Tag: Physics

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

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Pulsars the Cosmic Lighthouses

Super fact 108 : A Pulsar is a rapidly rotating neutron star that emits beams of electromagnetic radiation from its magnetic poles. The radioactive beam from a pulsar that is located where the sun is located would heat earth’s surface to tens of thousands of degrees. The pulsar may rotate hundreds of times per second, and we only detect the beam when it crosses our line of sight. A neutron star, or a pulsar, is vastly denser than the Sun, typically hundreds of trillions of times denser.

Illustration of the "lighthouse" effect produced by a pulsar| Pulsars the Cosmic Lighthouses
Illustration of the “lighthouse” effect produced by a pulsar. Michael Kramer, CC BY-SA 3.0 http://creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons.

As mentioned, a pulsar is a rapidly rotating neutron star that emits beams of radiation from its magnetic poles. A neutron star is an ultra-dense remnant left behind when a massive supergiant star runs out of fuel and collapses. You can read more about neutron stars in my post here and you can read about neutron stars that act like super magnets called magnetars here. This web page feature a calculation of what the intensity of a pulsar beam would be if it hit Earth and the pulsar is located where the sun is.

A blue pulsars / neutron star directs a beam toward earth and burns the surface.
The beam from a pulsar hits earth causing destruction. This is an AI picture generated by me and ChatGPT.

I consider this a super fact because pulsars are a very extreme type of star, which existence I believe comes as a surprise to many people.

Blue neutron star on black background with two bright blue beams. Compact supermassive object. | Pulsars the Cosmic Lighthouses
Pulsar with energetic jets in space. Shutterstock asset id: 2697475389 by Nazarii_Neshcherenskyi

Below is a one and a half minute NASA video explaining what a pulsar is. It is taken from this website.

Different Types of Neutron Stars and Different types of Pulsars

At top there is some text stating “A neutron star is a dense core left behind after a massive star goes supernova and explodes. Though only about 10 to 20 miles (15 to 30 kilometers) wide, they can have three times the mass of our Sun, making them some of the densest objects in the universe, second only to black holes. A teaspoon of neutron star material would weigh 4 billion tons on Earth. There are several types of neutron stars.” : Below the text at the top there is a picture of a magnetar, a pulsar and a magnetar plus pulsar. The text for each picture says: Magnetar - A magnetar is a neutron star with a particularly strong magnetic field, about 1,000 times stronger than a normal neutron star. That's about a trillion times stronger than a normal neutron star. That's about a trillion times stronger than Earth's magnetic field and about 100 million times stronger than the most powerful magnets ever made by humans. Scientists have only discovered about 30 magnetars so far. Pulsar - Most of the roughly 3,000 known neutron stars are pulsars, which emit twin beams of radiation from their magnetic poles. Those poles may not be precisely aligned with the neutron star's rotation axis, so as the neutron star spins, the beams sweep across the sky, like beams from a lighthouse. To observers on Earth, this can make it look as though the pulsar's light is pulsing on and off. Magnetar + Pulsar – there are about six known neutron stars that are both pulsars and magnetars.
Courtesy NASA/JPL-Caltech, Attribution, via Wikimedia Commons

Neutron stars are extreme stars. They are small super dense stars with extreme gravitational fields. They are in a sense like a gigantic atomic nucleus. Perhaps it is not surprising that they are extreme in other ways as well. There are pulsars, neutron stars which emit twin beams of radiation from their magnetic poles. Those poles may not be precisely aligned with the neutron star’s rotation axis, so as the neutron star spins, the beams sweep across the sky, like beams from a lighthouse. To observers on Earth, this can make it look as though the pulsar’s light is pulsing on and off.

There are different types of pulsars. Some spin extremely fast. They rotate hundreds of times per second, even 700 times per second. They are called Millisecond Pulsars. There are pulsars that emit beams of radio waves and pulsars that emit only gamma rays. A black widow pulsar a star system consisting of a rapidly spinning pulsar and a companion star that is being consumed by the pulsar like a black widow spider eats its mate. This link feature animation videos from NASA showing a star being consumed by a black widow pulsar.

Finally, there are magnetars, neutron stars with extremely powerful magnetic fields trillions and quadrillion times stronger than Earth’s magnetic field at the surface. You can read about them here.

