Tag: relativity

Everything is in Motion

Super fact 131 : There is no absolute reference point. All motion is relative. Since everything is in motion compared to something else, that means that everything is in motion. In addition, all material objects consist of particles that are in motion, and all objects with mass move through time.

A photo of planet Earth from space.
Photo by Pixabay on Pexels.com

I previously made a post on this topic called “Everything is in Motion – Stream of Consciousness”. For a Stream of Consciousness post you are supposed to write whatever comes to mind without editing, except for typos. Stream of Consciousness is a fun concept. However, it is not fit for a super fact post because a super fact post requires fact checking and linking to reputable sources and it needs to be well organized and well explained, and all that is editing. After writing Everything is in Motion – Stream of Consciousness I realized that “Everything is in Motion” is a super fact. It is an important observation and a fact that is far from obvious. With this post I am rewriting “Everything is in Motion – Stream of Consciousness” into a super-fact I call “Everything is in Motion”.

All Motion is Relative

All motion is relative and everything moves in comparison to something else. You may be sitting in your chair completely still thinking that you are not moving but you are. Earth rotates around its axis at 1,040 miles per hour at the equator, and at 733 miles per hour at latitude 45 degrees. Latitude 45 degrees goes through New York and other northern States, as well as Europe. Sitting at the geographic north Pole won’t help you either because Earth is also wobbling and it is rotating around the sun at roughly 67,000 miles per hour or 107,000 kilometers per hour.

Picture shows a man and his dog sitting in front of a computer. Earth and the sun are in the background.
Man thinking he is sitting still drawn with the help of ChatGPT

The picture below shows Earth’s three main orbital cycles. I used this picture in another context for super-fact #122 “Orbital Cycles are not the Cause of the current Global Warming”. In that context I wanted to point out that Earth’s orbital cycles are too slow (100,000 years, 41,000 years, and 26,000 years) to explain the sudden rapid rise in global temperatures that we are witnessing now. The orbital cycles are also currently slowly cooling Earth, not warming it. However, in this context I am using the picture for a different purpose, and that is to point out that even if you sit at the north pole (or anywhere else on Earth) you will be moving.

Three illustrated orbital cycles. On the left orbital eccentricity, in the middle is the axial tilt and on the right axial precession.
Illustration of Milankovitch cycles from MIT’s Climate Primer.

In addition, the sun is rotating around the center of our galaxy, the Milky Way at 514,000 to 560,000 miles per hour or 792,000 to 828,000 kilometer per hour, and our galaxy and the Andromeda galaxy are approaching each other at the speed of 110 kilometers per second, which is 396,000 kilometers per hour, or 246,000 miles per hour. Whether it is the Andromeda galaxy that is approaching us or our galaxy that is approaching the Andromeda galaxy is just a point of view. We are also moving at millions and billions of miles of hour compared to some other galaxies.

Photo of the Andromeda Galaxy
Photo by Pixabay on Pexels.com

You are also Moving Through Time

As mentioned, motion is not absolute. It is always relative to something else. The universe has no center, no ether to compare with, there is no absolute reference point. It is not possible to declare anything as truly standing still. Understanding this is the first step towards understanding the theories of relativity. According to the theories of relativity the speed of light, or the speed of light in vacuum if you will, is a universal constant c = 299,792,458. The speed of light in vacuum is the same for all observers regardless of their speed and the direction in which they are going. In other words, you are moving at the speed of c = 299,792,458 compared to all light.

A spaceship on the right is shooting out a laser beam towards the left. Alongside the laser beam are four rockets trying to catch up with the light beam.
Four rockets, A, B, C, and D, are traveling along a light (laser) beam. No matter how fast they travel along the light beam, the light beam will always travel c = 299,792,458 meters per second faster than they do. I generated this picture with the help of ChatGPT.

In addition, c = 299,792,458 is not a speed in a regular sense, but a conversion factor between space and time. All particles/objects without mass (light particles called photons, gluons and gravity waves) must always travel at this speed, whilst all objects that have mass can only travel slower than c = 299,792,458 (compared to other objects with mass).

