Is light bound to travel at C?

[CAllFlow]

So I'm kind of new to the whole physics thing so be nice please :P


If i guess "nature" keeps objects from being able to go the speed of light then does "nature" keep light from going slower/faster than that speed? I first thought of this when i read a thread asking if gravity actually pulls on light. I didn't want to hijack his thread with my questions so I decided to start a new one.

Basically he was wondering if light was to say bend around Earth due to gravity, wouldn't the area of this beam of light , the side closest to Earth, move quicker than the area on the outside?
-1MileCrash

But I was thinking... if objects are bound to never go 100% of light speed then wouldn't light be bound to always go 100% of light speed? Just as an object say a car gets close to light speed and seems to slow down wouldn't light particles adjust to going faster than they're "supposed to" and govern themselves?

I don't know as I said I'm kinda new to this stuff and would really appreciate some enlightenment.

 

[tiny-tim]

Welcome to PF!

Hi CAllFlow! Welcome to PF!

If i guess "nature" keeps objects from being able to go the speed of light then does "nature" keep light from going slower/faster than that speed?
…
... if objects are bound to never go 100% of light speed then wouldn't light be bound to always go 100% of light speed? Just as an object say a car gets close to light speed and seems to slow down wouldn't light particles adjust to going faster than they're "supposed to" and govern themselves?

Yes, that's right, the speed of light in vacuum (as measured by a local inertial observer) has to stay the same.

(though a distant observer may for example measure the light as slowing down near a massive object)

 

[yuiop]

But I was thinking... if objects are bound to never go 100% of light speed then wouldn't light be bound to always go 100% of light speed? Just as an object say a car gets close to light speed and seems to slow down wouldn't light particles adjust to going faster than they're "supposed to" and govern themselves?

I don't know as I said I'm kinda new to this stuff and would really appreciate some enlightenment.

Hi, welcome to PF

As tiny-tim said the speed of light near a massive body can appear slow to a distant observer, but the important things are:

1) A local observer always measures the the speed of light to be c.

2) If a distant observer measures the speed of a photon to be less than c, then he will also measure all distant material objects local to that photon to be traveling at less than the speed of the photon.

3) No observer ever sees a material object overtaking a local photon, whatever they think the speed of light is, it is always the local maximum speed for everything.

Or put another way:

All particles with rest mass are constrained to travel at less than the local speed of light.
All particles with zero rest mass are constrained to travel at c measured locally.

 

[tiny-tim]

hi yuiop!

i like 2) and 3) !

would you like to try writing a PF Library article on "speed of light" ?​

 

[HallsofIvy]

So I'm kind of new to the whole physics thing so be nice please :P


If i guess "nature" keeps objects from being able to go the speed of light then does "nature" keep light from going slower/faster than that speed? I first thought of this when i read a thread asking if gravity actually pulls on light. I didn't want to hijack his thread with my questions so I decided to start a new one.

Force causes acceleration but acceleration means a change in velocity, not necessarily a change in speed. The difference is that velocity is a vector quantity (with both magnitude and direction) while speed is a number (the magnitude of the acceleration). Gravity causes light to change direction, not speed.

Basically he was wondering if light was to say bend around Earth due to gravity, wouldn't the area of this beam of light , the side closest to Earth, move quicker than the area on the outside?
-1MileCrash

That would be true assuming that the light on the "side closer to the earth" had to arrive at some destination at the same time as the light on the "outside" which is not true.

But I was thinking... if objects are bound to never go 100% of light speed then wouldn't light be bound to always go 100% of light speed? Just as an object say a car gets close to light speed and seems to slow down wouldn't light particles adjust to going faster than they're "supposed to" and govern themselves?

That's not even logically valid! You are essentially asserting that "all things of type A" (objects) "must satisfy law L" (travel at less than the speed of light) and concluding that something that is not of type A (light) then must NOT satisfy law L. Saying "if A then B" does NOT imply "if not A then not B".

As for ' light particles adjust to going faster than they're "supposed to" and govern themselves', I have no idea what that means!

I don't know as I said I'm kinda new to this stuff and would really appreciate some enlightenment.