electricity and magnetism are two sides of the same relativistic coin

Special relativity (in particular, length contraction) allows us to understand that electricity and magnetism are not separate phenomena but rather two interrelated aspects of the same phenomenon

[themultigamer]

I love how it took you 6minutes to clearly explain this in simple words while it took 5 different essays, a complete overview of qauntam physics, and relativity, the soul of a newborn, and 4 dollars, for anyone else to try and explain this. It also explained why the magnetic force is perpendicular which you weren't even trying to explain. no one else could clearly explain that either. Thanks fam.

[glennfelpel]

If this is so then how do permanent magnets fit into this phenomenon. Likely they do but there is no flow of electricity yet there is a magnetic force on a charged particle. And apparently that force is irrespective of any velocity. Trying to understand the development. Thank you for the video.

[jeffer]

Why doesn't the same length contraction argument apply to situation one( where electrons would be squeezed together) Why isn't there a net repulsive electric field?

[douglasstrother]

I first came across the connection between the magnetic field and relativity in "Electromagnetic Fields and Waves" by Lorrain and Corson.
The Lorentz Force is a consequence of Coulomb's Law under a Lorentz Transformation.

[davidbrewer]

At what velocity are the electrons moving through the wire? Also, if the length changes as the velocity approaches c, does the mass of the electrons also increase?

[tommywhite]

I don't understand why the seperation of the moving particles decreases because of length contraction here while in Bell's spaceship paradox the seperation increases because of the length contracted spaceships.
What am I misunderstanding?

[joshicune]

It is more weird than just contraction of space. Forgot wire, think about one single particle, electron. If you move with him, you will see only electric field. If you stop and electron continue, you will see same electric field but in addition magnetic field. One observer see something what another can't. Looks like that there is transformation related to observer speed BUT if you use 2 moving electrons, magnetic field can make force in unexpected direction while electric field will always be directly repulsive. There is something fundamental in moving what I do not understand, more than what Lorentz explained.

[paxshild]

But explanation doesn't hold well when the charge is moving perpendicular to the wire still experiencing magnetic force

[figefago]

There is one problem. In first scenario force is zero when test charge is not moving so there is no interaction. In second scenario even if test charge is stationary there is a force :)
When test charge is moving whith a speed equal 1/2 of electrons in a wire then it "sees" protons moving in one direction and electrons in opposite direction and then net charge is zero -> electric force is zero -> no interaction -> Lorentz force does not works -> faulty phisics :D

[NotLegato]

great video- just... you could've just as well used electron flow for the right hand rules and it would've all worked out the same. just a bit of an extra step in there to think about. not that it matters much. but great explanation.

[joshicune]

Additional remarks: Any explanation should be applicable on single dot charge in move (like single electron), otherwise superposition will not work. This explanation is not applicable on single moving electron. Plus conservation law is broken with this explanation. Plus Gauss law is not relativistic, applicable on all observers and here is broken...

[JustNow]

Really? The energy in the mag field is the kinetic energy of the electric field. Kinetic energy is measured relative to the observer. Quite simple

[sedevacantist]

This may make sense if you are a relativist, but a wire cannot have a net positive force at the same time a net negative force depending on an arbitrary point of reference of movement. Without a stationary ether to measure velocity against you cannot have a north or south magnetic field produced electrically simple by assigning what is moving according to what you believe is stationary. You claim that if the wire is thin enough the electrons and protons will be closer, I don't believe this is the case.

[hansmoser]

so what i understand, each of both can´t exist without the other.
h.m.