The problem with the concept of energy is, simply, that it's so damn useful. It has been, ever since we began using it - it's hard to imagine energy as actually getting in the way of progress. But, just what is energy? At its core, energy is a definition. It is used to describe how much work can be done on an object, or is being done by a force. So, the concept of work is involved. By work, a scientist means the movement that occurs when a force being applied to an object causes it to move. Thus, both force and movement are integral to the definition of energy. Also, for a force to cause movement to happen, it must be what is called an unbalanced force - the force is not the same everywhere.
Consider a tug-of-war game. When both teams pull the rope with equal strength in opposite directions, the rope doesn't move. However, if one team pulls harder, the rope starts to move in their direction. This movement means work is being done on the rope. It's important to note that even when the rope isn't moving, the players are exerting effort and may feel strain on their muscles and begin to sweat. This occurs because their bodies are exerting energy internally, even though no external work is apparent. But in terms of the physics of the game they're playing, work is only done on the rope when there's movement in the direction of the force. So, while the players might be getting a workout, if the rope isn't moving, no work is done on it. And usually, the team that doesn't pull as hard ends up in the mud!
To understand electricity, think of a battery. For electrical energy to flow through wires and power a device, there must be a difference in electrical force. Electrical engineers refer to this unbalanced electrical force as EMF, or electromotive force. When there is an unbalanced electrical force between the positive and negative terminals of a battery, there is potential to do work. As this electrical force equalizes between the terminals, the battery can no longer perform work and is discarded. Notice how we’re focusing more on force than energy? Stay tuned for more insights!
Whew, there are sure a lot of things that go into the definition of energy... an unbalanced force causes movement. When the object moves we say work is being done on that object. The more movement, the greater the energy. In it's own way, using energy to describe all these things is a sort of shorthand for defining the amount of work done. Put succinctly, energy is what we use to define a work function. Here's the rub - the movement is real movement (a ship rocking up and down in its mooring, for example). That means the force causing the motion is also very real. But the energy being used to describe the force is not real - it's only a definition. Sometimes it is very easy to loose sight of that fact - we begin to treat energy as though it were not merely a concept used to define other things, but as a real property in and of itself. Is your shadow 'real'? A shadow is defined as the absence of light. It is a definition too. We use definitions to describe things. Your shadow describes the absence of light. Energy describes the ability to do work. I find it more useful to discuss the potential of an object or system because it is often more precise than talking about the energy it contains for this reason. Potential is context-dependent and is related more closely to the state a system is in, rather than simply describing the energy it contains. Definitions are useful to have around, but that doesn't make them real things.
Radio takes advantage of the fact that electromagnetic energy naturally propagates at the speed of light which also means any unbalanced force it carries can also propagate at this speed as well. Looked at in this manner, radio is just a clever way we have developed to be able to do useful work at the speed of light. And, it is the information we overlay on the electromagnetic carrier wave that causes useful work to be done in the detector portion of the receiver. This is a useful insight: in a radio, it is the propagating EM (electromagnetic) wave that is bounded by the lightspeed limit - not the information imprinted on it. Information it seems, is the key. Use water waves, and any information is bounded by the speed of the water wave, a few hundred miles per hour. If you use metal, say the steel rails of train tracks for example, as the medium for transmitting sound forces, you can go as high as 6,100 meters per second. A dramatic example of this disparity in different mediums happens during a thunder storm. You see a lightning strike, and several seconds later, you hear the thunder clap. You see the light first because it is electromagnetic, and EM waves need no medium (light actually slows down by around 90,000 meters per second in air). Since air is needed to act as a mechanical conduit for the sound information to reach your ears, the maximum speed for sound information is limited by the movement of the gas molecules that make up the atmosphere, so you see first, and hear later. In all cases, we are dealing with the speed of the thing that carries the information, not the actual speed of information itself (at its most basic form, information, too, is simply a definition. Can anyone tell me what the speed of a definition is? ). The speed of information is defined by what carries it. This is a perfect example of confusing the message with the medium.
The reason why energy gets in the way is because it acts as a brake on the information it contains. Force, work, and by extension energy, are all limited by the speed of light. But, information is not. It is simply hitching a ride along the way, going as fast as it is allowed. Think of it this way: the medium is acting as an anchor on information, dragging it along, its speed limited by whatever anchor you care to use. Get rid of that anchor, and the speed information can travel may literally be infinite. This is what happens in nature. The universe uses information traveling instantaneously to communicate with parts of itself. This is what is happening when you make an electron flip its spin state in an EPR - style experiment. The information of this occurrence is instantly transferred to the other particle, and it reacts. In the wild, this occurrence is random in nature, and so can't be used to make a meaningful signal. In the language of quantum physics, we say the properties of the two particles are 'entangled' because they share a common origin. They share information without the benefit of an anchor. Can we somehow untangle them and bend them to our will? Unfortunately, no. The reason why is simply because we can't control a truly random process, which is what the spin states of the electron in your EPR experiment are exhibiting. A truly random process, which is to say, stochastically random, can not be controlled. It's like I said earlier. How do you modulate static noise? That is what those spin flips are. Random. The best you can do is to run your experiment, then sit down later, after the experimental run is over, with your lab partner, and see if you can correlate data points over a cup of coffee. Very much slower than light... this is why any attempt to base faster than light communications schema directly on EPR type research is doomed to failure.
At best, we can take EPR-style research as a signpost that the universe doesn't explicitly forbid faster-than-light (FTL) information transfer. That is an important clue—it doesn't seem to be information itself that is forbidden as an entity to move superluminally, just the form that information takes. Of course, the form itself is defined by whatever carries the information. This perspective emphasizes the critical role the carrier has in determining how information can be transmitted, which aligns well with our understanding of the constraints in physics.
Maybe we need to develop a broader and more powerful definition of information?
There is one more item that needs to be mentioned. The quantum world is not like the world we see around us. By our perceptions, strange things can happen to individual subatomic particles that will never happen to the huge aggregates of particles that we can see. First, it is necessary to understand that on the quantum level, both particles and waves can share common properties. Sometimes particles act like waves, and vice versa. It's called wave - particle duality. A moving particle possesses a wavelike character and has a frequency, and wavelength. This is so strong a fact that you can represent a discreet particle with a wave equation called Psi, named after the letter in the Greek alphabet. Psi is the so-called Schrödinger wave equation, formulated by the physicist Erwin Schrödinger (1887 - 1961).
A uniquely fascinating scientist, Erwin Schrödinger introduced humanity to the concept of entanglement, and his famous Schrödinger's cat thought experiment. All matter can be represented by a wave equation, even cats, leading to the concept of matter-waves. Now, the thing about the wave equation is that it is inherently imaginary and to make it 'real', we square it, as squaring an imaginary number or quantity makes it mathematically real.
The foundational concept for being able to square the wave equation is given by the Born rule. The Born rule, formulated by the physicist Max Born (1882 - 1970), dictates that the probability of finding a particle in a particular state is proportional to the square of the amplitude of its wave function, which just so happens to be described by Schrödinger's wave equation. This interplay between the Born rule and Schrödinger's wave equation is one of the most elegant and useful aspects of quantum mechanics.
There are more manipulations as well, but the key point is that the entire foundation of modern science, from the physics we learned in high school, to the advanced theoretical work being done in large university and government labs is based ultimately, on something that is imaginary. This bears some looking into. The fact that physical reality is describable by something that is imaginary almost seems like a funny joke and another clue towards superluminal communication—more in a bit.