10 quantum myths that need to be busted

 The physics principles appeared to be entirely deterministic for many years. You could accurately predict each particle’s location and behavior at any time in the future if you knew where it was, how quickly it was traveling, and what forces were acting on it at that given moment. The laws that governed the universe, from Newton to Maxwell, had no intrinsic uncertainty embedded into them in any way. Your only constraints came from your meager levels of expertise in measurements, calculations, and knowledge.


All of that was altered a little more than a century ago. We started to understand that, in many situations, we could only anticipate the likelihood that different outcomes would occur as a result of the quantum nature of our Universe. Examples of this include radioactivity, the photoelectric effect, and the behavior of light as it was passed through a double slit. But many myths and misunderstandings have also emerged in response to this novel, paradoxical view of reality. 10 of them have their real science explained here.

1.) Quantum effects only happen on small scales.

The peculiar qualities that individual particles (or waves) exhibit come to mind when we think of quantum phenomena. However, there are large-scale, macroscopic phenomena that are unavoidably quantum in character.

When cooling conducting metals below a specific temperature, they transform into superconductors, where their resistance is zero. These days, building superconducting tracks—built on an intrinsic quantum effect—where magnets levitate above them and circumnavigate them without ever slowing down is a common scientific project for students.


On enormous, macroscopic sizes, quantum drums that simultaneously vibrate and don’t vibrate can be made. Six Nobel Prizes have been given out in the last 25 years for distinct macroscopic quantum phenomena.

 

2.) Quantum always means “discrete.”

Although it’s a key theory in physics, the notion that matter (or energy) may be divided into discrete pieces, or quanta, falls short of defining what it means for something to be “quantum” in nature. For instance, think about an atom. Atoms are composed of atomic nuclei with bound electrons.

The electron is a quantum object, but unless you measure it, you don’t know where it is. It is common to find that when several atoms are bound together (as in a conductor), even if the electrons have distinct energy levels that they occupy, their locations might literally be everywhere in the conductor. It is very likely that space and time are fundamentally quantum phenomena because many quantum effects are continuous in nature.


 

3.) Quantum entanglement allows information to travel faster than light

Here’s an experiment we can perform,


Create two entangled particles, Separate them by a great distance, and Measure certain quantum properties(like the spin) of one particle on your end, and you can know some information about the quantum state of other particles instantaneously: faster than the speed of light

The problem with this experiment is that nothing can be transported faster than the speed of light. Simply put, you are limiting the likely outcomes of the other particle by measuring the state of one particle. They won’t be able to tell that the first particle has been measured and the entanglement has been destroyed if someone goes and measures the other particle. The data of the two measurements must be combined once more at a speed slower than light in order to establish whether or not entanglement has been broken. A theorem from 1993 established that no information can travel faster than light.

4.) Superposition is fundamental to quantum physics.

Imagine that a system can exist in a variety of quantum states. A state “A” with a likelihood of 55%, a state “B” with a probability of 30%, and a state “C” with a probability of 15% are all possible outcomes. However, whenever you attempt to perform a measurement, you will only ever observe one of these alternative states; either it is “A,” “B,” or “C.”

Although we can never directly measure superpositions, they are immensely helpful as intermediate calculational stages to ascertain your probable possibilities (and their probability). Additionally, not all measurables are subject to superpositions equally; for example, momenta may be subject to superposition but not locations, or vice versa. Superposition cannot be quantified, unlike entanglement, which is a fundamental quantum phenomenon.

 

5.) There’s nothing wrong with us all choosing our favorite quantum interpretation.