The E = mc2 formula
Mass is energy and vice versa, a direct result of the way time and space are related. Stock Photo ID: 2163111377 by Aree_S

You could say that compared to the reference frame of my choosing, which happens to be the chair I am sitting in, I am sitting still. I am not sure that would be fair but according to the theories of relativity you are also moving through time at the speed of c = 299,792,458. Well, that is assuming you have mass. For mass-less particles, like photons, time does not exist. Anyway, the fact that you are always moving kind sneaks in, no matter what you try.

An eye with photons streaming into it.
Billions of photons coming into the eye. For them time does not exist. Shutterstock asset id: 2629068895 by muratart.

You could raise a couple of objections to some of the claims in the last paragraphs. Very far away, beyond the limit of the visible Universe, galaxies can move away from us faster than the speed of light. However, they are not moving faster than the speed of light compared to the space where they are. What is going on is that space and time are stretching fast due to the expansion of the Universe.

Another objection might be that light can move slower than c = 299,792,458 through transparent materials such as glass and water. So, how can the claim that all massless particles must always move at exactly the speed of light in vacuum be true? The answer to that is that the light particles (photons) in those materials are being absorbed and re-emitted as new photons by the atoms. However, in between the atoms the photons move exactly at the speed c = 299,792,458, or more correctly at the time-space conversion factor c = 299,792,458.

From left to right, an atom absorbs a photon, which excites an electron that jumps into a higher orbit. Then it emits a photon and the electron falls back to the ground state again.
From ground state to excited state, absorption and emission of a photon in an atom. Shutterstock asset id: 2180385419 by rktz.

All Matter Consist of Molecules and Atoms that move

But wait, we are not done. Another fact is that everything is made of atoms and molecules that are never completely still. Temperature is a measure of their average kinetic energy (energy of motion). Even at the temperature absolute zero molecules and atoms are still moving. Yes, even at the lowest possible temperature they are still moving. It is impossible for atoms and molecules to stand completely still, just like children.

A vibrating protein molecule.
Thermal vibration of a segment of a protein’s alpha helix. Its amplitude increases with temperature. User:Greg_L on English wikipedia, uploaded to commons by User:Frokor, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/&gt;, via Wikimedia Commons.

Other Super Facts Related to Relative Motion

To see the other Super Facts click here

Everything is in Motion – Stream of Consciousness

Today is the sixth time I participate in Linda Hill’s streams of consciousness. To read about the rules and participate click here. To read my five previous entries click here “Prediction Failures and My Lucky Day from Hell”, or here “The Review Wars on Amazon”, or here, “Reindeer Hide Memories”, or here “25 Sweet Leonberger and Dog Photos”, or here “Bad Travel Memories”. I put this post on my Super-factful blog because it is factual and not related to Leonbergers. “Everything is in Motion” could be a super fact, but a super-fact post requires editing, looking up facts, or verifying facts, and lots of links, so that is for another post. This post is just my musings.

The badge features a twig with rain drops and it says Stream of consciousness Saturday #SoCS
2019-2020 SoCS Badge by Shelley!

Today’s prompt for Stream of Consciousness Saturday September 5, 2026, is “Motion”. Use it anyway you’d like. The first rule is: there should be minimal planning and no editing except typos. I did not edit but I did add a few pictures. I like adding pictures. I just copied the pictures including captions from a few of my other posts.

A photo of planet Earth from space. | Everything is in Motion
Photo by Pixabay on Pexels.com

The first thing that came to my mind for this prompt was that Motion is relative and everything is in Motion. You may be sitting in your chair completely still thinking that you are not moving but you are. Earth rotates around its axis at hundreds or thousands of miles per hour and you follow along wherever you are sitting. Sitting at the geographic north Pole won’t help you because Earth is also wobbling and it is rotating around the sun at more than 60 thousand miles per hour, and the sun is rotating around the center of our galaxy the Milky Way at several hundred thousands miles per hour, and our galaxy is moving compared to the Andromeda galaxy at millions of miles per hour, and it moves billions of miles per hour compared to other galaxies.

