If you gamble £100, and win £60 back, does that count as a profit? 
Free in the sense that we are getting something back that we might otherwise have thrown away, yes (although it is probably better seen as just an overall improvement of the efficiency of the entire system.
But not free in the ‘free energy’ sense - which tends to mean something that the universe gives us for nothing (and also hasn’t been demonstrated to work).
While far from free (actually pretty damn expensive if this were the only reason to be up there) i remember that an experiment on one of the shuttle missions consisted of paying out a length of wire to see how much power would be generated by passing through earth’s magnetic field. The conductor quickly began to glow and eventually burned itself in the clear. Still, a great idea and a good way to keep the batteries charged (with a little tweaking…)
Fiat Lux,
Yeah, I guess it’s more prepaid than free. We had to use fuel to get the energy that we recover.
Not free energy, but the OP reminded me of the whispering wheel, which I’d read about last year.
Anybody heard of this, know of it, think it sounds like it will work, IS it working, etc.?
Even if you keep the wires from melting, it’s still probably not a good way to keep the batteries charged. Just like with the car, the wire would produce a drag force on the spacecraft, causing its orbit to decay a little faster than usual, and requiring a little more fuel to be spent to boost the orbit. Effectively, you’re burning that extra fuel to generate the electricity, and I can’t help but suspect that it’d be more economical to just burn fuel in a fuel cell.
Mangetout, you’re right. There are two ways to overcome that problem, either have a pantograph attached to the car and overhead wires, or use some magnetic insulator 
I am sure that some crackpot scientist has designs for such a thing!
It works. It’s not a new concept. It is basicaly an electric car that has an onboard diesel generator. The advantage over a typical car is that the generator works at the optimum rpm at all times. Although this configuration adds an additional energy conversion step, the overall gain is bigger than the loss.
“The abdomen, the chest and the brain will forever be shut form the intrusion of the wise and humane surgeon,” said sir John Eric Erickson, British surgeon appointed to Queen Victoria in the Year 1873.
Except that the Laws of Thermodynamics are about fundamental characteristics of energy, while Dr. Erickson’s statement was about the complexity of these organs being undecipherable. While, as another Brit knight, Sir A.C. Clarke puts it, any sufficiently advanced technology might as well be magic, creating energy truly out of nothing would BE magic. Obtaining it from something/somewhere you did not previously know was there, OTOH, violates neither, but it is still NOT creating it out of nothing, and it still is not overcoming a fundamental property. (And if you can give no coherent explanation of where the energy came from, you’re still gonna have a bitch of a time selling it to science.)
Of course, those cables that can convert the energy of the shuttle’s orbital velocity into electricty can also run in reverse. You can use electricty from the solar panels on a satellite or space station to alter the satellite’s orbit so you don’t have to expend reaction mass.
Agreed. I’ve got no dog in this fight, just playing dueling Brit quotes.
I know I’ll live to regret this but the second law is not defined in the same as the first and violating it is a bit more of a gray area. I am not a crackpot* and I totally agree with the second law but it describes a trend in closed systems rather than an absolute rule.
Thought experment. Diver A stands at the top of a 10 metre platform and has potential energy X which is derived from his mass, the acceleration of gravity and his height above the pool. He dives and now has kinetic energy X as he hits the water. On striking the water much of X is tranferred to the water, sloshing the pool around and making it a tiny bit warmer.
Some of the water molecules will bounce off our diver/swimmer and make him a little warmer. Waves in the pool which are somewhat more ordered will move him around a bit as he swims back to the ladder. What prevents the energy in the water molecules from pushing in the right direction to spit the diver back out of the pool, back onto the 10 meter platform, making the water slightly cooler and more still in the process? Nothing really.
Now that isn’t the same as saying you can cause that to happen or that it is remomtely likely in the span of our known universe. Odds are probably better that a quantum fluctionation will cause a maskrug of fine Deutsch bier to materialize on my desk… now. Damn, that really sounded good.
For the record I will state that no one can design a refrigerator that doesn’t make the kitchen a bit warmer or power a motor from a generator that in turn is driven by the motor. There is no way to succinctly define the second law. People make entire careers based on it so no way to wrap it up in a sentance. One way that hopefully isn’t totally incorrect is to day that there is no way to make a process where the only result is to move energy from one place to one with higher energy.
*If you tell people you are not a crackpot then you have removed all doubt.
[QUOTE=Padeye]
I know I’ll live to regret this but the second law is not defined in the same as the first and violating it is a bit more of a gray area. I am not a crackpot* and I totally agree with the second law but it describes a trend in closed systems rather than an absolute rule.
Before he even hit the water, he lost some energy due to friction and air resistance.
If the molecules gain kinetic energy, there’s lost kinetic energy in the diver. That’s what slows him down on entry. The gained heat is negligible in comparison.
Waves in the pool will be turbulent, therefor disordered. Therefore, the following idea of the waves pusing him to the ladder relies on compound probabilities which make the scenario so unlikely to ever happen that we can reliablely say that it won’t. Or in other words, the odds are probably far worse than those of bier materialising, because there’s far more atoms involved.
Chronos,
I was actually thinking that this would be applied to satellites, not the space shuttle (although my comments were vague enough that i could have been talking about damn near anything). Unless i’m mistaken, satellites are boosted into orbit and then are basically in free-fall with no additional navigation adjustments made. What batteries there may be would be used to boost reflected communications or to transmit information.
yes, satellites are basically in freefall, ignoring the miniscule amounts of drag that originate from all sorts of sources…but quite simply, paying out a long wire to create current will slow the satellite down, and any length creating significant current will also create significant drag.
None of this is necessary, given that solar power is so plentiful in space.
That’s exactly what I said GorillaMan. My point was that even though the odds are ridiculously low that an event could happen is not the same as there being an axiom that says it cannot happen.
How does this follow? I guess that i don’t understand how a thin wire is going to create a lot of drag in space. Yes, there may be a bit more mass to propel to orbit, but once it is ‘parked’ in a stable orbit it should be no different than any other satellite of similar mass.
I actually found some info on the NASA site. On flight STS-75 in 1996, a joint US/Italian test of the Teathered Satellite System in the ionosphere was cut short when the tether snapped; although they claim to have gotten some useful information:
Unfortunately, it doesn’t explain exactly what they were hoping to accomplish other than “…to study electrodynamics of a tether system in electrically charged portion of Earth’s atmosphere…” and the parting of the line on the third day cut the experiment short. Still, i can appreciate someone thinking this up, i just wished it would have worked.
As I understand it, for the same reason there is drag on the armature of a generator.
That’s a hellava lot of unsprung weight.
Lenz’s Law (the Murphy’s law of Physics): An induced electromotive force generates a current that induces a counter magnetic field that opposes the magnetic field generating the current.
The drag is an electromagnetic effect, rather than one of physical friction (although it could rightly be argued that physical friction is an electromagnetic effect at the atomic scale).