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“Bennett, Einstein’ın düşünceleri üzerine eğlenceli, harikulade bir giriş kitabı yazmış… Anlattıklarının bu kadar anlaşılır olması şahane.”
-CHOICE-
“Görelilikle ilgili birçok kaynak okudum, ama hiçbirinin anlatımı bu kitaptaki kadar açık ve merak uyandırıcı değildi. Hem özel hem de genel göreliliğin, özünde basit ve buna rağmen sezgiye dayalı olmayan fikirlerini öğrenmeye hevesli herkes için Jeffrey Bennett’ın kitabı biçilmiş kaftan. Etkileyici biçimde anlaşılır ve ilgi çekici…”
-Seth Shostak, Üst Düzey Gökbilimci, SETI Institute-
“...Bennett’ın bu eğlenceli kitabı, okurlara göreliliğin ne olduğunu ve evrenimize dair neleri ortaya koyduğunu gösteriyor.”
-Publishers Weekly-
Bir kara deliğe yolculuk etseydiniz, bu yolculuk sırasında gerçekten neler yaşardınız?
Çoğumuz, Güneş bir gün ansızın kara deliğe dönüşse Dünya’yı ve beraberinde diğer tüm gezegenleri yutacağını düşünürüz. Fakat yazar ve astrofizikçi Jeffrey Bennett’ın da belirttiği gibi, kara delikler aslında yutmazlar. Bu düşünceyle Einstein’ın görelilik teorilerinden yola çıkan Bennett ışık hızını, zamanın genişlemesini ve uzay zamanın bükülmesini ele alarak konuya oldukça eğlenceli bir giriş yapıyor ve size şöyle bir hikâye anlatıyor:
(Tanıtım Bülteninden)
-CHOICE-
“Görelilikle ilgili birçok kaynak okudum, ama hiçbirinin anlatımı bu kitaptaki kadar açık ve merak uyandırıcı değildi. Hem özel hem de genel göreliliğin, özünde basit ve buna rağmen sezgiye dayalı olmayan fikirlerini öğrenmeye hevesli herkes için Jeffrey Bennett’ın kitabı biçilmiş kaftan. Etkileyici biçimde anlaşılır ve ilgi çekici…”
-Seth Shostak, Üst Düzey Gökbilimci, SETI Institute-
“...Bennett’ın bu eğlenceli kitabı, okurlara göreliliğin ne olduğunu ve evrenimize dair neleri ortaya koyduğunu gösteriyor.”
-Publishers Weekly-
Bir kara deliğe yolculuk etseydiniz, bu yolculuk sırasında gerçekten neler yaşardınız?
Çoğumuz, Güneş bir gün ansızın kara deliğe dönüşse Dünya’yı ve beraberinde diğer tüm gezegenleri yutacağını düşünürüz. Fakat yazar ve astrofizikçi Jeffrey Bennett’ın da belirttiği gibi, kara delikler aslında yutmazlar. Bu düşünceyle Einstein’ın görelilik teorilerinden yola çıkan Bennett ışık hızını, zamanın genişlemesini ve uzay zamanın bükülmesini ele alarak konuya oldukça eğlenceli bir giriş yapıyor ve size şöyle bir hikâye anlatıyor:
(Tanıtım Bülteninden)
248 pages, Paperback
First published January 1, 2014
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Displaying 1 - 30 of 86 reviews
December 31, 2021
Bennett explains Special and General Relativity in a straightforward consistent manner. He shows how to make a few calculations using high school algebra, but the math is not needed to understand the text. He uses lots of illustrations with his examples to make the book very accessible. Bennett’s material is taken from a college class he teaches on astronomy for non-science students. Bennett believes that an appreciation of relativity is important to the way we see ourselves and the world around us. He covers Special Relativity topics such as reference frames, time dilation, length contraction and mass increase. In General Relativity he reviews key ideas such as the equivalency principle, gravitational redshift, the curvature of spacetime. He offers as clear an explanation of the twin paradox as I have read. An astrophysicist, he also discusses black holes, their observable properties and formation as well as a brief discussion of the expansion of the universe, just enough to whet the appetite. It’s a great introductory book to relativity and a light review for those who’d like to revisit these topics.
March 15, 2021
"It's not your fault; rather, it is a result of the fact that we don't commonly experience the extreme conditions under which the true nature of time and space is most clearly revealed."
Jeffrey Bennett's handy resource is probably the best primer on Einsteinian relativity on the market today. Far more lucid than your average physics textbook, Bennett runs through a slew of accessible thought experiments that are easy to commit to memory. While quick to emphasize that each of the ideas discussed has sound mathematical basis, there is almost no math in the book. Its focus is on the conceptual—how relativity works, how it is applied, and what Einstein's ideas can tell us about the nature of scientific inquiry.
It is often said that the concepts of relativity upend our common sense in ways that make them difficult to grasp. But as Bennett points out, this might not be the best way to think about it. Our local experience of spacetime does not include traveling at speeds approaching the speed of light, orbiting in the vicinity of black holes, or compressing objects to infinite densities. How can we have "common" sense about things we don't commonly experience, Bennett asks? Instead, Einstein's ideas ask that we revise our everyday intuitions about spacetime in the same way that learning the Earth isn't flat occasioned us to revisit our intuitions about the meaning of 'up' and 'down'.
