Topic: I don't believe Quantum Computing will ever threaten Bitcoin - page 2. (Read 5478 times)

Yes. 'Empty' spacetime still has a minimum vacuum energy, as described by Heisenberg's uncertainty principle for time and energy (rather than as we normally use in quantum physics, position and momentum). The 'endless fireworks of birth and annihilation' (which is a really nice description, by the way) is simply a manifestation of what spacetime is, with the quantum fields that are properties of spacetime.


Yes, it would be truly profound to be able somehow to 'see' this happen. I have been lucky enough in the past to be given particle traces from CERN to analyse, and it is remarkable to see the evidence in front of your eyes, even if it is  just a record of what has happened, rather than seeing it first-hand.


I'm not sure I agree. As far as we know, of the protons, neutrons and electrons that sit within an atom, the electron is a fundamental indivisible particle (I am simplifying again, meaning particle as the manifestation of the relevant underlying quantum field). Protons and neutrons are composite particles, built of quarks (which are fundamental). The quarks are held together by the strong nuclear force, which is mediated by (virtual) gluons. As far as we know, there is no further division possible beyond this point - and indeed this fits with the laws of physics as described by the standard model.

As far as I'm aware, Hund's 'bus seat' rule works because the lowest energy state is the one that maximises spin. So it is just 'easiest' (or 'most efficient') for the subshell to be singly occupied before the electrons start pairing up (because doubly occupied +1/2 and -1/2 equates to net zero spin).


When we talk about spontaneous birth and annihilation (as we have above), we are referring to the energy-time uncertainty inherent to the universe, as described by Heisenberg. We are talking about the uncertainty associated with an absolute minimum energy state, and the fact that this is non-zero. We must also consider that these quantum fluctuations manifest as virtual particles (i.e., they can't be detected directly), andd that they do so only for an extremely brief timespan. If we then consider the region of spacetime that is within an atom, then we are no longer talking about a minimum vacuum energy. However the uncertainty still remains, but it is uncertainty above that tiny non-zero limit.  It gets difficult when we start considering virtual particles, when really all we are talking about is a field fluctuation.


No, it's not empty space. Or, it's only empty space if we consider electrons, quarks etc as actually being particles, as being little dots with a physical size. When in fact, we know that the 'particle' has a wave function, and what we think oif as a 'particle' is simply a classical outcome of the wavefunction resolving to a discrete point. But quantum field theory describes it more eloquently. Everything that we see, everything that exists, is the relationship between perturbations of all of the quantum fields that exist as a part of spacetime. So 'empty space' within an atom is not the same as 'empty space' outside, because we have the wavefunction, because we have the electroweak force, because we have the strong force mediated by virtual gluons, and because these forces are fluctuations of quantum fields at that local point within the atom. Additionally, when we say 'if the atom is the size of a football field, the electron is the size of a large apple', what we actually mean is I think that if the atom is a football field, then the minimum resolvable unit of space as determined by Planck is the size of an apple. We can't ever say that the electron has a 'size' as such.


A qubit is just the fundamental unit of quantum information, so in theory any quantum property that resolves to two classical outcomes can be used as a qubit. Electron spin. Photon polarisation.


I think the term 'spin' as applied to an electron is just a description of its state, and does not refer to an electron actually rotating. It is an expression of the electron's inherent angular momentum. Firstly, electrons have no size (as far as we know), secondly, they are not physical objects, but rather field fluctuations. I don't think we can say that an electron rotates. However I certainly agree that time flows differently from the perspective of an electron.
This is all complicated by the fact that we have no real way as of yet of linking quantum mechanics with relativity.

