Now if we ask how far it is from A to b we can at least make an imaginary ruler using the distance of B to C: and then measure the distance from A to b using our new ruler: by comparing the distance from. Remember you are looking at these drawings on a computer screen or on paper. The screen/paper gives us an extra object that really does not exist in our one, two, and three ball universes. There is no background in our examples, the balls are simply suspended in empty space. As you read remember, and imagine, that there is no screen, no paper, no background the balls simply float in absolute nothingness. We could have chosen to build our ruler using the distance from A to b instead of B to C: then the distance from B to c would have been 1/5th the distance from A. We can ask what the distance is from A to b by comparing it with B to c - and say that it A to b is 5 times the distance from B to c, or we can ask what the distance is from. What we have done is to choose a to b or B to c to be our "ruler".
Time by heidegger: Summary - philosophers
How far is the ball from anything else in this one object universe? There is no resume answer, because the ball is the only object in the universe, so there is absolutely nothing else in the universe that we can measure a distance to, not even some kind of background like a sky full of stars (we ignore the. Now add a second ball "B" to our universe. How far is it from ball A to ball B? We reach for a ruler but wait remember that the only two objects in the entire universe are the two balls, there are no other objects, no rulers, not even a background grid to measure against! Just two balls floating in nothing. Here we can see the problem - since there are only two objects in the entire universe, ball a and murree ball b, there is no ruler you can go get to measure the distance between ball a and ball. There is no way whatsoever to measure the distance between a and B because there is nothing to compare the positions of the balls. So it seems that we must conclude that there is separation but there at least appears to be no such thing as "distance" in this two object universe. Add a third ball "C" to the universe (remember there are three objects a, b, and c in the universe and absolutely nothing else).
So to better understand what we are talking about set your imagination free and take a journey with me into space-time. First there is an underlying question, if we travel to the end of the universe and find a brick wall, what is behind the wall? Is our universe inside a walled "container" that might allow us to measure distances from points on the fixed surface of the container? Or is our universe the container itself with nothing beyond the boundaries? If so then there is no fixed background we can use to measure time and space. Einstein's General Relativity favors year a background free universe where distance and time are measured by relative positions of objects in our universe, quantum Theory favors (but does not necessarily require) the existence of a complex, yet still fundamental, time. To better understand what "relativity" means imagine a universe that is totally empty except for one single ball. There is absolutely nothing else in the entire universe, no atoms, no rocks, no people, just a single ball we will call ball. The ball is floating in totally empty space, there is no background behind it, no horizon, nothing.
Space-time is commonly thought to plan be the history of the entire universe, containing every "event" that ever happens. A "world-line" is the history of an object in "space-time". Special relativity allows us to define a distance from the origin for all the points on a world-line, allowing the world-line to be a set of points that have physically distinguishable properties. Therefore, we can identify each of the events on a world-line as distinct points in space-time. Each point on the world-line is a particular event that happens at one place in space (represented by the values of the x, y, z coordinates) at one particular time (represented by the value of the t coordinate) -. One place in space-time. Each point on the world-line of a human being is generally thought to be a real physical event that represents a unique sequential moment in the life dates of that individual, from birth to death. Einstein said Imagination is more important than knowledge.
Both time and space are relative, and are "different" for observers in relative motion to one another. For one observer the two firecrackers actually did explode at precisely the same time, while for the other observer one firecracker exploded a few seconds before the other. The time and distance measured by each observer is different, both are right, neither is wrong! Relativity tells us that time and distance change depending on the relative motion of the observers. If Observer A measures the passage of one hour on their clock, another observer B who is in relative motion to observer A may measure the passage of 30 minutes on the clock. If Observer A measures a distance of one mile on their ruler, another observer B who is in relative motion to observer A may measure a distance of 1/2 mile on the ruler. We don't see time or distance shrinking on earth because the effect is virtually undetectable until the relative motion of two observers approaches the speed of light (299,792.458 kilometers or 186,000 miles per second). None-the-less, the time and distance measured by two observers in relative motion to each other is different, only the speed of light measured by all observers is the same. Einstein-Minkowski space-time is made up of three spatial dimensions x, y, and z, and one time dimension.
