E & B Fields from Moving Charges: The Magnetic Monopole Mystery

[cragar]

Lets say I have a negative line charge on a long thin rod, if I am at rest with respect to that rod I will see an E field. But If I am moving with respect to that rod I will see a B field. So why are people looking for magnetic monopoles, If B fields are E fields in disguise, wouldn't the electrons need to show magnetic monopoles if they existed?

 

[tiny-tim]

hi cragar!

Lets say I have a negative line charge on a long thin rod, if I am at rest with respect to that rod I will see an E field. But If I am moving with respect to that rod I will see a B field.

yes, but it's only a tiny-weeny B field …

it's still mostly an E field ​

E²/c² - B² is invariant (the same in all frames), so since it's positive for the stationary rod, it's always positive

(if the speed is tanhu, then |E| = cE₀coshu and |B| = E₀sinhu)

similary, a stationary magnetic monople (if it exists) will have E = 0, and so E²/c² - B² will be negative, in that and any other frame …

there's no frame transformation that will turn pure E into pure B ​

 

[cragar]

I though it was E(dot)B that was invariant . Or is your way also equivalent. We can have frames where there is pure B then some E and B, but that probably doesn't help my case.

 

[tiny-tim]

I though it was E(dot)B that was invariant .

they're both invariant

see eg http://en.wikipedia.org/wiki/Electromagnetic_tensor#Properties"

(ooh, i forgot the 1/c factor in my previous answer …

i've gone back and corrected it )​

 

[PJC01]

The search for magnetic monopoles is driven by theoretical predictions and experimental evidence that suggest the existence of these particles. While it is true that a moving charge can create both an electric and a magnetic field, the properties and behavior of these fields are fundamentally different. The electric field is a vector quantity, meaning it has both magnitude and direction, while the magnetic field is a pseudovector, meaning it has magnitude but no direction. Additionally, the electric field is caused by the presence of electric charges, while the magnetic field is caused by the motion of electric charges.

The concept of a magnetic monopole, a particle with a single magnetic charge, is consistent with many theories in physics, such as the Grand Unified Theory and string theory. The existence of magnetic monopoles would also help to explain certain phenomena, such as the quantization of electric charge and the origin of the magnetic field in the universe.

While it is true that electrons do not exhibit magnetic monopole behavior, it is possible that other particles, such as magnetic monopoles, exist in the universe. The search for these particles is important in furthering our understanding of the fundamental laws of physics and could have significant implications for technology and energy production. Therefore, it is important to continue searching for magnetic monopoles and other particles that may help us better understand the universe.