# Does Time Exist at the Speed of Light?

1. Feb 23, 2010

### dewaite

Does Time Exist at the Speed of Light???

I do not want to "speculate" but to me, if Light has a frequency and frequency is defined as 1/s or Hertz, then how can time not exist at c, when it is used to define a property of the only phenomena we know to move at c (light)? I hope this is a legitimate question and someone can explain this one to me. Simply put - How can light have frequency if time doesn't exist at c? ----- Consider this speculation if you must.... Some "Accepted" Physical theories just are not based on sound reasoning.

Is the Only thing constant - the speed of light OR is "Change" the Only thing Constant? I cant imagine measuring light or any motion or frequency without Time, However i can measure time without light.

I know this can't be answered with current theory - i just want ya'll to surpass current limitations - they only exist by your definitions!!!

2. Feb 23, 2010

### Frame Dragger

Re: Does Time Exist at the Speed of Light???

This is not hard to explain at all, because your initial supposition that 'time does not exist at c' is wrong. Remove that, and the rest becomes fairly obvious. Why do you believe such a thing? Are you misinterpreting Time Dilation or Differetial Aging and assuming that time simply slows to a halt at c? That isn't true, and the afformention Relativistic effects are... well... relative.

3. Feb 23, 2010

### dewaite

Re: Does Time Exist at the Speed of Light???

Perhaps i am misinterpreting relativity - to much web searching. According to the Lorentz transform, what happens to time at c? Does it become zero or something else? The indeterminant 1/0 - perhaps doesn't mean zero time.

If this effect is only relative, then what makes us see light in different frequencies? I have never heard any physcist state that time exists at c - they all say the contrary - assuming that a photon is everywhere similtaneously because of its zero time nature.

Maybe, I am being misguided. I question also - what happens to mass as it approaches c - does it get infinite? This seems implausible as well simply because an electron is the closest "natural" particle that we know is moving near c, yet it is also the lightest - if things got more massive as it approached c, then why at c does this mass suddenly disappear?

4. Feb 23, 2010

### Mentz114

Re: Does Time Exist at the Speed of Light???

The relativistic formulae do not give sensible answers for velocities equal to c.

WE see light at different frequencies because it is a wave. The assumption above is wrong. There's no such thing as 'zero time nature'.

Yes, you are misguided. Mass does not increase with relative velocity ( recall that only relative velocities can be meaningfully discussed). Electrons can travel at different speeds ( always less than c in any reference frame ). Nothing that posses mass can be accelerated to c.

Do some basic research, you have lots of misconceptions.

5. Feb 23, 2010

### jp2code

Re: Does Time Exist at the Speed of Light???

If I understand it correctly, as an object approaches to the speed of light, its mass can be transferred to an equivalent amount of energy. An electron is mostly energy with very little mass.

I've personally always felt that from an observer's perspective time would appear to be moving progressively slower for an object as it goes faster and faster. From the object's perspective, the observer would appear to be moving progressively faster and faster. At the speed of light (my hypothesis, here), the object traveling at the speed of light would not notice any time dilation in its own reference frame and the observer would appear to be moving infinitely fast (whatever that means). From the observer's podium, the object traveling at the speed of light would appear to be frozen in time.

Crazy stuff to wrap my mind around, though.
~Joe

6. Feb 23, 2010

### dewaite

Re: Does Time Exist at the Speed of Light???

I am doing basic research right NOW. I asked what happens to mass as it approaches c? The rest may be misguided assumptions - so i want the scientific answer - Relavitivistic Mass - how does it change as one approaches c - increase or decrease?

7. Feb 23, 2010

### Frame Dragger

Re: Does Time Exist at the Speed of Light???

You need to begin with first principles again. Take this as friendly advice or don't, but you should listen to Mentz and start from the beginning. This isn't an insult, just a fact of life.

8. Feb 23, 2010

### Fredrik

Staff Emeritus
Re: Does Time Exist at the Speed of Light???

No one uses the term relativistic mass anymore (except in dicussions like this). When when we say "mass", we mean rest mass, which is independent of velocity. (The statement that you might be looking for is probably one of the following: a) The work that needs to be performed to accelerate a massive particle to speed v goes to infinity as v goes to c. b) If E(v) is the total energy of a massive particle in an inertial frame in which the particle has speed v, then E(v)→∞ as v→c.)

Your concern about time at the speed of light is answered by the following, which I originally posted in another forum:

The reason why we associate a specific inertial coordinate system with the motion of an inertial observer is that there's a clock synchronization procedure that makes that the natural choice. All the statements about Lorentz contracton, time dilation, etc., are consequences of that choice. The claim that massless particles experience no time comes from applying the usual time dilation formula for speed v and taking the limit v→c, but there's no reason why we should think of the result of that procedure as "a photon's point of view". There is however a good reason not to: The clock synchronization procedure doesn't work for massless particles. See my posts in this thread (at Physics Forums) for more about this.