Photo of the Andromeda Galaxy
Photo by Pixabay on Pexels.com

Motion is not absolute. It is always relative to something else. The universe has no center, no ether to compare with, there is no absolute reference point. It is not possible to declare anything as truly standing still. Understanding this is the first step towards understanding the theories of relativity.

The E = mc2 formula | Everything is in Motion
Mass is energy and vice versa, a direct result of the way time and space are related. Stock Photo ID: 2163111377 by Aree_S

You could of course say that; well, compared to my reference frame, my room right here, I am sitting still. I am not in motion compared to my chair. So, in that sense it is possible to say that I am not in motion. Well, I am sorry to disappoint you. You are still moving through time at the speed of light. To bring up relativity again, space and time is a four dimensional continuum, and space can be converted into time and vice versa. The conversion factor between space and time is a constant identical to the speed of light in vacuum. Without explaining the details this means that you when you are sitting absolutely still in space, relative to something like your chair, you are still moving through time, in that reference frame, at the speed of light. You see “Everything is in Motion” is an unescapable fact.

Picture shows a man and his dog sitting in front of a computer. Earth and the sun are in the background.
Man thinking he is sitting still drawn with the help of ChatGPT

A related interesting fact is that nothing that has mass can move through space at the speed of light. Everything that has mass must move slower than the speed of light through space. Conversely, particles that do not have mass, such as light particles (called photons), and gluons, must always move through space at the speed of light, and as a result for them time does not move. Actually, for them time does not exist.

An eye with photons streaming into it. | Everything is in Motion
Billions of photons coming into the eye. For them time does not exist. Shutterstock asset id: 2629068895 by muratart.

There are a couple of obvious objections to the last paragraph. Very far away, beyond the limit of the visible Universe, galaxies can move away from us faster than the speed of light. However, they are not moving faster than the speed of light compared to the space where they are. What is going on is that space and time are stretching fast due to the expansion of the Universe.

Another objection is that light can move slower than the speed of light in vacuum through transparent materials such as glass and water, so how can the claim that all massless particles must always move at exactly the speed of light in vacuum be true? The answer to that is that the light particles (photons) in those materials are being absorbed and re-emitted as new photons by the atoms. However, in between the atoms the photons move exactly at the speed of light in vacuum.

From left to right, an atom absorbs a photon, which excites an electron that jumps into a higher orbit. Then it emits a photon and the electron falls back to the ground state again.
From ground state to excited state, absorption and emission of a photon in an atom. Shutterstock asset id: 2180385419 by rktz.

Anyway, the conclusion is, “Everything is in Motion”, through space, and through time.

To see the Super Facts click here

Time is a Fourth Dimension

Super fact 58 : In relativity, time is considered the fourth dimension, inseparable from the three spatial dimensions to form a four-dimensional continuum called spacetime. Adding time as a fourth dimension, not (x, y, z), but (x, y, z, t), results in spacetime measurements called spacetime intervals that all observers can agree on.

Before relativity the distance between two points was the same for all observers. The distance between points is calculated using the Pythagorean theorem: (d^{2}=x^{2}+y^{2}+z^{2}). You calculate the distance between two end points in a coordinate system using Pythagoras theorem because the points make right angled triangles along the x-axis, y-axis and z-axis. See the picture below.

The image shows the formula for Pythagoras theorem in two and three dimensions and Pythagoras theorem applied to the distance between two points.
Pythagoras theorem in two and three dimensions which also apply to the distance between two points. The points are indicated in red.

Let say you add another coordinate system (x’, y’, z’). The new coordinate system could be translated and rotated compared to the first one. The values of (x, y, z) and (x’, y’, z’) would be different and yet the distance between point-1 and point-2 would be the same. Well as long as you don’t change units, like using meters in one coordinate system and feet in the other. The distance between the points would be a so-called invariant. Now imagine that you forgot to include one coordinate in Pythagoras theorem, for example, y and y’ or x and x’, then your calculation for the distance would be different for the two coordinate systems. We need all coordinates, or all dimensions. See the picture below.