It is interesting to communicate with a competent interlocutor who has his own views.
Let's put our knowledge of the micro-world together again and think. Because it is at this level of being that quantum phenomena occur, which we want to use to solve our problems. 
1) Note that the whole space of the microcosm is an endless fireworks of birth and annihilation of particles. There is an impression that it is not only not homogeneous, but also does not have its stable, calm state. It is the same as life, if we classify the term "life" in terms of energy processes. Space is reminiscent, by all attributes, (and hence time - if their continuum has no breakpoints, it is still an open question) of living essence. Energetically, it is a continuous converter of one energy into another, there is no peace, there are no "silence" points, there is something similar to our evolution. I can imagine what it looks like when you look at this phenomenon from below, from the microcosm itself. It's a slow and majestic fireworks, a salute, an endless holiday of "life", special and incomprehensible to us. Yes, I hope you haven't forgotten that in the microworld, time is different. And these beautiful "salutes", these endless processes of birth and annihilation of all things (particles, for example) around the observer - are slow, not as fast as it seems to us when we look at it from the microcosm. It must be beautiful.
2) Let us add to this picture - the atom next to it. What strikes me in it is order and infinity. All atoms have one law of structure. The disintegration of an atom into its constituents is infinite; a micromir can decrease infinitely (this is an assumption, a fantasy, a feeling). And also - electrons which rotate around the nucleus, only 2 on one atomic orbit (Pauli's prohibition - no more than 2) and only with different spins. After all, it is the spins of the particles that we use in quantum systems. And here's the rule. And there's one more thing. In the theory known to me - orbits of one sublevel of the atom are always, at first, filled with electrons with the same spins (Hunda rule). But why is that? And again, these laws are about the same "our" spins of particles. Isn't it a reason to think, why the electron in the atom always pulls its brother on the back? How does the atom know which spin the electrons that came in? It's something like a system of accounting, control, program. It's like a computer - what the programmer wrote, he did. There's not a single person who's dissatisfied. It's like a prison for space... Or are atoms prison cells for free, living space? 
By the way, I couldn't find an answer to the question, maybe you know, the birth and annihilation of particles discussed here, observed in "empty" space in a vacuum, is possible in the points occupied by the atom? It is fundamental to know that it would be correct to develop the point of view proposed here. 
3). Yes, looking with the eyes of a creature from the macrocosm, there is no space inside the atom or it is fundamentally different from what is outside the atom. The atom itself is empty, it is actually a huge volume of emptiness filled with small particles. Approximately if the nucleus of the atom is the size of a football ball, the electron is the size of a large apple, the distance to the nearest s-electrons of the level will be about 30 km. That's only to the closest ones. Well, isn't that an empty space? The question is, is it as empty as outside the atom or another? In other words, is it the same space, with the same properties as outside the atom or not?
4). All electrons inhabiting the atom, and there can be many of them, always spin in strictly defined orbits. The question is, in case there is no electron in orbit, the space of this orbit is the same as the rest of the space inside the atom as those places inside the atom where electrons are NEVER and NEVER can be.
No matter how mentally I build a model of the atom with homogeneous properties of space inside the atom and homogeneous properties of space outside the atom, I do not get a slender model. But as soon as I assume that space is discrete everywhere, inside and outside the atom, the model built looks more attractive.
Yes, and why what is inside the atom so critical exactly to the back of the electron, exactly to the physical characteristics of the particle, which is used by man for quantum models of the computer, the Internet and other things?
And if we fantasize, is it possible to construct a model of quantum computer using other quantum characteristics of elementary particles?
To build a quantum Internet using anything other than the photon's back is possible if there are other quantum properties connected between particles. And are there such?
I will notice that the spin of an electron is a rotation.
Note that everything around, in the universe - necessarily spins.
And here's the question for the theory of relativity. The point which is on the surface of the rotating object has a higher linear speed relative to the center than the point which is near the axis of rotation. For these two points, time flows on different silt.

No matter how mentally I build a model of an atom with homogeneous properties of space inside the atom and homogeneous properties of space outside the atom, I do not get a slender model. But as soon as I assume that space is discrete everywhere, inside and outside the atom, the model built looks more attractive.
Yes, and why what is inside the atom so critical exactly to the back of the electron, exactly to the physical characteristics of the particle, which is used by man for quantum models of the computer, the Internet and other things?
And if we fantasize, is it possible to construct a model of quantum computer using other quantum characteristics of elementary particles?
To build a quantum Internet using anything other than the photon's back is possible if there are other quantum properties connected between particles. And are there such?
I will notice that the spin of an electron is a rotation.
Note that everything around, in the universe - necessarily spins.
And here's the question for the theory of relativity. The point which is on the surface of the rotating object has a higher linear speed relative to the center than the point which is near the axis of rotation. For these two points - time flows differently or not?   
Before answering, take into account the fact that the rotating object has its linear speed relative to other objects. Which means that time is different from them. The time of a moving object flows slower relative to the one that is at rest. This is understandable. And what can be the definition of time for our 2 points, the same object that has its spin (rotation), for a point on the surface and points on the axis of rotation? What their time concerning moving past them object with the big linear speed?
If the time is split and the answers are different relative to the reference point, then the answers are easy to give, even you can calculate them.
And if time is different for all, and time is in a continuum (allegedly inseparable) with space, then not only the time is different for these points, but also the space in which they exist. And this is a journey to other worlds...

2,3 and 4 - yes.
1 - yes if we remove the 'all particles' bit.

If we look at quantum field theory, at what we perceive as 'waves' and 'particles' actually being manifestations of underlying fields, then it becomes more intuitive. All fields are everywhere, always. The electron field is a property of spacetime, and has a value everywhere within spacetime. Under certain conditions, in certain spatio-temporal instances, the excitation of this field is sufficient to manifest as an electron. But there is no 'electron', there is only the state of the field. We can see this is true if we consider the manifestation of virtual particles. A virtual particle is a more temporary excitation of the field, which does not quite manifest as a 'particle', but nevertheless can be said to exist and indeed is proven to exist, as for example the mediator of electromagnetism. Consider also quantum chromodynamics, and the mechanism by which a proton or a neutron is held together, by the strong force, mediated by gluons, which are virtual, which are a representation of the excitation of the gluon field. All fields can be said to exist everywhere in space and everywhere in time, nothing is created or destroyed, there is only a change in quantum excitation.

It does seem likely, if the way that spacetime fields manifest is discrete and quantised, that spacetime itself is discrete and quantised, and can have a minimum unit. However... we can't prove this, it may be just a mathematical convention to remove troublesome infinities. I doubt we will have an answer to this question until we have a proper unification of quantum theory and gravity.


Yes. The double-slit experiment is the essence of quantum mechanics and its implications are profound. The Copenhagen Interpretation may be the standard, but is not without its flaws. Your interpretation sounds closer to Everett's 'many worlds' view, which is perfectly legitimate.
The question of whether time can only flow forward is an interesting one. This obviously has implications for entropy. Obviously we have no way as yet to prove or disprove anything in this regard.

