[deleted]
Dear Emmanuel,
To interpret the speed of light as a velocity is to treat what essentially is a quantum mechanical phenomenon as something which obeys the rules of classical mechanics. We can only speak about the velocity of an object with respect to something if and when it interacts with that something as it moves. (Interacting includes the energy exchange between particles by means of which they express and preserve their energy). To be able to interact, a particle must have a position to act from. In www.quantumgravity.nl in Chapter 1.2 'Mass, a quantum mechanical definition' I have defined the rest mass of a particle as being greater as its position is less indefinite, as it remains longer within the area corresponding to that indefiniteness, as the probability to find it inside a smaller area is greater. This is why I in my essay I said that the rest energy of a particle depends on its ability to express that energy as gravity, on the definiteness of its position and vice versa. The less indefinite its position is, the greater its mass is, the stronger a source of gravity it is. So if we define the 'speed of light' as that 'velocity' at which its position is completely indefinite, then it cannot express its properties at that speed, which is why it appears to have no mass or any property at all, why it cannot be accelerated, act or be acted upon. (All interactions the photon is supposed to be involved in as travels, all Feynman diagrams of all possible interactions with virtual electrons, positrons, photons, are taken care of by the particles it is transmitted between as they themselves are the product as well as the source of all such interactions.) Only in this way photons can transmit force between particles without that force being involved in intermediary interactions with particles in the environment it is supposed to travel through. This info about the environment is already present at the emitting and absorbing particles as they continuously exchange energy and objects in between affect this exchange, information which is already is accounted for in the photon energy. So if a photon doesn't interact with, exist to the objects along its path, nor the environment to the photon, then it makes no sense to speak about its velocity: there's nothing with respect to which it moves. (This is no to say that we cannot predict where/when we can intercept, detect a photon if we know the position of the source, the direction and time of its emission).
If particle A emits a photon which is absorbed by B, a transmission changing the state of both A and B, then A sees the state of B change at the time it emits the photon, whereas B sees the state of A change as it absorbs the photon. That is, unless B after absorbing the photon sends back a message to A to confirm the receipt of the photon, a thank-you-note saying that A can from now on start to see B in its new state. A gravitational field is an area of contracted spacetime: the stronger the field, the more space, distance is 'folded' within a smaller area as measured with a rule outside that field. Whereas to a massive particle penetrating the field, this 'condensed' distance unfolds, to a massless particle there exists no field, and hence no distance to its source. So whereas to a massive observer A and B are separated in spacetime so to him the emission doesn't coincide in time with its absorption, as to the photon there's no distance between A and B, its transmission is instantaneous. So though an observer measures a duration, that doesn't mean that the transmission isn't instantaneous, it only isn't instantaneous to him. Whereas to the observer a space distance is a time distance, the photon bridges this distance in no time at all, so to the photon its transmission doesn't take any time at all.
If A sees B's state change at the time it emits the photon, then a finite velocity would mean that since nothing is allowed to happen which might prevent B from absorbing that photon, time would have to stand still for as long as the photon is traveling. Anyhow, we don't know whether A wants to get rid of some energy, or B incites A to produce the photon: if there's no absolute time, no clock outside the universe, then it doesn't even make sense to ask what causally precedes what, even though we see one event to happen before the other.
''Some physicists think that time is totally relative and does not really exist.''
The ''does not really exist'' seems to refer to an imaginary observation from outside the universe, so I can agree with this as in my essay I argue that the universe as a whole has no physical reality either. A universe which creates itself without any outside intervention creates, keeps producing time itself, containing all time within.
As a Self-Creating Universe can hardly stop creating itself, it keeps creating energy, so we don't need any dark energy to explain why the universe keeps expanding unhampered by gravity. It is this continuous creation which powers any change we experience as the passing of time. Since I cannot believe in a bigbang tale which implicitly states that the universe and everything inside of it has been created by some outside intervention, to me there's no (''problem of the nature of the'') Planck epoch either. It is because we believe that particles only are the source of their fields and interactions that we need a naïve and unnecessary tale like the bigbang hypothesis.
As to the origin of the energy in the universe, I cannot think of any more important question in physics. The problem with present physics is that it implicitly assumes that the (rest) energy of particles only is the source of their interactions, as a given, and not, as I propose in my essay (topic 838), as being also the product of their interactions, which it must be if in a SCU particles have to create one another.
Regards, Anton
