The laws of mechanics describe quantum behavior the microscopic world, a world in which objects are so faint that the pressure of a light beam, however tenuous, can cause sudden movements. These atoms and molecules-objects invisible to human eye move and interact with each other in a qualitatively different than they do tennis balls, cars, planets and the rest of the fauna of the visible world.
Both the description of the microscopic world as in the macroscopic is useful to discuss the state of an object. A possible state of a tennis ball is, resting next to the network. Another possible condition is: feet off the ground and moving up to a speed of one meter per second. In this language, specify the state of the tennis ball at a given time is then state your position and speed at that time. The laws of classical mechanics, enunciated by Isaac Newton, predict, given the state of the tennis ball in an initial instant, the state of the tennis ball at any later time. The sequence of states is nothing more that the trajectory of the tennis ball. In quantum mechanics this description does not work. Atoms and other microscopic particles do not support a description that indicate the state of the particle at a given time corresponds to indicate the speed and position: in quantum mechanics, specify the state of a particle at a given moment is to indicate a certain function containing the probability that the particle is in a certain place with a certain speed. The laws of quantum mechanics, as set out in this case by Erwin Schrödinger and Werner Heisenberg, to calculate the temporal changes of the probability function, or in more technical terms, the wave function. We thus return to a conceptual revolution of quantum mechanics: the loss of the idea of \u200b\u200bhistory in favor of a description in terms of probabilities of paths.
In order to compare two visions probabilistic classical and quantum, consider the simplest of randomized experiments the macroscopic world: Alicia throws a coin and held it in your hand. Mary must predict whether the currency Alicia holds in his hand fell heads or tails. From the standpoint of Mary, the state of the coin can be described by a probability function (classical), indicating that every possible state, heads or tails, has a fifty percent probability. While Mary Alice will have to wait open hand to see if the coin fell heads or tails, it is "obvious" that the currency fell in one, and only one of the two possibilities and that the probabilistic description in this case quantifies the ignorance that is Mary's state of the currency. When Alice opens her hand, Mary proves that the currency fell, say, cross. On the one hand we can speak of change of state of the memory of Mary, who happened to ignore how the currency fell, namely that cross fell. On the other hand, in the process of observation, the state of the currency did not change: the currency had fallen cross and observing what he did was unveil a result that existed beforehand. Compare this experiment with its microscopic equivalent. While there are no coins microscopic There are systems (atoms) that can be in one of two mutually exclusive states: the spin of an atom, which can take two values: "up" and "down." Say we have an atom in a "box" closed and that we know the atom's wave function corresponds to a fifty percent up and down fifty percent. In analogy with the coin of Alice, if we open the box we see the atom in one of two chances and if we repeat the experiment many times preparing the atom in the same initial state, we find that about half of the time the spin is up and almost half the time down. So far the two visions probabilistic match. However, quantum mechanics allows for the possibility that the atom is in a superposition of states before being observed and in a defined state after being observed. Suppose that Mary is now a detector capable of opening the box and observe the spin of the atom. After the measurement process not only changes the memory of Mary but also changes the state of the atom. The crucial difference is that before Mary to observe the atom is in a superposition of two states, and makes no sense to say that is either up or down, because the atom is simultaneously in the two states. This peculiar feature has no place in our intuition, we put in front of another conceptual revolution of quantum mechanics: the loss of the existence of an objective reality in favor of several realities that exist simultaneously.
The central question, which summarizes the measurement problem, still unresolved, can be formulated in the context of our example as follows:
If both Mary and the atom are subject to the laws quantum, and if the atom is in a superposition of states before the measurement and a well defined after the measurement, what is the mechanism by which the atom "choose" a state and not another? The general consensus is that the solution to this dilemma exceeds quantum mechanics, one theory goes beyond the physical more explanatory and predictive power.
The only "solution" to the paradox would be in the Everett theory, or quantum mechanics is incomplete or resisted accept the parallel worlds theory of Everett and DeWitt, in which case the world would be precisely the maze of Ts 'ui Pên that:
"believed in a number of times, in a growing, dizzying net of divergent, convergent and parallel. This network of times which approach, forked, broke off, or ignored for centuries, embraces all possibilities. We do not exist in most of the time, in some you exist and not I, in others, I, not you, in others the two "(Works, I: 479).
In " The Garden of Forking Paths " Borges mentions Pên Tsui, a Chinese astrologer who has written a remarkable book: The Garden Forking Paths. Ts'ui Pên proposed two tasks was unthinkable: building infinitely complex labyrinth and write a novel endless. After his death he thought he had failed as the existence of the maze was not clear and the novel was not only incomplete but that it was absurd and inconsistent (for example, some characters die and reappear in later chapters). To the surprise of Yu Tsun, Albert reveals that he has discovered the secret of the enigmatic novel, the book is the labyrinth and the labyrinth is not spatial but temporal. The garden is the image of the universe as conceived Pên Tsui, and if we accept the hypothesis of Everett, the world is a garden of forking paths.