Again, we have no answer here. Is the world or the field more fundamental? If a quantum wave function can collapse to an outcome of 0 or 1, then in 'many worlds' both outcomes occur, we have a universe where the result is 0, and a universe where the result is 1. We have two universes. But can we say we now have two 'particles', one that gives a 0 and one that gives a 1, or is this the same 'particle', the same field, a single field manifesting across universes?


Thank you again for the discussion, by the way. And again - it is impressive that you are able to discuss this in a second language!

Let us return to the terms of physics: "elementary particle" and "wave" (or wave function of the corresponding field).
I see the main obstacle to our mutual, common, better understanding of these phenomena: 1) in words, in terms. They seem to have an exact designation. What is difficult here is to read the definition of the term, what does it mean by the word and use them as intended. But it's not that simple. Words on the one hand unravel the question and explain it, and on the other hand leave anchors that cannot be raised and floated on.  I think this comes from the fact that all definitions, all interpretations of certain terms, are based on our language's syntax, our three-dimensional macro-metric thinking, and on our genetic memory, which makes everything that exists be viewed from the perspective of: birth; growth; development; dying; disappearance. It seems to me that such a syntax, such thinking, is absolutely inapplicable to the microcosm. And hence the second reason preventing a better understanding (the first is 1)) - 2) we consider, we say, that a particle is formed (born) from another particle or... it doesn't matter. Well, nothing seems to be right - it was not there and it was formed, we say "born". But if we change this term to a similar one, to a synonym, for example: it was born (formed) - manifested. At first glance - a game of words and nothing serious. And if you think about it, the term has appeared means that it was, is and will be, but it has not manifested in our world until now, and then suddenly it has. Let me give you a good example. Astronomers have found a new star. It did not appear at the moment when it was found, it was before that moment, but after it was found - it for us, for science, as if it has appeared. And then the term "born" is totally unacceptable. Only the term "manifested" in terms of our knowledge of the stars. Now let's get back to our particle waves. If to suppose that this phenomenon exists "always", but for us, for the observer, the particle manifested itself at some moment, it means that its existence before - was not noticed by us, not that it was "born", as for example the electron from the neutron in the proton formation. The question now is different. What made it manifest itself? And here we approach our new view of the world, only slightly changing the words describing observed phenomena, we come to surprising conclusions:
1. All particles, all fields, everything that exists is always there;
2. Something is now available to us for observation, and something is no longer available or not yet available;
3. our three-dimensional world is only a part of the big world where the particles and fields we observe exist;
4. their manifestation in our world is only partially, the phenomenon itself is much deeper and more than is available to us to observe;
The electron has to appear in our world when the proton from the neutron appears because for our model of reality it is necessary to observe the law of preservation (in this case of electric charge). For the value of the negative charge of the electron is exactly equal to the value of the positive charge of the proton. He (the electron) went to work (manifested) not because he was in the neutron, but because now it was his turn to manifest here in our reality.   
What do you think, replacement of one word "birth" with another word "manifestation for us". It seems that both words are about the same thing, and conclusions about the world structure can be made absolutely opposite. In the first model of the world, the electron should have been present in the neutron, and in the second model - it is not necessary for it to be there, though nobody forbids it.

Now let us return to my assumption that time and space are discrete. Let the moment when time and space exist for us or we exist and move in them - "1". And the state of this continuum when our time and space stops is "0". For simplicity of modeling, "1" for space and "1" for time occur simultaneously, which means in one phase. Therefore, in such a model of existence, our entire conscious life has a discrete nature that has not been noticed by us. That's fine.
Now let's try to find a confirmation of this by looking at the phenomena known, but not explained by science, from this point of view.
Let us return to the perpetrators of this conversation, our wave particles.
Everybody from school (we were told it in the school of secondary general education) knows the pronounced "observer effect". Let me remind you of the essence of experience. When a bunch of electrons (I deliberately do not specify a particle or a wave) were passed through a dispersive lattice (very narrow, relative to the size of the electron, physical slot, lumen, hole), that:

- If this experience, this experiment, simultaneously with the experiment itself, was controlled by an external observer (a person with devices), then on the control surface, located on the path of electrons and located behind the disperse lattice - there is a distribution of electron hit probability characteristic of a particle;
- if this experience is not observed by an external observer, then distribution of the same electrons on the same control surface has a probability peculiar to a wave, not to a particle (visually it is a saturated wide band in the centre, and on the sides it is a smaller and less wide and saturated band - in physics this is called, it seems, an interference wave pattern).   

Now observe the thought. We live in a world of "1". The electron in both worlds and the "1" and the "0". If we observe it from the world "1" - it makes a picture of our world for us, the world "1" - it is a particle, the picture of probability saturated in the center and smoothly saturates to the edges.
If we do not observe, the world "0" acts and the electron shows itself as a wave, as a phenomenon of the world "0". By our presence, by our observation, by our thought and word - we show the world "1", the world of human consciousness and not only.  In metaphysics it is called the first attention or manifested world. The world "0" is called the "not manifested world", or the second attention of a human being. It is those people who have the second attention that see a more complete, miraculous and completely different picture of the world than those people who have only the first attention, the scientific view from our conscious three-dimensional spatial reality. By the way, who said that time can only flow forward. Or only forward and backward. And at an angle? If you think broadly, time can have as many dimensions as space. There are so many worlds, so many uninhabited.

