Overcoming Gravity

[Guest jtalbott]

Earth is surrounded by a magnetic field that extends beyond the orbit of sattelites. Magnetic fields repel super conductors. With that said why couldn't we create a space ship made out of a super conducter that would lauch itself into orbit using the earths magnetic field?

[aaronmyung]

um, if it could do that. wouldn't it be possible to float etc?

and also, it'd have to be pretty big wouldn't it?

And how would it get back to earth?

 

I'm just 16, but that just seems a bit weird to me.

[lepidoptera]

Yeah, I'm thirteen. I agree with aaronmyung. I guess, if you found the chemicals that the "earth magnent" is made of, and find the opposing chemicals, and you made a space ship the size of earth, then yeah, ur plan would work.

[mezarashi]

Sounds very interesting. The unfortunate thing is that it's not possible considering how superconductor levitation works. This is how it works basically. Understanding that you are still very young, you might need to consult some guides on the internet for the science background or ask within Because super conductors have no resistance, once you can induce a current within it, it will flow forever. Moving currents create a magnetic field. Magnetic fields in opposite directions oppose each other, and thus we have that apparent floating effect.

 

The problems to implement this large scale? (people have actually though about applying this to hyper-speed vacuum bullet trains that float on their tracks)

 

1. Superconductors are relatively expensive to produce. Building something even as large as a train with superconducting tracks would be extremely costly.

 

2. Superconductors are "super conductors" but not "perfect conductors". Over time, you will lose some of that magnetic field generating current.

 

3. The superconductors we know of now only work at VERY cold temperatures. Have you seen such an experiment at school? Your physics teacher will pour in liquid nitrogen to cool down the super conductor to proper operating temperature.

 

4. Magnetic fields need to properly align to "float". North and North repel we know that right? But South and North, and you'll instead be stuck to each other like glue. This stability is an issue. Once your in space, which direction is the magnetic field pointing towards? There would be some limitations to where you can go.

 

Superconductors are still so far only finding applications in small scale electronics. But I hope for the day our technology can give us all that

[swansont]

The earth's field is also very weak - less than a gauss at the surface. Levitating superconductors use much stronger magnets.

[lepidoptera]

And in order for a magnent to work, the device, or ship, opposing the earth's force would have to be as large as the earth, with a magnent with at least half the strength. good luck finding a magnent like that, cuz if you do, chances are, there would be many things that would cling to that giant magnent.

[[Tycho?]]

And in order for a magnent to work, the device, or ship, opposing the earth's force would have to be as large as the earth, with a magnent with at least half the strength. good luck finding a magnent like that, cuz if you do, chances are, there would be many things that would cling to that giant magnent.

 

Why would the device have to be as large as earth?

[Tom Mattson]

Made a mistake. Please delete.

[calbiterol]

Sounds very interesting. The unfortunate thing is that it's not possible considering how superconductor levitation works.

 

To be terribly honest with you, we simply don't know enough about superconductors to say that. It isn't currently practical, though, as room-temperature superconductors have not yet been found. However, this idea is under heavy research in some circles. I've wondered a few times whether the magnetic field of a superconductor could be "exploded" (in size) with the same concept that M2P2 (mini magnetosperic plasma propulsion, a NASA concept, maybe with independent contracts - google it, or search space.com for it) uses to expand conventional magnetic fields. So, needless to say, I've done some research. By the way, if you want to do more research, the process is called geomagnetic levitation in the more technical circles. This post is a little long, but bear with it - you might find a lot of the information to be useful.

 

This is how it works basically. Understanding that you are still very young, you might need to consult some guides on the internet for the science background or ask within Because super conductors have no resistance, once you can induce a current within it, it will flow forever. Moving currents create a magnetic field. Magnetic fields in opposite directions oppose each other, and thus we have that apparent floating effect.

 

Not to be offensive, and mezarashi, please don't take this as a dig on you, because it isn't, but youth has nothing to do with anything. I know a few 17-year-olds who are significantly smarter than a lot of 45-year-olds. Never underestimate the abilities of youth. It's one of my pet peeves.

