Well, no-one has said “external magnetic charge”.
What both I and Sapo were getting at, is whether you could arrange magnets on the outside of two cars such that those magnets act to repel the two cars from some angles (e.g. it’s pretty obvious we don’t mean putting magnets on the roof).
This seems trivially possible based on an everyday experience of magnets.
Seems to me a glancing collision would be a lot worse, since the cars would spin off in random directions. On a road with two-way traffic, this could easily turn a minor fender-bender into a head-on, as the deflected car goes careening into an oncoming vehicle.
Quoth Brian Eckers:
The room-temperature superconductor was, I’m pretty sure, from Danny Dunn on a Desert Island. In the climax, they use some sort of electric fish to start up a current in a coil of the stuff, to accomplish something-or-other. Man, I need to get ahold of a copy of those books.
Quoth Indistinguishable:
Gauss’s Law works the same way for magnetism as it does for electrostatics, except the charge enclosed is always zero. So there always have to be the exact same number of field lines leaving any closed surface as there are entering it.
Quoth Timewinder:
I read about that when it came out. What they’re looking at is just flux tubes, and solar physicists and others who work with plasmas have known all about them for ages. It’s kind of interesting that they’re showing up in solid state materials as well, but that’s no reason to go calling them “magnetic monopoles”. All you have to do to turn the end of a flux tube into a magnetic monopole is to take the tube itself outside of the Universe. Doesn’t sound so trivial any more, now does it?
Sure it does. There’s very little chance anyone’s going to ask me to do it.
Ignorance fought. I had always thought that’s what rail guns were. I think you could still control the rate that a rail cannon fires.
You’ve got the story right, but the wrong book. Danny Dunn on a Desert Island was when they actually went down on a desert island and had to wait for rescue (shades of Anti-Gravity Paint’s long stranding in outer space, eh?). The book you’re thinking of, with the room-temperature superconductor and the giant electric fish at the end who powers the superconductor and prevents them from being attacked by the bad guys and their metallic weapons, is Danny Dunn and the Swamp Monster.
It’s a really common terminology mixup out there on the web - not sure why.
And you’re probably right about the variability of rail gun speed - they are just a variety of electric motor.
You would have have to change the vehicle’s horn sound, from “beep beep” to a more appropriate " AARRGGHH".
The only way to make it impossible for cars to physically bump into each other is to remove the loose nuts behind the wheels!
IMHO - I would rather see cars incorporate Faraday cage-like mobile phone jammers.
…I know, I know, you can drive while talking, unfortunately most can’t!
The difference between you and me being, of course, that I am talking straight out of my ass. (well, I hope that’s a difference for your own sake).
On that note, Could you make a magnet (or magnet arrangement) in the shape of a coin where all the norths point out along the edge and all the souths point up or down on the faces?. That could still mean trouble for our drivers since one of the cars would probably lift off the ground and ram the other from the top, but we can engineer that one later.
I don’t remember reading either of those books. The details about the room temperature superconductor that most stood out for me was the professor trying to pick it up but the magnetic field was so strong that it repelled his wristwatch, keeping his hand at bay. What they subsequently did with the breakthrough (let alone any icthyological applications) escapes me, but I suppose it might have involved an island.
It wasn’t an island, it was an African river, and they used the room-temperature superconductor, powered by a jolt from the new species of giant electric catfish they’d discovered (the “swamp monster” from the title) to keep the bad guys at bay, since their knives and other metal weapons couldn’t pass through the magnetic field.
Why use magnets? Put a strong electric change of the same sign on all cars, as well as the guard rails. Run a hyper-insulated wire around your car and suck all the electrons out.
Cars would travel down the freeway in a lattice structure. If someone tried to tailgate you, you could just take your foot off the accelerator and enjoy the energy-saving push.
That would, in principle, work, but I don’t think it’ll surprise anyone to learn that there would be huge practical problems with it.
Or the opposite. If someone is driving too slow on the fast lane, the whole lane can pitch in and push him ahead.