I mean, when you build technologies for quantum systems with only materials of the world "1", for particles that exist in many worlds at once, you always need a huge amount of energy. Does man get a good advanced result, when he still uses such ancient methods of working with other worlds, such as lowering the temperature and so on ...

I am very impressed that you are able to discuss quantum physics in a second language! For me, it would be impossible.

Science advances by teaching us that our previous truths were inaccurate or mere approximations. Perhaps we will find a way to exceed the speed of light, although this is speculative in the extreme. It may need negative mass/energy... but at present is limited to thought experiments.

I don't think there is such a thing as absolute time. It can only have meaning within a reference frame. Certainly time from the perspective of an elementary particle is utterly different to time as experienced by a human in everyday life.

Particles and waves are often discussed (by me, too), but these are just convenient representations. An elementary 'particle' can perhaps best be considered as an excitation of a quantum field (Quantum Field Theory). It is fields that underlie everything. If we think of the Higgs boson as being the particle that gives other particles their mass, then this becomes difficult to conceptualise. If we think instead of the Higgs field, it becomes more explicable.

Consider neutron decay. A neutron does not contain a proton and an electron, that somehow burst out from it, it is rather that a change in the excitation of the neutron field causes changes in the proton and electron fields. There are no particles, there are no waves, there is simply 'particle-like' and 'wave-like' behaviour which is the result of changes in fields.



I would say that the perturbations of the micro average out to the macro. Similar to how if you look at bitcoin price from minute to minute, you get a jagged line... but look at it over a period of years, and the noise smooths out into an overarching pattern.

Yes, it is. Here's your last quote.
It's a bit difficult to express your idea precisely in words, as such, without carefully selecting words, and even more so if the language of communication (for me - English is alien).
Still, it's getting interesting.
Here is your final quote. It is correct, until the exceptions are found, in the form of speeds greater than the speed of light. When I was talking about the microworld, I was talking about the flow of time there in a general sense, regardless of the speed of the object. I was not referring to the relativistic effect of time slowing down associated with the increase in speed (again, let us specify the speed relative to which reference system - ours or any other? And if the reference system is moving in the same direction as the object under study and the half of its speed?).

My assumption is that for any object of the microcosm, relative to the object of the macrocosm, even in the absence of their mutual relative motion, time in these worlds necessarily flows differently. Absolutely. And it is significantly different.
Besides, space is different. For the macrocosm, it looks like a solid canvas, without holes and spaces. That's what it seems to us. That's exactly what our human illusion is. Euclidov's geometry is built on this error. And moreover, physics itself used to be built on this mistake, if you remember, then all big thinkers from our past (and in the past science did not stand out as a separate subject) were searching for the basis of being - the atom, the particle from which the whole being is built.  And they found it. And indeed it was built, but the atom turned out to be dividable. And it was when they looked at what to divide the atom, what to divide what constitutes the atom and so on - they understood that there was no end to this division. And so there is no that very small particle, on which our whole world is built. Nature is as infinite in the decreasing line - as it is infinite in the increasing line. It was infinite in any direction. And it means in the direction of its cognition by man (and other subjects), knowledge is infinite. And it would be very advantageous for us that the microcosm is far away in its infinity - merged with the macrocosm in its distant infinity. Nature tells us that everything is round. But these are only our delusions. So is the fact that the speed of light is at its maximum. I suspect that, too.
And based on these assumptions, I assume that the space of the microcosm is discrete in its essence, in its nature. Let us remember one of its interesting and known to physics property - constant birth and "instant" annihilation of completely opposite elementary particles in vacuum (to be more exact - observed in vacuum, most likely it happens everywhere). Well, isn't it the miracle of emptiness. Constantly, continuously, forever to form something out of nothing. Or rather, that's what we think of "nothing".  Obviously, the fabric of space is absolutely not homogeneous. One point - is radically different from the other standing next to it, but may have an exact clone with a point standing a little further.   And that means that time is discrete as well. And it means that the metric measurements of the macro-world that we use are not applicable to the micro-world in any way. And it means that the measured speed of elementary particles of the microcosm - through the units of macrocosm - is both an error and a truth at the same time. After all, any measurement, and especially such as "speed", is relative. The term "speed" does not mean anything without reference to the coordinate system. And it means mass, time and everything.
Now it's about cubits again. There are two times - what's flowing and what's standing still isn't flowing. There's a discreteity of everything and space.  Photons, like all elementary particles, are "seeing" their environment. The discreteness of space and time is not always in the same phase at one point. Sometimes in a phase. It's a single cell of being.   Sometimes there's a second cell of being in a counter phase. Sometimes in a phased random state it is the next cell of being. Discretion implies instant transition, from one cell to another. With a speed greater than the speed of light, otherwise it is not discrete but analogue.
From such model of being - simultaneous state of qubit and other phenomena of quantum mechanics can be represented absolutely under another angle. We therefore spend efforts (we freeze) on deduction of elementary particles that in not that system of cells of space creates the quantum computer. It's like trying to drive a ship far in the ocean with a stick from the shore. You only have to control the ship from the ship itself. It's about the same with quantum technology today...   

