[LeeE]

If you've lived zero time up until now, you're not living in a 'different' time; you've lived, as you said, zero time.  With time being absent as a factor in your frame of reference, you don't keep going because you aren't doing anything.  Nothing can happen and there is no scope for change to occur because there is nowhere else for a different state to exist.

That I have coloured is wrong.

What you have coloured is correct.

Then we're on a loop...

You have acknowledged that that zero time has passed in that frame of reference, so how can it be a factor if it's value is zero?  How can this be incorrect?

Just high-lighting a bit of text and saying it's incorrect without explaining why is worthless.

[yor_on]

From a photons perspective nothing can be, it is its 'destruction' we measure from our perspective, do you agree? There is no way I know of, measuring anything from a photons 'perspective'. But it's still interesting to wonder if one can observe a single photon and 'isolate' its action on one atom f ex. Probably it isn't possible?

[lightarrow]

If you've lived zero time up until now, you're not living in a 'different' time; you've lived, as you said, zero time.  With time being absent as a factor in your frame of reference, you don't keep going because you aren't doing anything.  Nothing can happen and there is no scope for change to occur because there is nowhere else for a different state to exist.

That I have coloured is wrong.

What you have coloured is correct.

Then we're on a loop...

You have acknowledged that that zero time has passed in that frame of reference, so how can it be a factor if it's value is zero?  How can this be incorrect?

Just high-lighting a bit of text and saying it's incorrect without explaining why is worthless.

Because I have already explained it, and sincerely I don't know how to explain it in a different way.

[LeeE]

Oh I give up.

[lyner]

How can you guys get so airated about something which can't have any meaning? If time doesn't exist in a particular model then what is the point of discussing things as if it did?
Too much concrete thinking, I feel.

[lightarrow]

How can you guys get so airated

[]

about something which can't have any meaning? If time doesn't exist in a particular model then what is the point of discussing things as if it did?
Too much concrete thinking, I feel.

What do you mean? I was discussing about time in a very fast starship (because, as already said tens of times, the photon's frame of reference doesn't exist).

[amrit]

time is run of clocks and does not relate to photon in any way

[yor_on]

Let's put it slightly different.

We have two possible effects.

1. If a photon would be shown to possess a mass.

Can it then be regarded as intrinsically timeless?
And what kind of Boson would it be then?
After all, we can 'make' them in a Bose Einstein condensate?

2. What are the actual proofs for it being intrinsically timeless?
I started to look for that but I can't seem to find them?

My own reasoning would possibly be, assuming that light propagates, that we need this as a definition for explaining how it conserves its energy, considering the 'distances' it covers, as well as the 'time' we notice it to have.

On the other hand. Without a clock, how can it propagate?
Not easily, if we assume distance needing a clock?

Also, it is often referred to it being a direct consequence of it being at 'c' but how do you prove that relationship? We talk about it as being a boson, and therefore having those properties, but I would still like to see the causality-chain clearer, leading to the conclusion.

You can say that as the equations prove that matter can't reach 'c' as the slope gets infinitely steep there is a clear difference between what we call bosons and fermions, but the idea of a photon possessing a mass would in my eyes degrade it from being 'time-less' if so?

So, anyone that can show me the proofs?
==

The clock on this server is slightly weird
It says ten minutes before my correction 'intrinsically' came to be
Hmm, it's relativistic

[yor_on]

You can relate it to so called world-lines and say that a photon motion is totally through space, leaving nothing to left for time as it 'moves' as fast that's possible for any object in SpaceTime. Normally we move in Space and in Time, but on the other hand this seems to build on on the (pre?)conception that a photon actually do move as fast as it is possible inside SpaceTime.

But assume that it would be found to have an ever so slight 'restmass'?
Could we then say with certainty that nothing can move faster?

And what would that do this axiom?
==

In a way this idea seems sort of circular, as it build on the premise that light is as fast as anything can be and from there reasons that if we assume that we normally have a motion through both space and time, then with a faster motion you will have a lesser motion through time, all the way up to a photons 'no-time'.

If we go back and look at the theory of relativity, it builds on the idea that light will have the same velocity no matter what frame you measure it from, right? So if I use this definition of world-lines and assume that I send a light-corn from a speeding rocket near light-speed I will still measure it to be 'c' but what have I done to its worldline? Nothing it seems, as it already was as fast as can be? But I must have done something? The photon will see the exact same plane in both cases, that is, nothing.

So how do it do it, seeing nothing, but interacting with us?
Because it do interact, and have a speed as measured by us.

You can relate that to your 'invariant frame' as in your frame time never change, only the 'relations' do.

[JP]

There are two possibilities:
1) A photon is massless, in which case it always moves at c, the cosmic speed limit, and it's probably a meaningless question to ask what it experiences, since we, as objects with mass, can't ever see what it "sees," nor can we measure it, since our detectors also have mass.

2) A photon has mass, in which case we would have to rename the cosmic speed limit something other than "the speed of light"!  Special relativity should still hold, although now photons are like all particles with mass and can't reach that fastest possible speed.  There are probably other tiny fixes that need to be made in various theories.  But, since we know a lot of theories do hold to a high degree of accuracy, and various tests have been made looking for photon mass, the maximum allowable photon mass has to be very tiny, if it is non-zero.

[yor_on]

Sorry JP, missed your reply as I was 'filling in' my question. But yes, that's one answer. We can use those experiments we already made for testing the theory to prove that it still holds.
==

Ahhaa But that's where we don't agree JP. I don't find it meaningless to look at from a photons frame. The only way that would be meaningless would be if they didn't exist for us. But they do, and therefore I will guess

And no, I assume that the reason we exist is our arrow of time, aka a 'clock', and I also assume that the reason we can measure that light to have a velocity is that same 'clock' ticking for us. And then I assume that without a clock you can't discuss a distance, and I don't have to discuss it from the frame of a photon to reach that conclusion.