9. Feb 23, 2010

### mryoung

Re: Does Time Exist at the Speed of Light???

newbie here,

hello everyone.

My take on this is that photons are in a time-less dimension.
if you are a photon, everything goes in an instant. you die immediately when you are created and you go instantly where you are directed.
that is why photons have no acceleration.

- about its light speed and other properties.
photons are time-less particles in a universe governed by time. it is like a 2dimensional lifeform being observed by 3d people like us. a dot for a 2d person may actually be a line passing thru a 2d plane when viewed by a 3d person. That is why we can observe light properties like velocities and frequencies that are non exisent to a photon's world

my way of treating the constancy of the speed of light is to treat the universe the way physicists have been treating it for decades. scientists have been graphing space time in an x-y coordinate system with y axis representing space and the x axis as time. any event can be plotted on this x-y axis. now what this does is actually slice our existence into different frames like movie films, a series of still pictures layed out in time.
each picture should contain the whole universe itself including every photons. except of course if a particle suddenly went out of our universe.

now... we live in one frame at a time (like movie films), but that frame moves at a constant but in a very fast rate. and to follow Einstein's relativity, that "frame rate" should be the same in any frame of reference. Although photon's speed is undefined in its world and infinite to ours, it has to pass thru these frames which limits its speed to c. it doesnt matter wheter the source of light is going away or towards an observer, the photons will go to its destination in an instant(in his world) but to the observer, and to any observer the speed of light is c. c is constant because our frame rates are constant.

Last edited: Feb 23, 2010
10. Feb 23, 2010

### Frame Dragger

Re: Does Time Exist at the Speed of Light???

https://www.physicsforums.com/archive/index.php/t-319308.html

11. Feb 23, 2010

### Naty1

Re: Does Time Exist at the Speed of Light???

dewaite...I wouldn't take all the above too, too seriously...the situation is rather complex...
At least one famous physicst has said time does not exist for photons...those of the cosmic background radiation are exactly as they were when emitted after the big bang and are just reaching us now....

But I would agree that thinking of light as a frequency based phenomena is not the best way for thought experiments in all situations...say the photoelectric effect, for example....

Because we don't understand time precisely, nor likely speed, nor why c is a limiting speed in this universe, etc,etc, it's kinda hard to draw unambiguous conclusions about how they all combine.

12. Feb 23, 2010

### Mentz114

Re: Does Time Exist at the Speed of Light???

The phrase 'Time does not exist for photons' has a mystical ring to it, but has little physical significance. It's an anthropomorphism of 'photon', itself a doubtful concept outside quantum interactions.

But the frequency of the light is crucial in understanding the PE effect ! That's the whole point - the frequency has to be such that the light quantum has enough energy to overcome the work function.

13. Feb 23, 2010

### edpell

Re: Does Time Exist at the Speed of Light???

I'll jump in. At rest (and approximately for v<<c) the time axis and the travel axis are orthogonal. As v approaches c the two axises are no longer orthogonal. At v=c the two axes are coincident. If you know the photons position you know its time and likewise if you know it's time you know is position.

From a math point of view this is easy and reasonable. From an intuition point of view ... well I have been thinking about it for over 30 year and still find it unintuitive.

14. Feb 23, 2010

### danielatha4

Re: Does Time Exist at the Speed of Light???

Would it not be safe to say, that if a light beam moves past an observer at c (which it should) then a clock aboard that light beam will not tick?

15. Feb 23, 2010

### Fredrik

Staff Emeritus
Re: Does Time Exist at the Speed of Light???

No, because you're describing a logically inconsistent scenario.

16. Feb 23, 2010

### Frame Dragger

Re: Does Time Exist at the Speed of Light???

As in this entire thread... which should be locked, then burned. Then the ashes should be compressed into a 1 caret diamond, and fired into space from a submarine railgun. Requiem In Astro Pacis.

17. Feb 23, 2010

### edpell

Re: Does Time Exist at the Speed of Light???

I would say there are vast differences between massless things and massed things.

Light carries it's own clock just count the number of waves passing by.

A clock made of massed parts will if started at rest in our frame, then brought to a high velocity relative to our frame, then held at that high velocity for some time (in our frame), then brought to rest in our frame will show fewer clock tricks than a clock that stayed the whole time at rest in our frame.

I do not think you can ever get a massed object to the speed of light. It takes an asymptotically raising amount of energy to push the object faster as we get near c.

18. Feb 23, 2010

### danielatha4

Re: Does Time Exist at the Speed of Light???

Ok, then let me rephrase my question as an attempt to understand what it was dewaite was referring to.

If a clock is traveling a constant velocity with respect to an observer then as its velocity approaches c, then the rate at which that clock ticks approaches.... ?

Out of my own curiosity, how would this affect observed frequency?

19. Feb 23, 2010

### edpell

Re: Does Time Exist at the Speed of Light???

zero.

20. Feb 23, 2010

### danielatha4

Re: Does Time Exist at the Speed of Light???

right, so is the frequency of light affected by relative time measurements?