The picture shows two different coordinate systems. One is rotated and translated compared to the other. There are also two points and the distance between them is indicated. The formula for Pythagoras theorem is shown for both coordinate systems.
Pythagoras theorem is used to calculate the distance between two points from two different coordinate systems, with different coordinate values for the points. You still have the same distance for both coordinate systems. The points are indicated in red.

 In relativity the length of objects, as well as the time between events is relative and varies from observer to observer. In other words, distance and time varies from coordinate system to coordinate system. However, if you add time to the three space dimensions and calculate the distance between events using the Pythagorean theorem for intervals (between two events): or  (s^{2}= x^{2}+y^{2}+z^{2} – t^{2}) or (where the ‘t’ represents time in appropriate units), then the difference between different observers vanish. The interval is the same for all observers. It is a so-called invariant. The formula for the spacetime interval comes in a few different forms. One for distance like intervals (space distance bigger than time) (s^{2}= x^{2}+y^{2}+z^{2} – t^{2}), and one for time like intervals (time is bigger than the space distance) (s^{2}= t^{2} – (x^{2}+y^{2}+z^{2})). There is also one that includes the imaginary number (s^{2}= x^{2}+y^{2}+z^{2} + (it)^{2}). See below.

The image shows three formulas for the spacetime interval Euclidian: “(s^{2}=x^{2}+y^{2}+z^{2}+(it)^{2}”. For Time like intervals, the standard form: “(s^{2} = t^{2} – (x^{2}+y^{2}+z^{2}))”. For distance like intervals: “(s^{2} = ((x^{2}+y^{2}+z^{2}) – t^{2}))”.
The three formulas for the spacetime interval above all assume that the unit used for time is the time it takes light in vacuum to travel the distance unit used. If that is meters, it would be the time it takes light to travel one meter. The top formula is the Euclidian form of spacetime. It contains only the ‘+’ operator at the expense of adding the imaginary number (square root of -1) in front of the time coordinate. The second form is typically used with time like intervals and considered the standard form. The third form is used when the distance between two events is larger than the time distance, or distance like intervals.

The interval concept was developed, not by Einstein, but by Hermann Minkowski (a few years after special relativity) and is often referred to as Minkowski space. Time is like a space coordinate but the opposite signs in the equation make it different. Based on articles I found it appears that the opposite signs (minus vs. plus) means that you cannot move “backwards” in time as you can in a space dimension.

I admit that this is a very abstract super fact, but it basically means that if you add time as an extra coordinate to the three space coordinates x, y, z you get something, the spacetime interval, that everyone regardless of speed, orientation, etc., agrees on, despite relativistic length contraction and despite time dilation and non-simultaneity.

Time Expressed in Appropriate Units

I would also like to explain what I mean by (where the ‘t’ represents time in appropriate units), as I stated in the above. For physical formulas to work they need to be expressed in consistent units. For example, you can’t use kilometers for the coordinate x, and miles for coordinate y, not without adding a constant to adjust for it. For the formula (s^{2}=x^{2}+y^{2}+z^{2}-t^{2}) to work you need to express time in a unit that corresponds the time light travels in one meter if x, y and z are expressed in meters. If you express x, y, and z in meters and express time in seconds you must adjust the formula with the constant c = 299,792,458, the speed of light in meters per second, so you get (s^{2}=x^{2}+y^{2}+z^{2}-(ct)^{2}). See the picture below.

The image shows the formulas for the spacetime interval with the constant representing the speed of light in vacuum “(s^{2}=x^{2}+y^{2}+z^{2}+(ict)^{2}”, “s^{2}= (ct)^{2} – (x^{2}+y^{2}+z^{2})” and “(s^{2}=x^{2}+y^{2}+z^{2}-(ct)^{2}”.
If you measure the space coordinates in meters and the time in seconds you must adjust the units to match by inserting the speed of light in vacuum c = 299,792,458. The three forms of the space interval now have the constant c attached to the time coordinate.

