviously broke the Second Law would safely be classified as a miracle, in the original sense of the term (a proof that there is something "supernatural", extremely deviating from normal reality, going on).
The exception is at the quantum level, where, indeed, you get something from nothing and order from randomness all the time; things are so small and simple at that level that many events can go in either direction with no problem. At the macroscopic level, the one we live in where quantum effects become undetectable, the probabilities *always* add up to an increase of entropy.
Meep-eep: the point of entropy is not just that the energy is "lost" from some particular place, but that the distribution of energy becomes more random. What we mean by "heat" is randomness -- when energy is released randomly into molecules, we say that the molecules are heating up.
Think of it this way: Your machine, however it works, is trying to get a bunch of energy to push in a certain direction. Whenever it does so, a bit of energy is leaked away, energy that's pushing in *all* directions, randomly. Every single thing you can do to *that* energy will *also* leak a bit of energy in all directions; there's nothing you can do to stop it. No matter how many times you try to "capture" the waste heat and put it to work, some always slips through the cracks, and you will always end up putting in more energy than actually comes out as work.
Any example you use will fall prey to this problem. If the work you're doing is heating things, then in order to be useful work you have to be heating a certain space, making that space warmer than some other space, and no matter what you do there will be heat energy spinning off into the outside, or into the interior parts of your machine, or radiating off as infrared radiation, or *something* other than heating the space you want to heat. (And every system you build to capture that heat or radiation that's not where you want it to be will *itself* spin off some energy as heat or extra radiation or something, and on and on and on.)
Think of it like pouring water through a series of pipes to fill a bucket; no matter how clean and smooth my pipes are, in real life there will always be a bit of water that sticks to the pipe on its way through and doesn't make it to the bucket. The more pipes I use, the more water I lose. And even if I try every possible method to clean the pipes, by wiping the pipes with a cloth or sponge and wringing it into the bucket, blowing air through the pipes, etc., the water will always stick to anything I touch it with and I'll lose a little that way (the sponge will still be slightly moist; the water will evaporate a little into the air; etc.)
The perfectly water-resistant surface that will let the water flow straight through without any sticking at all does not exist. The perfectly energy-conducting system that will transfer energy without any loss in waste does not exist, and since we have to build *everything* out of imperfect conductors of energy, every single part of every machine we build, every little nut and bolt, will waste some energy. That's life, unfortunately.
Note that "perpetual motion machines" don't necessarily have to be *true* perpetual motion machines; they can "cheat" by using an energy source that, itself, will run out, but that lasts so long that from our perspective it will last forever. Something that runs directly on the continuous light of the sun outside the atmosphere would be like that, or something that runs on the energy of the Earth's rotation, or on the slow decay of radioactive substances.
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Art
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It's called a "metaphor".
But one of the aspects of being very anal-retentive about real-world events is that even things with almost no adhesion to a surface at all, like mercury on glass, will leave a few undetectable traces at the molecular level. Nothing in the real world is perfectly non-adhesive.
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Culture20
Enlightened
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Thraddash Flower Child
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Semi-perpetual motion devices are possible. They last so long that they outlive us (possibly even our species).
The Sun is one example: Its own gravity keeps most the materials in the fusion reactions from exploding throughout the solar system. Eventually though, even its 2hydrogen->helium reactions won't be enough to counteract its gravity.
Creating a Sun is beyond our technological capability though. 
Before the accelerating-expanding universe theory, many Astronomers believed that the universe was a perpetual motion machine (gravity would eventually bring everything together into a big crunch, and the bang, crunch, bang, crunch was cyclical).
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« Last Edit: August 31, 2004, 03:32:39 am by Culture20 »
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Art
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Actually there is such a thing as a teleporter. While still in the early stages, scientists have discovered that they can "teleport" small amounts of
matter instantly across small distances. This was big news in the scientific and sci-fi communities about four or five years back.
I'm not sure exactly what you mean by this. Could you post a link to the article you mean?