A line consists of points and has an infinite number of points. This was explored by Zeno in ~500 BCE, his famous paradoxes of motion - it takes time to travel between two points on a line, but before you can travel to any given point you have to travel halfway to it, before you can travel to that halfway point you need to travel half of the distance to it, etc, to infinity - so it should take an infinite amount of a time to travel a finite distance, because there are an infinite number of intermediary points you must visit first.
The resolution is that velocity always remains finite unless there is an external force applied (Newton's first law). Since velocity is distance/time, the two 'infinities' of an infinite distance taking an infinite time cancel out.
This problem has also been extended to QM as the Quantum Zeno Effect, in which by increasing the frequency at which measurements are taken, the evolution of the wave function can be inhibited.
There's also a point of discussion here on the quantisation of spacetime, and how Planck time, the minimum measurable unit of time, could be interpreted. It is the time it takes a thing travelling at the speed of light to travel one Planck length. Space and time, as Einstein demonstrated, are inseparable, we can't define one without the other. 'Spacetime' is the fundamental 'thing' here.

Yes, Planck's constant. Electromagnetic radiation is quantised. Energy is quantised. The effect of this on the wave function is what leads to only certain energy levels being possible - for an electron in an atom you would need an integer number of complete wavelengths to avoid destructive interference.  

I'm not sure I share the same conclusion. If spacetime is quantised, it wouldn't mean anything to say 'a moment when time flows' or 'a moment when time stops'... because you are defining time in terms of itself.

Relativity and the quantum world are intertwined. The speed of light in vacuum is a universal constant so, counterintuitively, as we increase the speed at which something travels, we simultaneously decrease the amount of time it takes to do so. Length contraction and time dilation are real and experimentally verifiable. If we consider a photon, which is massless and travels at the speed of light... not 'close to', but 'at', then it makes no sense to even discuss time at all. No time passes for a photon, everything is instantaneous. If we imagine a photon emitted billions of years ago, travelling across the entire universe to hit the Earth today, then from the perspective of the photon, across that huge journey, no time passed whatsoever.

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Yes, I agree, it is a good continuation of the dialogue on "what is the world of elementary particles". After all, it is this very material that we are trying to understand and put at the service of us, the representatives of the macro world. And as a matter of fact, so far we cannot understand the nature of the microcosm with the look from the macrocosm.
I am most likely wrong, because my "common sense" resists (as always), but the main difference between our two worlds (macrocosm and microcosm) is that there is one, important, principal mistake in our common sense - mistake of perception of continuity of phenomena and events. The key word here is continuity, in other words, a smooth transition, as we like to say, a continuous flow of our time.
The mistake is precisely that time flows continuously.
This is the first one.
The space around us is the same at any point. It is this feeling, this delusion, that underlies our Euclidean model of geometry (in general, this is the science of the properties of the surrounding space), one axiom of which is the statement that one line consists of points and one line has an infinite number of points. Roughly speaking, having thought a bit about it, such an axiom can take place only in monogamous, homogeneous space.
I suspect that our surrounding space is not homogeneous. It's discrete. At one point, it is. But it's not in the next one. That's why electrons rotate around the nucleus of the atom only in certain discrete orbits. It seems, if I am not mistaken, that energy between two neighboring orbits - is determined by a strictly calculated constant - Planck's constant (I have long taught, I can be mistaken, but this value is called somehow).
Here we go.   Electromagnetic wave. Spreading in space - in one point behaves like an electric wave, in the next one it does not, only as a magnetic wave. Moreover, in some points it is equal to absolute zero. And it's at these points that the magnetic wave has its maximum. I think this is because of the heterogeneous properties of different points in our space. Which means that you can't build an infinite number of identical (namely, this is meant by the term "point") points on one line. Only the finite set.
And since time and space are a single continuum, as well as having other arguments on the subject of "continuity or discreteity of the category "time" (this is a long subject), I will suggest that our time is as discrete as space. In other words, there are moments when time stands still. And there are moments when time "flows", "exists". Like the heart beats. Like a wave (there are moments when the oscillation of any wave in one measurement system is zero).   And that changes everything. It indirectly explains the "observer effect", at least as something, because there is still no clear explanation why the same matter (creatures of the microcosm) choose their existence either as a particle or as a wave depending on who is watching them and when. This is why an elementary particle either has a coordinate or its physical characteristics. But not simultaneously, as we are creatures of the macrocosm. And who says that we have the same parameters (coordinate and weight, for example) - at the same time? If the period of such discreteity is very small, we will never notice it. But this does not mean that there is no such discreteness at all. But in the microcosm - everything is very small, the course of time there is very slow, the electron sees how it rotates around the nucleus of the atom - slowly and steadily (and it rotates through our time at a speed of 200 000 000 meters per second), slowly looks at other electrons of its atom and neighboring ... For such guys - the discreteness of space and time - a way of existence, the visible tissue of existence.
What is all this philosophy for?
And for understanding the seeming "simultaneous" state or finding, the meaning of cubite: "zero" or "unit". For us, it's simultaneous. And for the discrete space-time continuum it's not simultaneous.
One still has to think, not whether the discrete space-time discrete alternates with the time discrete, how the electric field alternates with the magnetic in light photons - light waves or in radio waves of our phone (which is essentially the same phenomenon, only a different number of oscillations per unit of time, which tells us that the photon is more a wave than a particle, and any particle is an illusion of our perception, and we consist of particles - so we are illusory, we are fantasy, a matrix ...). In other words - in those moments when there is space - there is no time. Or are they simultaneously there, and then they are not there at the same time?
I suspect that here is the key to understanding quantum phenomena, to building new quantum computing technologies.
Maybe, because nobody forbids to think...