Time Like Space Intervals

The formula for time like intervals is typically used for the situation where the time component is larger than the space component, which also means that it is possible to physically travel between the two events forming the space interval. As you can guess, that is a pretty normal situation. Let’s say you are watching TV and having a pizza. Your sofa is your coordinate system. You turn on the TV and 100 seconds later you move 2 meters to get a slice of pizza. Let’s calculate the spacetime distance between those two events.

The space component is easy, that’s 2 meters. However, if we express time in the time it takes light (in vacuum) to travel one meter we get 100 times 299,792,458. If you express time in seconds, you adjust it using the constant c = 299,792,458, and again you multiply 100 with 299,792,458, which is 29,979,245,800. So, the distance in time is almost 15 billion times larger. You really did not move far in space, but you moved very far in time. Now ask yourself. Are you spending your time well?

The Minus in Front of the Time Coordinate

There is one obvious difference between time and the space coordinates. In a coordinate system you can walk forward, along let’s say, the x-axis and then walk back the same way. You can walk back and forth as many times as you want, no problem, but you cannot do that with time. Time may be a space-time coordinate, but it is different from the other three coordinates in that way, and that’s where the opposite signs in the formula for the space-time interval comes in. This is beyond the scope of this super fact blog post, but you can read more about this here and here.

Other Relativity Related Superfacts

To see the other Super Facts click here

Relativity by Albert Einstein

This is not a super fact post but another kind of fact-oriented post. It is a book review for a book that I find interesting, Relativity: The Special and the General Theory by Albert Einstein. Yes, the book was written by Albert Einstein in 1916 and translated into English in 1920. It is written for laymen, average readers, and despite being more than 100 years old (well this reprint is from 1995) it does not feel outdated.

I should say that I wrote my review decades ago and Amazon has hidden about 900 of the oldest reviews including mine. So, you can no longer find it. Luckily, I still had it, but I cannot provide a link to it. The book comes in formats, hardcover (2024), paperback (1995), Kindle (2014), Audio (2009). I bought the paperback version.

  • Publisher : Independently published (July 29, 2024), ASIN : B0DBQVVJVQ, ISBN-13 : 979-8334454118, 109 pages, item weight : 7.8 ounces, dimensions : ‎ 6 x 0.47 x 9 inches, Translator : Robert W. Lawson, it costs $12.33 on US Amazon. Click here to order it from Amazon.com.
  • Paperback –  Publisher : Crown (June 6, 1995), ASIN : 0517884410, ISBN-13 :  978-0517884416, 208 pages, item weight : 8 ounces, dimensions : ‎ 5.2 x 0.5 x 8 inches, it costs $7.89 on US Amazon. Click here to order it from Amazon.com.
  • Kindle –  Publisher : Amazon Kindle Direct Publishing (February 23, 2014), ASIN : B004M8S53U, 126 pages, it costs $0.99 on US Amazon. Click here to order it from Amazon.com.
  • Audiobook –  Publisher : HighBridge, a division of Recorded Books (November 14, 2009), ASIN : B002XGLDAA, Listening Length : 2 hours and 14 minutes, it costs $12.09 on US Amazon. Click here to order it from Amazon.com.
The front cover of the paperback version feature Albert Einstein in front of a black board full of equations, title “Relativity: The Special and the General Theory” and author – Albert Einstein | Relativity by Albert Einstein
Front cover of Relativity: The Special and the General Theory by Albert Einstein. Click on the image to go to the Amazon page for the paperback version of the book.

Amazon’s Description of Relativity by Albert Einstein

This book was originally written in German by Albert Einstein in 1916 and later translated to English by Robert W. Lawson in 1920. In Einstein’s own words, “The present book is intended, as far as possible, to give an exact insight into the theory of Relativity to those readers who, from a general scientific and philosophical point of view, are interested in the theory, but who are not conversant with the mathematical apparatus of theoretical physics. It is an easy-to-understand collection of the ideas of one of the greatest scientists of the twentieth century including the idea he is most known for, the theory of relativity.

Redesigned inside and out to have a fresh, appealing look, this new edition of a classic Crown Trade Paperback is a collection of Einstein’s own popular writings on his work and describes the meaning of his main theories in a way virtually everyone can understand.