 

Again, not to be offensive, but this is... Incorrect. The phenomena that you referred to (loosely) is called the Meissner Effect. First off, if you induce a current in a superconductor in the same way as a conventional conductor or semiconductor, you will most likely destroy the superconductivity of the superconductor. In other words, it's kaputt. Superconductors have a very high resistance to external magnetic fields. That said, it's possible to levitate magnets in this way. And by the way, there's nothing "apparent" about the floating effect - it does, in effect, levitate. Now, back to the situation. Quoted from wikipedia - superconductors:

 

The Meissner effect is sometimes confused with the "perfect diamagnetism" one would expect in a perfect electrical conductor: according to Lenz's law, when a changing magnetic field is applied to a conductor, it will induce an electrical current in the conductor that creates an opposing magnetic field. In a perfect conductor, an arbitrarily large current can be induced, and the resulting magnetic field exactly cancels the applied field. The Meissner effect is distinct from perfect diamagnetism because a superconductor expels all magnetic fields, not just those that are changing. Suppose we have a material in its normal state, containing a constant internal magnetic field. When the material is cooled below the critical temperature, we would observe the abrupt expulsion of the internal magnetic field, which we would not expect based on Lenz's law. A conductor in a static field, such as the dome of a Van de Graaff generator[/url'], will have a field within itself, even if there is no net charge in the interior.

 

If you follow the link to wikipedia's superconductors page, you'll find a picture of a magnet demonstrating the Meissner effect - by levitating. It's a very interesting and informative page. If you're interested in superconductors, it's a good resource to start out with.

 

The problems to implement this large scale? (people have actually though about applying this to hyper-speed vacuum bullet trains that float on their tracks)

 

Well' date=' implementing superconductors, and sometimes the Meissner effect, in such trains has been done. Yes, it's wikipedia again, and you'll probably have to read (or scan) the whole thing to find out about the current incarnations of it, but it's there. Also, it has been proposed to make a transatlantic vacuum tunnel that operates on this principle - with supersonic trains, I might add. Quite simply, this is easy enough to implement, because you have two strong magnetic fields in oppostition. The earth, on the other hand, has a very weak field when you refer to something so small as an orbital craft. As lepidoptera said, if you had something with a magnetic field as large as the earth itself (I'm not sure if lepid put it that way, but as far as I understand, that's the limitation in that respect, not the actual size of the craft), there would be such an opposition. However, a craft such as this doesn't have to be as large as the earth - it's just got to have a strong enough magnetic repulsion with the relatively weak field of the earth to bear its own weight. I forgot/misplaced the link to the site I found that details this process - if anyone discovers a site that says how this would be possible, please send the link. Anyways, it's theoretically possible.

 

 

1. Superconductors are relatively expensive to produce. Building something even as large as a train with superconducting tracks would be extremely costly.

 

2. Superconductors are "super conductors" but not "perfect conductors". Over time' date=' you will lose some of that magnetic field generating current.

 

3. The superconductors we know of now only work at VERY cold temperatures. Have you seen such an experiment at school? Your physics teacher will pour in liquid nitrogen to cool down the super conductor to proper operating temperature.[/quote']

 

Not only could all of these problems be solved by room-temperature superconductors, not all of them exist. 1st, superconductors are not that expensive to produce. You can buy a kit for one, if you'd like, and the average 16-year-old (in the US) could probably afford it. And as I said before, it has been done. I'm not sure if it was the tracks that superconducted though, and a craft that uses superconductors to levitate wouldn't require anywhere near as much material. 2nd, no, you won't lose current in a true superconductor. As you yourself said, they have no resistance. Read the wikipedia link on superconductors for more info. That's just not how it works. 3rd, liquid nitro isn't that cold. Conventional superconductors must be cooled with liquid hydrogen or, eventually, liquid helium - but high-temperature superconductors are what we're talking about. Liquid nitrogen also isn't that expensive.

 

4. Magnetic fields need to properly align to "float". North and North repel we know that right? But South and North' date=' and you'll instead be stuck to each other like glue. This stability is an issue. Once your in space, which direction is the magnetic field pointing towards? There would be some limitations to where you can go.

