the time of light relative or actual

[Kenneth Bibby]

if time slows at the speed of light, is this slowing relative or actual. If it's actual from the lights point of view it must not be travelling at the speed of light. So I presume it's relative, I would like to know thanks.

[Klaynos]

There is no such thing as "actual time". Also considering the rest frame of a photon is not really physical, so the concept of time does not apply.

[syadnom]

think of it like this. from any one point, the speed of light must always be the speed of light. so if you travel near the speed of light and you turn on your headlights, you must perceive that light as traveling at the speed if light. Your perception of time will then be slowed by the same ratio as the speed of light - your speed = v so v:c is the same ration as (your time):(a viewpoint at rest relative to your speed).

 

I dont know if that helps but you should be able to conceive that there is no actual or relative time. time is just time, there are no varieties.

 

also, light would have no point of view. light is a special thing and does perceive time as it is traveling at the speed of light, it will experience no time. That may be why it is a special thing, because it has no time, no halflife, never expires.

[NowThatWeKnow]

I see the speed of light as constant relative to its current location measured using time from its current location.

[Kenneth Bibby]

If light experiences no time then there is no time for it to change so no red shift?

[iNow]

If light experiences no time then there is no time for it to change so no red shift?

 

The redshift is relative to an outside observer, a frame of reference beside the photon, so is still an observable phenomenon. We see it all of the time.

 

The reason people say that light has "no time" is because it cannot ever stop moving at the speed of light, therefore has no reference frame (it can never be "at rest"), and is experiencing infinite time dilation relative to all objects moving at less than the speed of light.

[Mr Skeptic]

if time slows at the speed of light, is this slowing relative or actual. If it's actual from the lights point of view it must not be travelling at the speed of light. So I presume it's relative, I would like to know thanks.

 

The equations break down at the speed of light, so you can't just plug them in to see what would happen. However, if I get the gist of what you are asking, if you have something moving really fast, does time actually slow down for it in accordance to the equations of relativity? Well, suppose you have a particle traveling really fast and the particle has a very short half-life. The half-life of the particle will be extended by the same amount that time is slowed in its frame of reference.

[swansont]

The equations break down at the speed of light, so you can't just plug them in to see what would happen. However, if I get the gist of what you are asking, if you have something moving really fast, does time actually slow down for it in accordance to the equations of relativity? Well, suppose you have a particle traveling really fast and the particle has a very short half-life. The half-life of the particle will be extended by the same amount that time is slowed in its frame of reference.

 

And this has been experimentally confirmed.

[einsteinium]

Well if you were travelling away from us at the speed of light your clock will still be tickin anda tockin at its usual rate from your POV but if we looked at your clock from our POV it will appear frozen in time. Maybe because we are seeing the same image over and over or due to the relative velocity of the photons emitting from your clock to us or maybe because the fundamental equations for time break down at this point.

[Klaynos]

Well if you were travelling away from us at the speed of light your clock will still be tickin anda tockin at its usual rate from your POV but if we looked at your clock from our POV it will appear frozen in time. Maybe because we are seeing the same image over and over or due to the relative velocity of the photons emitting from your clock to us or maybe because the fundamental equations for time break down at this point.

 

The rest frame of a photon is invalid, so your first statement and anything that leads from it is invalid.

[Kenneth Bibby]

I see light can not be at rest, so it can be thought of as moving from it's start point to end point but the journey in between can not be broken down into stages, so my question is invalid, and my view of time is wrong because if you use maths to describe the motion you do not need time in the equation. My problem with this is that I can imagen the light being streched so why no model. Is it the maths, maths are stupid they never stop they have no wall of reality.

[Mr Skeptic]

If I understand what you are saying, you are wrong. Math does have some places that it will not give you an answer. For example, if you take the limit of 1/x as x approaches zero, you get either an arbitrarily large number or an arbitrarily large negative number, depending on whether your x is positive or not. So that limit does not exist -- you have to stop before you get to x=0. It is this same problem that prevents us from plugging a reference frame at the speed of light into the equations of relativity. It may be possible, but certainly not with those equations.

[east]

There is no such thing as "actual time". Also considering the rest frame of a photon is not really physical, so the concept of time does not apply.

 

i think this is very relevant to all what is said, 'time' as we know it is measured by the natural frequency of caesium atom, but that is our own human choice of measurement.

 

so there is no real time, there is only a series of events, of things happening.

and if the event did not happen or has not happened yet, time is not and cannot be defined or perhaps defined as none.

 

if this very real phenomena is not taken into account, all arguments about time is quite absurd. thus all formulation becomes absurd.

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The reason people say that light has "no time" is because it cannot ever stop moving at the speed of light,.

 

i beg to differ. 'light' has been made to slow down in real experiments. it has also been made to 'freeze'.