Quantum teleportation, the thing that's closest to your idea, is not a true form of "instantaneous" travel (that idea itself is meaningless according to relativity). It transfers a quantum state from one place to another "instantaneously", but has to do so over a classical communication channel. In other words, it works by linking two particles or sets of particles together so that changing the state of one set changes the state of the other; in theory by linking a quantum state to an information pattern you could pop information from one place to another easily this way. However, the particles have to be in contact to be entangled initially, and to put distance between them they have to be transported by "normal" methods that are limited by the speed of light. The actual matter and energy has to travel at normal speeds; indeed, the information being "sent" is technically already in the entangled particle when it moves, so the information, too, is traveling at classical speeds.
The chief benefit of quantum teleportation is that it would allow the transfer of information without the distortion and interference you get from classical communication, sending information in a perfectly reproducible form. It also allows for quantum computing by the use of the many-worlds feature of a quantum state; a set of particles can be in multiple states at once and have its wavefunction collapsed to match a certain condition, allowing certain forms of computation. However, it's not a method by which you can cheat the Theory of Relativity and skip having to move things around in space under the speed-of-light speed limit.
In any case, this is tangential to the main idea; the use of an imaginary teleporter in a perpetual motion machine is to move things around for free; a basic idea for a perpetual motion is to have two linked teleporters, one suspended directly above the other, and pour water onto the bottom one. The endlessly flowing stream of water can then be used to drive turbines without ever running out; we harness the power of gravity without having to pay the cost of moving back up all the water that falls down.
No real-life system can work this way; every method of moving the water up again, whether by hauling it in buckets, using sunlight to evaporate it and let it condense higher up in the atmosphere, or setting up some sort of wormhole to transfer the water from one point to another will cost energy, and will cost more energy to move the water back up than the water gave us falling down. It may be that natural processes are inputting the energy so that from a human perspective *we're* doing no work and getting the energy for free (indeed, this is how we view waterwheels in real life, which are run by the free power of the sun's heat), but the energy must come from somewhere and eventually run out.
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Profound_Darkness
Zebranky food
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Current Mood: RL-Buisy...
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Whew, finaly read through it all, interesting.
Glad someone mentioned the photon teleportation.
As for a good source of potential energy why not stick a long bit of wire into orbit and grab some "free" electrons. As I understand it we have done a test similar to this but the wire burned up from nowhere to put the energy that got built up.
Think about how moving current through a bit of wire in a cylindricle shape gives you a magnetic field. Now take a magnet and spin it inside the coil of wire and you get energy. Finaly take a long bit of wire and set it in orbit perpendicular to the north/south magnetic line and notice some energy produced, the problem then would be a way to get the energy down to earth. A microwave would be dandy if you like lots of fried fowl and crispy airliners...
As for the light weight material for a dison sphere, it would need to be strong enough to counteract or capture the solar wind. Though if it did manage to deflect the solar wind back on the sun our sun would last a bit longer (probobly only a bit).
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meep-eep
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Meep-eep: the point of entropy is not just that the energy is "lost" from some particular place, but that the distribution of energy becomes more random.
I know what entropy is. Why are you saying this? What in my message gave you the impression that I didn't?
What we mean by "heat" is randomness -- when energy is released randomly into molecules, we say that the molecules are heating up.
No, we don't. It's about "random" movement. Energy can put into molecules in a different way (like exciting the electrons around an atom core).
Think of it this way: Your machine, however it works, is trying to get a bunch of energy to push in a certain direction. Whenever it does so, a bit of energy is leaked away, energy that's pushing in *all* directions, randomly. Every single thing you can do to *that* energy will *also* leak a bit of energy in all directions; there's nothing you can do to stop it. No matter how many times you try to "capture" the waste heat and put it to work, some always slips through the cracks, and you will always end up putting in more energy than actually comes out as work.
Reread my message. I was claiming was that if heat is the intended outcome, there is no waste energy. All energy in the form of heat is not wasted. If you want to attack my position, you should direct yourself to energy in other forms.