Physics is all about what you can predict, observe, and measure in this Universe. Yet with quantum physics, there are multiple ways to conceive of what’s occurring at a quantum level that all agree equally with experiments. Reality can be:

a series of quantum wavefunctions that instantaneously “collapse” when a measurement is made, an infinite ensemble of quantum waves, where a measurement selects one member of the ensemble, a superposition of forward-moving and backward-moving potentials that meet in a “quantum handshake,” an infinite number of possible worlds corresponding to the possible outcomes, where we simply occupy one path,


as well as many others. Yet choosing one interpretation over another teaches us nothing except, perhaps, our own human biases. It’s better to learn what we can observe and measure under various conditions, which is physically real than to prefer an interpretation that has no experimental benefit over any other.

 

6.) Teleportation is possible, thanks to quantum mechanics.

There actually is a real phenomenon known as quantum teleportation, but it most definitively does not mean that it’s physically possible to teleport a physical object from one location to another. If you take two entangled particles and keep one close by while sending the other one to a desired destination, you can teleport the information from the unknown quantum state on one end to the other end.


This has enormous restrictions on it, however, including that it only works for single particles and that only information about an indeterminate quantum state, not any physical matter, can be teleported. Even if you could scale this up to transmit the quantum information that encodes an entire human being, transferring information is not the same as transferring matter: you cannot teleport a human, ever, with quantum teleportation.

7.) Everything is uncertain in a quantum Universe.

Some things are uncertain, but many things are extremely well-defined and well-known in a quantum Universe. If you take an electron, for example, you cannot know:

its position and its momentum, or its angular momentum in multiple, mutually perpendicular directions,

Under any situation, precisely and simultaneously. However, some aspects of the electron may be precisely known! Its rest mass, electric charge, and lifetime (which seems to be limitless) can all be determined with absolute precision.

Only pairs of physical qualities with a clear link between them—that is, pairs of conjugate variables—are subject to uncertainty in quantum physics. For this reason, there exist relationships between uncertainty in energy and time, in voltage and free charge, or in angular momentum and angular position. Even though there is intrinsic ambiguity in many pairs of values, many quantities are nonetheless precisely known.

 

8.) Every particle of the same type has the same mass.

If you could take two identical particles — like two protons or two electrons — and put them on a perfectly accurate scale, they’d always have the same exact mass as one another. But that’s only because protons and electrons are stable particles with infinite lifetimes.

If you instead took unstable particles that decayed after a short while — such as two top quarks or two Higgs bosons — and put them on a perfectly accurate scale, you wouldn’t get the same values. This is because there’s an inherent uncertainty between energy and time: if a particle only lives for a finite amount of time, then there’s an inherent uncertainty in the amount of energy (and hence, from E = mc², rest mass) that the particle has. In particle physics, we call this a particle’s “width,” and it can lead to a particle’s inherent mass being uncertain by up to a few percent.

 

9.) Einstein himself denied quantum mechanics.

It’s true that Einstein had a famous quote about how, “God does not play dice with the Universe.” But arguing against a fundamental randomness inherent to quantum mechanics — which is what the context of that quote was about — is arguing about how to interpret quantum mechanics, not an argument against quantum mechanics itself.

In fact, the nature of Einstein’s argument was that there might be more to the Universe than we can presently observe, and if we could understand the rules we have not yet uncovered, perhaps what appears to be randomness to us here might reveal a deeper, non-random truth. Although this position has not yielded useful results, explorations of the fundamentals of quantum physics continue to be an active area of research, successfully ruling out a number of interpretations involving “hidden variables” present in the Universe.

10.) Exchanges of particles in quantum field theory completely describe our Universe
This is the method we most frequently employ for computing the interactions between any two quantum particles, and it is the “dirty little secret” of quantum field theory that physicists learn in graduate school. We imagine them as particles moving back and forth between those two quanta, along with any other exchanges that might take place in between.
This would result in nonsense if extrapolated to cover all potential interactions, or to what physicists refer to as “arbitrary loop-orders.” This method, an asymptotic, non-convergent series that collapses after a given number of terms, is simply an approximation. Though tremendously helpful, the image is basically unfinished. Virtual particle exchanges are an intriguing and logical concept, but they are not likely to provide a solution.

By Nikola