Bennett shows readers how, armed with just two foundational principles—that physical laws (or patterns) are the same for everyone (what Hume called the "Principle of Uniformity of Nature") and that the speed of light is a universal constant—Einstein forever changed our understanding of the universe. Those principles ultimately fused the concepts of space and time such that we can no longer speak of certain phenomena in Newtonian terms, of spooky "action at a distance" between objects orbiting other objects. Einstein resolved this dilemma in 1916 by giving us a new view of gravity, otherwise known as the general theory of relativity. As Bennett writes:
There is nothing here that should make your head hurt, excepting perhaps any futile attempts to grapple with the interminable distance between the stars and what that means for our getting there. Early in the book he lays bare this reality while pondering the preposterous speeds at which light travels in a vacuum:
Consider that Andromeda is our closest neighboring galaxy. It is 2.5 million light-years from Earth. Yeah. The math on that is not pretty for aspiring spacefarers.
Throughout the book Bennett patiently debunks the 'just a theory' rhetoric often applied to not just Einstein's ideas but to various other cornerstones of the sciences. More than anything else, what sets science apart is its evidence-based approach to explaining the natural order of the universe. The corroboration of theories by way of experimentally verifiable predictions affords us deeper insight into the workings of physical reality.
Far more than a 'theory' in any colloquial sense, the relativistic effects described by Einstein's equations have been multiply attested using everything from particle accelerators and nuclear power to mobile phones and GPS navigation and other common-use technologies. What began as fanciful speculation in the young Einstein's brain became the empirical bedrock of modern physics through repeated testing and validation. We cannot truly understand the universe without first understanding relativity, and we cannot truly understand the essence of science until we understand its commitment to evidence.
Postscript: Double kudos to Bennett for using the proper terminology: 'general theory of relativity', as opposed to the 'theory of general relativity', the latter of which is not only a semantic contradiction but commonly found in popular press and even in some introductory texts.
Note: This review is republished from my official website.
Jeffrey Bennett's handy resource is probably the best primer on Einsteinian relativity on the market today. Far more lucid than your average physics textbook, Bennett runs through a slew of accessible thought experiments that are easy to commit to memory. While quick to emphasize that each of the ideas discussed has sound mathematical basis, there is almost no math in the book. Its focus is on the conceptual—how relativity works, how it is applied, and what Einstein's ideas can tell us about the nature of scientific inquiry.
It is often said that the concepts of relativity upend our common sense in ways that make them difficult to grasp. But as Bennett points out, this might not be the best way to think about it. Our local experience of spacetime does not include traveling at speeds approaching the speed of light, orbiting in the vicinity of black holes, or compressing objects to infinite densities. How can we have "common" sense about things we don't commonly experience, Bennett asks? Instead, Einstein's ideas ask that we revise our everyday intuitions about spacetime in the same way that learning the Earth isn't flat occasioned us to revisit our intuitions about the meaning of 'up' and 'down'.
Bennett shows readers how, armed with just two foundational principles—that physical laws (or patterns) are the same for everyone (what Hume called the "Principle of Uniformity of Nature") and that the speed of light is a universal constant—Einstein forever changed our understanding of the universe. Those principles ultimately fused the concepts of space and time such that we can no longer speak of certain phenomena in Newtonian terms, of spooky "action at a distance" between objects orbiting other objects. Einstein resolved this dilemma in 1916 by giving us a new view of gravity, otherwise known as the general theory of relativity. As Bennett writes:
“Gravity arises from the curvature of spacetime, and the curvature of spacetime is shaped by the masses within it. The greater the mass, the more it curves spacetime around it. A small object orbiting a more massive object simply follows the straightest possible path that it can given the local structure of spacetime." (p. 112)
There is nothing here that should make your head hurt, excepting perhaps any futile attempts to grapple with the interminable distance between the stars and what that means for our getting there. Early in the book he lays bare this reality while pondering the preposterous speeds at which light travels in a vacuum:
"The fastest spacecraft we've ever built are traveling out into space at speeds of around 50,000 kilometers per hour, which is the same as about 14 kilometers per second. This is quite fast by human standards; in fact, it is about 100 times as fast as a "speeding bullet." However, it is less than 1/20,000 of the speed of light, which means that at this speed, it would take more than 20,000 years to go the distance that light travels in a single year." (pp. 9-10)
Consider that Andromeda is our closest neighboring galaxy. It is 2.5 million light-years from Earth. Yeah. The math on that is not pretty for aspiring spacefarers.
Throughout the book Bennett patiently debunks the 'just a theory' rhetoric often applied to not just Einstein's ideas but to various other cornerstones of the sciences. More than anything else, what sets science apart is its evidence-based approach to explaining the natural order of the universe. The corroboration of theories by way of experimentally verifiable predictions affords us deeper insight into the workings of physical reality.
