# Waves, particles and Einstein ! 1

Waves are something that have no mass and move at the maximum speed, mass m = 0. speed c = 1. So whats their momentum? p = m.v = 0? Right?

No. For pure waves; momentum does not come from mass. It comes only from motion.

(pure wave; they do not have mass)

For matter waves, on the other hand, momentum comes in two ways, mass as well as motion.

(impure, now they have mass)

Albert Einstein recognized this fact and derived his relation; $latex E = \sqrt {(pc)^2+(mc^2)^2}$

This relation is called as Einstein’s relativistic equation, also Einstein’s mass-energy relation. But more appropriately mass-energy-momentum relation.

Let us consider E as the hypotenuse, p and m; as base or perpendicular as is your choice.

triangle_copyThen $latex E = \sqrt {(pc)^2+(mc^2)^2}$ is Pythagoras Theorem; when p is momentum and m is mass.

For pure waves such as photon … the quanta of light, m = 0.

Hence the Pythagorean Triangle is now one, where the mass side is arbitrary small. Thus E = p. More…

# How to add speeds; Galileo and Einstein won’t agree. 1

How to calculate the speed of anything, when their speed becomes closer to the speed-of-light.

— To correct the comment I have made earlier ” unless something is completely massless 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, and better late than never; when something is massless, it will never have a rest-frame, because by Einstein’s transformation rules known as Theory of Relativity to be consistent, a massless particle will always move at the speed of light, no matter which frame we are looking at it from.

# Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity by Steven Weinberg .. review Reply

A highly sofisticated and an elegant text book on general Relativity and its application. I would say a super book. I have read this book and solved for now a few daunting problems in Physics by applications of the content in this book. My research is available on my website but for context I recommend this book for serious practising physicists. More…

# What is Theory of Relativity !! 3

Just from a simpler form of Gravity I have proved in an article written couple days ago thats to be completed with these derivations but the ideas have been described: that gravitational time dilation can be derived from old classical theory without using any Einsteinian concept [such as changing mass with speed of frame of reference or universal speed limit] More…