As for a sphere, it will — as Penrose showed — retain a circular outline no matter what its speed and subtended solid angle, albeit rotated and partly distorted. It will also undergo all the colour and intensity changes noted above. The bottom line is that the observed shape of any object will not depend on its Lorentz transformation.
Yes, length contraction occurs — and can be detected by careful measurement. You can view a short film of part c online here. Courtesy: U Kraus Eur. Cool findings Over the years, only a few hardy researchers have studied the geometrical appearance of large objects moving at relativistic speeds.
Strange things also happen to the apparent speed of a relativistically moving object. In Robert Deissler, who is now at Case Western Reserve University in Ohio, showed that an object with a measured speed v will appear to be travelling faster than it actually is Am. Indeed, this effect, which is purely geometrical, has been observed in some stars and galaxies that seem to be moving faster than the speed of light. Considering all these effects — geometrical plus relativistic — is a challenge, but one rendered easier by computer graphics, as described by Zachary Sherin, Ryan Cheu and Philip Tan from the Game Lab at the Massachusetts Institute of Technology and Gerd Kortemeyer from Michigan State University in Am.
Many such graphics and videos have also been collected at the website spacetimetravel. One way to answer this question has been suggested by Jack Singal , a physicist at the University of Richmond in Virginia. For simplicity, he ignored any potential distortion from the atmosphere and assumed the ship is bright enough to see. Such an object would take only four minutes to get from Earth to the Moon, and its purely relativistic length contraction would be, for a m-long ship, only 2 cm.
However, that limiting observational speed may be too high. Jordan DeLong , a psychologist who is a data-science director of the Los Angeles market-research firm Research Narrative, thinks the situation is more complex. DeLong points to a classic study from , in which a team led by Craig Meyer , now of the University of Virginia, immobilized the heads of five male subjects, who were asked to track a moving spot as closely as possible. It wold take 25 years for the light of that event to arrive and at the ship being 24 lights years out, would take 24 light years to arrive and so on.
So when it gets to earth, assuming you could see it all. The light from all events would arrive all at once. Well truth is the ship is still the same length, but all we are seeing is the effect of light bringing the image to us out of event. Maths can be used to work out length dilation based on an observation, but I think it is being used the wrong way around.
Objects look longer at speed, and we use their speed and reverse engineer the length to work out the actual length of the object. But I could be wrong and everyone contradicts the way I see it, but I am yet to be convinced. Can you help. The effect you described at the end, with a ship approaching at the speed of light, is a strictly visual effect. Pingback: Q: In relativity, length contracts at high speeds. Is it distance or space or is there even a difference?
In the pole vaulter example, I can see why the pole vaulter views the pole as longer than the barn because they are approaching the front of the pole and moving away from the back of the pole.
In the train track example the observer who was stationary relative to the lightning strikes saw them happen at the exact same time not one before the other. Conor The briefly shut barn doors take the place of the lightning strikes, not the ends of the pole passing through the doors.
The farmer sees them simultaneously closed for a moment, with the pole vaulter inside. The pole vaulter sees the door in front of him briefly closed first, then a little later the door behind him closed.
Notify me of follow-up comments by email. Notify me of new posts by email. There's a book! It's a collection of over fifty of my favorite articles, revised and updated. It's interesting. It's good. You should buy it. Click the photo for a link to the amazon page, or this link for the ebook. Email Address. Skip to content. Home About Faq. Q: Why does relativistic length contraction Lorentz contraction happen? Posted on January 27, by The Physicist. Email Print Facebook Reddit Twitter. According to the theory of special relativity, it is impossible to say in an absolute sense whether two distinct events occur at the same time if those events are separated in space, such as a car crash in London and another in New York.
The question of whether the events are simultaneous is relative: in some reference frames the two accidents may happen at the same time, in other frames in a different state of motion relative to the events the crash in London may occur first, and still in other frames, the New York crash may occur first. If we imagine one reference frame assigns precisely the same time to two events that are at different points in space, a reference frame that is moving relative to the first will generally assign different times to the two events.
This is illustrated in the ladder paradox, a thought experiment which uses the example of a ladder moving at high speed through a garage. In , Albert Einstein abandoned the classical aether and emphasized the significance of relativity of simultaneity to our understanding of space and time. He deduced the failure of absolute simultaneity from two stated assumptions: 1 the principle of relativity—the equivalence of inertial frames, such that the laws of physics apply equally in all inertial coordinate systems; 2 the constancy of the speed of light detected in empty space, independent of the relative motion of its source.
Observer Standing on the Platform : Reference frame of an observer standing on the platform length contraction not depicted. Observer Onboard the Train : The train-and-platform experiment from the reference frame of an observer onboard the train. Time dilation is an actual difference of elapsed time between two events as measured by observers moving relative to each other. Time dilation is an actual difference of elapsed time between two events as measured by observers either moving relative to each other.
For instance, two rocket ships A and B speeding past one another in space would experience time dilation. That is, inside the frame of reference of Ship A, everything is moving normally, but everything over on Ship B appears to be moving slower and vice versa. From a local perspective, time registered by clocks that are at rest with respect to the local frame of reference and far from any gravitational mass always appears to pass at the same rate. Thus, time dilation effects and extremely small and can be safely ignored in a daily life.
Notice that for small speeds less than 0. The twin paradox is a thought experiment: one twin makes a journey into space and returns home to find that twin remained aged more. The twin paradox is a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This occurs because special relativity shows that the faster one travels, the slower time moves for them.
This result appears puzzling because each twin sees the other twin as traveling, and so, according to a naive application of time dilation, each should paradoxically find the other to have aged more slowly.
In other words, from the perspective of the rocketship, the earth is traveling away from the ship and from the perspective of the earth, the rocket is traveling away. However, this scenario can be resolved within the standard framework of special relativity because the twins are not equivalent; the space twin experienced additional, asymmetrical acceleration when switching direction to return home , and therefore is not a paradox in the sense of a logical contradiction.
The Earth and the ship are not in a symmetrical relationship: regardless of whether we view the situation from the perspective of the Earth or the ship, the ship experiences additional acceleration forces. This phenomenon is not due to actual errors in measurement or faulty observations. The object is actually contracted in length as seen from the stationary reference frame. The amount of contraction of the object is dependent upon the object's speed relative to the observer.
The animations below depict this phenomena of length contraction.
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