speed of light

What happens when cows move rapidly !

Cows not moving and moving fast. How does this difference impact the image in a modern digital camera?

Honestly I haven’t checked it with old day manual camera neither do I remember what impact motion brings into mages taken by such, eg does anyone remember when he/she took a picture of a friend standing in a platform and a train was coming, what happened to the image due to such motion?

Do you see where the fuzziness coming from, in the pictures, where the cows are moving?

Its coming from the relative motion between “objects being imaged” (cows and grass etc) and equipment of imaging (camera). This fuzziness is quite small when they are both still (the object and camera, wrt each other).

Ideas that changed our notion about the Universe.

1. Aristotle Fallacy; A notion that objects need force for their movement. It contradicts the idea of inertia. Newton corrected this by introducing the first law, things continue in their state of motion, a quality called as inertia, without requiring force and the motion changes due to application of force.

2. Earth is flat; that there is a boundary where you fall off its edge. [I am not going to explain or tell you how and when we found this was a horrendously hilarious and misleading notion we had. But it might have been used in the past by parents to discipline their teen-age kids. Don’t go out, you will fall off earth. That would have kept them in check.]

3. Rotational Dynamics; Earth is accelerating in a near circle in addition to about itself, so additional forces are acting that changes our observation about the world. Newton tried to understand this (not successful) in his last days, by rotating a bucket full of water, his laws could not explain the effects observed. His laws needed to be modified slightly. The same thing makes objects feel weightless by a given amount if they are accelerating towards a gravitational field (eg merry go round, satellites) This is the basis of many works of Einstein. First came Mach’s Principle which says observations made from objects that are accelerating in circular paths are to be corrected by fixing frames of references to stars that are so far away that the rotational motion is neglected. [if you shake your head while looking at stars and shake your head by looking at nearby objects such as a light post, evidently the light post shakes more and the stars less]. This helps in correcting observed phenomena from earth. Earth moves at 30 kms/second wrt sun …

Whats Light. A small primer.

A small primer on optical attributes of Light.

Manmohan Dash,

( — largely edited, 18-19 January 2014, originally from; Wednesday, March 27, 2013 at 3:58 pm UTC + 05:30 )

Updated Discourse.

If you ever seem, to be caught up between: they say light always moves at the same speed-c, they keep on harping, why then, its energy so different; we have light of various energy and frequencies. One that are harmful, like x-ray or ultraviolet and one that are quite soft on us all. The answer is there are two kinds of speed, when it comes to vector emissions like light, one speed is on the plane of polarization, giving us the energy or frequency or intensity of light waves, and the other, the speed perpendicular to that plane, that is; the speed at which energy of light is transmitted across the galaxy, its this latter speed, which is slated to be known as speed-of-light (instead of, speed of light’s energy transmission vs speed that determines the energy value of light transmission) and always a constant known as c, whose value is unchanged, as long as a single quantum of light is considered and in vacuum.

Note that vector emission means there are 3 dimensions, in which this wave is created or propagated, light wave, its a plane + a perpendicular dimension to that plane. The plane is called plane of polarization which always contains two fields, Electric and Magnetic field, and the perpendicular dimension is the direction in which the energy of the light wave is propagated, therefore, gives the light-wave-speed; which are again of two definition, the physical or actual speed known as group velocity, and the virtual, conceptual speed of each wave train, known as phase velocity. This definition of phase and group velocity are always to occur; for any kind of waves and not just light wave. So, the light-wave-group-velocity (for a single quantum-of-light, called photon) is always c = 2.99 x 10 (8) meters/second, in vacuum.

How to add speeds; Galileo and Einstein won’t agree.

How to calculate the speed of anything, when their speed becomes closer to the speed-of-light. 
This article was originally a comment in the linked article;  Why Nothing Moves Faster Than Light.

— In order to correct the comment I have made earlier  ” unless something is completely mass-less in its rest-frame ” I also add the following. This is a fact which I have realized lately — or rather trapped myself to commit an inconsistent remark, by following the same comment in making other remarks elsewhere. 

But it’s better late than never to realize; when something is mass-less, it will never have a rest-frame, because by Einstein’s transformation rules, known as Theory of Relativity, to be consistent, a mass-less particle will always move at the speed of light c, no matter which frame we are looking at it from. This then leads to the velocity addition formula of Einstein.

Now we will discuss in a slightly more detail the two kind of velocity addition formula, one prior to Einstein and one that came from Einstein’s work. 

Prior to Einstein. 
According to Newton and Galileo ( Galileo Project ), known by a name Galilean Relativity, the following follows; if C moves at speed

Optical Path and Fermat’s Principle.

Mirror and Fermat’s principle: We can see ourselves in the mirror and take our mirror reflected selfie as a consequence of Fermat’s Principle, the topic of discussion of the blog.

Snell’s Law governs refraction which is adjustment of optical paths in in-homogeneous media because light can no more travel at its speed in free-space.

Snell’s Law and Refraction.
The above expression comes from Fermat’s optical theorem, called as “Fermat’s least time principle” which can in turn follow either from;

a. Huygens’s Principle; that light travels like spherical wave-fronts hence satisfies geometric rules or,

b. Principle of least or stationary action ( or Hamilton’s action principle ).

So in the beginning of our understanding we thought “Light travels a path which is shortest, or the least-path”. This is due to Heron of Alexandria, who lived between 10 AD and 70 AD. Then this path which is traversed by light was redefined to something called optical path, which led us to our understanding that “light travels the path of least time”.

All physical laws are derivable mathematically –with appropriate physical understanding, from Hamilton’s Action variation or Principle of Action, made to provide the least or stationary time. Then time is replaced by definition of action as the most general formulation of the law.

So all in all, path/distance >> Time >> Action . That is crudeness goes towards abstract physical understanding. This can be recognized as an attribute of unification and tells us why Mathematics reigns supreme in Physics.

In the last few weeks I am trying to understand why light traverses straight lines and why it refracts. The other day, I saw a little mug, floating inside a bucket full of water. Inside water any object would look shortened, this is known by a phenomenon called as refraction.

Lets envisage the phenomenon or observation, via this quickly reproducible trick. Lets dip our favorite pencil in a glass of water and another in a glass filled with air. This is how it looks, I quickly made this arrangement to which my 3 year old niece just glued with rapt attention.