Inertia is still a big trouble for everyone. Why is it actually?
The basic definition of inertia we usually studies is ‘it is something that resists any motion except the uniform one’. It’s simple,if we think normally. Whenever,we try to do something,there will be a resistance to whatever it is. But,at the same time,its quite funny that,inertia fears uniform motion. Inertia doesn’t mind if the body is in uniform motion. Why? No answer!
Newton Stated the law of inertia,which made the space Homogenous and Isotropic; Which we can consider to be the first Cosmological Principle. But however,he created a wide variety of forces and generalized them to be fictitious,for which he failed to find an origin or the predicted one was wrong.
Leonard Mach tried to solve this illusion created by newton,by Introducing a universal concept. He just said ‘Inertia is that SOMETHING which acts upon the body,by the entire universe’. If you are the object then everything else in the universe,has some influence on you.
This is more philosophical than,physical. However, We can’t experiment or prove his statement; brilliant Mach! 😛
The major fact which denied Mach’s interpretation is Anisotropy.
When we measure something and gets the same value,irrespective of the direction – that is what Isotropy is. So,Anisotropy is – we get different measurements when we measure the same stuff,from different directions.
Mass is distributed Anisotropically through out the galaxy. So,we will get an Anisotropy in measuring the mass of a particle,if we measure its mass,while being accelerated.
To be precise – Consider a stable particle ,like electron or proton. We are accelerating it towards a particular direction inside our Milkyway. Now we measure it’s mass from different directions. We get different values. Can the same particle have different mass? Absolutely no! But we gets it! Hence the initial assumption – Mach’s idea is unfit!
If we consider,a single mass (only that one) in this universe. Mass and Velocity creates force (momentum rate). If there isn’t any other mass,this mass can’t interact and can’t experience an external force; [f=ma=0].
Take the acceleration as zero (in ma),We could see it obeying newton’s law of Inertia,which gives our mass,a constant velocity. But sorry to say,we can’t measure that velocity. Hence we should drop that concept.
Now we have to check whether the remaining mass is zero. When there is no mass,there isn’t any inertial properties.
From this we can assume, inertia can appear only when more than one – multiple masses are present. If it fears to cast out,alone in a single mass,then how can we say inertia I a property of mass?
It’s a bluff!
Inertia isn’t Inherent to any mass.
It only arises with multiple masses.