Other extreme Celestial objects

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The Second Law of Thermodynamics Does Not Contradict Evolution

Super fact 73 : The second law of thermodynamics, or the fact that entropy is always increasing in an isolated system does not contradict evolution. Life is not a closed system. The environment is providing energy, the sun is providing energy, geological forces are providing energy, etc.

A photo of a trilobite fossil. | The Second Law of Thermodynamics Does Not Contradict Evolution
Does physical laws such as the second law of thermodynamics disprove evolution? This is a trilobite fossil. Shutter Stock Photo ID: 1323000239 by Alizada Studios

A lot of people have never heard of the second law of thermodynamics, or entropy and are unaware of the claim that the second law of thermodynamics contradicts evolution. So how can debunking this claim be surprising, and a super fact? The reason is that this is a popular claim among creationists and according to this Gallup poll 40% of Americans believe in creationism. The fact that this popular but false claim is rooted in a very basic misunderstanding of the second law of thermodynamics and what entropy is makes it super fact.

In the past I’ve read many creationist books that make the claim that the second law of thermodynamics contradicts evolution. One of them was Scientific Creationism (1985) by Henry M. Morris (the father of modern creation science), where he stated that the second law of thermodynamics says that everything tends towards disorder, making evolutionary development (ordering) impossible. The Death of Evolution: Restoring Faith and Wonder in a World of Doubt by Jim Nelson Black, another book I read, and which I gave a one star review on Amazon, makes the same claim. I’ve also come across a lot of people making this claim.

The people who make the claim that the Second Law of Thermodynamics contradict evolution typically do not understand the second law of thermodynamics and do not know what entropy is. Despite that fact they see it as a powerful argument against evolution. I’ve even seen it used against highly respected physics professors who “believe in”, well accept the reality of evolution, by people who had no understanding of the second law of thermodynamics. At one point I even believed the claim myself. Then I studied physics, and well, oops, I was forced to admit that I had been bamboozled.

The Second Law of Thermodynamics

The Second Law of Thermodynamics states that the total entropy (disorder) of an isolated system always increases over time. This means that natural processes tend to move from order to disorder (within the isolated system). It should be noted that disorder is a popular but imperfect metaphor for entropy. Entropy is not the same thing as what people think of as disorder. In physics entropy refers to the logarithm of the number of microstates compatible with the system’s measurable macroscopic state. As molecules randomly arrange themselves into new macroscopic states, the number of possible microstates will increase.

It also means that heat will spontaneously flow from hotter to colder objects, but never the reverse. Another thing it means is that mechanical energy can be converted to thermal energy, but never the reverse. It turns out that those seemingly different statements are physically identical.

Second law of thermodynamics. S corresponds to entropy. Ludwig Boltzman’s formula from 1874
Second law of thermodynamics. S corresponds to entropy. Shutter Stock Vector ID: 2342031619 by Sasha701

It is very possible that the entropy of an organism is lower compared to a blob corresponding to all its molecules randomly distributed within a blob. However, that organism did not evolve in isolation inside a hermetically enclosed box without any energy from the outside. Life and evolution operate in an environment full of energy coming from the sun, the Earth, winds, oceans, geological forces, radiation, etc. Evolution does not take place in an isolated system.

It is also important to understand that within an isolated system, pockets of lower entropy can form if they are offset by increased entropy elsewhere within the system. That’s what the word “total” in total entropy means. Crystal formation is an example of creating local pockets of lower entropy (less “disorder”) within a system, but this is always accompanied by a greater increase in entropy in the surroundings. The Universe is an isolated system so the entropy within the Universe should always increase, but again the local pockets of lower entropy that evolution may create are accompanied by a greater increase of entropy elsewhere.

Crystal structure. This is model of a unique arrangement of atoms in a crystal.
Atoms in a crystal. The crystal represents a pocket of lower entropy. As this pocket of lower entropy forms there is equal of greater increase in entropy in the surroundings. What is true for the crystal is true for the molecules in living beings. Neither the formation of crystals nor the evolution of life contradicts the second law of thermodynamics. Asset id: 689181712 by BK_graphic.

Below is a YouTube video explaining how the second law of thermodynamics does not contradict evolution.

Entropy – Arrow of time

An interesting aspect of the second law of thermodynamics is that it makes entropy serve as an arrow of time. In general, the fundamental laws of physics are time reversible. The equations work the same forwards and backward in time. The equations for gravity, electromagnetism, and the strong nuclear force work the same regardless of time’s direction. An example is if you filmed a planet orbiting a star and played it backward, it would still follow the laws of motion the same way.

