The pole barn has some features that are common to nearly all models. But in the runners reference frame, the barn will undergo length contraction, and the entire pole can never be entirely within the barn at any time. What is the pole in the barn paradox in relativity. Length of pole and barn when stationary relative to one another 3. Draw spacetime diagrams which show the measurements from both frames. The pole diagram of f s tells us a lot about longterm behavior of ft. The main purpose of this work is to showcase the multitude of ways in which minkowski diagrams can be used for instruction. D is the point where the end of the pole enters the barn ab is simultaneous in barn frame so this will be what the barn sees as the pole length at the time of event a and thus, the pole. Their respective points of view are shown below in what are called spacetime diagrams.
As soon as both ends of the pole are in the barn, slam. The horizontal line is considered the space axis of observer 1. The pole diagram and the laplace mit opencourseware. The crosses represent clocks in bs frame separated by a unit length. As soon as both ends of the pole are in the barn, slam the. In between these events, twin b must be seen by twin a as traveling first away from, and. Barney stands beside a barn with doors open at both ends.
Some paradoxes in special relativity rochester institute of. Write a short 1 paragraph description of your \paradox and its resolution based on your spacetime diagram. The ladder paradox or barnpole paradox is a thought experiment in special relativity. Consider a pole 10 m long and a barn 5 m long with a front and rear door. As soon as both ends of the pole are in the barn, slam the doors. Spacetime diagrams part 3 of the series proper physics. In order to find the time interval, i tried using the spacetime interval. Consequently, the pole can fit within the barn for an instant, whereupon the back door is swung open.
In the above representation, notice that the larger. But in the poles frame of reference, the barn is only 5 m long, so the pole cannot possibly fit in the barn. Lorentz transformations and spacetime diagrams may be used to obtain andor. Drawing a spacetime diagram draw horizontal and vertical axes. However, i want to comment on a few of the finer points that emerge from the material we have covered today. Pole barn construction post frame buildings fetterville sales. Spacetime diagrams, spacetime, geometry introducing spacetime classically we have an absolute time, which can be viewed as a onedimensional euclidean space, r, plus an absolute threedimensional space, r3. The ladder is imagined passing through the open front and rear doors of a garage or. According to relativity, in your reference frame, the barn is shorter tha. Be able to interpret the behavior of worldlines on a spacetime diagram. Explain how the pole and the barn are treated by relativity without internal inconsistency. Therefore at some instant the pole will be observed entirely contained within the barn.
On the first leg of the trip, the second twin moves to the right black sloped line. Above, is a spacetime diagram that helps explain the pole vaulter paradox. Together, the two materials work to produce a structure that is suitable for both livestock and additional storage. Lines in the diagram are like \contrails through time. In this course we will seek to understand einstein, especially focusing on the special theory of relativity that albert einstein, as a twentysix year old patent clerk, introduced in his miracle. We offer the most color combination options in the industry for a design as unique as you are. If it is moving at relativistic speeds the theory of relativity says that it can at least in some reference frames. If youre interested in physics, youve probably heard of this paradox, and probably know the solution. The farmer will see that the pole fits into the barn if the.
The minkowski diagram, also known as a spacetime diagram, was developed in 1908 by hermann minkowski and provides an illustration of the properties of space and time in the special theory of relativity. Poleinbarn paradox jan 29 video on special relativity. Jan 27, 2017 perhaps the most famous paradox of this sort is the twin paradox of special relativity. Assembled with a control seal washer for a consistent, weather tight seal. Since the order of events depends on the frame of reference, the apparent paradox. Now someone takes the pole and tries to run at nearly the speed of. Prologue1 in some distant arcade, a clock tower calls out six times and then stops. Board and batt board and batt can be stained or painted.
This entry borrows heavily from the original faq entry for the twin paradox, by kurt sonnenmoser. Spacetime diagram explanation of the twin paradox the answer to this question is that for the astronaut to return to the earth, heshe must change direction and thereby switch from one inertial frame to another, and that breaks the symmetry between the two observers. Twin and ladder paradoxes help really bugging me physics. Todays lecture covers material found in exercise 5. A speci c point on a spacetime diagram is called an \event. Jan 23, 2017 hanson tam resolves the pole barn paradox using world lines and shows the invariant hyperbola that connects the different reference frames. Nevertheless, the pole diagram of f s carries a lot of infor mation about f s, and if f s is the laplace transform of ft, it tells you a lot of information of a speci. The pole and the barn a 20 foot pole is moving towards a 10 foot barn fast enough that the pole appears to be only 10 feet long. Physics 5i lecture 6 november 4, 2011 successive lorentz. Lets finish off the pole in the barn paradox by doing a spacetime diagram, as weve done several times before now. You own a barn, 40 metres long, with automatic doors at either end, that can be opened and closed simultaneously by a switch. A spacetime diagram shows the history of objects moving through space usually in just one dimension. But it has also been extensively modified, so he is not responsible for any sloppiness or infelicities.
A pole is 20m long, a barn is 10m long, but the pole is moving at u0. The socalled twin paradox is easily resolved by noting that there is a physically meaningful disinction between the experiences of the two twins during the trip. The parallelogram in dark outline is the unit cell of bs grid. To make a spacetime diagram, take many snapshots of the objects over time and set them on top of each other. Jun 12, 2009 but in the runners reference frame, the barn will undergo length contraction, and the entire pole can never be entirely within the barn at any time. The pole and barn paradox or the ladder and garage paradox pose the question. Four equally separated clocks move to the right at a constant 0.
