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its just that the probability of being in most places other than where it is, is rather small!!!
If you're observing anything it can be an experiment.
It doesn't get measured in any way.
As has been explained elsewhere, for a photon travelling at c time has no meaning.
Quote from: DoctorBeaver on 19/12/2008 09:28:13As has been explained elsewhere, for a photon travelling at c time has no meaning.Your basic premise is flawed.
Because we have yet to discover a way to accelerate light past the speed of light.
Yes expansion has an effect.If you consider the point the photon was emitted and the point it is detected (presuming that the two are separated by large (intergalactic) distances) then the red-shift of the photon is a measure of the expansion between the two points (after we subtract the gravitational red-shift/blue-shift).
If, indeed, it's "there" to notice anything.
I can see that you are still insisting that, somehow, the photon (like a bullet) is speeding on its way from a to b. If you look at it that way then I can see there may be a problem. But why does it have to exist between a and b? The only places and times that you can prove it's there are at each end of 'its' journey.There is a great difference between a photon and all other so-called particles. An electron can make a journey and make its presence felt by many systems on the way - giving a little (in principle, measurable) nudge to every charge it passes. But a photon only interacts at each end of its 'journey'. As far as I can see, then, it is not necessary to consider what it is getting up to on the way - it gets up to nothing, in fact. I also hold that the 'it', to which we refer , is just the energy, which will behave according to the wave with which it's associated. It can't / needn't be considered as a particle except where it is interacting.You seem to be over concerned about the changing distance between source and detector - why should that concern an object which doesn't really exist on the journey? What about the situation where source and detector happen to be approaching each other at the same speed that the space between them is expanding - wouldn't that situation be just as difficult to explain?My way of looking at it is not to say "Off the photon goes on its journey through the universe without interacting with anything else" because, for a start, you can only say that it hasn't interacted yet. I say it is potentially everywhere at all times between its creation and its absorption. It's journey is only described once it has actually completed the two interactions.There is, of course, a very finite time involved in the interactions at each end because they are, essentially, resonances which take time to build up. As far as the photon is concerned, the two ends could be one atom's width or the whole universe apart.The bullet picture makes it extremely difficult to reconcile the effects of diffraction - requiring a message to travel instantly all around the Universe to tell all other atoms that the photon has arrived 'here' and can't be seen anywhere else. But, even in the simplest, two slits, experiment, something has to tell each photon that it is part of a number of others which must, somehow sort themselves out into an interference pattern - which will always occur when there are 'enough of them'. It's a nightmare this way round; stick to the wave interpretation.
Quote from: DoctorBeaver on 19/12/2008 09:28:13As has been explained elsewhere, for a photon travelling at c time has no meaning.Your basic premise is flawed. Time has no meaning without the observable context of mass. Photons have mass(albeit infinitesimally small mass). This is the reason why black holes can capture light....if photons had no mass they would pass by black holes. Also effects like gravitational lensing would not be observed if photons had no mass."It therefore follows that a photon could be everywhere in the universe at the same time."Time does exist for photons (because they have mass) which is why they cannot accelerate past the speed of light in a vacuum.
My little beaver brain is working overtime again. This is what its murky depths have churned out this time.As has been explained elsewhere, for a photon travelling at c time has no meaning. In fact, time doesn't really exist for it. It therefore follows that a photon could be everywhere in the universe at the same time. But the universe is expanding, so there is now more "everywhere" for it to be in than there was at any time in the past. How can the photon be everywhere at once if everywhere is getting bigger? 
Yes SC, I see some as coming from the Sun.Most of them we see in fact:)And I have no problem with accepting them to be waves, if traveling in spacetime.What I have problem with is the idea that they only will exist as a 'interaction'.To me that imply, if that idea is correct of course:) that they would exist independent of any source.Accepting that view, all our ideas of spacetime seems to collapse.Then what are what we call sources?
We have built spacetime around concepts as distance motion 'c' etc.All of those seems questionable, to say the least, if we allow for photons to be at 'all paths'.Our descriptions 'falters' if you see how I think:)
Then again.We can send coherent laser light in a very straight path, can't we?And if we measure that specific wave length outside what we might call its 'path' it won't be there, right?So light have a path, doesn't it?
Are you talking about coherent light or incoherent light here Lightarrow?
I still have trouble seeing photons as something just appearing as 'interactions'.
But my question wasn't about what would happen if you put matter in its path.It was if one could prove that the lasers light had a certain path in space.And from there ask if ordinary light also might have a defined path in spacetime.
As for building spacetime, didn't that start a long time ago:)With Newton and Einstein, Feynman appearing relatively recently?It's all a question of definitions of course.
Hhmmm How about this then:)If our Sun got quenched.If now light do have a path, isn't there something called spontaneous particle creation?That, it is said, the light enjoys itself 'playing' with, even though it goes back to being a wave very quickly?If that is true, can't then light be seen as a particle having a geodesic path following spacetime.
And if that is true, as well as space containing 'in itself' a huge amount of energy.And if Feynman is correct in his interpretation of possibilities innumerous for that 'waves/photons' path.And if I'm right in wanting to allow that wave the properties of a particle?Will then all be dark here as that sun goes out?
Why?In my view it's quite simple.The Sun went out, what do you expect?From the other view it seems more of a question of probabilities, not discounting the one, wherein the 'light' still will shine with or without a 'source', even if it would be of extremly low probability.Or am I thinking wrong here?You could say that even without Feynman's 'many paths', spacetime still would have that possibility.But to me that concept makes it so much more probable, as it invites us to a spacetime in where all paths are taken at all times, not caring for the 'geometry' we observe versus matter.
Ah the headache:)"A photon must be a physical object.1.How would you define the existence of a physical object without ever using the word "measure"?2.Can you measure a photon between source and detector? "How do you mean by 'physical object'?Only at its moment of 'interaction' or at all times?
But we also expect 'cause and effect' (times arrow) to work even without us observing.For example you filling a bath tube, leaving it for a while and when coming back finding it overflowing.
Do you think you and everything you use/meet today is made of light?Explain that, no theories.Just those experiments proving we are light.
Well, :(At least it seemed logic to me:)Lightarrow, as far as I understand we start everything by archetypes, or do you see it differently?
One of the first archetypes needed to be defined is if 'anything' exist at all outside ones mind.
Is one and one still two??
Although we can move through three spatial dimensions, at any point in time the movement vectors for all three spatial directions can be summed to a single vector. Thus movement is essentially in a single direction and can be expressed by a single value, just as when we drive heading North-West we don't say we are driving West at x mph and North at y mph; we just use the summed vector.With movement induced time dilation, the same thing is happening, except this time the two vectors being summed are the summed spatial movement vector and the temporal movement vector. The reason we get time dilation is because it is the sum of these two vectors, spatial and temporal, which cannot exceed 'c', so as the spatial movement vector increases, the temporal vector must decrease. With zero spatial movement then, we move temporally at 'c', which in turn implies we have zero length in that direction