Light speed holds the key to understand the universe

How Quantum Mechanics and Relativity can tell the same story

1. A tale of two theories

2. Chasing a beam of light

  1. The speed of light in vacuum is the same for all observers, independent of the relative motion of the source (c = 299.792.458 m/s).
  • Matter moves below c: Nothing with mass can reach c speed (because it would need infinite energy to accelerate).
  • Spacetime warps: Objects in motion experience length contraction and time dilation. (It has to be that way if we want to keep the speed of light constant, despite observer’s motion.)

3. A brave new world

  • No space or distance: Going at c, photons experience maximum length contraction. So much contraction they have no concept of distance. All the 3D paths we think they describe wandering the universe are compressed into a single point for them. The evolution of the material world defines those “paths”, yet photons feel just an emission/absorption point.
  • No time or duration: They experience maximum time dilation. So much dilation they don’t know what time is. Their internal clock is so slow that any interval we could imagine would be instantaneous for them. Imagine a photon being emitted when the universe began, being absorbed whenever the universe ends. All those billion years would be just an instant for that photon.
  • No evolution: Thus, photons can’t evolve while traversing vacuum at c, because they feel everything as a single interaction. The vast distances we see in our universe don’t exist for photons “in flight”. For them, fields and field lines describe how emission and detection points connect together. They feel emission point “glued” to detection by the field lines that lie on free space, so any medium in which they don’t travel at c would join with the next seamlessly.

4. Through the looking glass

5. Reality bites

  • Causality develops: As we reduce speed, we are not limited to feel everything in a single event or interaction, and we start collecting different entities that are able to reach us. We get the concepts of time and causality by arranging similar, periodic or frequent events that happen to us while we traverse our lifespan below c.
  • Laws of physics emerge: Although the exchanges that pop up into our new reality are different ones each time, they keep a remarkable consistency. This recurrence (both in space and time) is what defines the rules for the evolution (the physical laws) for the universe we can perceive now we move below c.
  • Distances and intervals unfold: Space expands and time slows down as we reduce speed, because we go from feeling everything instantly to having to collect events bit by bit while traversing a stretching path in space.

6. Down the rabbit hole

  • Massless carriers don’t feel spacetime: Massless quanta at c don’t experience spacetime dimensions. Distance, duration, locality or causality get meaningless at light speed.
  • Interactions are new each time: Each observer has the consistent illusion of an evolving universe caused by the continuous detection of carriers coming from other places. This constant influx of information composes the “frames” of reality that allow them to infer the dynamics for matter and energy in the universe. These causal rules only apply to “persistent” matter connections, where floods of similar exchanges (closely related in origin, distance, frequency and duration) keep taking place consistently, but they’re not valid for each individual interaction.
  • Total energy of the universe is zero: Any energy transference we observe is an instantaneous action-reaction event for the carriers involved, so they don’t even feel the energy imbalances that set out their journeys, as their proper time is zero. The universe is a zero-sum game of energy conversions, but for each interaction supporting the play, everything appears balanced in an instant.
  • Absorption is part of any exchange: Any carrier traversing any medium at c will be absorbed somewhere else. It has to be that way because, otherwise, the journey never really starts (remember, emission and absorption is the same thing for them). A carrier “in flight” is just the promise that an exchange, interaction or measurement will take place, no matter what. Once we know a carrier has left birth place, we can be sure it’ll pop up elsewhere following the c speed rule, because the contract is already settled for the carrier. If we put something trying to stop it, our actions contributed to the history it tells when it materializes on our detector.
  • Carriers don’t have intrinsic properties: Any spatio-temporal magnitude or constant we assign to a massless carrier when detected doesn’t belong to the carrier itself. Those properties describe something about the conditions that took place during the whole journey, what made that particular carrier manifest in reality. Properties like energy, frequency or momentum are specific to each individual matter interaction, but vacuum constants like Planck constant or the speed of light tell something about the way all exchanges come into existence.
  • Interactions shape the geometry of spacetime: General Relativity states that matter and energy warp the geometry of spacetime. Now, we know the interactions that transmit information also support spacetime, so we could say matter presence sets how and how many exchanges develop each time. That’s why mass (or charge, or flavour, or any other property of matter) is able to “bend” spacetime: curved spacetime is nothing more than a higher probability of having interactions on a region due to how matter is arranged (there and elsewhere). There’s even a mass/volume ratio (the Schwarzschild radius) that defines regions of space where the matter configuration is so dense that any carrier generated inside can’t escape anywhere else, as all possible paths end on a matter particle contained there (that is, black holes).
  • Time travel to the past is impossible: We can compress or expand time intervals changing velocity, but not reorder the interactions. Observers can’t reach instantaneity, as they move below c. It’s true that each observer has its own subjective way of ordering events depending on speed, but there’s no way an observer could detect a carrier before it’s emitted.
  • c speed = infinite speed: It doesn’t matter there’s a speed limit in the universe because, for all purposes, things that travel at c feel they’re instantaneous. They traverse any distance in no time (for themselves) so they’re, effectively, teleporting instantly at infinite speed.
  • All forces are contact forces: Long time ago, humanity thought all forces were contact forces, but then some forces seemed to act at a distance. Later on, we stated all forces act at a distance by gauge boson exchanges (except gravity, maybe?). But, from the point of view of things going at c, all forces are “contact” forces because they don’t feel any spacetime taking place, they just “happen to be”.

7. Everything is relative

7.1. Entanglement

7.2. Nondeterminism

7.3. Wave-Particle duality

7.4. Wave function collapse

7.5. Bell’s theorem

7.6. Faster than light communication (FTL)

7.7. EPR paradox

7.8. Scrhödinger’s cat experiment

7.9. Double slit experiment

  • Without which way information: If we only measure the interference pattern at the screen, we don’t disturb the space in between trying to catch carriers “mid-flight”, so they keep delocalized the whole journey, they don’t have a “checkpoint” in between. This way quantum information can keep the correlations, as if really passing through both slits at the same time, revealing the interference pattern.

7.10. Wheeler’s delayed choice experiment

Light speed holds the key to understand the universe

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