I think there is some nuance here. Quantum properties are well understood from a mathematical perspective; the problem comes when we try to interpret something such as an electron as a particle. An electron is not a particle, it simply doesn't have a definite position. Neither is it a wave. It is a thing that, when we interact with it, in certain circumstances manifests wave-like behaviour, and in other circumstances particle-like. The Heisenberg Uncertainty Principle does not suggest that there is uncertainty because we don't know what is happening, or that the uncertainty arises as a part of the act of measurement, but rather that we can't force particle-like behaviour on an electron. We can approximate it to a limit of the reduced Planck constant, but we can't absolutely perfectly describe it as a particle... because it is not a particle. We understand the maths, and can build engineering solutions based upon it, but we do so without knowing what an electron, fundamentally, is. For example, the apparent contradiction in that it has mass, but it has no physical size. Perhaps we will understand one day, or perhaps our human brains are not wired in such a way to make sense of it. This brings us onto whether the Copenhagen interpretation is perfect (it's not), and whether wave function collapse does actually occur, and then to questions as to the nature of the a priori framework of our perception: time and space. We exist within time and space; it is extremely difficult to define a thing that you exist within and that you have no conception of being outside.

A quantum computer will work and will stand on our desk and even be in our smartphones (or whatever they are called), regardless of the correct explanation of the technology or the wrong one if a person needs it - he will do it. There are many examples in history where a person has misinterpreted and understood what they were doing, but they were doing it right. Specifically, even after something started to work in practice, new explanations, new insights, perhaps closer to the truth, may have emerged afterwards.
A man is the champion of the universe by explaining everything that would come to his mind. The most vivid example is a god, gods, faith in invented explanations. A human being (unfortunately, mine) has an alien mind that closes its own. A foreign mind, which possesses our consciousness, likes to talk especially to itself, likes to important, to protect its own ego (this is EGO), likes to explain everything, especially when it has little understanding of the question. And for this purpose he has a foreign language, exactly the one which we were taught from birth. 
It's the same with quantum phenomena. The quantum world itself - is not definitely defined, the elementary particles themselves have no and can not have an unambiguous definition - so says the quantum mechanics. As you know, quantum mechanics says that an elementary particle either has mass, charge, spin, etc. at this point in time - but then it does not have any exact coordinate in space (defending this point of view, science says that knows only the area of space in which this particle can be at any point - ONE!!!). Or vice versa, if we know the coordinate of a particle - we have no idea about its physical parameters. So where is the unambiguousness here? Mystery and uncertainty - this is what quantum mechanics, the fundamental science of elementary particles, deals with. And relying on this liquefied foundation, not at all turning around, engineers bravely build working quantum models (the Big Collider among them).
That's how our quantum technology is built, almost blindfolded.
And no one is embarrassed by that.
In fact, if the current explanation is not relevant, there are new ones standing in line to replace it long ago. Has the lack of knowledge of the truth ever stopped the technology? Same as today.

Certainly, when measured, the result is 0 or 1, either/or, with 100% probability. I agree that far. But when we say that a qubit is 'simultaneously 0 and 1', that is a simplification. What we mean is that, prior to measurement, the qubit is best defined as a wave rather than a particle. The Schrödinger wave equation is the best description of what the qubit 'is'; really it makes no sense at that point to say that it is both 0 and 1, because 0 and 1 are classical end states. But we can say that the qubit, because of its wave-like nature, can resolve to either possibility. It has the potential to be either a 0 or a 1. This phenomenon can be described as the qubit 'exploring all paths', but the fact remains that the power does scale 2^n, because all possible classical states are potential outcomes upon measurement.


Quantum mechanics describes how the universe behaves at an extremely small scale. It does not make sense in terms of our everyday, macroscopic view of the world. We have evolved to hunt food, search for shelter, escape predators. This is how our brains are built. Our understanding of what constitutes reality is heavily influenced by our sensory apparatus. A rainbow, for example, only appears as does because of the way our eyes work; other eyes would see it differently, and the mathematical description would see it perfectly.
Any attempt to explain QM in everyday human terms will fail; this is why no human really understands what the quantum world 'is'. But we have mathematics that describes it. And we have devices built on that underlying mathematics, and these devices function correctly according to the laws of QM. We cannot say this is wishful thinking, rather it is verifiable, reproducible experimental evidence. It is fact. Modern computers are built on quantum mechanics. It is impossible to describe semiconductor-based electronics without quantum mechanics.