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Every time we set the coffee cup down in our moving car, the coffee would hit statements us in the face! One startling conclusion that we reach from all this is that the velocity of light must have the same value for all inertial observers, even if they are moving toward or away from the source of the light. If this was not true, an observer could perform an experiment using a beam of light to measure the velocity of their inertial reference frame, and then use that result to determine which of several frames of reference (frames in constant motion) they were actually. The disastrous results of a speed of light that is additive (not constant in all frames) would include being hit in the face by the coffee, and, even worse, being plastered to the floor by the speed of the earth flying through space. Experimental results fully support the counterintuitive predictions of special relativity. Clearly, the idea that the speed of light is constant is inconsistent with an absolute space that is distinct and separate from an absolute time. Modern physics replaces Newtonian space and time with a single entity, space-time.
Minkowski, who along with Einstein formalized the math of Spacetime, said, "henceforth, space by itself, and time by itself, have vanished into the merest shadows and only a kind of blend of the two exists in its own right." Space-time is essentially a "curved" geometric. In other words, if one observer correctly concludes that two events occur simultaneously, the same events would appear to take place at different times to an observer who was in motion relative to the first observer. Both the observer who measures the two events to be taking place simultaneously, and the observer who measures the events as taking place at different times, are right! Our example above is correct, one observer will see a firecracker they light and a second firecracker that a friend lights explode at exactly the same time, while a third observer moving relative to the other two will see one firecracker explode before the other. Relativity tells us that both are right!
There is no experiment that you can do inside the car (which is your inertial frame of reference) that will tell you if you are standing at a red light, or going down the road at 90 miles per hour, or even 90,000 miles per. What happens when a car accelerates smoothly after the red light turns green? The same thing that would happen if the car fell (smoothly) off the edge of a cliff, as the car falls toward the ground below the coffee will still remain in the cup on the dashboard (until you reach the valley floor). Note that Newton's first law of motion, which in essence states that an object in motion will remain in motion unless acted on by an external force, is consistent with this result at lower speeds. So long as Newton's laws are applied only where relative velocities do not approach the speed of light, newton's laws of motion give us "close enough" results, even in a relativistic universe. That is why they are still taught in schools as "true" physical laws.
You cannot determine if the car is moving at constant velocity, or is standing still, or is in a uniformly accelerating gravitational free fall. That does not mean that you cannot determine non-uniform acceleration. If you press the accelerator so that the car "speeds up or if you swerve from a straight path, you will feel the acceleration and be able to measure it (the coffee cup will fly off the dashboard). None-the-less, there is no physical experiment whatsoever that can distinguish between a state of rest, a state of constant velocity, and a state of gravitational free fall. Our solar system is located on a spiral arm of the milky way galaxy, which rotates at a constant velocity (creating a nearly inertial frame). If we did not live in inertial frames then every time we got out of bed the speed of our Earth rotating around the sun rotating around the milky way galaxy(at about 155 miles/sec or 250 km/sec) would knock us to the floor!
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Einstein used the concept of relationships between frames of reference to explain how these "crazy" observations are real and actually do occur. Frames of reference may be thought of as invisible "coordinate map grids like the letters and numbers on the sides of roadmaps, attached to every observer so that the observer can measure the position of surrounding objects. Special relativity tells us that observers who are in a state of uniform motion with respect to one another are in "inertial frames of reference and that they cannot use the laws of physics to distinguish the frame of reference of one observer from the. In an inertial frame of reference, there is no physical experiment whatsoever that you night can perform that can distinguish between a state of rest and a state of constant velocity (if you are going down in an elevator, a ball released from your hand does. If you are in a windowless room, there is no experiment that you can perform in that room that will tell you if the room is stationary, or is moving in some direction at a constant velocity, or is in uniform "free fall" acceleration. Think about being in a silent electric car with all the windows painted black (you cant see out so you can't tell if you are moving relative to the road and you cant listen to the engine for clues about your speed). If the car is standing at a red light, and you put a coffee cup on the dashboard, the cup will not move. If the car is going a steady 120 miles an hour (you did not feel the acceleration because you were asleep and you put the cup on the dashboard, the coffee will not fly back and hit you in the face.
