Yesterday I made the mistake of entering the search term "perpetual motion" at youtube.com. Then I lost an hour of my life looking at videos claiming to make perpetual motion engines out of natural magnets. These videos fascinate me because I presume they are all fake. It seems to me that if any of these devices worked I wouldn't have to hunt around on youtube to find them. I'd already have one in the garage charging my electric car. So what is up with these videos?

One theory is that all of the inventors started out seriously trying to build perpetual motion machines, realized at some point they couldn't do it, and decided to salvage something out of the effort by making fake videos and getting some attention.

Another theory is that the so-called inventors never intended to do anything but create fake videos. But it sure seems like a lot of work for that. That option seems unlikely to me.

Lastly, we must entertain the possibility that the laws of physics have some sort of loophole, inventors sometimes find it, and the big corporations send around hit men every time it happens. That's why you never see the invention beyond youtube.com or some local news show. But that seems unlikely too. So it remains a mystery.

As I was googling around on this topic, I discovered that there is an element called gadolinium that is attracted to magnets up to about room temperature, then it abruptly loses its attraction . It seems to me you could build a generator using that principle. All you need is an external source of heat, and not much of it, to power the thing. A natural magnet could attract the gadolinium, which creates some mechanical energy, and some portion of that energy could be used to introduce heat from the outside that makes the gadolinium non-magnetic and puts the device back to its original position. Some of that energy from the return trip would turn off the outside heat source and the process repeats forever. It would only operate at about room temperature, but that's still pretty nifty. The inside of my house, for example, is always at about room temperature, so there is no shortage of that environment.

Yeah, I know, someone probably already invented it.
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May 21, 2008
To generate useful power, you need a difference in temperature. If it warmer outside than inside, you could use that temperature differential to generate power, but you would have the heat flowing into your house and would then need the air conditioner to remove the heat again. In the winter, vice versa. There would be net energy loss.

You could use the fact that the ground is cooler 10 feet down than the air in the summer (and vice versa in the winter) to generate some power, but you would be limited by the grounds ability to conduct the heat away. In short, you wouldn't be able to get much energy from it. Maybe enough to run a clock.
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May 21, 2008
I've just instructed my broker to buy me 2,000 lbs of Gadolinium secure in the knowldge that the $4/ounce I paid for it today will seem like a pitance when your idea takes off. Thanks for the heads up!

May 21, 2008
Hmm... Varying heat... Can you combine gadolinium with a Stirling Engine?
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May 21, 2008
All we need to do is breed more hamsters, and feed them used-up hamsters from the wheels they run in to generate our power.

Per-"pet" ual motion will ensure we get out of our greenhouse problems. All we need to do is stop making fuel out of all the grain and give a little to our willing energetic furry chums.
May 21, 2008
Doncha really hate it when you think of some really cool invention and 13 people tell you "Phooey! Been There. Done That."

It's a Dilbert kind of life, isn't it?

May 21, 2008
Already been done: by the famous Italian inventor Gado Li Nium in 1879.

You're Welcome.

May 21, 2008
Quote (http://en.wikipedia.org/wiki/Perpetual_motion_machine):

"A perpetual motion machine of the first kind produces strictly more energy than it uses, giving the user unlimited energy. It thus violates the law of conservation of energy. Over-unity devices, that is, devices with a thermodynamic efficiency greater than 1.0 (unity, or 100%), are perpetual motion machines of this kind."

For your machine, you input a little energy in the form of heat to heat this element. The magnet delivers useful. mechanical work. Now, since your description is vague, I can't really say whether or not it is a perpetual motion machine.

The machine could not output more energy than what is put into it, i.e. the heat source. So, basically there will always be more energy generated from the heat source than would be output by your machine.

Now, I don't know for sure, but I'd be willing to bet that the theoretical thermal efficiency of your system is not at all comparable to that of some of the current systems for converting heat energy into mechanical work, such as a Brayton, Otto, etc.

May 21, 2008
there are no free lunches in physics - to put it in economic terms every joule(/calorie) extracted from a system has an "opportunity cost", that is the mass that would have been accelerated and/or heated were that energy not intercepted/diverted. do it on a large enough scale and you get unexpected macro effects (ex. global warming, etc). I can't tell you what or when but I can assure you that if we ever scale wind, solar, etc to giga-watts there WILL be unintended consequences. not saying we shouldn't as they will almost certainly be less bad than CO2 but be prepared for breat-beating once they're identified. I guess what I AM saying is that there are NO zero-impact energy sources and we need to get over that and accept the fact that it's all relative.
May 21, 2008
Here's the clock that winds itself using temperature changes - ~The Atmos clock...
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May 21, 2008
This seems to me to be just a plain old heat engine-- the magnet transports thermal energy from one heat reservoir to another. It keeps going because the heat reservoirs have unlimited amounts of energy. Am I missing something?
May 21, 2008
When non-magnetic it wouldn't be repelled by the magnet, right? So it's probably not going to be returning to the original position. Unless maybe you hook it up to a spring or something. Or maybe if you would place the metal above and would rely on the magnet's attraction to allow it to counteract gravity while magnetic. But then, it probably wouldn't have the magnetic strength to counteract either the spring or gravity enough to generate additional energy.
May 21, 2008
That lasting thing should have read IE7 - Doh!
May 21, 2008
And further to the mashups not loading IE& thing - seems to work fine in the morning (UK time) but by afternoon there's loading problems - is the server overworked when the USA is up and about?
May 21, 2008
The closest thing to a perpetual motion machine that's ever been built is a clock that can wind itself up for 24 hrs by using a thermal temeprature difference of only 1 degree - easily the difference between day and night.
Can't remember who built it, but it's probably on Youtube somewhere.
All the rest are bunkum - including yours.
May 21, 2008
Have you ever thought about getting some physics education (not some wussy high school version or non-mathematical intro to cosmology crap, I'm talking actual physics with calculus equations written with Creek letters)?
I'm sure you could do it and I have a feeling it would be a mind blowing experience for you.
May 21, 2008
I can't believe that my previous post was censored! What is objectionable about "H" "O" "R" "N" "Y"? You gotta be kidding! I thought that this was the Dilbert Blog, not the Partridge Family blog.
May 21, 2008
There're only a few actual perpetual motion machines in nature: queen bees, queen ants, queen termites, !$%*! rabbits, and !$%*! rats and other tiny rodents. Even sharks sleep.
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