3 ms·
The second law of thermodynamics basically stipulates this is impossible. All materials wear out no matter what, even black holes eventually turn to entropy. Yo
by Arbalest 7y ago
The second law of thermodynamics basically stipulates this is impossible. All materials wear out no matter what, even black holes eventually turn to entropy. You could create one with much better resistance to wear, but never completely resistant. Also I doubt true superconductors exist, it may be their losses exist below measurement error, but the fact that electrons are in relative motion, and are subject to the effects of the world around it, they must lose energy at some point.
Edit 1: Second, not first law
Edit 2: In your second paragraph, you literally described a perpetual motion machine, electrons going around a circuit is still 'motion'
- garmaine 7y agoUm, no there are such things as frictionless machines which without interruption can run forever. That’s actually what superconductivity is—moving electrons without resistance (friction).
- Arbalest 7y agoThat is what superconductivity is defined as, perhaps, but I'm saying, no such material is, nor can any construct be built to insulate a subset of the universe from the rest of the universe. So even if you magically made a material that in itself causes no friction, the electrons still have the rest of the universe to deal with. For example, how would electrons go around corners without having a force applied on it? How do you prevent magnetic interactions of electron in motion with things beyond the material from causing friction?
- ouid 7y agoI'm definitely not an expert, but just because you need force to go around corners doesn't mean you need work. An unchanging magnetic field in fact exactly accomplishes this, as it always accelerates an electron perpendicular to its motion, thereby leaving the energy of the electron unchanged.
- Arbalest 7y agoThat sounds a lot like a slingshot maneuver around a planet to get more momentum. Strictly speaking you're taking energy from the planet/sun to do so. An unchanging magnetic field still exists in the real universe, and I find it difficult to believe that it would be completely unaffected by the interaction. fwiw I'm also no expert edit: I'm taking unchanging to be a practical implementation of say a permanent magnet here, rather than a theoretical construct.
- ouid 7y agono, what I'm talking about is more like a perfectly circular orbit around the sun, where the direction of the acceleration is always exactly perpendicular to the motion.
- soulofmischief 7y agoBut there is no perfectly circular orbit around the sun. The mass of the two bodies causes the center of mass to be slightly off center from the sun, and both the sun and earth orbit around this center of mass in a fashion that AFAIK loses energy.
- garmaine 7y agoIf the two objects were either perfect spheres or tidally locked, then a circular orbit would continue forever. There are no losses due to pure motion in a vacuum.
- Arbalest 7y agoI thought the theme of my reply is that we're not talking about theoretical constructs, but instead reality... Space is not a vacuum, just much lower pressure than on earth.
- mrpgraae 7y agoIt is clearly possible to change the direction of an objects movement without doing work on it, if you consider forces perpendicular to the direction of movement. In other words, you can change the direction of the velocity vector without doing work, as long as the magnitude stays the same (ignoring potential energy here). In fact, a magnetic field is unable to do work, since it always acts perpendicular to the direction of movement of the charge that it acts upon.