The Theory of Relativity…


The Theory of Relativity is quite possibly the greatest modern scientific discovery of all time and yet I would venture to guess that most of us have no concept of it or at the very least fail to see how everyday life is absorbed in the major concepts of the theory. We all know it:


But what does that equation really say? It’s simply saying that the mass of a body is a measure of its energy constant, where ‘E’ stands for Energy, ‘m’ stands for Mass, and ‘c2’ represents the speed of light squared. This equation is often in physics referred to as the mass-energy equivalence concept. We wont get into the math behind it, and lets face it, most of us can’t (myself included).

Einstein’s Theory of Relativity consists of two separate theories called special and general relativity. Special relativity is an expansion on Galilean relativity, which expresses how matter moves through time and space. General relativity is an expansion to his own special relativity theory, which essentially adds gravity into the mix.

So many people ask, ‘How is this a factor in my everyday life?’ We’ll let’s take a look at some things that you deal with constantly (and some I hope we never have to deal with) that are directly related to these theories.


Time Dilation:

So time travel is pretty sweet and one day maybe we can travel forward, far in time, and experience the future. Impossible? Well, the thing is… we already have at a smaller scale. You’re doing it right now in relation to anyone that is at a lower elevation than you on Earth, though it’s a small enough measure that you and I would never be able to tell without extremely sensitive equipment. Basically what time dilation describes is that the stronger the force of gravity the slower time moves for you in relation to someone who is experiencing weaker gravity. That being said, time for you wont seem to be moving slower relative to you, just as time for the other person experiencing weaker gravity wont seem to move any faster. Now only is this mathematically proven, but we have recorded the effect in real life and it is essential to one piece of equipment we all use daily now.

GPS is a staple technology found in almost all phones and every car. We use it to help us get to places we are unfamiliar with, however if GPS satellites didn’t account for time dilation, we would never get where we needed to go. Imagine the Earth with a GPS satellite coasting in motion far in orbit around Earth. The pull of Earth’s gravity (which is quite weak in relation to other objects in space) is weaker for the satellite where as your car on Earth is closer to the Earth’s mass and thus the pull of gravity is stronger. GPS works by essentially firing a radio wave from your phone to a set of satellites that triangulate your position. Easy enough, I suppose.


This is where it gets interesting and where atomic clocks located on the satellites must be exact. Your phone sends requested signals to satellites located above you in orbit, and because they are constantly moving some may be further away from you than others. If a satellite were to be directly above you then the distance the radio waves need to travel is shorter than a satellite that is located north east of you. These radio waves travel at the speed of light (which is about 670,616,629 mph. Not bad.) However, even at this speed, the satellite directly above you has less distance to travel than the one north east of you. Once the distances of at least four of the twenty-four GPS satellites in orbit are estimated by your phone in can then pinpoint your location in three dimensions.

Now time dilation has to be accounted for because the satellites are experiencing time faster than you due to your stronger gravity, so atomic clocks are programmed to account for this small difference and therefore your location will be accurate to around 10 meters or so based on your ability to broadcast and receive signals. This is why GPS tends to have a harder time in wooded areas. If your phone cannot get an accurate idea of how far the satellite is away from you because the atomic clock on board doesn’t account for time dilation (or because your signal is being obstructed), your phone would be completely inaccurate in its guess of your position on a map. Our ability to account for time dilation is precisely why your GPS gets you (most of the time) where you need to go.


Looking Back in Time:

The speed of light is constant. The reason this is so has to do with the fact that mathematically the more mass an object has the more energy it needs to reach faster and faster speeds (remember the mass-energy equivalence?). So an object with mass would need an infinite amount of energy to reach the speed of light. That being said, the smallest mass-less light, energy, or information particles are also limited to this speed. Because light is limited to this speed as well, we know a few things.

Walk outside and look quickly at the sun (don’t stare!). The image burned onto your eyes is what the sun looked like 8 minutes ago. This is because the light that is traveling from the Sun to the Earth is traveling at the speed of light, which even at that great speed takes about eight minutes to reach us. Now do the same thing later in the evening with the moon (feel free to stare all you want). The image you are seeing in the sky is about 1.26 seconds behind. It only takes 1.26 seconds for light to travel the distance between the Earth and Moon. So imagine that the sun exploded. Even after it happened, it wouldn’t be until 8 minutes later that we saw the effects in our sky. The moon would be much quicker but still delayed that 1.26 seconds.


