This question was provoked by my knowledge of the kochen specker theorem, which if I am correct is a theory that states measurements sometimes, within a system, do not exist until it is consciously observed with a question in mind. The results are not observed by an unconscious apparatus(a physical measuring device with no question involved in measurement) exclusively, and needs a conscious observer. The theory suggests that measurements are directly warped or created by a question that proceeded them, which makes me curious about the nature of measurements.

Lets assume a system is a series of observable objects, interacting within the world exclusively physically.

lets define a question as a perspective; a construct, of piece of data from a measurement as to solve a problem

If the system was able to be observed without a question or goal, then the possibility of a specific measurement to not exist before a question; a construct, must also be a construct, for this to be possible.

Is this true? are measurements constructs? Or is there an error in my thinking process?

  • You may need to rethink your understanding of the Kochen-Specker theorem. It does not say what you think it is saying. Perhaps ask at Physics.SE to check your understanding first? Commented Oct 16, 2021 at 4:34

4 Answers 4


Terminology is tricky. Not everybody agrees on the exact meanings of things like "measurement" or "construct." However, there is a common grain with these definitions.

In most versions of measurement that I have seen, one requirement of a measurement is to isolate the measuring device from the measured entity before it can be called a measurement. A physical example would be the use of calipers to measure an object while it is changing shape. Typically people would not use the word "measurement" until the calipers are no longer being held to the object, so they are not part of a coupled system with the object. The meanings can vary, but I have found that trend to be reliable.

This requirement shows up on the fringes of quantum mechanics as well. In many interpretations of QM, there is a concept of a "measurement," or a "classical measurement," which transitions from a quantum interpretation of the system to a more classical one. The best description given to me as to this process is that you have to couple the system to transfer some of its state to your probe, and then you must "separate" the probe from the system using a process to remove any entanglements between the probe and the system. (not always a fully defined process)

Another common requirement is that the measurement should result in information. This is not as universal as the idea of having to be isolated from the measured entity, but it is very common. Some would argue that the calipers do not actually "measure" anything until someone turns their state into a number (such as 3 inches). Others might define it otherwise, but its so natural to talk about the state of a measurement device as information (such as the angle between the caliper legs), the line may be blurry.

If you choose to define "measurement" in a way which includes both isolation from the measured entity and the transfer of information, and take those two rules to an extreme, you get something similar to what you describe. Many choose to define a conscious observe as one which can observe information, and many choose to define conciousness as decoupled from the physical world. Thus, this idea of a "measurement" being a "construct" makes sense, if one chooses to take an extreme viewpoint on what a measurement could possibly be.

  • I wonder if one could build a quantum computer that is strongly dependent on quantum superposition in it's performance, and then have it somehow operated by monkeys (or cats) and see if it still performs they way it should. On could then at least determine whether all consciousness or just human consciousness causes wave function collapse. Commented Nov 18, 2015 at 19:12
  • @AlexanderSKing One of the neat arguments I have heard (and I think I comprehend) is a way of modeling measurement at the quantum level as introducing an object whose state is well modeled as random variables, and interacting it with the system. Do this enough times, and the central limit theorem starts to make the quantum result appear well modeled as a classical observation. That definition of measurement would make strong suggestions as to whether a monkey's consciousness can "collapse a waveform" the same as a humans does or not.
    – Cort Ammon
    Commented Nov 18, 2015 at 20:28
  • @Cort Ammon The measurement process is a notorious problem for quantum mechanics. The traditional interpretation by "the collapse of the wavefunction" at the moment of observation states the problem, but it is not the solution. Probably the principle of decoherence by a bulk of external interactions will explain in a consistent and unified manner, how the wave function concentrates around one of the possible outcomes of the measurement; see the chapter "Decoherence and Quantum Reality" in Green, Brian: The Fabric of the Cosmos.
    – Jo Wehler
    Commented Nov 18, 2015 at 20:44
  • @JoWehler I heard somewhere that the measurement problem is only a problem, if you deny that consciousness affect the universe. And I strongly doubt that decoherence will ever solve the problem. The measurement problem is probably strongly related to the mind body problem
    – tristo
    Commented Nov 19, 2015 at 0:10
  • @tristo The measurement problem is due to the fact that the wave function of the unobserved system develops according to the Schroedinger equation in a differentiable way, while the observation discontinuously changes the wave function, the so called collapse of the wave function. The collapse of the wave function cannot be described by the Schroedinger equation. - Green, in the book I mention in the comment to Cort Ammon, discusses several interpretations. - Considering the mind of the observer as cause serves only to indicate the problem.
    – Jo Wehler
    Commented Nov 19, 2015 at 0:48

A measurement, in a general sense, can be thought of observation: I observe your height or weight; or the exact colour of the sky in an unclouded night and the number of stars.