Far more than a 'theory' in any colloquial sense, the relativistic effects described by Einstein's equations have been multiply attested using everything from particle accelerators and nuclear power to mobile phones and GPS navigation and other common-use technologies. What began as fanciful speculation in the young Einstein's brain became the empirical bedrock of modern physics through repeated testing and validation. We cannot truly understand the universe without first understanding relativity, and we cannot truly understand the essence of science until we understand its commitment to evidence.
Postscript: Double kudos to Bennett for using the proper terminology: 'general theory of relativity', as opposed to the 'theory of general relativity', the latter of which is not only a semantic contradiction but commonly found in popular press and even in some introductory texts.
Note: This review is republished from my official website.
December 27, 2018
Before reading this book, I had a rather confused idea about relativity. Basic concepts lying around in my head without anything to connect them in a coherent way. I knew that time slows down the closer you get to the speed of light. I knew that the same happened the closer you got to a black hole. I had no idea how those things were connected. This book helped a lot putting some order in my head.
There's no math here at all. It begins with a couple of assumptions (e.g.: everyone records the same speed of light) and, using a series of thought experiments, extrapolates the basic concepts of special and general relativity. I just love this way of doing things, because once I understand how something works, then I tend not to forget about it. Not the same if you just throw sparse notions at me.
The only downside is that now I've been hit by a huge fascination for black holes. I think my next read will be about that (if I can find something not too technical).
There's no math here at all. It begins with a couple of assumptions (e.g.: everyone records the same speed of light) and, using a series of thought experiments, extrapolates the basic concepts of special and general relativity. I just love this way of doing things, because once I understand how something works, then I tend not to forget about it. Not the same if you just throw sparse notions at me.
The only downside is that now I've been hit by a huge fascination for black holes. I think my next read will be about that (if I can find something not too technical).
July 10, 2020
Extremely intense read!
The idea of relativity is just amazing to imagine and wonder. The book literally tells you how to stop yourself from turning old (Actually, dying young 😅). Rush to your nearest black hole and yup, you won’t be aging while falling to black and turning to bits. 😂
The relativity literally tells you that how you can literally be only 7 years older since the time you left earth for a great space voyage while the whole world is suffering from the aches of old age. Relativity explains the concept of black holes and worm holes. The original paper is better to read than this book but definitely much much much much much tougher to understand as even in a single line a lot is going on. But here, the author has made it amazing easy and shrunk the whole concepts into just 8 chapters along with awesome examples.
The idea of relativity is just amazing to imagine and wonder. The book literally tells you how to stop yourself from turning old (Actually, dying young 😅). Rush to your nearest black hole and yup, you won’t be aging while falling to black and turning to bits. 😂
The relativity literally tells you that how you can literally be only 7 years older since the time you left earth for a great space voyage while the whole world is suffering from the aches of old age. Relativity explains the concept of black holes and worm holes. The original paper is better to read than this book but definitely much much much much much tougher to understand as even in a single line a lot is going on. But here, the author has made it amazing easy and shrunk the whole concepts into just 8 chapters along with awesome examples.
This entire review has been hidden because of spoilers.
February 7, 2017
Do you know everything about the Theory of Relativity? Then this book is not for you. However, if you are like me, and know little-to-nothing about Relativity but are highly intrigued by the topic, then this new book by Jeffrey Bennett may be just what you are looking for. Bennett takes the reader through the reality of the universe on a quest to understand why “black holes don’t suck”.
Bennett’s tone makes the book approachable. He uses humor well and writes in a way that minimizes the daunting nature of this topic. He takes the average reader though a complex subject with ease and depth. Bennett’s use of thought experiments helps to make the topics discussed accessible but also is the one area that can get overwhelmingly complex at times. This is to be expected. Bennett, while writing at an introductory level, is covering a topic that is contrary to what is the common understanding of much of the universe. Needless to say, you can get quite lost in the consequences of these ideas.
I saw comments about the mathematics in the book being complex but I couldn’t disagree more. Add to that the fact that all of the math used is supplemental to the text and you really don’t need any grip on mathematics to completely understand the points he makes throughout.
Gravitational redshifting, time running slower in gravity, tidal forces, event horizons, singularity, Special Theory of Relativity, General Theory of Relativity, and on and on and on. This book covers much that is quite interesting. Why would it literally take forever to cross the event horizon? What do ocean tides have to do with entering a black hole? What is actually “relative” in the Theory of Relativity? How is acceleration related to gravity and what effect does this have on our understanding of space and time?
I read mostly books from a Christian perspective so this might seem like a break from my normal routine of theology books. But it is not really. Too often Christians run away from the natural sciences because so many of the ideas seem to be competing or contrary to their own. This is sad. If the Bible is true, which it is, all truth is God’s truth. We should never be afraid to learn something new, even if it were to contradict something we have thought we understood. God is found in the truth and gaining a deeper understanding of His creation should only lead to greater praise and awe and worship. Bennett’s book led me to this and I am appreciative of that.
After reading this book I am an expert on Relativity. Nah, just kidding. But I do have a firmer grasp of much and many more questions I want to learn about. You really cannot ask for more from an introductory text than that. Black holes don’t suck. Neither does this book. :-D It is actually quite good.