We can drive from east to west, north to south, and go up and down mountains. While we are driving sales in any direction we are always driving from our past to our future that is basically why space and time are linked, we cant move through space without moving through time! Before einstein, Isaac Newton shared the popular belief that both absolute time and absolute space exist. Newton believed that the grid that defined absolute space was undetectable, but that there is a universal time that ticks away for all observers in all locations, and that universal time can be accurately measured by clocks. If it is 5 o'clock on planet earth, it is simultaneously 5 o'clock on the most distant star. Similarly, newton believed that absolute space exists that can be measured using the same yardstick (meter-stick) anywhere in the cosmos, a mile measures the same distance anywhere on Earth and on any distant star as it does where you are standing right now. There are lots of problems with this idea, experimental observations simply do not support the conclusion that absolute time and absolute space exist. In 1905 Einstein published his theory of special relativity, which introduced the then radical idea that different observers see the same event occurring at different times and places. For example, john and Marge may see two firecrackers that they ignite explode at exactly the same time, while henry (in motion at a distance on his Speed-o-light rocket motorcycle) may see john's firecracker explode a few seconds before marge's.
work(beginner - intermediate). C-ship, a cool graphics site(effects of the finite speed of light are not accurately portrayed beginner - intermediate). Sites for Physics Students, general, relativity math course hr an overview of the math behind General Relativity (intermediate - advanced) History of Physics - american Institute of Physics (beginner) Cambridge relativity overviews of many current topics in physics and cosmology (beginner - intermediate) UseNet Physics. Absolute being and Relative becoming Interpretation that harmonizes the atemporal block universe of Relativity with the temporal model of quantum Physics Physics meets Philosophy at the Planck Scale Pre-print of chapter by carlo rovelli that outlines his views, which we basically agree with, on Space. Please visit our site: a brief Summary of SpaceTime einsteins theories of relativity tell us that Space, for example - the room you are sitting in, and Time, the minutes that tick away on your watch, are all part of a single physical entity, the. SpaceTime has four dimensions, roughly corresponding to east-west, north-south, up-down, and past-future.
Spacetime, brief Summary of SpaceTime - you may want to jump to our own summary and then jump back to the other links (beginner). Spacetime hr, wikipedia entry on Space and Time (beginner). Einstein for everyone hr, excellent Introductory textbook/Reference for Students (beginner). SpaceTime, a simple explanation of SpaceTime (beginner - intermediate). SpaceTime warps, a discussion of SpaceTime curvature and Time Travel (Large 5 meg. Pdf file) (intermediate - advanced alternative paper theories - do we live in an Atemporal Universe? Forget Time hr, an essay that discusses the very existence of Time (beginner - intermediate). What makes Time Special hr, an essay on what we may lose if Time does not exist (intermediate relativity. Reflections of Relativity hr 700 page textbook - great way to learn about Relativity and SpaceTime (intermediate).
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Another excellent place for students to start is the University new south Wales award winning website einstein Light (beginner - intermediate). Because it requires Adobe Flash for the animations you need to click here to go to the website, preferably with a browser that supports Flash, and enjoy "the finer points of relativity in less time than it takes to eat a sandwich Scientific American 2005). For an overview of quantum Theory click here to visit our sister site: Which has excellent videos, book including explanations of quantum Entanglement and the 2-slit wave-particle duality Experiment. Links to the best websites, here is our list of some of the best Websites hr is Highly recommended / bold. Hr is even better. We do not necessarily agree or disagree with the content on any internet websites linked to below, including advertising on our site. If a web link is broken please tell.