The speed of light expressed in Einstein’s theory allows us to measure great distances in space and so a general rule of thumb is that the further you look into space the older the image you see in the sky really is. So another example is the Helix Nebula (commonly referred to as the “eye of God”), whose image in our skies is about 700 years old. This again means that it takes light 700 Earth years to cover the distance from the nebula to Earth. To see it from Earth is to look back in time 700 years. The furthest galaxies (in our observable Universe) that we can see with our current technology show that they are a distance of about 13.3 billion light years, meaning that the earliest light first generated by that galaxy has been traveling almost the entire life span of the Universe as we know it to be at an age of about 13.7 billion years old. We are literally traveling back in time just by looking in the sky, because not even light photons can travel faster than the speed of light.

Black Holes:

Given that light travels at a maximum speed of about 670,616,629 mph, there is a greater beast that even light cannot escape. One of the interesting things about Einstein’s theory was that the math involved ended up predicting an anomaly that was quite perplexing in what it said and meant. Even Einstein thought that despite the prediction his math made, that it more than likely would not actually exist in the cosmos. The math simply predicted that extremely compact mass would deform space-time to form what they labeled as a black hole.


The best way to imagine a black hole is to pretend that you’re floating in a rowboat in an endless body of water. We’ve all seen waterfalls and we all know that the human body has limitations, because we can only row so fast. This limitation would be the speed of light in relation to a black hole. So we paddle towards what looks like a giant whirlpool waterfall where all the water is rushing towards and falling down into. We can paddle fairly well as long as we stay far away from the event horizon. This is the point at which the force of gravity is pulling stronger than the speed at which we can row. Since nothing can travel beyond the speed of light, we cannot simply row our way out of our impending doom. Gravity is stronger and will continue to become even stronger as we fall further and further in.

What this shows is that since light has a maximum speed, even light itself cannot escape the stronger pull of gravity beyond the event horizon. Any light that crosses the event horizon of a black hole cannot escape, hence the name, black hole. The pull of gravity is so strong in fact that it distorts light around the black hole, giving the outside viewer a kind of “lensing” effect around the black hole. Light bends and distorts around the black hole. Till this day we have not physically seen a black hole in the way in which we imagine them, though we are close. Lensing is one way to know a black hole is possibly near by (possibly, because other things in space also cause this), but we have, however, seen objects that are orbiting around a black hole and how they interact and thus can identify them as well.


Our own Milky Way was discovered to contain a super-massive black hole at its center by observing star orbits over a period of 15 years. It was observed that a cluster of stars were traveling in elliptical orbits around an unidentified object at speeds that would require the sort of gravity known only to a black hole. It is now believed that black holes are a prominent feature of most, if not all, galaxies. 

Many consider the Theory of Relativity one of the greatest human discoveries, and because it has been rigorously tested and proven to be accurate time and time again in both mathematical and observable experimentation, it has withstood the test of time. It not only explains our Universe and makes sense of our surroundings, but also helps to push us further in understanding even more of the unknown. It makes our everyday lives easier and explains with other collected evidence how much of our Universe operates. Scientists are still looking for the link (via string theory) as to how the theory of relativity connects back to the microscopic actions of gravity, or how to explain the physics of the very small and the very big. Maybe one day Ill try and tackle some of the more easy to understand concepts of string theory or even m-theory, but they are a whole new can of worms that require patience. One day…

"They’re coming outta the walls!"

I spent the better part of two hours last night watching a lecture broadcast that brought both the ethologist (the study of animal behavior) and evolutionary biologist, Richard Dawkins and the astrophysicist and science communicator, Neil deGrasse Tyson together onto one stage. It was an exchange that allowed the two men to construct a conversation and ask questions of each other surrounding any topic with no moderator to lead them. Some very interesting topics and concepts were discussed, but it was the later part of the conversation that I feel is fitting to share, since this Friday the feature film Prometheus will be released in theaters. Prometheus deals with a crew of scientists who answer an ancient message on a distant planet in search for the origins of life. It is a sort of prequel to the original Ridley Scott Alien film. Needless to say, my ticket is in hand.