***I received a review copy of this book from the publisher through NetGalley.
Bennett’s tone makes the book approachable. He uses humor well and writes in a way that minimizes the daunting nature of this topic. He takes the average reader though a complex subject with ease and depth. Bennett’s use of thought experiments helps to make the topics discussed accessible but also is the one area that can get overwhelmingly complex at times. This is to be expected. Bennett, while writing at an introductory level, is covering a topic that is contrary to what is the common understanding of much of the universe. Needless to say, you can get quite lost in the consequences of these ideas.
I saw comments about the mathematics in the book being complex but I couldn’t disagree more. Add to that the fact that all of the math used is supplemental to the text and you really don’t need any grip on mathematics to completely understand the points he makes throughout.
Gravitational redshifting, time running slower in gravity, tidal forces, event horizons, singularity, Special Theory of Relativity, General Theory of Relativity, and on and on and on. This book covers much that is quite interesting. Why would it literally take forever to cross the event horizon? What do ocean tides have to do with entering a black hole? What is actually “relative” in the Theory of Relativity? How is acceleration related to gravity and what effect does this have on our understanding of space and time?
I read mostly books from a Christian perspective so this might seem like a break from my normal routine of theology books. But it is not really. Too often Christians run away from the natural sciences because so many of the ideas seem to be competing or contrary to their own. This is sad. If the Bible is true, which it is, all truth is God’s truth. We should never be afraid to learn something new, even if it were to contradict something we have thought we understood. God is found in the truth and gaining a deeper understanding of His creation should only lead to greater praise and awe and worship. Bennett’s book led me to this and I am appreciative of that.
After reading this book I am an expert on Relativity. Nah, just kidding. But I do have a firmer grasp of much and many more questions I want to learn about. You really cannot ask for more from an introductory text than that. Black holes don’t suck. Neither does this book. :-D It is actually quite good.
***I received a review copy of this book from the publisher through NetGalley.
June 5, 2014
I really enjoyed this book, even the parts I didn’t understand until I had read it several times. That is not a reflection on the author’s writing ability, it is just that my knowledge of relativity is lacking. Some of the math parts, I confess, I just skipped over as there is no way I could understand it. However, if you are like me, and have little or no background in this area, this book is for you.
The actual theory of relativity is not so hard to understand after the author explained it. But the part of the book I still have difficulty with is thinking of “time” as anything other than a man-made, measurement device. To say that space-time is another dimension, is hard for me grasp. If you say that space is another dimension, then I get it, but “time”? To me, time is artificial, not real, just a measurement of passing moments like a calendar measures passing days. Anyway, since I am not a scientist and have never been confused with one, I will have to take their word for it.
If you are someone who is really interested in physics and finds the discussion of relativity, black holes, and these types of subjects elementary, then this book is definitely not for you. But if you are interested in these topics but don’t have any real depth of learning in the area, this is a good book to open your eyes to the quest for knowledge and understanding around these topics. Simply put, if you want to read a really good science book, you should give this one a try.
I was provided a free copy of this book for review from Columbia University Press and Net Gallery. I was under no obligation to provide a favorable review.
The actual theory of relativity is not so hard to understand after the author explained it. But the part of the book I still have difficulty with is thinking of “time” as anything other than a man-made, measurement device. To say that space-time is another dimension, is hard for me grasp. If you say that space is another dimension, then I get it, but “time”? To me, time is artificial, not real, just a measurement of passing moments like a calendar measures passing days. Anyway, since I am not a scientist and have never been confused with one, I will have to take their word for it.
If you are someone who is really interested in physics and finds the discussion of relativity, black holes, and these types of subjects elementary, then this book is definitely not for you. But if you are interested in these topics but don’t have any real depth of learning in the area, this is a good book to open your eyes to the quest for knowledge and understanding around these topics. Simply put, if you want to read a really good science book, you should give this one a try.
I was provided a free copy of this book for review from Columbia University Press and Net Gallery. I was under no obligation to provide a favorable review.
January 26, 2015
Very good starter book for these topics. I teach HS physics, and most books get too mathematical too fast. This book clearly explains these topics at their conceptual level. A science-minded middle-school student could fully grasp these explanations. Extremely logical progression of all the topics chosen for inclusion. I would recommend this book highly prior to every tackling these topics mathematically. I found the writing very engaging, finishing the book in <24 hours.
April 2, 2017
I really enjoyed this book. Even as an introductory text, I felt I learned a lot about special and general relativity. To be honest, I realized how much I didn't know about what I didn't know.
This book has whetted my appetite to learn more about relativity, spacetime, and quantum mechanics.
This book has whetted my appetite to learn more about relativity, spacetime, and quantum mechanics.
February 15, 2018
Bennett's four hour overview was very intuitive and enlightening. His descriptions were clear and understandable, and I would recommend this book to anyone interested in a simplified view of General and Special Relativity.