Throw a bunch of billiard balls on the floor and film them bouncing and hitting each other and the walls. If you then run the film backwards and forwards it would be far from obvious which is forward and which is backwards, except for the fact that the balls will slow down due to friction. However, balls slowing down due to friction is mechanical energy turning into heat, which is an example of the second law of thermodynamics. The fundamental laws of physics are time reversible, but the second law of thermodynamics is a notable exception. Entropy always increases in an isolated system (like the Universe). By measuring entropy, you can distinguish the past from the future, giving time a direction

Another evolution related post is: Evolution is a fact

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Superfluid Liquids are Like Magic

Super fact 60 : Superfluids such as liquid Helium cooled below -455.58 Fahrenheit exhibit some very strange characteristics such as it flows right through many solids, it climbs walls, it has near zero viscosity, it exhibits circulating flows that never stop despite no energy being added. It is a Macroscopic Quantum Phenomenon.

When gases are cooled far enough, they will turn into liquids and eventually typically to solids. For example, Oxygen becomes a liquid when its temperature drops to -297 Fahrenheit, which is -183 Celsius, or 90 degrees Kelvin. Kelvin is 0 at absolute zero, the coldest possible temperature, and in addition it uses Celsius for the scale. So, 90 degrees Kelvin is 90 degrees Celsius above absolute zero or 162 degrees Fahrenheit above absolute zero. When Oxygen becomes a liquid, it turns into a pale blue liquid. Oxygen becomes a solid at 54 Kelvin, or −218.8 Celsius, and −361.8 Fahrenheit (at normal pressure). It becomes sky blue ice.

Helium stays a gas until very extreme temperatures. Helium becomes a liquid at 4.2 kelvin or -269 Celsius, or -452.11 Fahrenheit. If the temperature is reduced further by almost half to 2.17 Kelvin, or -270.98 Celsius, or -455.8 Fahrenheit, then Helium suddenly becomes a superfluid, exhibiting macroscopic quantum phenomena. It is so different from normal liquid Helium that it is called Helium II. Its heat conductivity (speed of heat/cold transfer) suddenly increases by one million, and the temperature will become the same throughout the liquid instantly. Even a big pool of liquid helium would almost instantly get the same temperature throughout, and the atoms will start behaving in unison. Regular bubbles can no longer exist (atom sized electron bubbles can exist though).

The liquid starts behaving in bizarre ways. If you place an open metal container of Helium II in a closed room the Helium II would climb out of the container and escape, and a thin film of Helium II would climb the walls and the ceiling. If the floor was made of metal or glazed tile the Helium II would remain on the floor. If the floor was made of unglazed tile or stone, it would leak right through the floor as if the floor was a sieve. If you get a whirlpool or fountain going it will keep going forever without any energy loss. In addition, it would also exhibit many quantum effects that are out of scope for this post.

Superfluid Liquids are Like Magic
Unlike ordinary liquids, helium II will creep along surfaces in order to reach an equal level; after a short while, the levels in the two containers will equalize. The Rollin film also covers the interior of the larger container; if it were not sealed, the helium II would creep out and escape. From : Hampel, Clifford A. (1968). The Encyclopedia of the Chemical Elements. New York: Van Nostrand Reinhold. pp. 256–268 (referenced by Wikipedia). Design: Aarchiba; SVG rendering: Júlio Reis, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0&gt;, via Wikimedia Commons

I consider this a super fact because this is a strange, surprising and not a well-known phenomenon. It is a quantum effect that you can observe with your own eyes. It is important because the discovery of superfluidity and its twin effect superconductivity are very important for science and might lead to revolutionizing energy transport in the future. It is no doubt that the phenomenon is real  (true), and it has been documented by numerous experiments and papers. It is described in thousands of textbooks, and I’ve observed the phenomenon with my own eyes (that is next).

Our Experiment with Superfluid Helium

During my first class in Quantum Physics, we performed experiments with liquid Helium. We started out by cooling helium using liquid nitrogen (colder than -196 Celsius or -321 Fahrenheit). Then using vacuum pumps, we kept cooling the Helium until it became liquid. We continued cooling it and we could see lots of bubbles and boiling as we kept going, and then it boiled extra much, and then very quickly the bubbles vanished, and the content of the entire glass container settled down and then stood perfectly still.

