Big Bang of Physics

Welcome to the Big Bang of Physics.

This is Mangesh Sonawane, and I'm here to introduce to you, in small ways, the huge and extremely interesting world of Physics. Of course, many of you know much about what I'm going to tell, but this is largely devoted to those who do not know much.

What is Physics?

Physics is the branch of science that deals with the physical realm of our Universe. The 'how' of things is associated with physics, and by extension, all the 'what','where','when' and 'why'.

I'm gonna start of with the basics of the Universe, and then move on to the Big Stuff.

What is this physical Universe?

The physical Universe is what we can observe in a very tangible way. What we can see, touch, tast, hear, feel and sense, all come under physics, or at least, analysis of the phenomena does. It includes everything from the largest stars to the smallest particle. From spacetime to th cosmic foam, everything comes under the physical Universe.

Let's start with the birth of the Universe.

How was the Universe born?

The most convincing and widely established theory is that of the Big Bang. So how did this theory come by?

Combining his own measurements of galaxy distances based on Henrietta Swan Leavitt's period-luminosity relationship for Cepheids with Vesto Slipher's measurements of the redshifts associated with the galaxies, Hubble and Milton L. Humason discovered a rough proportionality of the objects' distances with their redshifts. He discovered that with the increase in the distance, the redshift also increases. This led them to formulate the empirical Redshift Distance Law of galaxies, nowadays termed simply Hubble's law.

Redshift is a phenomenaon that is associated with the Doppler effect with light. As the distance between two points increases, the light becomes increasingly redder. This is because the expansion of space expands the wavelength as well.

If all stars and galaxies are moving away from each other, than means at some point of time they were all close together. Even further back, the Universe might have been cramped into a space smaller than an atom. At such a high density, all laws of Physics might have broken down. So anything that came before the Big Bang need not be considered.

Of course, the above explanation fits well with Euclidean space, which has three physical dimensions and one of time. But physicsits don't really like this theory, because it includes singularities, and physicists hate singularities because all laws of physics break down here. But the string theory has another view of space and time; that of Imaginary space. It is not imaginary in the general sense, but in the mathematical sense.