By Talha Mustafa and Musawwir Ahmed (Team Publications)
The talk consisted of Mechanical Formalism and its incompatibility with certain concepts in Physics , Principle of Relativity, and different transformations relating two inertial frames of reference. History and discoveries in Electrostatics and Electromagnetism were briefly spelled out mentioning the craziest stories of all great minds in mechanics. Concepts of divergence, curl, and circulation with reference to Electrical field were also illustrated.
Titus initiated the talk by a question, “Why does an object drop from a certain height, falls vertically and is not displaced? Through discussion it was answered that object falls vertically and is not displaced because everything on Earth moves with same acceleration and inertia is another major factor for this phenomenon.
Then talk was moved forward with an experiment of a ship: A man in the basement of ship knows that ship is at rest. He then falls asleep and wakes up sometime later, now he doesn’t know whether ship is moving or not and even if another ship comes in front of this ship he can’t tell which ship is moving. Whether it’s his ship or the other?
Well, these are the complexities when you are observing any motion and rest state from only one frame of reference. This idea was further supported by Titus from two frame of reference: Davy jones and Jack Sparrow. If there frames move with uniform velocity or are at rest then laws of Physics are applicable and we can tell about their motion but what if one frame of reference is accelerated? Now we can’t tell which is accelerated from same frame of reference which means laws of physics are not applicable.
That’s the principle of relativity : All laws of Physics are same in all inertial frames.
Further, the audience was informed that ancient Physicists used to think that charge is not quantized but later on by experiments conducted by different Physicist such as, Volta, Coulombs, Hans Oersted , Benjamin Franklin, and above all the famously dubbed King of Experimentalists – Michael Faraday, it was found that charge can move and movement of charge in Electric field generates a Magnetic field. It was proceeded by a basic concept building of divergence and curl which are essential properties of any vector and whose understanding is vital for Electromagnetism. In this way concept of field is introduced.
As the talk went on, Electricity and Magnetism’s relationship was explained via Helmholtz Theorem. Helmholtz Theorem explains the relationship between Divergence and Curl and how they can effectively explain any vector field. A complete divergent field will have zero curl and vice versa. Then the discussion went on towards Electromagnetism which comprises electricity and magnetism, both of which were considered independent until 1820 when Hans Oersted discovered the magnetic effects of electricity. The Helmholtz theorem can combine electrostatics and magnetostatics as divergence and curl, like both electric and magnetic fields, are vector fields. This discussion extended about the field generated by the motion of accelerating electrons. Michael Faraday established a magnetic field and set up a circuit around it. When the magnetic field was changed Ammeter, a device that detects current, showed deflection.
Thus, he concluded that, a changing Magnetic Field can produce Electric Field!
Things got interesting when four Maxwell Equations for electromagnetism were described which led to the revelation that a changing Electric Field can produce Magnetic Field.
The nature of light was uncertain at that time whether; it was a particle (Newton’s experiment) or had wave nature (Young’s Double Slit Experiment). The speed of light was known but its propagation was uncertain. This mystery was also uncovered by Maxwell. He proposed that light is the oscillation of electric and magnetic fields i.e., it’s an electromagnetic radiation. Hertz proved this experimentally. And hence it was proven, both theoretically and experimentally, that light is the oscillation of electromagnetic field, and its speed of propagation is a number.
An ether theory was also discussed which was that the light flows through a mysterious fluid medium i.e. Ether.
Next, the discussion went on towards the concept of relativity. Discussing its basis that “all laws of physics are same in every inertial frame of reference”. The talk rose toward how Galilean transformation failed to hold the relativity principle and why there was a need of Lorentz transformations and how Albert Einstein miraculously came up with his infamous equation E=mc2
The speed of light in a vacuum is independent of the speed of the observer. Galilean transformation provides the relationship between two reference system. It gave the idea that all laws of physics are identical in all the reference system which move with uniform velocity or are at rest, i.e. inertial frames of reference. Hence, he concluded that all laws of physics are invariant in inertial frames. However Galilean transformation failed and there was need of Lorentz transformation because Galilean transformation treated time and space distinctively. Galilean transformations were valid if the two inertial frames move with uniform velocity or at rest. But what if there was an acceleration? Galilean transformation failed.
Remember, this is the relative velocity not the actual speed of light. Galilean transformations fail on Maxwell’s equations because of the fallacy that the electric and magnetic fields as well as the speed of the wave are independent of the inertial frame of reference. A constant factor was required when converting one frame of reference to another – this welcomed another concept of special theory of relativity. On this basis Lorentz gave his transformation where speed of light was constant, and concept of time dilation and length contraction were introduced.
Thus, we reached to the conclusion that Electrodynamics is indeed the road which led us to Special Relativity. The talk ended with a quote from Hermann Minkowski,
Henceforth space by itself and time by itself , are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality
Ending note, its SPACETIME not SPACE-TIME!
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