As 2.17 Kelvin was reached the viscosity (flow resistance) was instantly lowered with about one million times, and non-microscopic bubbles could no longer exist. The heat conductivity (the speed with which temperature spreads) increased by one million times. It means that the heat of a drop falling in one end of a swimming pool of Helium II would spread throughout the swimming pool in a second. Except, we only had a glass container in which sameness reigned throughout the liquid.

We continued doing experiments such as watching the Helium II climb walls inside the experimental setup, and of course the famous fountain. Insert a little metallic straw and watch a Helium fountain start to flow, by itself. Without any energy or pressure added, it just kept going by itself because no energy was lost either.

I can add that it was more of a demonstration than an experiment that we actively participated in because playing with extreme temperatures high or low is dangerous. If you’ve read this blog for a while you might remember when I put a Cesium-137 sample (800 times more radioactive than Plutonium-239) in my jeans pocket instead of back into its lead brick container and walked around with it a whole day. Or that time when I replaced a fuse for a 380 volt three phase powered laser with my finger because I was curious what would happen if I put my finger in there, and I was shocked, and it hurt. Students shouldn’t play with dangerous stuff.

Below is a one minute and forty four second YouTube video of a Superfluid / Helium II experiment showing an eternal fountain.

Below is a four minute explanation of a superfluid / Helium II experiment.

I can add that Helium II (super cold helium) is not the only superfluid but the easiest one to achieve.

Other Physics Related Superfacts

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Relativity Visualized by Lewis Carroll Epstein

The goal of this blog is to create a list of what I call super facts. Super facts are important and true facts that are nevertheless highly surprising to many or disputed or misunderstood by many. In a sense this is a myth busting blog regarding important information. However, I also make posts that are not super facts but feature other interesting information, such as this book review and book recommendation.

Relativity Visualized by Lewis Carroll Epstein

Lewis Carroll Epstein <<Link-1>> is a physicist, teacher and author who has written a number of physics books for layman. He is somewhat famous for coming up with ingenious ways of using diagrams, pictures and puzzles to explain complex matters without using mathematics. His approach is unorthodox but, in my opinion, quite successful. You still have to invest time in reading this 200-page long book and solving most of the puzzles to understand what is going on. The book features some math, notably regarding the derivation of the formula for energy-mass equivalency E = mc2. However, it is in a special section for “teachers only”.

It is an old book and the only version currently available on Amazon is the paperback version. The publisher of the paperback is Insight Press; First Edition (January 1, 1985), ASIN : 093521805X, ISBN-13 : 978-0935218053, 206 pages, item weight : 12.8 ounces, dimensions : 6.25 x 0.75 x 9 inches. It costs $48.99 on US Amazon. Click here to order it from Amazon.com.

The front cover features the title “Relativity Visualized” and the author’s name and in the background is the night sky with the milky way. At the bottom of the front cover is a train with a head lamp and a light beam | Relativity Visualized by Lewis Carroll Epstein
Front cover of the paperback version of Relativity Visualized by Lewis Carroll Epstein. Click on the image to go to the Amazon page for the paperback version of the book.

Amazon’s Description of the Relativity Visualized By Lewis Carroll Epstein

Perfect for those interested in physics but who are not physicists or mathematicians, this book makes relativity so simple that a child can understand it. By replacing equations with diagrams, the book allows non-specialist readers to fully understand the concepts in relativity without the slow, painful progress so often associated with a complicated scientific subject. It allows readers not only to know how relativity works, but also to intuitively understand it.

This is my five-star review for Relativity Visualized

Note, I wrote this review in 2016, so it is relatively old, pun intended. In my original Amazon review I used very large paragraphs. I have changed that by breaking up the paragraphs a bit but without changing the content in any way.

Relatively Intuitive

In my opinion the theories of relativity are among the most interesting intellectual achievements in human history. They revolutionized physics and changed the way we think about physics, space, time, mass, energy, electromagnetism and essentially everything in nature. Despite that fact, the theories of relativity are deterministic and possible to visualize, and unlike Quantum Physics they are not statistical in nature and they don’t have a big issue with interpretation.

I’ve been interested in this topic ever since I came across it as a high school student. Therefore, I did not learn a lot about relativity from this book. I was more interested in the approach to explaining it, and I think his approach is a very good one.