Below is my review for Relativity: The Special and the General Theory by Albert Einstein. First, I should mention that the book is divided into two sections, one for the Special Theory of Relativity and another for the General Theory of Relativity. In addition, there are five short appendices. The five appendices are not written for layman and require at least high school mathematics.

Relativity Explained by Einstein himself

I found it very interesting to read an explanation of the theories of relativity by the developer of those theories. However, it is important to remember that the inventors of science theories aren’t always the best ones to explain them. Isaac Newton is a prime example.

Another thing to remember is that today there are a lot of books and online graphics that use clever pedagogic techniques and visualizations to assist you in understanding these theories, and naturally this book does not contain any of that.

This book was originally written in 1916 and updated in 1920 and since then it has been reprinted/edited several times (as this book is an example of). I should say that the General Theory of Relativity had just been published so there weren’t much else out there for laymen at the time.

I’ve already read many good books on relativity, and I believe I understand special relativity pretty well, but my understanding of general relativity is partial. I did not buy this book to understand relativity. The reason I bought this book was to gain another perspective on the subject. If you just want to learn and understand relativity, I recommend Relativity Visualized by Lewis Carroll Epstein instead.

“Relativity: The Special and the General Theory” features no derivations of the formulas in relativity (except in the appendix) and no visualizations demonstrating relativistic effects and phenomena. The book is focused on the conceptual foundations of relativity and physics.

For example, what are Geometrical propositions, what does it mean to measure the length of a rod, or the time of an event, what do we mean by speed, what is simultaneity, what is the difference between what we observe and what we measure, etc? Einstein spends one and a half page explaining addition of velocities in classical-pre-relativistic kinematics (w = v + u) and what assumptions that are inherent with the approach. In that sense the book is quite philosophical, which is what I meant by “another perspective”. The book covers both the Special Theory of Relativity and the General Theory of Relativity. However, the sections on the General Theory of Relativity are quite short and very introductory.

There are some issues with the book. In appendix 1 Einstein (I presume) derives the Lorentz transforms. However, it is not, in my opinion, the best derivation from a pedagogical standpoint and it also had typos in it. As far as I can tell the formula on page 50 is wrong unless what Einstein means with the “m” is “additional relative mass” and not actual “mass” as stated.

The book features an addition written in 1920 where he is discussing an ad hoc modification to his theory that he had previously made but it turned out to be unnecessary (related to cosmology). The language is also very old fashioned. On the other hand, this kind of stuff makes you feel as if you travel back in time to when the theories of relativity were being churned out.

I don’t recommend the book for learning the theories of relativity but overall I liked the book. It focuses very much on basic concepts and near philosophical aspects of time, space and relativity. The book presents a valuable perspective if you already understand what the theories of relativity are about.

The back cover of the paperback features an overview of the background to relativity and to this book as well as ISBN number and publisher | Relativity by Albert Einstein
Back cover of Relativity: The Special and the General Theory by Albert Einstein. Click on the image to go to the Amazon page for the hardback version of the book.

Other Relativity Related Posts

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What is Time

Image above by Kevin from The Beginning at Last

Many and strange are the universes that drift like bubbles in the foam upon the River of Time—first sentence of Wall of Darkness by Arthur C. Clarke, 1949.

What is Time? What is the arrow of time? Does entropy define an arrow of time? Is there a past and a future? Has time always existed as, for example, in the eternal inflation cosmological model in which universes continuously pop into existence via Big Bangs like the bubbles on the River of Time in the Arthur C. Clarke quote above. Does time have a beginning as a recent Big Bang model by Stephen Hawking imply. If time came into existence with the universe itself then there is no place for creation, just as in an infinitely existing universe. There cannot be anything north of the north pole, and there cannot be anything before time itself.

In the theories of relativity time is relative. The speed of clocks as well as the order of events differ from observer to observer. The presence of energy or mass will bend time. There is no universal flow of time. There is no universal time.