December 25, 2024
Best book yet
March 7, 2014
This is a primer on the basic ideas of relativity. It includes great, illustrative cartoons and very little math. The author addresses many of the misconceptions people might have about concepts related to relativity because of pop culture and introduces some surprising ways relativity affects our daily lives.
Even though relativity is a topic I’ve been interested in since high school, I learned fascinating new facts from this book. The author made incredibly complex and counterintuitive concepts simple. He started with facts that made sense to me and built on them to make the odder results of relativity make sense too. I liked that he revisited the same thought experiments over and over. This made me comfortable with the ideas and helped me learn.
I liked that the author talked about the implications of relativity for our daily lives. He made a pretty convincing argument for why we should all care about the concepts he teaches here. I also loved that he taught the scientific method as he went. I think this is a book that would be perfect for introductory physics classes. It’s easy to follow and could inspire students to become interested in the topic.
This review first published on Doing Dewey.
Even though relativity is a topic I’ve been interested in since high school, I learned fascinating new facts from this book. The author made incredibly complex and counterintuitive concepts simple. He started with facts that made sense to me and built on them to make the odder results of relativity make sense too. I liked that he revisited the same thought experiments over and over. This made me comfortable with the ideas and helped me learn.
I liked that the author talked about the implications of relativity for our daily lives. He made a pretty convincing argument for why we should all care about the concepts he teaches here. I also loved that he taught the scientific method as he went. I think this is a book that would be perfect for introductory physics classes. It’s easy to follow and could inspire students to become interested in the topic.
This review first published on Doing Dewey.
October 5, 2023
This was a fantastic book.
I have been really interested in higher-level physics and wanted to know more about the subject without diving immediately into the deep end. I found the perfect book. Jeffrey Bennett presents the ideas of general and special relativity in remarkably easy to understand ways, while also providing a much deeper level of detail than I had ever heard before.
This is not the end all be all of relativity. If you are looking for mathematical models or proofs of the concepts, you won't find them in this book (I honestly can't remember Bennett using a single equation more than E=mc^2). That simply isn't the objective. This book intends to give an intuitive and palatable overview of relativity and it knocks that goal out of the water.
I would absolutely read this book again. I read a library copy and fully intend to buy one online. Additionally, I wish that I had read this much earlier. As Bennett says, a lot of our resistance to relativity is our preestablished notions. I wish I had read this before taking quite so much Newtonian physics!
I have been really interested in higher-level physics and wanted to know more about the subject without diving immediately into the deep end. I found the perfect book. Jeffrey Bennett presents the ideas of general and special relativity in remarkably easy to understand ways, while also providing a much deeper level of detail than I had ever heard before.
This is not the end all be all of relativity. If you are looking for mathematical models or proofs of the concepts, you won't find them in this book (I honestly can't remember Bennett using a single equation more than E=mc^2). That simply isn't the objective. This book intends to give an intuitive and palatable overview of relativity and it knocks that goal out of the water.
I would absolutely read this book again. I read a library copy and fully intend to buy one online. Additionally, I wish that I had read this much earlier. As Bennett says, a lot of our resistance to relativity is our preestablished notions. I wish I had read this before taking quite so much Newtonian physics!
May 18, 2016
Grundläggande och pedagogisk. Har dock en känsla av att den förenklar så pass mycket att man går miste om en stor del information om orsak och verkan.
April 17, 2018
It seems that with SR and GR you are either forced into a math-heavy textbook or into an “introductory intuition” category. Being insufficiently committed to suffer through the math of Lorentzian manifolds I was looking for the latter, so Bennett is what I got. Unlike Landau’s classic it covers both SR and GR, and unlike say Brian Green or Max Tegmark who cover the subject in passing, with Bennett you get a dedicated but light 150-page dip. Glad I read it, although I wish Bennett took it easy with cosmology connection - my white dwarf interest was gnomish to begin with.
Notes to self:
Special Relativity: non-accelerated motion is relative and c is absolute in any frame. I was surprised to see how cleanly time dilation, length contraction, mass increase, simultaneity inconsistencies fall out from these seemingly innocuous postulates. Bennett’s floating spaceships cartoons with beams of light were intuitive, cute and useful.
- Mass-energy equivalence and space-time equivalence, once c is fixed. Brian Green frames it as c being constant across all 4 dimensions, so you can give up part of c in space to gain time or vice versa.
- Experimental verification: nuclear bomb (mass->energy), particle colliders (energy->mass), longer observed radioactive half-lives at high speed.
- Impetus for SR: Einstein’s dissatisfaction Maxwell’s equations being in conflict with Newton and Galilean transformation. (Q: in Maxwell’s equations c is constant with respect to what? A: c is absolute, Newton is off at high speeds, and Lorentz transformations supersede Galilean).
General Relativity. Acceleration and gravity don’t just feel the same, they are the same (equivalence principle). Even accelerated motion is relative once gravity is factored in.
- “Straightest possible path” along a curved space. “Worldline” plots.
- Matter curves spacetime (SR is GR in flat spacetime, no gravity). Gravity as a property of geometry of a warped spacetime.