In each measurement branches quantum universe, with one component for each possible outcome of the experiment. In one of the memory of Mary universes corresponds to spin up, in the other, with spin down. The sequence of memory configurations of Mary, or "trajectory" of the reports is different in each of the universes.
The two authors describe the central idea in ways strikingly similar. Section 5 of the original article, Everett says
The "path" of the memory configurations of an observer who performs a series of measurements is not a linear sequence of memory configurations but a tree branching (a branching tree), with all possible outcomes existing simultaneously.
In "The Garden of Forking Paths," Borges says
In all fictions, each time a man is confronted with several alternatives, he chooses one and eliminates the other, in the almost inextricable Pên Tsui, choose "simultaneously" for all. He thus creates diverse futures, diverse times which themselves also proliferate and fork.
But where are all these universes? One answer is that they can be "here", where "our" universe. According to the theory these universes do not interact, so there is no reason to exclude the possibility that they are occupying the same space. Another answer is that the universes are "stacked" on an additional dimension that we know nothing.
Borges seems to be then the first to formulate this alternative to linear time. The other possibility, that of cyclical time, has numerous precedents in archaic cultures and literatures to which detailed reference Borges in various writings. Multiple times with a different story: "Hume has denied the existence of absolute space, which takes place every thing, and I, the one time, which link together all the facts. Denying Coexistence is not less hard to deny the succession (Other Inquisitions).
While compiling the material for this essay I asked Bryce DeWitt, now at the University of Texas at Austin, if he was aware of "The Garden of Forking Paths" to write the article in 1971 where he coined the term "many worlds." I said no.
Excerpted from the conference " Borges and quantum mechanics " Alberto Rojo
the window I saw the familiar roofs
cloudy and the sun six.
It seemed incredible that
that day without premonitions or symbols
out of my inexorable death.
Although my father died,
despite having been a child
in a symmetrical garden of Hai Feng,
I now going to die?
Then I reflected that all things that happen
one
happen precisely, precisely now.
Centuries of centuries and only in this
happen;
countless men in the air,
on land and sea,
and everything is really happening to me happens me.
JL Borges
Both the description of the microscopic world as in the macroscopic is useful to discuss the state of an object. A possible state of a tennis ball is, resting next to the network. Another possible condition is: feet off the ground and moving up to a speed of one meter per second. In this language, specify the state of the tennis ball at a given time is then state your position and speed at that time. The laws of classical mechanics, enunciated by Isaac Newton, predict, given the state of the tennis ball in an initial instant, the state of the tennis ball at any later time. The sequence of states is nothing more that the trajectory of the tennis ball. In quantum mechanics this description does not work. Atoms and other microscopic particles do not support a description that indicate the state of the particle at a given time corresponds to indicate the speed and position: in quantum mechanics, specify the state of a particle at a given moment is to indicate a certain function containing the probability that the particle is in a certain place with a certain speed. The laws of quantum mechanics, as set out in this case by Erwin Schrödinger and Werner Heisenberg, to calculate the temporal changes of the probability function, or in more technical terms, the wave function. We thus return to a conceptual revolution of quantum mechanics: the loss of the idea of \u200b\u200bhistory in favor of a description in terms of probabilities of paths.
In order to compare two visions probabilistic classical and quantum, consider the simplest of randomized experiments the macroscopic world: Alicia throws a coin and held it in your hand. Mary must predict whether the currency Alicia holds in his hand fell heads or tails. From the standpoint of Mary, the state of the coin can be described by a probability function (classical), indicating that every possible state, heads or tails, has a fifty percent probability. While Mary Alice will have to wait open hand to see if the coin fell heads or tails, it is "obvious" that the currency fell in one, and only one of the two possibilities and that the probabilistic description in this case quantifies the ignorance that is Mary's state of the currency. When Alice opens her hand, Mary proves that the currency fell, say, cross. On the one hand we can speak of change of state of the memory of Mary, who happened to ignore how the currency fell, namely that cross fell. On the other hand, in the process of observation, the state of the currency did not change: the currency had fallen cross and observing what he did was unveil a result that existed beforehand. Compare this experiment with its microscopic equivalent. While there are no coins microscopic There are systems (atoms) that can be in one of two mutually exclusive states: the spin of an atom, which can take two values: "up" and "down." Say we have an atom in a "box" closed and that we know the atom's wave function corresponds to a fifty percent up and down fifty percent. In analogy with the coin of Alice, if we open the box we see the atom in one of two chances and if we repeat the experiment many times preparing the atom in the same initial state, we find that about half of the time the spin is up and almost half the time down. So far the two visions probabilistic match. However, quantum mechanics allows for the possibility that the atom is in a superposition of states before being observed and in a defined state after being observed. Suppose that Mary is now a detector capable of opening the box and observe the spin of the atom. After the measurement process not only changes the memory of Mary but also changes the state of the atom. The crucial difference is that before Mary to observe the atom is in a superposition of two states, and makes no sense to say that is either up or down, because the atom is simultaneously in the two states. This peculiar feature has no place in our intuition, we put in front of another conceptual revolution of quantum mechanics: the loss of the existence of an objective reality in favor of several realities that exist simultaneously.
