Probability, Uncertainty, and Reflection

The absence of information can travel faster than light. If you wave your hand in-front of a very bright light that casts a very large shadow, the shadow can move faster than light as the shadow is not an actual thing, but rather the absence of a thing (no ‘thing’).

No ‘thing’ (including particles) can travel faster than light speed, but some ‘non-things’ can. In both ways ‘nothing travels faster than the speed of light’.

In 1807, an English physicist named Thomas Young asserted that light has the properties of a wave in an experiment called Young’s Interference Experiment. This Young’s interference experiment showed that lights (waves) passing through two slits (double-slit) add together or cancel each other and then interference fringes appear. This phenomenon cannot be explained unless light is considered as a wave.

Thomas Young’s double-slit experiment in 1801 showed that light can act as a wave, helping to invalidate early particle theories of light.

Showing the two oscillating components of light, an electric field and a magnetic field perpendicular to each other and to the direction of motion (a transverse wave).

What is the speed of dark?

It is the same as the speed of light (as dark is light canceling itself out). That said, shadows can move faster than light because a shadow is not a thing, it’s the absence of a thing.

The expansion of space also breaks the speed of light

As space expands, two galaxies traveling away from each other far enough away from each other will move much faster than the speed of light. The universe is ‘Expanding faster than the speed of light’ and the farther away objects are from each other, the faster they expand away from each other but expansion isn’t a ‘thing’ itself, and so it’s not information traveling faster than light.

Unless people are talking about relative time, they are almost always referring to the speed of light in a vacuum when they say “faster than light.”

It seems as though we must use sometimes the one theory and sometimes the other, while at times we may use either. We are faced with a new kind of difficulty. We have two contradictory pictures of reality, separately neither of them fully explains the phenomena of light, but together they do.
Albert Einstein

Niels Bohr regarded the ‘duality paradox’ as a fundamental or metaphysical fact of nature

Niels Bohr regarded the ‘duality paradox’ as a fundamental or metaphysical fact of nature. A given kind of quantum object will exhibit sometimes wave, sometimes particle, character, in respectively different physical settings. He saw such duality as one aspect of the concept of complementarity. Bohr regarded renunciation of the cause-effect relation, or complementarity, of the space-time picture, as essential to the quantum mechanical account. — Niels Bohr

What this means is that, nothing with mass can travel faster than the light speed constant i.e. the speed of light, in a perfect vacuum, measured from an inertial frame as a constant with an exact value of 299,792,458 metres/s. approximately 300,000 km/s (186,000 mi/s).

Special relativity says a ‘thing’ with non-zero rest mass needs infinite energy to accelerate to light speed. So non-massless energy can’t travel faster than light. That said, special relativity doesn’t explicitly forbid traveling faster than light, it just implies:

Light speed is the maximum speed of the universe.
Light speed is the speed at which all massless energy particles always travel. All the fundamental particles that make up the universe are massless energy particles, which travel at light speed.
Time as we know it stops at light speed.
Light speed can be thought of as ‘the speed of causality’ the speed at which casual relationships happen in the universe. All other time outside time measured by light is relative.
Crunching the numbers, only a special particle called a Tachyon* can travel faster than light. In a vacuum, it would always travel faster than light, and never go slower.

Tachyon particle is a hypothetical particle

Tachyon particle is a hypothetical particle that always moves faster than light. Most physicists believe that FTL particles cannot exist because they are not consistent with the known laws of physics.

The result is that light speed particles always travel at light speed. Those particles interact to form systems with mass, which are all the objects in the universe. The systems with mass require infinite energy to go light speed, theoretically the object is ripped apart and becomes pure massless energy again, like a black hole.

Light speed travel for non-zero rest mass objects is not something that seems actually to happen in our universe and certainly, faster than light speed travel only exists as an effect or perception (not as an actual thing).

Light can’t travel faster than light speed, and objects with mass can’t travel light speed, but their effects (like a shadow) can (because effects of a thing aren’t themselves things).

When we take into account that photons are the carrier particle for electromagnetic energy, we can say:

Photons (the carrier of electromagnetic energy).
Electromagnetic force (one of four fundamental forces in the universe).
Electromagnetic radiation or energy in any form, and in simple terms ‘light’ are all different words describing the same fundamental phenomena.

What is light?

Light is a particle (photon), that acts like a wave, and is understood as a localized vibration in the electromagnetic field. Or, we can describe light as a wave function of probable locations of excited states in the electromagnetic field in superposition that can be measured as ‘particle-like or a wave-like’ and travel in spacetime as electric and magnetic polarised transverse waves (unless they are behaving as virtual photons) moving in a straight line at a constant speed when unimpeded but manifesting as localized vibrating wave-packets in the electromagnetic field.