[/quote']

First off, with induced currents, such as with the Meissner effect, this doesn't matter - it flips, it induces an opposite current. Now, there is a law about stable permanent-magnet levitation that says it can't be done - but it assumes too much and has so many loopholes that, quite frankly, it can be done, and I've seen middle-schoolers do it. Not exactly your run-of-the-mill eighth-graders, mind you, but they were still only 12-13. And seeing as society expects nothing of children these days... Well anyways, it's not that hard to solve stability issues. It's a simple matter of thinking through the engineering process. And once you're out of the earth's magnetic field, conventional rockets can do the rest. The main issue here would be that you could have a massive amount of momentum when you break the field. And as far as coming back, just raise the temperature of the superconductors until they no longer superconduct, and reenter. Then, lower the temperature before you hit the ground. Alternatively, use multiple superconductors, and shut off enough that you go down slowly.

 

Superconductors are still so far only finding applications in small scale electronics. But I hope for the day our technology can give us all that

 

Small scale electronics? Do you call experimental fusion reactors (in the process of being built)' date=' nearly ALL MRI machines, massive amounts of research, and millions of other everyday applications simply [i']small-scale electronics?[/i] There are many little-known applications for superconductors, but there will be so many more when room-temperature superconductors become available. These are the el Dorado of many research facilities, the pot 'o gold at the end of the rainbow. Many things will be possible with these, including lossless powerlines, among other things. And we may yet see geomagnetic levitation. And I too hold much hope for the future, but politically, a lot of things have to change. But that is a debate for another time and another thread, especially since I've written a novel in this post. Sorry 'bout that.

 

Some links:

Here's a relevant page from the site of an R&D company that includes geomagnetic levitation in its current research.

Here's another good page.

[calbiterol]

Aha! I found the page that had the "how to" on geomagnetic propulsion. It was in the FAQ section of the site above:

 

Isn't the Earth's magnetic field too weak to lift anything?

Indeed, the Earth's magnetic field averages a mere 0.5 gauss at sea level. That's about 10,000 times weaker than the field around a small permanent magnet. Yet what the geomagnetic field lacks in flux density, it more than makes up for in size. In fact, one cubic kilometer near the surface packs a magnetic energy density of about 1.4 million Joules!

 

Theoretically, a craft could be levitated by the geomagnetic field in much the same way a helium baloon rises. A balloon rises because it displaces more weight in air than its own weight. Similarly, if a magnetic field displaced the energy equivalent of the geomagnetic field needed to overcome gravity, then it would float as well.

[DQW]

Besides the obvious technical difficulties, there's one theoretical problem that hasn't been mentioned yet : there's only one place on Earth where the local magnetic field points upwards - at the magnetic north pole.

[ydoaPs]

won't work where the field goes straight up even if the field were strong enough. force is perpendicular to orientation fo the field.

[DQW]

won't work where the field goes straight up even if the field were strong enough. force is perpendicular to orientation fo the field.

That's only the force on a moving charge, not the force on a magnetic moment !

[Hyd]

1. Superconductors are relatively expensive to produce. Building something even as large as a train with superconducting tracks would be extremely costly.

 

Actually, if the fusion reactor is completed and properly works, we will have a major excess of Helium (Fusion works as such H + H ----> He + Energy ) Thus the cost of a super conductor will drop for Helium is useful as a superconductor. Just thought I'd add that in.

[DQW]

Actually, if the fusion reactor is completed and properly works, we will have a major excess of Helium (Fusion works as such H + H ----> He + Energy ) Thus the cost of a super conductor will drop for Helium is useful as a superconductor. Just thought I'd add that in.

Most commercial superconductors are High Tc Superconductors. They work just fine at liquid nitrogen temperatures. No doubt, you can use cheaper superconductors at helium temperatures, but then the major technological cost there will be in minimizing thermal leaks into the system - and this is hardly just a minor technicality at 4K.

[Marian]

Here is another site on geomagnetic levitation: http://www.xprize.cz .