The fact that two events are simultaneous in one frame of reference does not imply that they are simultaneous as seen by an observer moving at a relativistic. The two light vertical lines are the locations of the doors at either end of the barn. Spacetime diagram explanation of the twin paradox the answer to this question is that for the astronaut to return to the earth, heshe must change direction and thereby switch from one inertial frame to another, and that breaks the. The ladder is imagined passing through the open front and rear doors of a garage or barn which is shorter than its rest length, so if. Pole layout as important as carefully investigating the style, quality and features of the building you are going to buy, is taking the time to look over a sample set of plans and directions of how it all goes together before you buy the building. A runner carrying the pole frame s moving with respect to the barn and a farmer frame s runs into the barn.
What is the expression for the time interval of the door closings in the pole vaulters frame. Twin and ladder paradoxes help really bugging me physics forums. You may also want to see professor lindbergs home page for additional materials he has created. As a consequence of this disagreement on when at the same time is, clocks that are moving relative to your frame will always be observed to be running slower than your stationary clock. But recently i was thinking about this paradox in general relativity, which turns out to have some fun consequences. The vertical axis represents the worldline of a stationary particle, called observer 1. Aug 10, 2007 the pole and barn paradox is a classic demonstration of the breakdown of universal simultaneity in special relativity.
Jul 04, 20 can a pole that is longer than a barn completely fit inside the barn. The tilted dark solid lines are snapshots of the pole in its rest. The pole and barn paradox, and the death of simultaneity 2. In the spacetime diagram on the right, drawn for the reference frame of the earthbased twin, that twins world line coincides with the vertical axis his position is constant in space, moving only in time.
In the next part, we will actually use these spacetime diagrams to see how they aid in understanding phenomena such as time dilation and length contraction, and also solve a famous paradox using spacetime diagram. It allows a qualitative understanding of the corresponding phenomena like time dilation and length contraction without mathematical equations minkowski diagrams are twodimensional graphs. You also have a pole, 80 metres long, which of course wont fit in the barn. The pole and the barn 3 aapt summer meeting 1991, vancouver, british columbia the standard resolution trailing edge of the pole does get inside the barn as observed by anybody. The pole and barn paradox ladder and garage paradox. The pole and the barn6 aapt summer meeting 1991, vancouver, british columbia barn frame pole frame the barn is 40 lighttics long. Now, lets specialize my spacetime diagram to the twin paradox. Pole and barn paradox runner with 10 m pole in his hand, moving toward a 5. Professor vern lindbergs notes for this course may act as a textbook for you this quarter.
Will the pole fit completely into the barn as it passes through. Time and space are two separate spaces and the movement in one space. The situation can be further illustrated by the minkowski diagram below. Here are some examples of different styles for you to consider. Pole %in% barn % paradox % a%sta1onary% barn %sits%in%a%. How do lorentz transformations deform the minkowski diagram. And heres a spacetime diagram, where the black axes, 90 degree axes, horizontal and vertical, are bobs barn frame of reference. Cen poleinbarn paradox jan 29 video on special relativity. You have a pole which is exactly as long as the barn at rest. The twin paradox in special and general relativity. Lorentz transformations and spacetime diagrams may be. The pole has a rest length of 60 light tics and moves to the right at 0. An athlete carrying a pole 16m long runs toward the front door of a barn so rapidly that an observer in the barn measures the poles length as only 8m, which is exactly the length of the barn. As shown above, you can select colors for every component of your lester building.
The earthbound twin remains in a single constant velocity reference frame the entire time while the traveling twin must accelerate to turn around and come home. Time and space are two separate spaces and the movement in one space time is independent of movement through the other space. Pole in a barn paradox in special relativity this is a classic braintwister, up there with the twins. Homework equations u speed of reference frame s v speed of particle spacetime diagram slopes. Be able to calculate relativistic momentum, rest energy, relativistic kinetic energy, and total relativistic energy. Einsteins theory of special relativity makes several predictions, some of which seem counter intuitive. In some cases, a concrete foundation will be added to the pole barn. Chapter eight introduces the astronomical distance unit, the light year, and gives a brief description of our home galaxy, the milky way. A graphical introduction to special relativity based on a.
Ph 429529 paradoxes ii winter 2011 oregon state university. The ladder paradox or barn pole paradox is a thought experiment in special relativity. It involves a ladder, parallel to the ground, travelling horizontally at relativistic speed near the speed of light and therefore undergoing a lorentz length contraction. Choose one of the following paradoxes and resolve it using a spacetime diagram. There is a pole vaulter with an the 11ft long pole running toward a 10ft barn. Can a pole that is longer than a barn completely fit inside the barn. Show that the farmer does see the pole in the barn, the athlete does not see the pole fit into the barn, and most importantly that both of these views are consistent with each other. The polebarn paradox the polebarn paradox is a famous variation on the twin paradox which must be addressed with the ideas of simultaneity in relativity. Hanson tam resolves the pole barn paradox using world lines and shows the invariant hyperbola that connects the different reference frames. In this course we will seek to understand einstein, especially focusing on the special theory of relativity that albert einstein, as a twentysix year old patent clerk, introduced in his miracle year of 1905.
Familiarity with spacetime minkowski diagrams, inter. We do so with a spacetime diagram in which spatial axes. The pole and barn paradox is a classic demonstration of the breakdown of universal simultaneity in special relativity. You may also want to see professor lindbergs home page for. Im having trouble reconciling two different versions of the pole and barn paradox.
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