However, I thought it would be interesting to share some of the evidence and ideas behind the concept of life in our universe as two top scientists in their respective fields discussed it, compared to the film’s general story. Keep in mind I haven’t seen Prometheus yet so I can’t spoil anything for you. In the trailer however we discover that the main scientists have found a reoccurring set of stars on many different ancient relics all over the Earth. They are all thought to correspond to a star map of sorts, or as one character puts it, “an invitation.”

The concept of contact with any possible intelligent life is intriguing, but as Neil points out in the discussion it would be likely that any effort to make contact would have to be made by them rather than us. This is because of the vast distances in the universe. He leads with an example of the Earth’s radio-sphere. This is essentially a bubble around the Earth that is a representation of how far we have sent radio signals (intentionally or unintentionally). We have been sending them unintentionally since the early 1900’s. We know that currently nothing moves faster than light in the universe (thanks to Einstein’s theory of relativity), and as of the time of their discussion that distance was about 70 light years. Impressive… at least until you zoom out. Neil asks the audience to imagine the Milky Way Galaxy (where we currently sit) as the size of the stage where the two men are sitting. Earth’s radio-sphere would take up only the distance of a small marble in relation to the stage. In this example you can see that even for as long as we have been projecting radio signals (which are increasing in distance constantly) we haven’t even begun to cover even the smallest fraction of our own galaxy, let alone the Universe.

We as Earth’s inhabitants are quite restricted to our speed limitations. The speed of light is about 186,000 miles per second. Currently, we only travel at a top speed of around 18,000 miles per hour using simple combustion and sadly we will most likely never leave our solar system physically, especially when our space program is all but completely cut off from funding. This idea leads scientist to theorize that any contact with intelligent life outside of our solar system would require technology and much higher intelligence on their part rather than ours. However there is another issue to consider. Who says we’re intelligent?

Neil tackles this concept by giving an example of a man’s encounter with a worm. It happens all the time. When it rains the worms come out and end up on our sidewalks. How many times have you seen the worm, avoided it, and left it to its own devices? Most likely your thoughts are not centered on how the worm is feeling, where it’s going, or if it’s worth communicating with. You pass by and continue with your day. Now take this example and apply it to our scenario. If we don’t even have the technology to travel vast distances and another intelligent being were successful with it, it would mean they would have to have greatly surpassed our intelligence, just as we humans have the worm’s. We could then be so far behind that what we tout as huge scientific breakthroughs are the equivalent of something rudimentary that the other being’s children can acheive on day one of their lives. This begs the question that if we barely notice the worm based on its lack of intelligence compared to ours; does possible greater intelligent life outside of our solar system bother noticing us? It’s food for thought.

In trailers for Prometheus we can see life forms that mimic that of the non-human, un-intelligent life that scatters our world today. The interesting evidence that Richard adds to the conversation of life outside of our planet is the idea that intelligent life has only appeared one time on Earth’s evolutionary journey, where characteristics such as sight, sonar, hearing, and almost every other characteristic of life has evolved more than a few times. This begs the question as to whether Intelligence (such as language communication and culture) is the final end result of Natural Selection, or whether it is simply a one off anomaly. Neil adds to this idea that the probability of life based on the size of the Universe as we see it today over almost 14 billion years of passed time, is actually quite high. And not high as in maybe it has happened once or twice, but high enough that the chances of a habitable planet existing around a common star like our sun would allow for the possibility of numbers that can barely be understood by man today. We’re talking numbers that are greater than the total sum of every single word ever spoken by every single human combined since the beginning of time and even more than that; numbers that are greater than the total number of grains of sand on a major beach.

The reason for this high number is simply because of what makes life possible in the Universe. Life exists because of a few simple core elements, explains Neil. For life on Earth, we require the basic biogenic elements (Hydrogen, Oxygen, Carbon, Nitrogen, Sulfur, Phosphor, and a few lesser elements), the presence of liquid water, and a source of energy. As far as Earth is concerned we have our energy source in the form of the Sun and our liquid water that is far enough away not to burn up and close enough to the Sun not to freeze (the habitable zone). The interesting thing is that the highest occurring elements found in even just our Milky Way galaxy are the following (in order of abundance): Hydrogen, Helium, Oxygen, Carbon, Nitrogen, Silicon, and Sulfur. With the exception of helium they’re almost 1:1. We have already spotted over 1,235 planets (54 of which contain the possibility for similar habitable conditions as Earth) and counting, but we are not done here.

