REAL MEANING OF E=mC2 (PART-1)

Hydrogen Atom has less mass than combined mass of proton and electron that makes it up.

YES!

How can something weigh less than sum of its constituent counter parts?

Well the answer is E=mC²

E=mC² is one of the most colossal equations of physics. But at the outset, in the paper published by Einstein in 1905, this equation is written slightly different.

I.e.,   m= E/C²

Because the bottom line is that this equation is basically a lesson in the corner of physics that helps us to understand and think, what mass actually is?.....

You often come across the statements like

Mass is a form of energy???

Mass is frozen energy??? (Seriously?)

Mass can be converted in to energy??? (Worst one!)

          

      None of the above statements is correct.

         

      These doesn’t make any sense and frustrating as well.

 We can get a better idea of this equation, m=E/C² by carefully taking up the examples from our everyday life.

         

        Let’s take an example of two identical objects with same composition. Does they weigh the same?

NO!

          Mass cannot be equated to the constituents of the object simply. Instead, the mass of an object depends on two major aspects

1.  The arrangement of the constituent elements in the object.
2.  The relative movement of these elements in the object.

          Let’s take up another concrete example. Take two identical watches one wound completely or running and another unwound or not running. Then according to Einstein, the mass of this ticking clock is more.

WHY?

         

        In the ticking clock, the hands of the watch rotate, thus it possess kinetic energy (E^k). The wounded coil and springs in the watch possess potential energy (E^p). At last, the movement of gears in the watch create friction and generate heat thus giving out thermal energy (E^T).

Got it?

Now let’s get back to the eqn.

The reason for the watch being higher in mass is due to these energies.

The total mass of watch is given by

                             

                    M_watch = M_components + M_Extra

This extra mass comes from the Einstein mass energy equivalence,

                             M_extra = (E^k + E^p + E^T)/ C²

          

                 That’s the extra mass contributed to the mass of the watch by these energies. Since C² is very large value, the extra mass is less but NOT ZERO.

          

                      That’s why Einstein has argued that most of us incorrectly believe mass is simply amount of matter present in the object.

                      So thus we’re neglecting the extra mass from consideration. This seldom small but definitely not zero quantity, but perfectly sensitive scalar to measure it.

                Wait a Second! Does that mean that the mass of the moving minute hand is greater because it is moving?

NO!

That’s an outdated view point.

         

      Most contemporary physicists term this mass as “Mass of rest” or “Rest mass”. In all the physics cases, rest mass is always redundant. There are lots of reasons for talking this way. Among them the property we can all agree upon is space time.

          

     I’ll discuss about this in a separate article because this is little complicated aspect directly connected to general relativity concept.

          But for us today, in equation m=E/C², m is rest mass.

One can think about this mass as an indication of how hard it is to accelerate the object or as an indication of how much gravitational force is acting on the object.

Either way, a ticking clock has more mass than that of its counterpart at rest. Perhaps, we can get a little clearer overview on this with some more examples and clarify what’s happening there.

          

         Consider a flash light. When it is ON, its mass starts to drop immediately. This is because the electro chemical energy stored in the batteries of the flash light is discharged as light energy and  the energy present in the light is being manifested and hence the mass decreases proportionately from the Einstein’s equation.

          

           And of course by this fact, sun which is a big flashlight by itself also losses mass simply by the virtue that it emits light. This is approximately 4,000,000,000 kg/sec. But don’t worry. We humans are safe. This 4 billion kg per second is only 1/10^21th of the sun’s mass over its life.

          

        So, does that mean sun converts mass into energy?

NO!

          All the energy from the sunlight comes from the expense of other energies such as kinetic energy, potential energy and light energy of the particles that make up the sun. Thus initially, all this energy is contained within the sun all along and we have been measuring that energy always. The reduction of 4,000,000,000 kg of mass of sun per second is simply the aforementioned energies lost by the sun.

          Thus, at the long insight weighing is simply the determination of energies contained in the matters all along and only we haven’t noticed this all these days contrary to what we have though or learnt earlier that mass is amount of matter present in an object.

Clear? No? Let us take another example.

          Imagine you’re standing with a flashlight in your hand in a closed box with mirrored walls placed on weighing scale. Now switch on the flashlight. Does the value on weighing scale change?

No!

          Although scale registers a change in electro chemical energy it is being equally compensated by the electromagnetic radiation emitted by flashlight in the form of light. The mirrored box doesn’t allow the light to escape to the surroundings. Therefore, light itself being weightless contributes to the mass of the system by electromagnetic energy that equals E_light/C².

Thus the mass is constant all along.

Thanks for reading. please do leave a comment below.

This is the first part of this topic. Stay tuned for the next.