June 28, 2018 Thursday
Bedtime Story
The Question of the Origins of Inertia
Last night I had left you with Mach’s own
statement that now goes as Mach’s principle which no doubt is very vague and
hard to comprehend.
It obviously would not have made much sense
to you unless you know the context in with it was made.
Even with the context known, it has been
stated so vaguely that it can be interpreted in several ways.
We are talking about the mid or late
nineteenth century when physicists and philosophers alike were feeling that
there is something amiss about Newton’s explanation of the workings of
universe.
There were many questions, even very
fundamental concepts that were left both unanswered and unexplained.
One of such concepts among many others was
the vexing subject of undefined inertia.
Inertia in classical mechanics is seen as
the primary manifestation of mass which in turn is a quantitative property of
any physical system that is measurable.
Just have a look at how Newton defined
inertia in his classic text ‘Mathematical Principles of Natural Philosophy’
(1687):
“The vis insita, or innate force of matter,
is a power of resisting by which every body, as much as in it lies, endeavors
to preserve its present state, whether it be of rest or of moving uniformly
forward in a straight line.”
Now, whenever you come across the use of
the word ‘innate’, get cautious because it is a warning beacon that something
has been left unexplained.
It only suggests that it is a subject open
for investigation by fertile young minds.
Where does inertia come from?
What is the meaning of absolute motion when
it is clear that if there were to be a single moving particle in an empty
universe the notion of motion becomes bereft of any sensible meaning?
Just look at this apparently silly questions
posed by Steven Weinberg in his 1972 book ‘Gravitation and Cosmology:
Principles and Applications of the General theory of Relativity’”
“You are standing in a field looking at the
stars.
Your arms are resting freely at your side,
and you see that the distant stars are not moving.
Now start spinning.
The stars are whirling around you and your
arms are pulled away from your body.
Why should your arms be pulled away when
the stars are whirling?
Why should they be dangling freely when the
stars don’t move?”
These lines if asked by a child would
instantly be dismissed as rubbish by any adult.
We shall continue to look into the Mach’s
principle in the nights to come.
Stay tuned to the voice of an average story storytelling
chimpanzee or login at http://panarrans.blogspot.com
Good night Mon Ami and my fellow cousin ape.
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Another great educator and a teacher that I am aware of is
Professor Subhashish Chattopadhyay in Bangalore, India.
While I narrate stories, Professor Subhashish an electronic
engineer and a former professor at BARC, does and teaches real mathematics and
physics.
He started the participation of Indian students at the
International Physics Olympiad.
Do visit him here:
All his books can be downloaded for free through this link:
For edutainment and English education of your children, I
recommend this large collection of Halloween Songs for Kids:
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