Light has a dualistic particle-wave like nature (as do all ‘quanta’ in the standard model).
Light is pure electromagnetic energy (and is also thus the carrier particle the ‘photon’).
Light is one of four forces (quantum interactions) in the physical universe.
Light exists as a charged energy field, and it exists in a quantum state (it is a ‘quantum particle,’ with quantum behavior, just like the other quanta studied in quantum physics).
Light has a charge, but has no mass, yet it can interact with other objects and add to their relative mass by adding to an objects total energy.
Light is both electricity and magnetism in constant oscillation.
Light exists in a state of superposition. It can’t be localized in both time and space.
Different wave lengths of light can be seen as different colors in the ‘electromagnetic spectrum,’ this spectrum can also carry information as radio waves, or carry information as wifi. Different colors and wave types differ by frequency (waves vibrating more frequently are higher energy).
Light can cook an egg on the sidewalk by speeding up the molecules in an egg (light is also heat).
Light reflects and refracts based off the laws of quantum probability.
Light can be trapped in a crystal, and when anything emits heat or light (like fire), it is emitting photons ‘electromagnetic energy’, light we call ‘electromagnetic radiation.’
Light behaves like a transverse wave (with electric and magnetic waves oscillating in space time at 90 degrees to each other, perpendicular to the wave direction, keeping a straight line trajectory despite their transversing and polarisation).
Light waves crest, cancel other light waves, amplify other light waves, and charged fields can gain or lose energy based on interactions (emitting and absorbing photons).
Light is subject to what was called ‘spooky action at a distance,’ but is now called quantum entanglement.That is, what happens to one photon can affect another paired, but distant, photon despite being separated in space.
Light seems to react differently when being observed (for example in the double slit experiment).
When things burn they emit light, one can tell their energy content from how they burn, because mass is in ways just a measure of energy content.
Light will travel in a single direction, at the constant speed of ‘light speed,’ forever, if unimpeded.
Many photons can exist in the same exact spot creating ‘wave packets,’ or just one photon can exist alone in its lowest energy state (still exhibiting a quantum wave-particle nature). The lowest energy state possible for a photon can be considered a single photon (although one could argue that state can be zero or infinitely small). Meanwhile, there is no limit to how many photons can be in one space (lasers are created from fitting many photons in a small space, this increases the energy content of the wave packet, and can be used to make precession ‘cuts’ via the ‘heat’ created).

In Special and General Relativity, a light cone is the path that a flash of light, emanating from a single event (localized to a single point in space and a single moment in time) and traveling in all directions, would take through spacetime.

The Photon, the Carrier Particle of Electromagnetic Energy

The photon is the carrier particle of all electromagnetic energy, and one of the four fundamental forces of the standard model of particle physics (the quantum physics model that describes how the building blocks of the universe, the elementary particles, interact with each other).
The photon is massless and is one of only two massless particles (the other being the gluon). These particles have momentum, but no rest-mass (it is worth noting here specifically that photons always travel light speed unimpeded and never truly rest, they are in a sense ‘pure motion’).
The term photon has been around for decades, and it stuck due to simplicity. Even though this terminology is correct, photons aren’t ‘just particles.’ They are a measurable excited state, or localized vibration, in the electromagnetic field that travels in a wave-like motion (quantum field theory).
Each wavelength/particle typically consists of a packet of waves forming an aggregate wavelength, at its core, a single wavelength in a packet can still be described as a photon, but can also described as a one dimensional vibrating string (superstring theory).
Newton called a single ‘light’ particle a corpuscle.

Photons can’t interact with each other directly (outside of forming wave packets and absorbing and emitting other photons) and have no rest-mass when traveling through empty space, yet in special circumstances they can exist as Photonic matter. Photonic matter phenomenon where photons interacting with a gas develop apparent mass, and can interact with each other, even forming photonic ‘molecules.’

