The Light Paradox

[M_Broz]

Fellow Scientists,

 

I have a perplexing thought for you. This is truly intellectual and most likely cannot be tested, but an interesting idea to think about to say the least. So, I was watching an episode of Into the Universe with Stephen Hawking, and I got caught up in some thoughts. I love to think about paradoxes, and this almost seems fitting, so I'll get on with it.

 

Light speed (3.00x10^8 m/s) is the fastest known speed, and nothing can ever match it. However, it does allow for things to get extremely close, about 99.99999% (maybe even infinitely close). Light is interesting in that a single photon doesn't have mass, yet it is there, but can still travel. Anyway, you can send an object (let's say a spaceship with people on board) very close to the speed of light and those people would "travel in time." So, since it cannot reach the speed of light things have to get slower to simply prevent it from reaching the speed of light. Which is a good question in the fact that if you were to graph such a thing, the closer you get to the speed of light, the slower time travels...right? I mean it takes light from the Sun 8 minutes to reach Earth. On such a graph, it would be a decrease in time as the speed increases and reaches closer to light speed.

 

Alright get ready, because this takes some thinking. What about light itself? If you were to plot the graph, it should follow the ever so decreasing time, right? So light itself would slow down. The graph shouldn't jump back to normal time? You at least think it would based upon what I just said, but that cannot be true, or could it? I mean it's not going to (at least based on evidence) go off the graph, It could be either two situations: one, is purely perception vs reality, and the other is that light isn't an object (without any mass) so it mustn't follow the laws of physics.

 

One, our perception of light could be way different that what it is in reality.Let me explain, because in reality this could be true, where light is actually slowed down, but it is the way we perceive it to be that it's instantaneous.

 

The other situation could be that [a photon of] light is a massless "thing" that we can't count as any normal object, and thus, it follows physics differently?

 

So, as I wrap this up, if you're still with me, the question is: What happens to light itself because of the fact it is traveling at the speed of light? Is it slowed down or not? With that, I suggest taking a look at the graph attached to this forum and give it a look because it is interesting to see what happens at the end of the graph, because for now it's a mystery.

 

Matt

 

P.S. Please enlighten me on what you have to say about this.

Edited February 5, 2014 by M_Broz

[md65536]

Several things...

 

1) v = d/t. If you only "slow time" you get smaller durations, which correspond with higher velocities. Don't worry too much about this though cause it doesn't matter in the end (since d can also be smaller), just that the reasoning isn't right.

2) Time of a moving object slows relative to the observer's "normal" clock. An object making a journey from the sun to Earth at high speed doesn't experience slowed time by their own clocks --- but to them, a relatively moving clock such as one on Earth ticks slower.

3) Moving distances are length-contracted. As you approach the speed of light, the distance between the Earth and Sun approaches zero length. From Earth, a fast traveler's clock may tick very slowly. Say it takes 8 minutes on an Earth clock for a ship to travel from Sun to Earth, but a ship clock ticks only about one second during that time. According to an observer on the ship, only one second ticks during its trip from Sun to Earth, but that distance has contracted to about one light-second (think very roughly distance to the moon). Either observer measures the same speed (close to c).

 

 

The way that light is not a normal object like something with mass, is that it has no frame of reference. If you try to figure out what light would measure, using limits as v approaches c, then you find that relative time slows to a stop, and its distances contract to 0. In other words, everything in the universe in the direction of travel contracts to a plane, and there is no distance to travel so it takes no time to travel, and there is no way to define a passage of time. This is not a valid frame of reference from which sensible observations can be described.

 

From an observer's perspective, no time passes for light. No clock can travel at the speed of light. As a clock approaches c, it slows to approaching stopped. If graphed up to c, there would be no discontinuity in the graph.

Edited February 5, 2014 by md65536

[ajb]

What happens to light itself because of the fact it is traveling at the speed of light? Is it slowed down or not?

Light always travels at the speed c with respect to any inertial observer. This means that there is no inertial frame in which light can be considered to be at rest. Thus there is no rest frame of a photon and so we cannot make statements about the "perspective of a photon" in the same way as we can for massive particles.