Any example you use will fall prey to this problem. If the work you're doing is heating things, then in order to be useful work you have to be heating a certain space, making that space warmer than some other space, and no matter what you do there will be heat energy spinning off into the outside,
Irrelevant. The goal is converting energy into heat. Whatever happens to that heat afterwards is besides the point.
or into the interior parts of your machine,
The interior parts will also give off heat. An equilibrium will form after a while.
or radiating off as infrared radiation, or *something* other than heating the space you want to heat. (And every system you build to capture that heat or radiation that's not where you want it to be will *itself* spin off some energy as heat or extra radiation or something, and on and on and on.)
Ok, you've got me there. A very small part may not be converted to heat. Negligible for practical purposes, but I have to give you that it's not a 100% effective conversion.
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“When Juffo-Wup is complete
when at last there is no Void, no Non
when the Creators return
then we can finally rest.”
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Art
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I know what entropy is. Why are you saying this? What in my message gave you the impression that I didn't?
People had mentioned that 100% efficiency was impossible because of the loss of energy as waste heat (in machines). You disputed this, because heat is still a form of energy and no energy is lost. I don't know the degree of your own understanding of thermodynamics, which may be greater than mine, but you gave the impression that you were saying energy inefficiency amounts to the disappearance of energy. I tried to clarify by explaining that the Second Law of Thermodynamics applies to an increase in entropy or disorder. If you feel I insulted your intelligence I apologize; this is a forum for general conversation, not a forum for professionals or technically trained people or a private conversation where we all know each other's credentials.
No, we don't. It's about "random" movement. Energy can put into molecules in a different way (like exciting the electrons around an atom core).
Yes. I apologize for being vague. The reason I said heat means "randomness" is that both heat and mechanical motion involve kinetic energy in molecules; the only difference is that heat involves random motion of individual molecules, resulting in an object that looks motionless at the macroscopic level, and mechanical motion is "ordered" motion of all molecules in a certain direction.
The point remains that when parts of a machine "heat up" the real phenomenon is a disordered release of energy.
Reread my message. I was claiming was that if heat is the intended outcome, there is no waste energy. All energy in the form of heat is not wasted. If you want to attack my position, you should direct yourself to energy in other forms.
Well, yes, except that just "making heat" is not the actual purpose of any machine. Machines by definition do work by applying energy in a particular way. There's always something you want to heat, and some things you don't care about heating, and any heating device can't help but heat some things you don't care about heating -- that's wasted heat.
If you aren't actually building a machine but are interested in the philosophical exercise of making heat, then that's not a problem; if you wait long enough, just about every form of potential energy (the chemical energy stored in complex molecules, the gravitational potential energy that allows stars to form, and so on) will end up dissipating into waste heat. That's the point of the Second Law of Thermodynamics, and unless something special happens to the universe (space-time collapses into a singularity where the laws of physics don't apply) the whole universe's eventual fate is to die a "heat-death" where clouds of slightly impure hydrogen dust swirl around at a universal equilibrium temperature.
So your hypothetical machine is not some theoretical future invention, but a rather basic description of, well, the whole world, and your efficient energy conversion is a description of the inevitable entropic process the whole world goes through. By extension it's also a description of the eventual fate of all energy that passes through any human-built machine at all. It's not terribly useful under the human engineer's definition of a useful machine, though.
Ok, you've got me there. A very small part may not be converted to heat. Negligible for practical purposes, but I have to give you that it's not a 100% effective conversion.
Actually, if your only goal is to just make heat eventually, then it is 100% efficient conversion, because all forms of radiated energy that escape your system, however weakly interacting, will eventually hit some matter and excite it, heating it up.
You're right that losses through radiation are small for practical purposes, but in practical purposes for heating devices the goal is to heat up a particular space, and the wasted heat is the energy lost heating up spaces you don't need to heat (because conduction and convection are not perfectly efficient ways of transferring heat energy). It's true that the relatively simple task of generating heat is easier to make efficient than more complex tasks, but the process is still never 100% efficient; some heat always escapes to a place you don't need it to go.
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