[Mr Skeptic]

Well, in a different sense, you could argue that the clock really does measure time. If you give each measurement of the cesium atom's frequency a number, ie first tick, second tick, etc., you have yourself a series of events. When you say when something happened, what you are saying is that it happened between the n'th and n+1'th ticks. I think relativity preserves cause and effect and order of events, so everyone will agree that the event happened between the n'th and n+1'th ticks of that clock. However, they may say that the clock in question is running fast or slow, and that clock need not agree with anyone else's clock.

[iNow]

i beg to differ. 'light' has been made to slow down in real experiments. it has also been made to 'freeze'.

 

Actually, no, it hasn't. You are confusing the results of the actual experiment, and mixing reference frames.

 

The light traveling through the materials in those experiments is absorbed and reabsorbed continually, and it's the absorption time and re-emission time that makes it appear to slow down from the frame of reference of the observer. However, the light itself is still moving at a constant velocity of c. When you account for absorption and emission times, and ensure you are not mixing reference frames, you will see that light has not been "made to slow down or freeze in real experiements."

[east]

Actually, no, it hasn't. You are confusing the results of the actual experiment, and mixing reference frames.

 

just maybe i am not.

 

The light traveling through the materials in those experiments is absorbed and reabsorbed continually, and it's the absorption time and re-emission time that makes it appear to slow down from the frame of reference of the observer.

 

from point A, to point B,

if light L1 takes n clock ticks,

but L2 takes >>n clock ticks of the same clock as reference,

you are saying light L2 is not slower than light L1 ?, that it is of the same speed ( only appearing to be slowed down ) ? c'mon.

 

maybe light has a maximum speed, but anything in between is very possible. for a start, when you have not switched on the torch light, what is the speed of light ( of the photon ? ). curious.

[iNow]

maybe light has a maximum speed, but anything in between is very possible.

Again, sorry... No. The speed of light is invariant, but thanks for playing.

[east]

Well, in a different sense, you could argue that the clock really does measure time. If you give each measurement of the cesium atom's frequency a number, ie first tick, second tick, etc., you have yourself a series of events. When you say when something happened, what you are saying is that it happened between the n'th and n+1'th ticks. I think relativity preserves cause and effect and order of events, so everyone will agree that the event happened between the n'th and n+1'th ticks of that clock. However, they may say that the clock in question is running fast or slow, and that clock need not agree with anyone else's clock.

 

which is i take to be the definitition of time within this range of measurement i.e. x number of occurences of the caesium atom. agreed. yes they may say it is fast or slow, but that is not to say that there isn't a dependable measurement unit, so perhaps not a problem.

 

what i'm saying is that any arguments not taking this real measurement unit into consideration is perhaps not valid, by virtue of lack of real reference. in the context of the slowed down light, it is relative to this entirely separate event (i.e. the caesium atom vibes ), and hence slow.

 

the interesting counter argument proposed is that it is not, light remains at the same speed. and my question would be relative to what ? for quite a simple requirement of measuring speed is that you need time. ( i.e. in this case a count of the number of occurences of an event ).

[Mr Skeptic]

My device for slowing light consists of two mirrors and I bounce light back and forth several times before it comes out again.

[Sisyphus]

from point A, to point B,

if light L1 takes n clock ticks,

but L2 takes >>n clock ticks of the same clock as reference,

you are saying light L2 is not slower than light L1 ?, that it is of the same speed ( only appearing to be slowed down ) ? c'mon.

 

That is what he's saying, and he's correct. It might help if you don't think of L2 as real at all. The photon that first leaves point A ceases to exist when it is first absorbed by an atom. A tiny amount of time later, that atom then emits a different photon in the opposite direction, also moving at C, which is then absorbed by a second atom, which then absorbs a third photon, and so on.

 

An analogy would be if you threw me a baseball at 60 mph from 50 yards away, which I catch. I then burn that baseball for warmth. Feeling guilty about this, I go about making a replacement baseball, which it takes me about a month to complete (hey, I’m working from scratch in the middle of a field, give me a break). I then throw this baseball in the same direction that you did originally, farther down the field another 50 yards to someone else, again at 60mph. Now, would it be fair to say that you throw baseballs at a speed of 100 yards per month?

 

maybe light has a maximum speed, but anything in between is very possible. for a start, when you have not switched on the torch light, what is the speed of light ( of the photon ? ). curious.

 

What photon? Photons are created when they are emitted.

[east]

What photon? Photons are created when they are emitted.

yes, sorry, i was sleepy when typing that.

you are right, there no photons as yet.

[cameron marical]

well. sisyphyus is right there. its just energy until it gets transfered to light and heat.{other forms of energy}.

 

but if your asking what the speed of light,{of a photon},is, it is 299,792,458 metres per second.