Now, there is a key on a table which I pick up in my left hand, and hide it in my palm with my fingers clenched in a fist; I ask you to observe it; so you look at my hand, and then I open my fist - you observe the key - and then I close my hand briefly, and open it again - and again you see the key.

This much is expected; from moment to moment the key in my hand is at it is; but this is not inevitable or indeed neccessary.

Say, in my right hand I pick up some plasticine; it is formless - without shape; and when I open my fist, I quickly shape it into a sphere; and then when I close it, I turn it back into some shapeless and formless piece of plasticine; and again when Inopen my fist - so you can observe what is in my hand, I quickly shape it into a cube and so on.

This notion is called Value-Definiteness (VD) and is a key input into the Kochen-Specker Theorem; the first example above affirms it, and the second denies it.

Aristotle would say, that for the second example, some thing - some value comes to be and ceases to be - condenses and rarifies; and this appears to be his understanding of things in the small; for example, in Physics VII.5, he writes:

in fact, the fragment in the bushel does not move ... because within the bushel no fragment exists, except potentially.

He would also say, given his comments on the notion of change (and recall that Heisenberg theorised measurement as a change); that measurements require a something that acts as a measurer and something that can be measurable.

But he would deny that a measurer can measure itself: this ruler in my hand can measure my height or yours - but it cannot measure itself; or rather it is as a vacuous truth - a tautology - an inch is exactly an inch; and by this, nothing new is said.

There are three inputs into the theorem; one we have mentioned - value definiteness; the other is non-contexuality (NC): it ought not to matter how you measure something - the result ought to be the same.

The final input is one specific to the formal structure of QM: that measurements are self-adjoint projections.

The theorem then denies that all three can be consistent together - one has to give; in QI for example projections are replaced by positivity.

  • very good answer, I was contemplating about similar ideas with a pen and a ruler a few weeks ago. Thankyou
    – tristo
    Commented Nov 22, 2015 at 3:16

In science one observes a phaenomen or one prepares an experiment. Stated in a bold way, the experiment is the question of the scientist, and the result of the measurement is the answer from nature.

A construct is an idea in the mind of the scientist; hence neither the measurement nor its value are constructs.


From the mathematical point of view, a measurement is an irreversible random walk.

The sufficient condition of the coin-toss-decision distance to be linear is that it is irreversiblly one-directional. Its kinetic energy is always quadratic.

Mathmatically, if something is quadratic, it is irreversible, and if something is irreversible, it's quadratic.

Typical physical measurements are always quadratic, because they are Baysinan probability matrix.

This matrix is sometimes called quantum tomography.

Physical measurement is always quadratic, because it is a matrix, and because it is quadratic, it is irreversible.

This is just a very simple mathematical consistency. The mathematical logic forces me to define physical measurement as an irreversible event.

As long as only mathmatics is concerned, a physical measurement is an independent logical Markov chain of irreversible noncomutative matrix events.

A measurement event is always irreversible(affecting the future), and it's always independent. It's a random walk of somebody who has a will to look around and walk on.

  • This definition seems to rule out superdeterminism by proclaiming independence and "will". These are assumptions. There are people in foundations of physics who don't subscribe to them.
    – J Kusin
    Commented Oct 15, 2021 at 23:33
  • -1: A measurement is not a 'irreversible random walk', otherwise we would get random numbers for measurements ... Commented Oct 16, 2021 at 4:32
  • A will could be replaced with an arrow, quantum parity, positivity, norm,etc. The walker is allowed to choose left and right ways forward, but he never allowed to look back.This is like a yacht in random wind. The captain is determined to move forward. Commented Oct 16, 2021 at 4:33
  • To be more strict, only the moment of the construction of the quadratic matrix is irreversible. All other things can be perfectly reversible. A coin could be replaced with an ignorence. Commented Oct 16, 2021 at 4:36
  • In order to make a mechanical clock, you need to insert at least one small irreversible part somewhere. Many theories mathematically have such parts. Commented Oct 16, 2021 at 5:47

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