- Resolves Newton’s “Force at a distance absurdity”. Also, changes in force in gravity (with change in mass) are not instantaneous as per Newton, but at speed of light of spacetime “ripples”.
- Einstein needs almost a decade and new math (tensor fields, manifolds etc) to workout GR after his “happiest thought” moment in 1907.
- Experiments, practice: Gravitational lensing (light bending) – first verification during eclipse; GPS needs both SR and GR,
Implications.
Black holes. Gravitational time dilation and redshift. Tidal force ripping you apart before crossing the event horizon was a nice image. While we are at it mass increases to an arbitrarily large value and times slows down to a halt.
GTR equations implied expanding universe. Einstein couldn’t stomach it and added the infamous cosmological constant fudge to make universe static. After Alexander Friedman (1922) and Lemaitre (1927) fully equip GTR for multiple solutions, and Hubble’s experimentally confirms expansion (1929), Einstein drops the constant calling it “biggest blunder of his life”. Over the next few years Big Bang theory naturally falls out of this expansion.
ps some modern physics are trying to rehabilitate cosmological constant as a plausible dark energy adjustment of sorts.
Notes to self:
Special Relativity: non-accelerated motion is relative and c is absolute in any frame. I was surprised to see how cleanly time dilation, length contraction, mass increase, simultaneity inconsistencies fall out from these seemingly innocuous postulates. Bennett’s floating spaceships cartoons with beams of light were intuitive, cute and useful.
- Mass-energy equivalence and space-time equivalence, once c is fixed. Brian Green frames it as c being constant across all 4 dimensions, so you can give up part of c in space to gain time or vice versa.
- Experimental verification: nuclear bomb (mass->energy), particle colliders (energy->mass), longer observed radioactive half-lives at high speed.
- Impetus for SR: Einstein’s dissatisfaction Maxwell’s equations being in conflict with Newton and Galilean transformation. (Q: in Maxwell’s equations c is constant with respect to what? A: c is absolute, Newton is off at high speeds, and Lorentz transformations supersede Galilean).
General Relativity. Acceleration and gravity don’t just feel the same, they are the same (equivalence principle). Even accelerated motion is relative once gravity is factored in.
- “Straightest possible path” along a curved space. “Worldline” plots.
- Matter curves spacetime (SR is GR in flat spacetime, no gravity). Gravity as a property of geometry of a warped spacetime.
- Resolves Newton’s “Force at a distance absurdity”. Also, changes in force in gravity (with change in mass) are not instantaneous as per Newton, but at speed of light of spacetime “ripples”.
- Einstein needs almost a decade and new math (tensor fields, manifolds etc) to workout GR after his “happiest thought” moment in 1907.
- Experiments, practice: Gravitational lensing (light bending) – first verification during eclipse; GPS needs both SR and GR,
Implications.
Black holes. Gravitational time dilation and redshift. Tidal force ripping you apart before crossing the event horizon was a nice image. While we are at it mass increases to an arbitrarily large value and times slows down to a halt.
GTR equations implied expanding universe. Einstein couldn’t stomach it and added the infamous cosmological constant fudge to make universe static. After Alexander Friedman (1922) and Lemaitre (1927) fully equip GTR for multiple solutions, and Hubble’s experimentally confirms expansion (1929), Einstein drops the constant calling it “biggest blunder of his life”. Over the next few years Big Bang theory naturally falls out of this expansion.
ps some modern physics are trying to rehabilitate cosmological constant as a plausible dark energy adjustment of sorts.
February 27, 2017
What is Relativity? by Jeffrey Bennett is a nonfiction book that describes Einstein’s Theory of Relativity in a simple way. It goes over the main ideas of relativity and uses thought experiments to help readers understand them.
The main ideas of the book are that the laws of nature are the same for everyone, the speed of light is the same for everyone, and that space and time can be different depending on the situation, but spacetime is the same for everyone. So, nature acts the same for everyone, and the speed of light is always the same in a perfect vacuum from any viewpoint. Also, it describes in the book that time can be dilated and different depending on velocity and gravity, but spacetime is the same, in brief summary, because even if you reach high speeds in space, the geometry of space is different than the geometry we are used to on Earth because spacetime is bent from masses in what we call gravity. This means that when you accelerate fast enough, you aren't going in a straight line, so space and time change but spacetime doesn't. The author goes over the ideas that are important in the Theory of Relativity. He explains the idea of redshift, which says that to an outside observer light would change colors along the spectrum until it turned red and then disappeared if it were to fall into a strong gravitational field. The reasoning would be that greater gravity causes time to go slower, even though people in the field of gravity themselves would feel like time is going at a normal rate. The author also describes that if you were to travel at high enough speeds, you could make a journey in 5 years across space, but come back to Earth in a time 50 years later. This is because your time would be running slower than time on Earth at such high speeds.
People that would be interested in this are those that can understand complex ideas and those who genuinely love science as I do. This book would interest those people as it helps to redefine our common sense by changing their ideas of things like space, gravity, and time. There was nothing to dislike about the book in my opinion, but many things to learn and enjoy.
