Introducing Time

Title : Introducing Time
Author: Craig Callender
Year:2001

I have been meaning to read something like this since I watched dark hahaha. It's a lame reason but it's the truth. That's not the only reason I actually find time quite interesting and everyone thinks  time travelling is fascinating. Well the book starts out trying to define the concept of time. And it makes you reflect on how hard it actually is. A quote I liked is "

“What is time then? If nobody asks me, I know; but if I were desirous to explain it to one that should ask me, plainly I do not know.” 

 This book explains without much detail in other words in a very brief way the different conceptions about time that have been known through the ages. It introduces us to different points of view from Kurt Godel, Albert Einstein etc.

It starts out talking about how we perceive time and clocks. Its curious if you pause to ponder about it , how time changes depending where you are , we live that everyday with the relatives we talk to who live far away from us. We have biological clocks in us as well, but Is time merely in our head, is It a psychological idea we create to assimilate the mysterious entity that time is , does it actually exist. Toward the end of the book it is suggested that time doesn't exist. 

J.M Mctaggart was an english philospher who published ana rticle in which he seeked to convinve readers about the irreality of time.

The B.A theory could also be called tenseless theory of time in the book , but I only found it as the former in the internet explains time does't exist and that past, present, and future can all be equally real.This branch of Philosphy has much to do with physics so it focuses mainly on philosphy but some physicist and their arguments are explained as well ;for Example Isaac Newton's theories state that time is absolute in the whole universe , but Einstein's idea of time is relative , so Relativity and tenses are in a way connected. 

H.A Lorentz  a Dutch physicist and nobel prize laureate has an alternative explanation of relativity, his theory doesn't have the profound consequences for time that relativity does. 

Kurt Godel discovered an exotic species of space time that allows for time travel; he'smostly famous for his incompletenes theorem.

Taub-Nut spacetime is an exact solution to einstein's equations. Kip Thorne and Igor Novikov propose a means of time travel through wormholes which is shown in the 2014 film Interstellar, It is also the means of travel in Carl Sagan's novel Contact , there's also a film for this book (Which I have already started reading) It shows an Interesting girl with important questions about life, but her love life seems a bit odd given her personality. The possibility of wormholes has been known almost since general relativity but gravity (an attractive force) always seeks to close it.

That's a mobius strip named after german astronomer and Mathematician August Ferdinand Mobius. Spacetime might also be non-orientable in time. Think of the Mobius strip as the guide that dictates the flow of time;what rules the way we age or plants grow, at one point in time travel it might exchange places. 

Geroch's theorem proved that if the topology of space changes with time which happens when space divides and time branches then the spacetime must be non-orientable which means it allows for time travel.

Friedrich Nietzche German moral philosopher made the idea of eternal recurrence famous. The eternal recurrence theory is possible according to what we know , and here's where the big bang comes into the picture. At a certain point, the paths of any traveller would run out , it'd become a singularity , matter and energy would be so concentrated that the forces would be infinite. the big bang rules out the eternal recurrence but singularity theorems don't.

The laws of nature are invariant , so physics doesnt particularly care which takes place first either past or future.

After that , Statistical mechanics is Introduced , the main developers of this theory are Ludwig Boltzmann and  Lord Kelvin. Some concepts like enthalpy and entropy are important to discuss thermodynamics(the science of heat). French Physicist and military engineer Sadi Carnot created the most efficient heat engine cycle is the Carnot cycle, consisting of two isothermal processes and two adiabatic processes.The Carnot cycle can be thought of as the most efficient heat engine cycle allowed by physical laws.

Thermodynamics and Newtons particles are explained in terms of probability. 

One of the last examples explained is about communication with time reversed which I liked very much; In this time reversed a galaxy that lies billions of light years away from us manages to communicate somehow with us , for them our big crunch is their big bang.

Some words I didn't know: 

Plethora: overabundeance, excess (greek origin)

Some books mentioned: 

Robert Heinlein's "all you zombies"(1959)

Philip K.Dick's novel "Counter-Clock World" (1967) 

Greg Egan -Science fiction writer, doesn't mention his book but I will find it.