This is a deep look at the issue, and it is important to take it into account. On the other hand, whatever the modern problems of technology, the developed technologies that are based on science, sooner or later, will give humanity practical solutions. Just like you in your position, I look back and observe how humanity is overcoming any difficulties and always finds successful solutions to technical problems. It finds ways to move engineering solutions from science to commerce and consumer use. This general line of development, and this pattern is necessarily preserved for quantum technologies.
Thus, I come to an unambiguous conclusion that the problems of quantum computing, its scaling and the entry of quantum technologies into our life - will certainly be solved.
I absolutely disagree that the presence of such technologies in our everyday life will somehow change our security. These technologies will not reduce or increase the reliability of encryption. Cryptography itself is developing much faster, with much greater growth potential than quantum technology.
Take a close look at the principles of modern encryption systems. Look at the new systems - candidates for post quantum. What elegant solutions are offered, what depth of thought. No matter how fast technology, thought, theoretical science, mathematics are developing, they go many steps forward. People have long been researching, creating models and working in mathematical n-dimensional spaces, in models with amazing properties that our rational mind is not able to understand. but mathematics can do it. For these reasons, encryption will never be in danger because it's math and combinatorial. 
But again, I would like to draw your attention to the fact that all encryption systems have keys. Keys as a function of selecting an encryption scheme. One of the many possible encryption schemes. That's where the danger is for us. Much more than the quantum computing that will be needed to solve scientific and engineering problems, not to break the ciphers.
If in doubt, look at what they say at all the security conferences. In short, it is a thought - almost always, almost 100% of all attacks start with stealing keys (passwords, identifiers).
Explain to me why you need a quantum computer that you want to use for a brutal attack on the code if you can steal the basics of encryption - keys.
That is why I see the only vector of development of protection systems, including after the era of quantum computers, in the introduction of keyless encryption technologies.
Look, in key technologies, for example AES-256 (until it breaks down by a quantum miracle, even if it worked), the task is in a complete search of two to the extent of 256 options.
In keyless technologies, such as output cipher-code bit rate, the same is true: two to the extent of 256 variants. But for the second cipher code it is already two in degree 256x2 variants. For the third it is two in degree 256x3 variants. Here is a real and beautiful departure from quantum superiority of any technology directed on full search of all variants, i.e. on attack by brute force.
The only difference in the attack on asymmetric cryptography is that out of all variants of the final number field only integers work, not all in a row. Plus, Shore's algorithm makes this task a little easier. But in its essence it is the same brute force attack, only a little bit of mind in this attack.
Another thing is finding mathematical solutions to problems of finding a discrete logarithm and factorization. Can a quantum computer help here?

Let me doubt.

A qbit is not simultaneously 0 and 1, it is probably 0 or 1, and eventually - when measured - certainly 0 or 1. That's why 2ⁿ is wrong. A system of n qbits is not simultaneously in 2ⁿ states, it is probably in one of them. Altering it via any constraints reduces the probability that the system is in certain state. But the system was already at certain state, and could transition to the more favorable one forced by constraints. So it has to travel to the correct state. But if there's a reasonable algorithm for this, no quantum stuff is needed.

Or let's say, that somehow, a system of n qbits is in most of the 2ⁿ states simultaneously. Then constraints are placed, and some of the states become "forbidden". The favorable states would have lower energy. Either there's a transition to lower energy, which has to be released, or influx of energy to make up for the unfavorable states. At the end finally we arrive at the correct single state. All this energy has to go somewhere. All 2ⁿ bits of energy. Would the solar system survive such energy blast? Would the Milky Way?

There's a lot of wishful thinking in quantum physics. It is believe based, and attracts all kind of believers. Something is fishy. It looks a lot like the geocentric solar system in Middle Ages. Circles upon circles, a very complex stuff, but never correct (except for a few isolated cases). So I would say, it is fundamentally wrong, and it is obvious. After all quantum physics is statistics, and statistics is never reality. Sometimes, many times, very useful, but still wrong.

No, it's not a misconception, the number of potential classical outcomes that a QC can assess does scale 2^n, it's inherently true based on how QCs work.

Having said that, I absolutely understand and agree with your main point that number of qubits isn't everything, it's merely a headline figure, which can be misleading. 2^n means nothing if there is a high rate of error in the final result. Decoherence - the loss/corruption of information - is the fundamental obstacle to achieving large-scale functioning quantum computers. Adding and entangling additional qubits is not what is stopping QCs today, it is, as you say, the increased noise as number of qubits increases. But it doesn't change the 2^n scaling that makes QCs so efficient at for example integer factorisation and the discrete logarithm problem.

The scaling is an inherent truth due to immutable physical laws. The noise is an engineering problem.

 

QC scaling as 2ⁿ is a common misconception. As n grows, the system scales worse and worse. At certain point, for n<50, the noise dominates, no signal is left. For example, last year Google claimed "quantum supremacy". It was supremacy in generating noise.

I sort of agree with this. The reason we need QCs to be cooled almost to absolute zero is to reduce decoherence. Cooling is a (partial) solution to a problem. There may be other solutions where cooling is not required (or where a smaller amount of cooling is sufficient).

I sort of agree here, too. A system is only as strong as its weakest link. That weakest link often turns out to be human errors or laziness. However we can't really argue that a) people will make errors or be negligent, therefore b) there is no point to implementing secure cryptographic systems.

Because the power of a QC scales exponentially due to superposition and entanglement. Superposition meaning that a qubit can be - to simplify somewhat - both 0 and 1 at the same time. Entanglement meaning that multiple qubits can be combined into a single state. So the number of classical outcomes that can be assessed scales 2^n. The nature of QCs means that they are strong on integer factorisation and the discrete logarithm problem (both normal and ECC). Shor's algorithm can dismantle current asymmetric cryptography.
There are as you know various quantum-resistant approaches to asymmetric cryptography that offer potential defences against a QC, however these do also bring new challenges such as increased key size.