I’ve found that an explanation for relativity that lacks rigor and quantitative reasoning creates misconceptions. The reader may end up thinking he understands it when he doesn’t. I’ve also found that books that focus on deriving complex equations were not only unattainable to the layman but sometimes left the mathematically inclined student with a poor understanding of relativity as well.

Lewis Carroll Epstein’s book “Relativity Visualized” seems to succeed in making relativity accessible to both the layman and those who are mathematically inclined. He explains the special theory of relativity and the general theory of relativity using graphs, visual constructs, and logical puzzles that the reader solves for himself. In a sense he allows the reader to develop the theories of relativity on his own. He avoids equations and formulas, but the reader will still discover more exactly what is going on.

One thing that really impressed me with this book is its special focus on the difference between what you see/experience and what you measure. As an example, take two lights that flash at the same time (in your reference frame). They could appear to flash at different times if the distance between them is large. So, you will see them flash at different times. However, if you time the light flashes and take the distance into account you can measure that they flashed at the same time (non-relativistic situation).

In relativity the differences you measure between frames do not only arise from the distance the light travels or from Doppler Effects but also from the relativity of time and space as well, and Epstein explains the details without confusing the reader. He focuses a lot on simultaneity/non-simultaneity right from the very beginning, and in my opinion understanding relativistic non-simultaneity is crucial to understanding what is going on.

The book also discusses the General Theory of Relativity. The General Theory of Relativity is often seen as completely off limits to the layman. It is typically explained using complex tensor calculus, differential geometry, and topology, or alternatively in a non-technical vague way that leaves the reader clueless. General Relativity was born out of an enigma. Special relativity had shown that energy and mass are the same things, so light has mass. A light beam traveling through a gravitational field must thus bend.

However, that means that the side of the light closer to the mass will travel a shorter distance. From known properties of light (always a transverse/orthogonal wave) this means that the side of the light beam closer to the mass moves slower than the outer rim which would violate the constancy of the speed of light in vacuum.

To solve this enigma Einstein had to introduce a time warp in gravitational fields. Later he discovered that this time warp would cause objects to fall towards the masses that caused the time warp and the practical effect of this turned out to be essentially identical to Newton’s theory of gravity and thus the mysterious force of gravity could be removed. Einstein also discovered that there is a warp effect on space which is negligible unless the speed of the objects is large (like magnetism for electric forces). The book helps you visualize all of this without using complex math.

Lewis Carroll Epstein’s book contains unique pedagogic approaches, novel geometric representations of relativity, as well as engaging questions and answers. For this reason, the book is fiercely protected by copyright law. On the negative side, his writing style is somewhat rigid and old fashioned, the drawings and the graphics are sometimes of low quality, and the book might be quite a bit of work for the layman reader, so it requires that you are really interested. However, overall, this is a very rigorous, detailed, correct, and yet entertaining book that I highly recommend.

Good Myths

I also would like to mention another tool that Lewis Carroll Epstein use in his book, and that is the concept of a Good Myth. A Good Myth is a description that isn’t technical and maybe not exact but that isn’t wrong either. In a loose way it captures the truth of what is going on.

An example of one of these myths is that everything, including all of us, is always traveling through time and space at exactly the speed of light in vacuum. In other words, we are all traveling at the speed of c = 299,792,458 meters per second. If we are sitting still, then we are traveling through time at the speed of light. If we are traveling through space at the speed of light then we are not traveling through time at all, like photons, for which time does not exist.

If we are traveling through space at a high speed, then if we add, in a vector way (Pythagoras theorem), our speed in space to our speed in time, they together will add up to the speed of light in vacuum. But that means that we are traveling through time at a speed that is less than the speed of light. So, our clocks will run slower.

The back cover features the title of the book, praise for the book and very brief description | Relativity Visualized by Lewis Carroll Epstein
Back cover of the paperback version of Relativity Visualized by Lewis Carroll Epstein.

Other Posts on Relativity

Below is a list of other posts I made on Relativity

  • The Speed of Light In Vacuum Is a Universal Constant : to see post click here
  • Two events may be simultaneous for some but not for others : to see post click here
  • Time Dilation Goes Both Ways : to see post click here
  • The Pole-Barn Paradox and Solution : to see post click here
  • Book-Review : The Special Theory of Relativity by David Bohm : to see post click here

Do you feel that you are traveling through time at the speed of light?

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