Light Speed and the Momentum of a Photon

The wave-like pattern it travels in aside, the photon only travels in a single direction only. It has “unidirectional” linear momentum.
The photon travels at a single and constant speed called light speed (in a perfect vacuum). Light speed is one of the universal constants and is one of the only non-relative things in the universe. As Einstein noted, because light speed is constant time and space are relative (but spacetime, a composite measure of space and time, isn’t).
The photon can travel over an infinite distance unless impeded.
Light doesn’t “slow down” under normal conditions (it doesn’t change linear momentum in free space), but it can change energy content (slowing its frequency of vibration and cooling down, or increasing frequency and heating up), bounce off objects, and be generally manipulated in strange ways within these criteria.
The photon also has spin (angular momentum). It, like other force carrier particles, has a spin of “1”. Matter particles (fermions) have a spin of “+ or — 1/2”.
Since a photon has a spin of “1” it doesn’t have to adhere to the Pauli Exclusion principle and thus more than one photon can be in the same place and the same time. Lasers are made from condensing many photons into one spot, this increases the energy content of the packet of photons, and results in a really “hot” laser.

The Quantum Nature of Light, Quantum Fields, and the Photon

As noted above, the photon is a quantum particle or a quanta. ‘Quantum’ describes the fact that photons jump to discrete states in the electromagnetic field. Instead of moving in a continuous wave, it ‘quantizes’ to probable locations.
All quantum particles, including the photon, exist as localized vibrating states in their respective field and move as quantized transverse waves. This behavior is explained by Quantum Field theory (QFT) and this behavior is where quantum physics gets its name.
The electromagnetic field is a single field that covers all of space and time, like a container for electromagnetic energy. Each particle of the standard model of particle physics has its own field.
When the electromagnetic field contains a localized vibration, we call it a photon.
Each particle has a separate field. Particle interactions occur when charged excited states in fields overlap.

Fifth Solvay International Conference on Electrons and Photons, founded by the Belgian industrialist Ernest Solvay in 1912.

The Solvay Conference, October 1927

The Solvay Conference, founded by the Belgian industrialist Ernest Solvay in 1912, was considered a turning point in the world of physics. Located in Brussels, the conferences were devoted to outstanding preeminent open problems in both physics and chemistry. The most famous conference was the October 1927 Fifth Solvay International Conference on Electrons and Photons, where the world’s most notable physicists met to discuss the newly formulated quantum theory. The leading figures were Albert Einstein and Niels Bohr, 17 of the 29 attendees were or became Nobel Prize winners, including Marie Curie.

Electromagnetic Radiation and the Electromagnetic Spectrum

A photon can emit other photons and can absorb other photons (within limits), this changes the photon’s energy content and frequency.
Other quantum particles can also absorb and emit photons; this is what happens when electrons change energy states.
Electromagnetic radiation describes emitted photons, like the ones that we call visible light (although not every emitted photon is visible).
Visible light is a specific range of frequencies in the electromagnetic spectrum (precise frequencies of electromagnetic radiation that the human eye can see).
The electromagnetic spectrum describes all the possible frequencies of vibration in the electromagnetic field, the visible spectrum describes the wavelengths we can see with the naked eye.
Different “size” waves have different properties, and each color of light has a unique range of vibrations.
White light describes multiple colors of light and can be separated into different colors of light (like Newton did with a prism and wrote about in his book Opticks).
The energy content of a photon is determined by its frequency times Max Planck’s constant (which represents the universe’s smallest unit). The equation is simply E=hf.
Despite the Planck representing the smallest unit, the minimum wavelength of a photon is zero and there is no maximum. Despite the quantizing nature of quanta, there is, in one sense, no minimum or maximum energy content of a photon. The rule is that it must be a positive integer greater than zero (it must have a frequency greater than zero).
Frequency is a way to measure waves and vibrations by examining their patterns. The wavelength is the distance between successive crests of a wave. The higher the frequency, the shorter the distance between crests.
Only certain frequencies of electromagnetic radiation produce visible wavelengths. Short waves are toward blue tones, including ultraviolet, which bees can see, and X-rays. Long waves are toward red and include infrared, which the pit viper can see, and radio waves.

A diagram of the electromagnetic spectrum, showing various properties across the range of frequencies and wavelengths. Wiki.

Light, Both a Particle and a Wave

The photon’s wave and particle qualities are two observable aspects of a single phenomenon. In 2015 the long-standing theory that light is both a particle and a wave was confirmed and published in Nature Communications.
The photon doesn’t just travel in ‘a wave,’ it travels as a transverse wave specifically. Transverse describes the direction the wave moves in (wave vibrating at right angles to the direction of its propagation).
Electromagnetic energy is a quantum wave, and it doesn’t need to travel through a medium. It is not a mechanical wave like gravity or sound (that travels through a medium).
All waves transfer energy, electromagnetic waves are no different.
Electromagnetic energy oscillates in a ‘near field’ of electricity and magnetism. The term ‘far field’ describes the potentially infinite field in which the photon travels via linear momentum (forward movement).