The central question, which summarizes the measurement problem, still unresolved, can be formulated in the context of our example as follows:
If both Mary and the atom are subject to the laws quantum, and if the atom is in a superposition of states before the measurement and a well defined after the measurement, what is the mechanism by which the atom "choose" a state and not another? The general consensus is that the solution to this dilemma exceeds quantum mechanics, one theory goes beyond the physical more explanatory and predictive power.
The only "solution" to the paradox would be in the Everett theory, or quantum mechanics is incomplete or resisted accept the parallel worlds theory of Everett and DeWitt, in which case the world would be precisely the maze of Ts 'ui Pên that:
"believed in a number of times, in a growing, dizzying net of divergent, convergent and parallel. This network of times which approach, forked, broke off, or ignored for centuries, embraces all possibilities. We do not exist in most of the time, in some you exist and not I, in others, I, not you, in others the two "(Works, I: 479).
Photos: GM
In " The Garden of Forking Paths " Borges mentions Pên Tsui, a Chinese astrologer who has written a remarkable book: The Garden Forking Paths. Ts'ui Pên proposed two tasks was unthinkable: building infinitely complex labyrinth and write a novel endless. After his death he thought he had failed as the existence of the maze was not clear and the novel was not only incomplete but that it was absurd and inconsistent (for example, some characters die and reappear in later chapters). To the surprise of Yu Tsun, Albert reveals that he has discovered the secret of the enigmatic novel, the book is the labyrinth and the labyrinth is not spatial but temporal. The garden is the image of the universe as conceived Pên Tsui, and if we accept the hypothesis of Everett, the world is a garden of forking paths.
In each measurement branches quantum universe, with one component for each possible outcome of the experiment. In one of the memory of Mary universes corresponds to spin up, in the other, with spin down. The sequence of memory configurations of Mary, or "trajectory" of the reports is different in each of the universes.
The two authors describe the central idea in ways strikingly similar. Section 5 of the original article, Everett says
The "path" of the memory configurations of an observer who performs a series of measurements is not a linear sequence of memory configurations but a tree branching (a branching tree), with all possible outcomes existing simultaneously.
In "The Garden of Forking Paths," Borges says
In all fictions, each time a man is confronted with several alternatives, he chooses one and eliminates the other, in the almost inextricable Pên Tsui, choose "simultaneously" for all. He thus creates diverse futures, diverse times which themselves also proliferate and fork.
But where are all these universes? One answer is that they can be "here", where "our" universe. According to the theory these universes do not interact, so there is no reason to exclude the possibility that they are occupying the same space. Another answer is that the universes are "stacked" on an additional dimension that we know nothing.
Borges seems to be then the first to formulate this alternative to linear time. The other possibility, that of cyclical time, has numerous precedents in archaic cultures and literatures to which detailed reference Borges in various writings. Multiple times with a different story: "Hume has denied the existence of absolute space, which takes place every thing, and I, the one time, which link together all the facts. Denying Coexistence is not less hard to deny the succession (Other Inquisitions).
While compiling the material for this essay I asked Bryce DeWitt, now at the University of Texas at Austin, if he was aware of "The Garden of Forking Paths" to write the article in 1971 where he coined the term "many worlds." I said no.
Excerpted from the conference " Borges and quantum mechanics " Alberto Rojo
the window I saw the familiar roofs
cloudy and the sun six.
It seemed incredible that
that day without premonitions or symbols
out of my inexorable death.
Although my father died,
despite having been a child
in a symmetrical garden of Hai Feng,
I now going to die?
Then I reflected that all things that happen
one
happen precisely, precisely now.
Centuries of centuries and only in this
happen;
countless men in the air,
on land and sea,
and everything is really happening to me happens me.
JL Borges
0 comments:
Post a Comment