May 6, 2022
What Is Relativity?: An Intuitive Introduction to Einstein's Ideas, and Why They Matter by Jeffrey Bennett is nothing special. There's nothing particularly intuitive about the way the material is presented, and the explanations and examples are similar to or exactly the same as can be found in hundreds of other books about special and general relativity. And the figures in the Kindle version are so small they are close to unreadable, which is actually a problem with most Kindle books, along with the lack of color illustrations in Kindle books.
For example, one of the examples of special relativity Bennett introduces involves someone falling into a black hole. This example is found over and over again in books about relativity. Another visualization technique presented in this book is to imagine the planets in the solar system as balls sitting on a rubber sheet, so the sheet is depressed in the vicinity of the planets illustrating the warping of space-time near objects of mass. Yawn! This is a very common way of picturing the concept, and is found in numerous other publications. Personally, though, I think space-time is just a construct to represent the effects of gravity, but doesn't really explain the mechanism behind gravity.
There's nothing wrong with this book, and it's an OK summary of special and general relativity for those of us who aren't actively working in the field of physics. I wouldn't, however, say that it presents the concepts in a way that someone will say "Gee, what an obvious, simple, logical way of seeing time and space."
For example, one of the examples of special relativity Bennett introduces involves someone falling into a black hole. This example is found over and over again in books about relativity. Another visualization technique presented in this book is to imagine the planets in the solar system as balls sitting on a rubber sheet, so the sheet is depressed in the vicinity of the planets illustrating the warping of space-time near objects of mass. Yawn! This is a very common way of picturing the concept, and is found in numerous other publications. Personally, though, I think space-time is just a construct to represent the effects of gravity, but doesn't really explain the mechanism behind gravity.
There's nothing wrong with this book, and it's an OK summary of special and general relativity for those of us who aren't actively working in the field of physics. I wouldn't, however, say that it presents the concepts in a way that someone will say "Gee, what an obvious, simple, logical way of seeing time and space."
February 11, 2025
This is more of a belated love letter to What Is Relativity? by Jeffrey Bennett than a review.
Thank you for making my turbulent adolescent years more bearable with your thought experiments, easygoing and humorous explanations, and creatively comforting tone.
At 13, I hadn’t yet come to terms with the fact that I was human. Back then, I felt more like a glob of energy and thoughts hovering on earth. I also really struggled with language courses and felt deeply embarrassed about it. Math and physics, on the other hand, came naturally to me, yet I had no interest in performing well in class - I never understood why we needed a whole semester j to learn rise and run. Besides, no matter my grades, no one seemed to care. Still, I had this insatiable thirst to understand what and why. I liked thinking in terms of limits: what would happen under extreme circumstances?
This book gave me hope - an entire new playing field, the outer space, of ideas to explore. Whether it’s the Doppler effect, time dilation, twin paradox, or the curvature of space-time, Bennett shifted the way I saw the world and allowed my imagination to fully engage with the physical universe.
Eventually I did not choose a career in anything related to theoretical physics. However, for at least the next five years, I had a container to hold me, a voice to keep me grounded.
If it weren’t for this book, I don’t know where I’d be. For that, I cannot thank you enough.
Thank you for making my turbulent adolescent years more bearable with your thought experiments, easygoing and humorous explanations, and creatively comforting tone.
At 13, I hadn’t yet come to terms with the fact that I was human. Back then, I felt more like a glob of energy and thoughts hovering on earth. I also really struggled with language courses and felt deeply embarrassed about it. Math and physics, on the other hand, came naturally to me, yet I had no interest in performing well in class - I never understood why we needed a whole semester j to learn rise and run. Besides, no matter my grades, no one seemed to care. Still, I had this insatiable thirst to understand what and why. I liked thinking in terms of limits: what would happen under extreme circumstances?
This book gave me hope - an entire new playing field, the outer space, of ideas to explore. Whether it’s the Doppler effect, time dilation, twin paradox, or the curvature of space-time, Bennett shifted the way I saw the world and allowed my imagination to fully engage with the physical universe.
Eventually I did not choose a career in anything related to theoretical physics. However, for at least the next five years, I had a container to hold me, a voice to keep me grounded.
If it weren’t for this book, I don’t know where I’d be. For that, I cannot thank you enough.
October 30, 2023
What is Relativity? is easy to understand and a great introduction to relativistic physics. I'm taking physics right now, and it helped me understand concepts such as velocity, friction, vectors, and gravity. Ideas and concepts are presented in a simple concise manner, and there are many different examples to help with different concepts. Pictures are plentiful, and if you're a visual learner like I am, it helps to have different things drawn out instead of explained in excruciating detail. Bennett dives deeper into why the ideas matter, and the real-world applications; like how he mentioned that, without taking relativity into account, GPS systems errors would accumulate at 7 miles a day. I would recommend this book to anyone wanting to understand the concepts of relativity instead of the math.
January 3, 2018
I have to give it to him, this is incredible. I read this book because I received “A Brief History of Time” for Christmas and quickly realized that I would need a little background in science and physics before I attempted that read. That’s where this book came in.