But applied to that frame you either have to define how the photon can 'propagate' or ..
Well, as I see it
=

Tachyons though
That's another parcel of fish.

[JP]

Ahhaa But that's where we don't agree JP. I don't find it meaningless to look at from a photons frame. The only way that would be meaningless would be if they didn't exist for us. But they do, and therefore I will guess

Meaningless might be a strong word, but how would we go about explaining what a photon experiences (if it is massless, that is)?  No theory covers this, so some new description would be required.  Something beyond special relativity, at least.

[lightarrow]

I don't find it meaningless to look at from a photons frame. The only way that would be meaningless would be if they didn't exist for us.

No, the only way in which such a frame could exist would be if photon's mass were not zero. Maybe you have not totally clear what a frame of reference is: not a simply abstract mathematical description, but a system of synchronized clocks put in all points of space (at steady intervals), or the possibility to really do it *physically*. You *can't* do this with massless particles.

[yor_on]

"I assume that the reason we exist is our arrow of time, aka a 'clock', and I also assume that the reason we can measure that light to have a velocity is that same 'clock' ticking for us. And then I assume that without a clock you can't discuss a distance, and I don't have to discuss it from the frame of a photon to reach that conclusion. "

Am I wrong there?

[yor_on]

Another point worth noticing.
If a photon was found to have a restmass it seems to me that it could be considered to intersect? According to this definition..

"One of the most basic geometrical ideas is intersection. In relativity, we expect that even if different observers disagree about many things, they agree about intersections of world-lines. Either the particles collided or they didn't. The arrow either hit the bull's-eye or it didn't. So although general relativity is far more permissive than Newtonian mechanics about changes of coordinates, there is a restriction that they should be smooth, one-to-one functions. If there was something like a Lorentz transformation  for v=c, it wouldn't be one-to-one, so it wouldn't be mathematically compatible with the structure of relativity. (An easy way to see that it can't be one-to-one is that the length contraction would reduce a finite distance to a point.)"

Am I right there?

[JP]

Let's come at this from a different direction.  When Einstein came up with special relativity, one of the postulates was that the speed of light is constant for all inertial observers.  The theory ended up describing how inertial observers who are moving relative to each other will measure space and time differently.  One aspect of the theory is that since light speed is constant, it can't be in an inertial frame, so its point of view can't be described by special relativity.  Arguments that photons are "timeless" and so on are flawed in that they're trying to make the theory work for something it just can't work for (when I first learned special relativity, no on told us it wouldn't work for light, so I also thought that way).  Talking about what a photon experiences in terms of special relativity is meaningless, so if you want to talk about what it experiences, you'd have to somehow come up with a new theory, but in order to do that you'd have to have some way of relating that experience to something you could actually measure.  Since all measurements are made from our point-of-view as objects with mass, I suspect that's impossible, and your quote about intersections seems to be saying its impossible as well...

I think the quote above about world lines intersecting is getting at the point that all observers should agree on whether an event happens or not, no matter how fast they're moving.  They might measure things differently, but the event itself should still happen.  It would be nonsensical, for example, if you could make two asteroids miss each other or collide with each other simply by moving faster or slower as you viewed them.  The above quote seems to be claiming that there is no theory compatible with special relativity that would give photons this property as they "viewed" the universe. 

If photons are shown to have rest masses, then their point of view is described by special relativity, just as our point of view is.

[yor_on]

Yep, I agree JP, but this whole excursion is just to ring in what proof we have for that a photon really have to be that 'massless' 'timeless' 'point' of no displacement in SpaceTime. So all ways we can think up to ring in why it have to be that way is good to me. And if there was some way proving it to be different I would be very interested. And, as you say "one of the postulates was that the speed of light is constant for all inertial observers."

So how about an accelerating observer?
Accelerating non-linearly?

Will that frame give another speed for light?

[yor_on]

GoodElf wrote an interesting answer to a similar question of mine on another place. It it he comments that "The speed of light actually appears to be the thing keeping stuff apart and making all that space and energy out there in our universe." which I found to be rather worth thinking over. What he was talking about here was the invariance of that speed as measured from all 'inertial frames'. So what would happen if a photon would be found to have a restmass, as seen from this definition? Could you use this as a 'proof' why we don't expect a restmass?

[JP]

Yep, I agree JP, but this whole excursion is just to ring in what proof we have for that a photon really have to be that 'massless' 'timeless' 'point' of no displacement in SpaceTime. So all ways we can think up to ring in why it have to be that way is good to me. And if there was some way proving it to be different I would be very interested. And, as you say "one of the postulates was that the speed of light is constant for all inertial observers."

So how about an accelerating observer?
Accelerating non-linearly?

Still constant. You'd see the light getting Doppler shifted, though.

[JP]

GoodElf wrote an interesting answer to a similar question of mine on another place. It it he comments that "The speed of light actually appears to be the thing keeping stuff apart and making all that space and energy out there in our universe." which I found to be rather worth thinking over. What he was talking about here was the invariance of that speed as measured from all 'inertial frames'. So what would happen if a photon would be found to have a restmass, as seen from this definition? Could you use this as a 'proof' why we don't expect a restmass?

I'm not sure I understand what he's getting at.  The speed of light has to do with the expansion of the universe, I guess, in the sense that its a cosmic speed limit and that somewhat determines how general and special relativity work, but I don't see how it directly does what he claims.  If light has a rest mass, then this speed limit still appears to exist (experiments involving things other than light seem to verify it).