If you were approaching earth at 99% the speed of light what?

Question

would you see. You know the story about the twins, one who travels at high speeds comes home younger than the other twin.
How if the first twin was to observe the twin staying at home wouldn't he see time speed up to account for the age difference when he gets back.
I just listened to a physicals course and the lecturer said in all circumstances when you travel at high speeds you see stationary objects slowed down.

I can't make sense of it...i can't sleep.

Answer 1

In my opinion, you've got to think about HOW the travelling twin would observe the stationary twin. Remember, there would have to be a signal sent from Earth to the spaceship. The further away the travelling twin got, the further the signal would have to travel - and it would only be travelling at ~1% faster than the spaceship. The images received would be getting further apart until the spaceship turned around to come back: and, even then would be slower than 'real time' on the spaceship.

Of course, when he turned around, not only would he be receiving new images faster, but the old ones that hadn't yet reached him - so the images would be scrambled. He could not see his twins' life progress in a logical order.

Hope that makes sense :)

Answer 2

No. Both twins wuld see time appear to 'slow down' for the other. But that only happens because they're in different frames of reference and making observations relative to each other.

Special Relativity is the easy part. And all of it really *does* have to work that way because, if it didn't, causality could be violated. That is, you could observe an 'effect' *before* observing the 'cause' in some particular reference frame. And that would just *never* do.

SR is more 'horse sense' (and learning how to understand a mathematical model and what must logically result from it) than anything else. It's when you get to General Relativity and have to start dealing with non-linear tensor mechanics and asking questions such as: Is it mass-energy that causes gravity and local non-linearities in space-time? Or is it a local non-linearity in space-time that causes energy to become mass and gravity? Then you can start to feel confused.

HTH ☺

Doug

Answer 3

wow what a question! i dont know a thing about physics and i did not take any advanced math or science courses. if im understanding your question right, you are suggesting that the twin who traveled at high speeds would SEE time speed up when he gets back. i dont think he would because once he gets back, time would not be going fast anymore. hes done traveling at high speeds, right? is that what u mean? if when he gets back and the high speed traveling is over, no, i dont think he would see time speed up because he is done traveling. now trying to think about it from the lecturers point of view...ok, the twin is traveling at high speeds...so WHILE he is going at high speeds, stationary objects would be seen as being slowed down? i guess that makes sense because if u r in a car going fast and the other cars r going slow, they wouldnt appear to be going fast. they would appear to be going slow. but he said stationary objects appear to be slowed down. if u were driving fast in a car or on a train, would posts along the road appear to be going fast or slowed down from the speed u r going? i would say they would seem, hm... well u KNOW they r not moving...but how would they appear....good question. i give up lol. hope it doesnt keep me awake too! sleep well! great question!

Answer 4

Okay, say you're on a train travelling at a constant relativistic speed. To people outside the train looking at you, they'll say that you're moving slower than normal. If you looked outside, you'd see the same thing and say the people outside are moving slower. This happens because on the train, you can say that you are at rest and the people outside are not stationary, while the people outside say they're stationary and you're moving. Both viewpoints are equally valid. That's what makes Special Relativity so cool.
The case of the "Twin paradox" can't be as easily solved though, General Relativity has to applied in that situation to account for acceleration.

Answer 5

Traveling at the speed of light, you would see other people moving slower. Speed is defined as distanced travelled divided by time elasped. So say you can fly and run at 99% of the speed of light. As you approached earth flying at near light speed and descended to earth to start running around at light speed what happens? As earthlings we measure time in terms of rotation of the earth on its axis and the revolution of the earth around the sun. If your twin brother is on earth as well walking around like other folks on earth, one day would be 24 hours. The same would be true of you, the super fast twin. Running around at light speed means that every 24 hours you would one day older. But the only difference is that you would cover more of the earth's surface than your much slower twin.

Answer 6

> I just listened to a physicals course and the lecturer said in all circumstances when you travel at high speeds you see stationary objects slowed down.

This is very poorly phrased, such that I do not understand what you are claiming that he said. I think that you misunderstood him, as this does not make any sense.

Answer 7

Don't lose sleep over this. According to Einstein's Theory of Relativity, this is correct. However, it that makes you feel better, as your velocity increases so does your weight. Therefore, in addition to living longer (relative to the twin on earth) the weight of the traveling twin would be astronomical.

Answer 8

Even Einstein was not able to tell why time slows at high speeds. All he could tell is that the speed of light is constant no matter how fast you are traveling. Speed is change in distance divided by change in time. The distance is the same, but to make the speed of light constant no matter how fast you are going, then the change in time must change.

Answer 9

(Direct copy from Wikipedia) Physics

Constant velocity from all inertial reference frames
It is important to realise that the speed of light is not a "speed limit" in the conventional sense. An observer chasing a beam of light will measure it moving away from him at the same speed as will a stationary observer. This leads to some unusual consequences for velocities.