The goal of this blog is to create a list of what I call super facts. Important facts that we know to be true and yet they are surprising, shocking or disputed among non-experts. It is a type of myth busting. However, I also create posts that are not super facts but that feature other interesting information, such as this book review and book recommendation.

In the picture there are objects from the past as well as futuristic elements and several clocks | What is Time
This picture reminded me of the mysteries of time. This is a submission for Kevin’s No Theme Thursday

About Time: Einstein’s Unfinished Revolution by Paul Davies

The book I am about to present focuses a lot on relativity. This is not strange since the theories of relativity shed a lot of light on time. Yes, pun intended. I’ve come across a lot of people who make various claims about time, and even consider themselves philosophers of time, and yet they do not even understand the special theory of relativity.

Because of this they say a lot of profound sounding things about time that ultimately are nonsensical. There is no way around it. If you want to say profound things about time and expand human knowledge on this topic you need to first have some understanding of relativity as well as other related physics such as thermodynamics and entropy. This book will provide that.

I should say that the book is somewhat outdated, being written in 1995 and 1996. However, most of it is still relevant and I know of no other book that approaches the topic in such an honest and rigorous way. The book comes in two formats hardcover and paperback. I bought the paperback version.

  • Hardcover –  Publisher – Simon & Schuster; First Edition (March 13, 1995), ISBN-10 : 0671799649, ISBN-13 : 978-0671799649, 316 pages, item weight : 1.3 pounds, dimensions : ‎ 6.25 x 1.25 x 9.5 inches, it costs $18.09 on US Amazon. Click here to order it from Amazon.com.
  • Paperback –  Publisher – Simon & Schuster; First Edition (April 9, 1996), ISBN-10 : 0684818221, ISBN-13 : 978-0684818221, 316 pages, item weight : 0.704 ounces according to Amazon but I think that should be 0.704 pounds, dimensions : ‎ 9.21 x 6.14 x 0.8 inches, it costs $12.28 on US Amazon. Click here to order it from Amazon.com.
Front cover of hardback version of the book About Time: Einstein's Unfinished Revolution by Paul Davies
Front cover of hardback version of the book About Time: Einstein’s Unfinished Revolution by Paul Davies. Click on the image to go to the Amazon page for the hardcover version of the book.

Amazon’s Description of About Time: Einstein’s Unfinished Revolution

An elegant, witty, and engaging exploration of the riddle of time, which examines the consequences of Einstein’s theory of relativity and offers startling suggestions about what recent research may reveal.

The eternal questions of science and religion were profoundly recast by Einstein’s theory of relativity and its implications that time can be warped by motion and gravitation, and that it cannot be meaningfully divided into past, present, and future.

In About Time, Paul Davies discusses the big bang theory, chaos theory, and the recent discovery that the universe appears to be younger than some of the objects in it, concluding that Einstein’s theory provides only an incomplete understanding of the nature of time. Davies explores unanswered questions such as:

* Does the universe have a beginning and an end?

* Is the passage of time merely an illusion?

* Is it possible to travel backward — or forward — in time?

About Time weaves physics and metaphysics in a provocative contemplation of time and the universe.

My four-star review for About Time: Einstein’s Unfinished Revolution

The link above will take you to my original review for About Time: Einstein’s Unfinished Revolution. Below is a slightly modified version of the review.

Our Evolving Concept of Time

Science, particularly physics, has revealed to us some profound insights about time, and yet it remains a mysterious topic. In the first chapter of the book “A Very Brief History of Time” the author describes how the concept of time has evolved throughout human history. The ancient philosophers had a very fuzzy notion of time, and they often dismissed both motion and time as illusions. The author tells us about “cyclic time”, and the “linear time” concept from Judeo-Christian thinking, and how it was incorporated into science as a “time variable”. This made it possible to solve the paradoxes created by such Greek thinkers as Zeno, who based on apparent paradoxes concluded that motion and time cannot really exist. Those “false” paradoxes were solved with the concept of linear physical time.

Physical time also made Calculus and Physics possible, and it became clear that there was a difference between physical time, which is a measurable entity used to sequence events, and experienced time, which is the subjective human feeling of a past, present, and a future.