The idea that a planet must be within a habitable zone to provide life, or that if a planet doesn’t exactly mimic our situation is being challenged constantly, and even within our own solar system. We know from surface samples and the geology of Mars that at one point water did flow on its surface and even today it sports its own polar ice caps. However, Mars is currently not a place you would want to be even in a space suit. There is no thick atmosphere to protect you from the Suns deadly rays that constantly pound the surface and the surface is made up of mostly 95% Carbon Dioxide. That being said water can still exist in repositories deep under the harsh surface and we know from examples on Earth that life can thrive in even the harshest of environments where even humans would perish. For example a snottite is a single-celled colony of extremophilic bacteria that thrive in toxic sulfur caves located in Mexico. This is the type of life that scientist think may very well exist underneath Mars harsh surface.

Europa (one of Jupiter’s moons) is another example of a body that could very well contain life. We know that the surface is covered in ice, but that the constant cracks that scar its surface are because of a warmer interior of liquid water and the pull of Jupiter’s tidal forces. A liquid interior could also mean a hot core, which would very well mimic the conditions of thermal vents on Earth, which despite their harsh conditions allow for much life to thrive. Prometheus trailers don’t give us an idea really of the type of planet they are visiting, but it could be possible that much of it is taken from examples like Mars or Europa, in that it consists of a harsh surface and obviously very active subsurface.

Earth was originally thought to be flat, which was first debated by the Greeks and then proven obsolete by Magellan and Elcano around 1519-1520. Then Copernicus showed that Earth was indeed not the center of our solar system then proved again and again when man finally exited the atmosphere. The invention of radiometric dating as well as multiple alternate forms of geographical dating brought the Earth’s age into light at a ball park of 4.5 billion years after millions of years worth of gravitational pull and battery from outside elements. The one thing that both men argue and are quite blown away by is the fact that we are indeed unique and very lucky to be present in the conditions that are required for life. When it comes to the possibility of the Universe repeating these conditions again for other life to exist unbeknownst to us, its hard to imagine given our small sample size of data, but it can be likened to a simple draw of the cards.

Suppose that every star that exists in our Universe (estimated at possibly 300 Sextillion, or 300,000,000,000,000,000,000,000) has a chance at these life creating conditions by form of playing a simple game of cards where we have a deck of 52 cards with each single card having a number that falls between 1 and 52, but no two cards have the same number. Assuming that the criteria for life that mimics Earth’s journey requires that you shuffle those cards and flip them over to reveal left to right a perfect ascending order of 1 to 52, you might say the probability is very low that it could ever happen. However, there is a slight defect in our game. This idea requires that based entirely off our small sample size of the existence of life, that the only way to form life is to have the exact same steps happen in the exact same order as it did on Earth. But life is varied even on Earth. Organisms exist in conditions on our own planet where humans would perish in a second. The other aspect to think about when it comes to the card game is that the probability of drawing a perfect ascending order of 1 to 52 is exactly the same as any other random order of the cards. Any hand I lay down after shuffling contains the same probability of ever happening again as would the perfect ascending 1 to 52.

What this basically means is that if the elements that formed life on Earth are found abundantly everywhere in our universe and the laws of physics and gravity (as we know them) show example after example of consistently formed planets, galaxies, nebulas, black holes, stars, meteors, moons, and life cycles, then it is more likely that the probably of life elsewhere is actually very large considering the sample size of space in the universe and the 14 billion years it has been allowed to operate. As far as how that life may look, act, think, evolve, survive, and more is currently best left up to people like Ridley Scott. Until we see it ourselves we can only speculate. One thing is for sure, time will certainly tell. Let just hope their not Xenomorphs. I’m not really into face hugs. See you in the theater!

It’s Not “Just A Theory.”