People have attempted to explain relativity to me before. All I knew is that it allows for time travel and has to do with gravity and black holes. This book took me infinitely deeper than that. Although I do have some questions that I’m currently working on solving, I do believe there is not a better book available that better explains the theory of relativity and the importance it plays in both our daily lives and for science as a whole.
I would recommend this book to anyone who is trying to find an answer to the daunting question “just what is relativity?” Don’t let the reputation of the complexity of the theory of relativity get to you. With this book in hand, anyone can understand relativity, or at least give you a strong enough base of information to continue reading or researching whatever else you choose that may have been impacted by Einstein’s greatest find.
People have attempted to explain relativity to me before. All I knew is that it allows for time travel and has to do with gravity and black holes. This book took me infinitely deeper than that. Although I do have some questions that I’m currently working on solving, I do believe there is not a better book available that better explains the theory of relativity and the importance it plays in both our daily lives and for science as a whole.
I would recommend this book to anyone who is trying to find an answer to the daunting question “just what is relativity?” Don’t let the reputation of the complexity of the theory of relativity get to you. With this book in hand, anyone can understand relativity, or at least give you a strong enough base of information to continue reading or researching whatever else you choose that may have been impacted by Einstein’s greatest find.
August 17, 2020
One of the best science books I've read. Unlike many popular science books aimed at laypeople, Bennett doesn't skim over the details in order to make something sound interesting. He goes right into every single detail, until you have a comprehensive knowledge of how and why the universe conforms to Einstein's theories of special relativity and general relativity. The book is kind of a hybrid cross between a popular science book and a text book, but that doesn't make it any less interesting. I think you need to read this book slowly, because if you do, you will actually finish the book genuinely understanding relativity.
November 3, 2017
While I have read dozens of books on physics and cosmology, I thought it would be good to see how well Bennett covered relativity. He did a fabulous job, hence 4-stars. Pretty much anyone with an interest in what is out there in the universe would enjoy this book. His teaching experience has honed an approach that is simple and effective in getting your head around some of the physics that are not apparent in the eveyday life of 99.99% of us. If you REALLY get it, it is literally awesome, scary, mind-blowing and humbling. Lessons all.
October 19, 2021
Relativity spoken
I’ve read a lot about these ideas for about fifty five years and this book does a better job than any I have read so far to bring together Einstein’s ideas. Simplified but not dumbed down, the author helped me to connect many points that I have never seen before and caused me to start thinking about our solar system and the universe in new a different ways. Foremost, he reminds me that scientific methodology must be applied and ideas not held as faith, examined and re-examined forever. Great read.
I’ve read a lot about these ideas for about fifty five years and this book does a better job than any I have read so far to bring together Einstein’s ideas. Simplified but not dumbed down, the author helped me to connect many points that I have never seen before and caused me to start thinking about our solar system and the universe in new a different ways. Foremost, he reminds me that scientific methodology must be applied and ideas not held as faith, examined and re-examined forever. Great read.
July 4, 2020
Fascinating, educational, and easy to understand for the average person who knows little to nothing about relativity. If you have read other physics books you may find some overlap here, but this book stands on its own with its sole focus on special and general relativity. I now want to read more complex books on this topic and brush up on my math... never thought I would voluntarily do math problems after finishing college calculus!
April 22, 2021
The Best Intro To Relativity Ever!!!
A great intro for me, a person who’d had college physics 50:years ago and none since. I really liked the author’s emphasis throughout on theory AND evidence as well as the process of science. He also provided many examples of the relevance of relativity, and many examples of the different ways in which the theory has been tested with nearly perfect scores. I highly recommend this book.
A great intro for me, a person who’d had college physics 50:years ago and none since. I really liked the author’s emphasis throughout on theory AND evidence as well as the process of science. He also provided many examples of the relevance of relativity, and many examples of the different ways in which the theory has been tested with nearly perfect scores. I highly recommend this book.
January 10, 2018
Learned a ton from this book. I now see why general and special relativity are so important to things like GPS (time dilation) and why we can see multiple images of celestial bodies (gravitational lensing). This should be taught at the high school level because our common sense is actually a liability to our knowledge of how things work deeper in the universe.
July 26, 2023
I appreciated this book! High school students should read this to engage their minds and stimulate their imaginations.
Thank you! Here is a book that explains the theory of relativity so that a person with average intelligence understands it. The examples in the book were entertaining and enabled me to visualize the various situations.
Thank you! Here is a book that explains the theory of relativity so that a person with average intelligence understands it. The examples in the book were entertaining and enabled me to visualize the various situations.
October 7, 2020
Well presented and very informative
Very readable and informative. It is not a technical introduction to relativity, but it is not superficial. Recommended to those who are new to relativity.
Very readable and informative. It is not a technical introduction to relativity, but it is not superficial. Recommended to those who are new to relativity.
September 29, 2017
Good background reading for novices like me who want to know more about Einstein and what relativity is.
January 11, 2019
This is not your definitive guide to the theory of relativity. Important concepts are glossed over and not elaborated on, so this book would serve better as an elementary introduction to the topic.
March 26, 2019
A very accessible introduction to the ideas of relativity for the layperson.
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