
Originally Posted by
SkyNet_Blue
I'm interested in this thread as i've seen this misconception before many times (I believe it is a misconception but I don't have enough understanding to prove the misconception wrong). I've heard that if you were to travel at the speed of light and you wore a watch and timed yourself traveling at the speed of light for 1 second before stopping. The observer watching you would have experience a significantly greater amount of time. And so from here the connection is made that light actually travels faster than light.
This idea does my head in.
The way I deal with this idea, is that velocity and mass is proportional and that mass and time are also related. For example, if i were to stand next to a black hole (somehow), I would experience less time than someone standing on earth. And with this idea, if your physical body was traveling at the speed of light, you would have the mass similar to that of the black hole (or greater) which would cause you to experience that time dilation.
My ideas are more assumptions than anything. Can you guys shine some more light on this seemingly flawed idea?
Well no, for a couple of reasons. For one, you can't travel at the speed of light, only just close to it. Secondly, traveling at near the speed of light does not effect your gravity. The thing to remember is that for the person traveling at this speed, nothing special happens, things are normal for him, and it is everything else that is traveling at near c. His gravity does not increase to equal that that of a black hole.
Here's a different way of thinking of it. Instead of having space and time we have space-time. What's the difference? Space and time might be considered like the directions North/South and East/West. Time is North/south and space is East/West. Ask bunch of people to point North and they will all point the same direction no matter how they are facing. There is a distinction between time and space that everyone agrees to. If you were to ask these people where a particular city was with respect to them they would all say the same answer in terms of North/South and East/West
Space-time is more like front/back and Left/Right. Ask the same bunch of people to point Left and they will point in different directions depending on how they are facing. Their is no Front/back or Left/Right that they all cab agree on. Each defines them relative to himself. Ask them where a particular city is and they will all give different answers in term of front/back and Left/Right. One person would says that it is 40 miles forward and 50 miles to the Left, while another will say that it is 50 miles forward and 40 miles to the left, even though they are standing at the same spot, just facing different directions. Neither is more correct than the other.
Space-time is like this. But instead of facing different directions and a difference in front/back and Left/right measurements, you have relative motion and a difference in space and time measurements.
Ask two people passing each other at a relative speed as to the "location" of an event, and they will give you different answer in terms of time and distance. Oe might say that it takes place x meters away and y sec from now, while the other say that it takes place w meters away and z secs from now. They measure time and space differently.
I can see how this can be confusing, since we don't see this in everyday life. A person standing on the street and a car zipping by on the road don't disagree as to how far it has to drive and how long it will take to reach a given city. But the thing is, they really do, it is just that at the speed that a car drives, the disagreement is so unimaginably tiny, that we don't notice it. It isn't until speeds start to reach a significant fraction of the speed of light that it becomes noticeable. (in our people facing different directions analogy, the car and person so nearly face the same direction, that they don't notice the difference.).