The definition of the word theory according to Merriam-Webster’s dictionary is as follows:

  1. The analysis of a set of facts in their relation to one another.
  2. Abstract thought: speculation.
  3. The general or abstract principles of a body of fact, a science, or an art.
  4. A: a belief, policy, or procedure proposed or followed as the basis of an action <her method is based on the theory that all children want to learn> B: an ideal or hypothetical set of facts, principles, or circumstances – often used in the phrase in theory <in theory, we have always advocated freedom for all.
  1. a plausible or scientifically acceptable general principle or body of principles offered to explain a phenomena <the wave theory of light>
  2. A: a hypothesis assumed for the sake of argument or investigation. B: an unproven assumption: conjecture C: a body of theorems presenting a concise systematic view of a subject <theory of equations>


That’s quite a bit to take in, but like almost every word in the English language we reveal a different meaning for the same word within different context, which is why English is one of the harder languages to learn. With this in mind, the use of the word in scientific terms differs greatly than that of its everyday use by an average guy like me.

For example the definition of theory takes a much different meaning when in relation to science. A scientific theory as defined by the United States National Academy of Sciences is as follows:

The formal scientific definition of theory is quite different from the everyday meaning of the word. It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence. Many scientific theories are so well established that no new evidence is likely to alter them substantially. For example, no new evidence will demonstrate that the Earth does not orbit around the sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the Earth is not divided into solid plates that have moved over geological timescales (the theory of plate tectonics). One of the most useful properties of scientific theories is that they can be used to make predictions about natural events or phenomena that have not yet been observed.


And with regards to that last part, all of the most well known theories are still proving accurate well beyond their inception. Now lets take my use of the word theory in everyday life. For instance while I’m standing at the gas pump cringing at the sight of $4.07 from the neon sign at my gas station versus the price I see later ($3.70) that day as I’m heading to work, I may throw out a thought such as, ‘If the prices are so different one place to the next, then in theory, we should just lower the price to anything we want?!’ I’d think this out of ignorance of how the overall system works, which would make my statement based off of conjecture or mere speculation. I’m not going to sit down a try to prove my theory on how the oil industry operates their pricing systems though I might do later research once the work day is over. In any case this is an example that falls under the abstract or unproven assumption context of the word. Call my gas comments, “just a theory,” and you’d be 100% correct.

Science, of course, does not operate that way and can’t operate that way because successful scientific theories purposed within scientific communities require reproducible extensive testing and peer review to then prove or illustrate their hypothesis. For example, I could say 1+1=3 but peer review and testing will prove otherwise. This is what science does in our culture. There is no claim to ultimate knowledge, which is not physically reproducible by peer review.

Lets look at some of the major scientific theories and how they relate to everyday life…

HELIOCENTRIC THEORY: (or Copernican Model)


This theory explains the fact that all of the planets within our solar system orbit around the Sun, the moon orbits the Earth, and that the Earth rotates rather than stars orbiting it. His philosophical hypothesis moved to a scientific theory (as we understand it’s context today) using geometry.

Before Nicolaus Copernicus published his idea in 1543, the general thought was that the Earth was the center of the solar system, that the other heavenly bodies were created of an unchanging substance not of Earth, and that the heavens contained uniform circular motion. He published his model towards the end of his life due to fear of ridicule and disfavor amongst his colleagues and church, according to most scholars. The Roman Catholic Church considered the idea of Heliocentric Theory to be heretical. Galileo would spend the last eight years of his life under house arrest for adopting this theory.

To this day it is still called the Heliocentric Theory. It is the scientific theory that explains our relationship to the Sun. It’s the reason we can predict exactly when and where planets and stars will be in our night sky views. Our first flights into space have proven its validity beyond any doubt. It has greatly shaped our understanding of our placement in the solar system. It is the foundation for some of the greatest scientific theories that have been discovered in the last 500 years.



This is a theory that encompasses of two of Einstein’s theories: General and Special Relativity. This is not an easy subject to explain.

Special Relativity deals with the structure of space-time. It states that:

1. The laws of physics are the same for all observers in uniform motion relative to one another.

2. The speed of light in a vacuum is the same for all observers, regardless of their relative motion or of the motion of the source of light.

It deals with ideas such as Relativity of Simultaneity, Time Dilation, Length Contraction, Mass-energy Equivalence, and Maximum Speed is Infinite. I’m not going to touch on any of that, but I encourage you to go and discover more on the subject.

General Relativity deals with the theory of gravitation. The best way to think about what this theory illustrates is to imagine a mattress where you have one large bowling ball representing the sun. It will sink the mattress down. Now place a baseball about 12 inches away from the bowling ball and accelerate it to the point where it circles the big bowling ball without falling in towards it or speeding off away from it. This is the model for how gravitation really works in the universe. Some of the consequences (in relation to our universe) of this idea are that:

1. Clocks run more slowly the deeper the well in the mattress they sit. So a clock sitting 3 inches from the bowling ball will run much slower than a clock sitting 20 inches away.

