# How to build a world with magnetic levitation?

Picture this:

Alpha Centauri Cb (AC) has

• 14% Earth's oxygen
• 110% Earth's gravity
• A 60-hour day/night cycle
• 240-hour orbit (10 Earth days = 1 AC year)
• Eccentricity produces all 4 seasons in 4 days

Proxima Centauri has 70% of our Sun's output, which still allows for plenty of infrared heat in "golden hour" hue.

Magnetic field is powerfully strong; strong enough to create these parameters:

• Magnetic levitation transportation does not require rails. Transports generate an opposing force, fluctuating and adjusting as necessary, while navigating 12 inches or less from the planet's surface.
• Electromagnetic wave activity is such that it disrupts the colonizing efforts of the human pioneers (let's call it the "Interference"). Earth seeds have difficulty germinating. Females do not conceive. In order to make human flourishing a success, something had to be done about the "Interference".
• The pioneers invented "The Barrier"; a counter-wave repellant system... like an electromagnetic exclusion zone, so that some can breed and grow on a protected base.

I'd like to start with a basis of hard science, and then handwave a little if needed.

How might this be plausible? Am I asking for too much of a magnetic field that would not seriously debilitate the humans? How related is gravity to the magnetic field: can it only be 110% Earth's gravity but a many-times-stronger-than-Earth's mag field?

Am also curious if a 240-hour eccentric orbit around Proxima Centauri would affect the magnetic field (ie. the "winter" day would have less magnetic force, so no travel is possible that day)?

How might seasons work on Alpha Centauri Cb?

What training would prepare you to colonize Alpha Centauri Cb?

• There seem to be multiple questions being asked. Some of the question points to the need for the need of more basic research: Magnetic vs gravity, Magnetic barriers, they exist Faraday cage. Magnetic field strength is inverse square, so given Earth radius that implies that if a train can levitate at 30cm it can levitate at 300m. Commented Feb 6 at 1:35

Apart from itself stretching belief, such a strong magnetic field would cause severe side effects. Magnetic materials like wrought iron or steel will be attracted in the direction of greater field strength, and will gain induced fields, align themselves with the magnetic field, cling to each other, etc. Magnets will even more strongly align themselves, and again, cling to anything magnetic.

Also, real maglev systems produce extremely intense fields across very small gaps using powerful magnets and materials that focus the magnetic fields to confine them to those gaps. Your vehicles would be working against the planetary magnetic field surrounding them. They won't hover, they will flip around to align their magnetic fields to that of the planet and each other, and crash to the ground while smashing into each other and anything made of steel. Ever see iron filings near a magnet? Your vehicles will be doing that, jumbled together with anything else magnetic.

In short, if you want hovering vehicles, maglev isn't the way to get there. Low gravity and a denser atmosphere might do the job, with a sufficient power source. Or you could come up with some reason for hovercraft to be especially useful...maybe cover the planet with vast marshes and shallow lakes.

As for the "interference": for electromagnetic radiation of wavelengths too long to deliver useful energy to pigments for photosynthesis or vision, or directly ionize molecules and cause damage like UV, the main biological effect is heating. Reproduction isn't especially sensitive to electromagnetic fields. The planetary environment would literally cook the populace before it started having such a specific effect. I would suggest a more conventional reproductive hazard...maybe the planetary crust has a lot of heavy metals, or the pollen-equivalents produced by local plants tend to be teratogenic to Earth animals.

There's no significant relation between orbit and planetary magnetic fields. The magnetic field is generated by convection currents in the core as it cools, if the planet was cooling quickly enough for the surface temperature difference in a single winter to make a difference, the whole thing would have cooled off long ago. Beyond that, why would people rely on maglev if it was unusable for part of the year? They'd just stick with wheels that work year round. For an alternative, things like summer plant growth can be an obstacle.

# Frame Challenge

As written, what you said doesn't work. You could, however, introduce a society (long gone) that made a lot of technology into the planet's crust. This would include the magnetic field and hostile wave-sometimes that are hostile to the reproduction of biological life. I do not recommend you include this "interference"; it won't be easy to explain realistically. Your orbit is not an issue here.

Random facts on magnetic fields...

An MRI scanner has a field of I Tesla. That is about 20 000 times stronger than Earth's magnetic field. An MRI scan can take 1 hour. A strong, static magnetic field has no obvious effect on life. A non-uniform magnetic field can give diamagnetic levitation. People have levitated frogs. It may be possible to levitate people.

A magnetic field of 10 Tesla has roughly the same energy per cc as TNT. It has no rest mass, so all that energy comes straight out. This is why superconducting magnets have shunt resistors: if the coolant gets low, there is something that can dump this energy in a controlled manner. You can engineer fields beyond 10 Tesla but the engineering gets rapidly more difficult. Neutron stars have natural magnetic fields that are a lot bigger, but the surface conditions there are not compatible with ordinary matter.

Superconductors repel magnetic fields This means they can just float where a magnet of the opposite polarity would flip over. Anything that floats either needs superconductivity or some sort of active stabilisation.

Can you put a superconducting loop of wire around the equator of Mars to create enough of a magnetic field to stabilise an atmosphere? This could be less than Earth's magnetic field as we are farther from the sun. The wire would have to carry about 500 amps, which doesn't sound too silly. The energy to establish the magnetic field would take more than the entire electric grid of the Earth for millennia. And all that energy would escape if the wire was broken.

Conclusion:

People can live in large magnetic fields for hours with no known ill effects. Large magnetic fields on a habitable planet seem implausible, because of the huge powers needed to replace the energies lost to solar winds and other processes. Even if you could create such a planet by magic or lost technologies, it would have to be actively maintained or to would collapse, possibly explosively. Maglev trains on Earth balance the energy budget by having tiny volumes of magnetic fields in precise gaps under the train.

You could flip the story on its head: have a planet with a large magnetic field. We want to go there because we don't see how this is possible. Once there, there are also possibilities of tapping this magnetic field as a source of electrical energy. But with the risk that all the stored energy may be released at once.