Most of the rest of the book is focused on the Special Theory of Relativity and the General Theory of Relativity. The theories of relativity revolutionized how we view time, and they enabled a much deeper understanding of time. Special relativity refuted the concept of universal absolute time. Not only do clocks in different systems run at different speeds, but there is no universal “Now”.

However, the theories of relativity are not all there is to know about time, and we are not even done drawing conclusions about time based on the theories of relativity. This is why the book is called “About Time Einstein’s Unfinished Revolution”. The book also discusses quantum time, the arrow of time, worm holes, neuroscience and modern psychological experiments.

The book contains a lot of information and yet it scratches only on the surface. Time is a quite complex concept when you start digging into it. Take, for example, the discussion on the arrow of time. The conclusion of the books seems to be that there really is an arrow of time. Time has direction. The author is presenting both “sides” of the issue and to really get a grasp of the issue you need to clarify and look at the physics. Time certainly seems to have a direction if you look at the concept of entropy. The Cosmos is filled with irreversible processes. Our memory, which is essential for our experience of a self, is another example.

However, time has a direction even on the most fundamental level in subatomic particles. Kaon, a type of meson, decays in a way that is not time symmetric. The same may be true for the neutron. These particles “know” the difference between the past and the future. One could easily imagine how this chapter could be turned into a several thousand pages long book by just digging deeper into the related physics.

“About Time Einstein’s Unfinished Revolution” covers a lot of interesting topics related to time and it is often quite informative. The book is also well written, well organized, it has a good pace, and it is very interesting. It strikes a good balance between depth and breadth, and it does not overwhelm its readers. However, I do have some critique of the book, which prompted me to give the book four stars instead of five stars.

To understand some of the discussions in the book you should have a decent understanding of the theories of relativity, in my opinion. The author is explaining the theories of relativity to some degree, but the explanations did not seem to be that good. I did not have a problem with understanding these explanations since I already studied these topics, but I don’t think I would have understood what I needed to understand had I encountered the theories of relativity for the first time while reading this book.

Another criticism I have of the book is that he introduces ugh Everett’s many-worlds interpretation of quantum mechanics and in my opinion promotes it. This interpretation is in my opinion both strange and implausible and is not necessary for the discussions in the book.

In short, it proposes that every quantum measurement creates new universes, each corresponding to a different possible outcome of that measurement. In essence, our Universe is just one of many, and each quantum event splits the universe into multiple versions, where each version experiences a different outcome.

The problem with this interpretation is not so much that you get multiverses, but that you an infinite number of new fully evolved universes every nanosecond, which in turn create an infinite number of universes, which in turn create an infinite number of universes, and so on infinitely, and there is no way to empirically verify their existence. It is a so-called solution to a problem that is fictitious in my opinion and is derived from an old naïve interpretation of quantum waves. It is “hip” and “cool” interpretation, but I don’t see how it is useful. I should add that I have no problem with, for example, the multiverse idea stemming from string theory.

Anyway, except for my two complaints I think this is a pretty good book that I can recommend.

Front cover of paperback version of the book About Time: Einstein's Unfinished Revolution by Paul Davies.
Front cover of paperback version of the book About Time: Einstein’s Unfinished Revolution by Paul Davies. Click on the image to go to the Amazon page for the paperback version of the book.

About Paul Davis

Paul Davies is an internationally acclaimed physicist, cosmologist, and astrobiologist at Arizona State University, where he runs the pioneering Beyond Center for Fundamental Concepts in Science. He also chairs the Search for Extraterrestrial Intelligence Post-Detection Taskgroup, so that if SETI succeeds in finding intelligent life, he will be among the first to know.

The asteroid 1992OG was officially renamed Paul Davies in his honor. In addition to his many scientific awards, Davies is the recipient of the 1995 Templeton Prize–the world’s largest annual prize–for his work on science and religion. He is the author of more than twenty books, including The Mind of God, About Time, How to Build a Time Machine, and The Goldilocks Enigma. He lives in Tempe, Arizona.

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