Going beyond bitcoin and cryptocurrencies, one common assumption is that there is no danger until a sufficiently powerful QC appears. This is not the case. Quantum-safe security needs to be implemented as soon as reasonably possible. I am quite sure that people are storing today's encrypted traffic for the future, so that it can be decoded once a QC is available. Anything communicated by public-key today can be deciphered tomorrow.

Quantum technology is a science. For now. Temporarily, but time is known to always go fast.
I think people can make quantum computing available to everyone, they can make a personal quantum computer. I suspect that inside this miracle of technology there will not be a system of cooling the substance to zero, but technologies to conquer magnetic fields for the same purposes, which, as the scientific press writes, are developing.
I do not see a solution to safety problems for the user, even if these technologies are available, even if they are absent.
I'll explain why.
What will break a quantum computer is cryptography.
What kind of cryptography would a quantum computer attack? Asymmetric, from the last century. All modern post quantum asymmetric and even the old symmetric AES level, let alone the Two Fish, will never be attacked by it.
Why do I say that so boldly?
Because today's old AES-256 is perfectly capable of handling the quantum threat, the foreseeable future. To extend the key length to 512 bits is worth nothing. It's not gonna put much strain on the processor when it comes to encryption. But for quantum computers, increasing the key length from 256 bits to 512 bits is absolutely impossible to improve this technique in a reasonable period of time.
From the scientific point of view - the world of numbers is infinite and to use this resource, you can increase the field of numbers for encryption instantly. But to improve the technique that will catch up with the "infinity of number fields" is a difficult and time-consuming task.
In fact, even modern cryptography is never broken, keys, passwords and information are always stolen. The same will happen after a quantum computer is available to everyone. Nothing will change. We will also be attacked by ourselves only by compromising sensitive data.
Why do you need a quantum computer to attack a bitcoin - I don't understand at all. Even the old asymmetric cryptography on elliptical curves, with a 4-fold increase in the length of the key - will remain a dream to crack the known algorithms on quantum computers.
Everybody looks the wrong way when they think about security issues.
There are billions of accounts on the darknet that are sold for nothing. We are all hacked a long time ago, and so we will in the future if we keep the old key encryption technologies and password (and biometric) authentication methods.   

This is very true. When advances in quantum computing are reported, the focus is often solely on the number of qubits involved. Whilst a degree of simplification is understandable when reporting what is certainly a complex and technical subject, this can mislead people into thinking it's the only important metric. Information loss through decoherence is a huge issue and the major barrier to production of large-scale QCs, and maintaining that near-absolute-zero temperature is a key requirement in minimising that decoherence.

However, whilst this is important and, as you say, expensive, the problem is perhaps not insurmountable. These are after all engineering challenges rather than absolute, universal constraints. My post above links to recent experimental verification of a process whereby the minimal viable temperature is increased by a factor of 15, resulting in an orders-of-magnitude cost reduction for cooling. But it is not necessarily all about cooling or the space required. Development is continuing at pace across the field, with advances being made all the time. Techniques are being refined, and new approaches adopted. Noise is being reduced and coherence is improving. Indeed, just last week Trinity College Dublin released a paper detailing a new technique in qubit-creation that may make the process both more powerful and much more controllable. Traditionally the quantum-dot-based approach to qubit emission involves affixing a metal point near to the dot... but the new approach involves controlled optical excitation of the point, which can then be scanned over the surface. Not only is this simpler than the current method, the new optical approach also generates greater quantities of single photon outputs and can force entanglement of dot pairs. The whole process is becoming more controllable all the time, and with increased control comes less noise, and so greater coherence.

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Edited for clarity; seems my sentence construction also suffers from coherence issues.

That's assuming Satoshi is not actively keeping up to date with quantum computer development or assuming that he has lost his keys. Satoshi may still have access to his wallet and is keeping them there for a reason. There could be multiple reasons why Satoshi is doing it but that would go off topic from the discussion.

Your concern is legitimate for other people though. Quantum computers have the capability once they have reached a certain qbit milestone to be able to attack addresses that may have been lost by other people. This could be attacked on a very wide scale. Some people could see this as a ongoing problem and could effect the longevity of Bitcoin as a currency. But as it has been discussed here the affordability of a quantum computer capable of doing this will not be open to the public for a very long time. I know there has been advances in keeping quantum computers cool but this does come at a cost that I think a lot of people are ignoring. The cooling system is not the expensive part its the amount of space that you would require to make it effectively cool and run at the required qbits for a extended amount of time that would be the issue.

Quantum computers are a long way off but the technology behind them is improving at an exponential rate. At the moment I have not seen any system which would protect against stealing of coins that have been lost. There are multiple technologies in the theory process right now that could be implemented into Bitcoin and reduce the effects of quantum computing on the industry but I think old addresses that have not been converted will always be vulnerable to quantum attacks unless someone comes up with a sleek new concept within the next couple of years.

You can change the algorithms of all the active wallets, but some wallets have lost keys or the people who had those keys died and they can't change the signing algorithm which means those wallets will be captured by quantum computers. So we will know what quantum computers exist when satoshi's coins move... That's one of the reasons why they will move. Eventually they will move and they will move because eventually someone will be able to break the keys. But for the rest of the eco system we can migrate quite easily to another algorithm. It's not really as big of a threat that people think it is."