Why don't we use the Earth's magnetic field to generate endless electricity for the whole world?

uh, really? how, pray tell, would we accomplish putting a copper cable around the entire world? Please do tell because I am now thoroughly intrigued.

Energy is induced into cables by a change in electric current. Try it for yourself. Take an empty toilet roll, wrap coated copper cable around it (many times), connect a lite bulb to the cable ends, then move a magnet in and out really fast. It will cause the bulb to glow. However, you are stating that we would just leave the wire around the earth. Unless I am incorrect (and I may very well be), the earth's magnetic field isn't changing all that fast, so we would not be generating electricity.

First of all that's pretty hard to say for sure if that is true, even for a trained scientist, much less us. BUT, giving the benefit of the doubt, I would say the hold ups are this. 1) You would have to get the whole world in a agreement and pull money together which would probably be impossible, unless only contributing countries would benefit. 2) It is much more a strutual feat than it seems. Remember, you have to run material through sub zero lands, underwater, hot areas, and who knows what else. It's not an easy thing to do. NOT IMPOSSIBLE, just not easy at all. 3) Nuclear energy is created by cutting atoms in half. That's a **** load of energy. And there's a never ending supply. Why go to the lengths of surrounding the earth in wire when we still have this option. Ultimately we will prpobably be using an anti-matter machine that will generate even more power. It's just not logical to wrap the world in wire with all these other options still in place.

there is a huge problem with this form of generate energy: 2º law of thermodynamics says you can`t generate energy without loosing any heat into the environment; this is a very serious problem, not only because the magnetic field of the earth is so weak that it ins`t profitable to make a device that generate the electricity (you have to take into account that you will loose most of it in transportation, a normal line of transmission loose almost 30% of the energy generated), also you will generate a lot of heat and the environment will be affected...

Think about the generator/alternator in your car. Does either make electricity when the engine is off? That is because the magnetic field (magnet inside the generator) is generating a field, but the wires in the coil around it are not moving. Current is generated when the magnetic field passes through the wires as they rotate through it. Either the cable or the magnetic field would have to be moving. How do you propose to suspend the cable such that the Earth's magnetic field can move through it?

To what would you anchor the coil so it wouldn't just turn with the earth? It's not renewable unless you find some other way to get the earth spinning again after you've converted its rotational energy into electricity. Who told you we have the technology and engineering ability to achieve it? Even if this were true, how much copper do you think you would need just to carry the electricity to a billion New York City's? Also, the change of flux through the coil changes only slightly during the earth's rotation. If the magnetic poles were at the geographic poles, there would be practically no flux change, therefore practically no induced current. Check your sources. I suspect Tesla knew better.

Don't you think if it was that easy we would've done it by now? There are thousands of scientists working throughout the world, I'm sure they've thought about it. A copper whire going about the earth is a practical impossibility, because to induce any electricity, the copper wire will have to constantly move side to side.

Well the problem with your theory is that the wire would need to circle many, many times and the wire must repeatedly pass through the magnetic field (or vice-versa) to produce any electricity not just sit within it. This theory lacks merit and is contrary to the laws of physics. There are plenty of renewable sources for electricity that are not being fully used which are much more feasable than scheme you describe. You can argue the point until you are blue, that does not make your case.

Because it wouldn't produce anything like that much power or it would be economical and it would be worth finding a way to do regardless of the maintenance costs, political/border problems and logistics.