Most individuals are accustomed to the addition rule of velocities: if two cars approach each other from opposite directions, each travelling at a speed of 50 km/h, relative to the road surface, one expects that each car will perceive the other as approaching at a combined speed of 50 + 50 = 100 km/h to a very high degree of accuracy.

At velocities at or approaching the speed of light, however, it becomes clear from experimental results that this rule does not apply. Two spaceships approaching each other, each travelling at 90% the speed of light relative to some third observer between them, do not perceive each other as approaching at 90% + 90% = 180% the speed of light; instead they each perceive the other as approaching at slightly less than 99.5% the speed of light.

This last result is given by the Einstein velocity addition formula:


where v and w are the speeds of the spaceships as observed by the third observer, and u is the speed of either space ship as observed by the other.

Contrary to one's usual intuitions, regardless of the speed at which one observer is moving relative to another observer, both will measure the speed of an incoming light beam as the same constant value, the speed of light.


Interference pattern produced with a Michelson interferometerThe above equation was derived by Albert Einstein from his theory of special relativity, which takes the principle of relativity as a main premise. This principle (originally proposed by Galileo Galilei) requires physical laws to act in the same way in all reference frames. Maxwell’s equations predict a speed of light, in much the same way as is the speed of sound in water. The speed of sound in water is a function of physical constants proper to water. The speed of light was believed to be relative to characteristics of the medium of transmission for light that acted as does water for the transmission of sound -- the luminiferous aether. But the Michelson-Morley experiment, arguably the most famous and useful failed experiment in the history of physics, could not find any trace of this luminiferous aether, suggesting, as a result, that it is impossible to detect one's presumed absolute motion, i.e., motion with respect to the hypothesized luminiferous aether. It should be noted that the Michelson-Morley experiment said little about the speed of light relative to the light’s source and observer’s velocity, as both the source and observer in this experiment were travelling at the same velocity together in space.


[edit] Technical impossibility of travel faster than the speed of light
To understand why an object cannot travel faster than light, it is useful to understand the concept of spacetime. Spacetime is an extension of the concept of three-dimensional space to a form of four-dimensional space-time. Having the classical concepts of height, width, and depth as the first three dimensions, the new, fourth dimension is that of time. Graphically it can be imagined as a series of static,three-dimensional 'bubbles', positioned along an arbitrarily chosen line, each bubble representing a separate position along one of the four dimensions. That graphical approach is analogous to using a sequence of two-dimensional cross-sections taken at some standard interval along the third dimension to represent a three-dimensional object on a two-dimensional surface. (Imagine a map of a multi-story building that is created by giving the floor plan for each story of the building on a new page.) The mapping of space and time can be rotated so that, e.g., the x dimension is replaced by the t dimension, and each "bubble" represents a cross-section taken along the x dimension. Supposing that travel is occurring along the y and or the z dimension, what one will observe is that change along the t dimension will decrease from "bubble" to "bubble" as change across the y-z plane increases from "bubble" to "bubble."

With this understood, there is a clear implication that an object has a total velocity through space-time at any instant, and for all particles of matter this velocity is equal to the speed of light. While this result may seem contradictory to the idea of speed-of-light travel being impossible, it in fact proves it, taking into account the fact that faster-than-light travel was a spatial, or three-dimensional concept, not a four-dimensional concept. In the case of four-dimensions, all of the total velocity of an object not accounted for in three-dimensional space is in the fourth dimension, or time. To go back to our bubble picture, if an object is remaining at the same x, y, z positions it will make maximum progress in the t dimension. And that is just to say that any clock associated with whatever we are watching at x, y, z is ticking away at its maximum rate according to a static observer in the same frame of reference, e.g., somebody at x+3, y+4, z+5 or any other position that is not changing with respect to x, y, and z. But the greater the changes of x, y, and z according to the clock of the other observer, the smaller will be the changes in t. But using the Phythagorean theorem to calculate the distances between a point at x,y,z,t and some later point x', y', z', t', then those distances will always be the same.

While this may seem confusing, it shows that as displacement through space increases, measured time will decrease to maintain the overall space-time velocity. If this is the case, it makes speed-of-light travel impossible, since when as an object approaches the speed of light spacially, it will have to approach zero velocity temporally. Another implication is that an object might be said to travel through four-dimensional space-time at the speed of light, but only in cases wherein its velocity through space is zero. That statement is just a counter-intuitive way of expressing the idea that when one is motionless (according to another observer) one's clock is ticking away most rapidly, and that as one moves faster and faster (according to the other observer) one's clock is ticking at slower and slower rates that approach zero. ( Direct copy)
http://en.wikipedia.org/wiki/Speed_of_light