2. Orbits precess and change based on the axis tilt of a planet.

3. Rays of light will bend when in the presence of a strong gravitational field.

4. The universe is expanding.


All this said, and again it’s a lot to take in, is proven constantly. Since 1905 (Special Relativity) and 1916 (General Relativity), no alternative theory has been able to disprove these concepts and ideas. For example, those of you who think about time travel may be shocked to know that it’s already been done. Sorry Back To The Future II fans. NASA has proved the concept of General Relativity related to clocks and their speeds. Every clock that is sent up and orbits the Earth at a lesser gravitational pull will tick faster. It has been shown true over and over though only percentages of a second faster, but using that information we can estimate how it may work when compared to larger planetary masses and gravitational pulls. Technically time moves faster for a person on the fourth floor of a building than that of a person on the first floor, however at that short distance its completely undetectable without massive spans of time (See illustration above).  And without scientist accounting for this weird time difference your car’s GPS system will send you straight off a cliff or into a wall. That’s the Theory of Relativity occurring in your everyday life.

Light has also been shown in Hubble photographs to bend around strong gravitational pulls (see above image). This is one way we can discover black holes, which were once thought (even by Einstein) to not have the ability to naturally occur, though that has since been proven wrong by scientist gazing at our Milky Way center. (I will touch on black holes one day in much greater detail)


Moving away now from some of these widely accepted scientific theories based entirely on collections of related, observable fact, why do I bother to touch on this today? Well, really it comes down to the idea that everything we physically know and experience in our life on Earth comes from observation. The word theory is thrown around in the media, on the Internet, and in everyday life as to why something isn’t true or is conjecture or speculation in regards to our physical surroundings within the realm of science. And in the everyday life of someone who doesn’t understand or intensely study (or even bother to skim) advanced mathematics, astrophysics, cosmology, history, chemistry, biology, geology, paleontology, anthropology, botany, or any other field that attempts to understand our physical environment; it’s easy for that same person to confuse the context of the word theory in a scientific field. When we see a scientifically published article that passes reproducible testing and overwhelming observable evidence (that also means it isn’t likely to be changed by insertion of any new evidence) on a subject we aren’t familiar with and say things such as, “It’s just a theory,” we are actually out of context in regards to science.

In regards to my original gasoline price example the word theory is in its proper context, because I am speculating or making assumptions on unknown information to me. For you to say, “It’s just a theory,” would be completely correct. But the Heliocentric Theory and the Theory of Relativity aren’t assumptions or speculation based on unknown information. These are (as to this day) still reproducibly provable and are even useful and accurate on all predictions made using them as the starting point. The amazing thing is that people like Einstein, Newton, Copernicus, Hawking, and others were predicting future concepts  long before testing could come and prove them and they would have labeled them hypothesis’s. They don’t publish works that lead to massive speculation and overwhelming doubt. They require intense research, observation, testing, re-testing and peer review. Even crazier is that nothing has proved Einstein’s Theory of Relativity wrong yet (Though scientists at the CERN facility thought they may have last year, but then realized it was due to equipment failure). However, even if something ever does prove Einstein wrong, the scientific community would gladly accept it as a welcoming of new knowledge and new rigorous testing and would continue forward. Knowledge of our human experience isn’t ultimate and is ever evolving, but a speculative theory in everyday terms is nowhere near the same thing as a published, peer reviewed scientific theory in scientific terms. A person calling an accepted scientific theory, “just a theory,” is interesting in that it does show a trait in them relating to the beginning thoughts of being deductive in nature, which is highly necessary in the scientific method, but the trait that lacks is follow-through which requires massive amounts of evidence and testing to disprove a current theory. I know that if I drop an apple it will fall to the ground (Thanks Isaac!), but I also know that if I drop an apple on the moon it will fall slower due to the moons smaller mass (Thanks Albert). I sure as hell am going to have a hard time proving their theories wrong.

Want to learn more about the Theory of Relativity? Check out the following book, which helps to explain it for laymen like most of us…



Or feel free to comb through a list of Einstein’s actual published works here.