MUSE

My favourite band – Muse. It is UK band. It consists of 3 members. My IDOL and the best guitarist in the world (in my opinion) –  Matt  (in the middle ) , drumer and bass guitarist ( who are best in their instruments too)   . It’s obviously an Alternative band.  They sing for problems of our society in a very accessible way, but still have other hidden meanings. Their songs express issues that we should think of : global warming (in their song and particularly in their video “Sing for Absolution” they clearly show what would happen if we continue to harm ozone layer), War , God ( Matt is an atheist).

He is interested in some physics theories and relate them with the real life: such as butterfly effect ( “Butterflies and Hurricanes”) , Parallel Universes (“Shrinking universe”). He show his interest in political and moral issues (“Ruled by Secrecy” and ”Time is running out” show his opinion of who rule the world).

But Muse has songs that show not so popular issues to think of , such as “Stockholme syndrome” , “Bliss” (About someone’s envying of the perfection of other person) , “Plug in Baby” (about the love of imaginary person), “New Born” ( About the effect of new technologies over young people).

As a conclusion this is the best band ever with the best live performances. And I really want to go one such.

boskone_0402.ppt

Schematic illustration of splitting as a result of a repeated measurement.

[edit] Relative state

The goal of the relative-state formalism, as originally proposed by Everett in his 1957 doctoral dissertation, was to interpret the effect of external observation entirely within the mathematical framework developed by Paul Dirac, von Neumann and others, discarding altogether the ad-hoc mechanism of wave function collapse. Since Everett’s original work, there have appeared a number of similar formalisms in the literature. One such idea is discussed in the next section.

The relative-state interpretation makes two assumptions. The first is that the wavefunction is not simply a description of the object’s state, but that it actually is entirely equivalent to the object, a claim it has in common with some other interpretations. The second is that observation or measurement has no special role, unlike in the Copenhagen interpretation which considers the wavefunction collapse as a special kind of event which occurs as a result of observation.

The many-worlds interpretation is DeWitt’s popularisation of Everett’s work, who had referred to the combined observer-object system as being split by an observation, each split corresponding to the different or multiple possible outcomes of an observation. These splits generate a possible tree as shown in the graphic below. Subsequently DeWitt introduced the term “world” to describe a complete measurement history of an observer, which corresponds roughly to a single branch of that tree. Note that “splitting” in this sense, is hardly new or even quantum mechanical. The idea of a space of complete alternative histories had already been used in the theory of probability since the mid 1930s for instance to model Brownian motion.

Partial trace as relative state. Light blue rectangle on upper left denotes system in pure state. Trellis shaded rectangle in upper right denotes a (possibly) mixed state. Mixed state from observation is partial trace of a linear superposition of states as shown in lower left-hand corner.

Under the many-worlds interpretation, the Schrödinger equation, or relativistic analog, holds all the time everywhere. An observation or measurement of an object by an observer is modeled by applying the wave equation to the entire system comprising the observer and the object. One consequence is that every observation can be thought of as causing the combined observer-object’s wavefunction to change into a quantum superposition of two or more non-interacting branches, or split into many “worlds”. Since many observation-like events have happened, and are constantly happening, there are an enormous and growing number of simultaneously existing states.

If a system is composed of two or more subsystems, the system’s state will be a superposition of products of the subsystems’ states. Once the subsystems interact, their states are no longer independent. Each product of subsystem states in the overall superposition evolves over time independently of other products. The subsystems states have become correlated or entangled and it is no longer possible to consider them independent of one another. In Everett’s terminology each subsystem state was now correlated with its relative state, since each subsystem must now be considered relative to the other subsystems with which it has interacted.

Successive measurements with successive splittings

[edit] Comparative properties and experimental support

One of the salient properties of the many-worlds interpretation is that observation does not require an exceptional construct (such as wave function collapse) to explain it. Many physicists, however, dislike the implication that there are infinitely many non-observable alternate universes.

As of 2006, there are no practical experiments that distinguish between Many-Worlds and Copenhagen.

In the Copenhagen interpretation, the mathematics of quantum mechanics allows one to predict probabilities for the occurrence of various events. In the many-worlds interpretation, all these events occur simultaneously. What meaning should be given to these probability calculations? And why do we observe, in our history, that the events with a higher computed probability seem to have occurred more often? One answer to these questions is to say that there is a probability measure on the space of all possible universes, where a possible universe is a complete path in the tree of branching universes. This is indeed what the calculations give. Then we should expect to find ourselves in a universe with a relatively high probability rather than a relatively low probability: even though all outcomes of an experiment occur, they do not occur in an equal way.

As an interpretation which (like other interpretations) is consistent with the equations, it is hard to find testable predictions of MWI. There is a rather more dramatic test than the one outlined above for people prepared to put their lives on the line: use a machine which kills them if a random quantum decay happens. If MWI is true, they will still be alive in the world where the decay didn’t happen and would feel no interruption in their stream of consciousness. By repeating this process a number of times, their continued consciousness would be arbitrarily unlikely unless MWI was true, when they would be alive in all the worlds where the random decay was on their side. From their viewpoint they would be immune to this death process. Clearly, if MWI does not hold, they would be dead in the one world. Other people would generally just see them die and would not be able to benefit from the result of this experiment. See Quantum suicide.

The many-worlds interpretation should not be confused with the many-minds interpretation which postulates that it is only the observers’ minds that split instead of the whole world

The Many-Worlds Interpretation of Quantum Mechanics

- a brief description for the lay reader, some philosophical considerations, and links to more rigorous treatments

 

In 1957, Hugh Everett III proposed a radical new way of dealing with some of the more perplexing aspects of quantum mechanics. It became known as the Many-Worlds Interpretation.

According to this interpretation, whenever numerous viable possibilities exist, the world splits into many worlds, one world for each different possibility (in this context, the term “worlds” refers to what most people call “universes”). In each of these worlds, everything is identical, except for that one different choice; from that point on, they develop independently, and no communication is possible between them, so the people living in those worlds (and splitting along with them) may have no idea that this is going on.

In this way, the world branches endlessly. What is “the present” to us, lies in the pasts of an uncountably huge number of different futures. Everything that can happen, does, somewhere.

Until Many-Worlds appeared, the generally accepted interpretation of quantum mechanics was (and perhaps still is) the Copenhagen Interpretation. The Copenhagen Interpretation makes a distinction between the observer and the observed; when no one is watching, a system evolves deterministically according to a wave equation, but when someone is watching, the wavefunction of the system “collapses” to the observed state, which is why the act of observing changes the system. The Copenhagen Interpretation gives the observer special status, not accorded to any other object in quantum theory, and cannot explain the observer itself, while Many-Worlds models the entire observer-observee system.

The Many-Worlds Interpretation is an interpretation of quantum mechanics, and pertains to quantum events. But it also has implications for macroscopic systems like you and me. Although you may think that there are certain alternatives you would never choose, can you really be sure of that? There are a practically infinite number of versions of you, who have all split off at some time in the past from the path you are now following. There may be versions of you that split off five or ten years ago, or perhaps five minutes after you were born, to whom those choices may not seem unthinkable. But in a very real sense, those people are still “you” (but it can be argued that we should not use the word “are”, or even “were”; we need to invent a new kind of tense…)

Many people find the Many-Worlds Interpretation, and the consequences that flow from it, deeply disturbing. This includes a great many physicists. It is also apparent that many physicists, including many who teach physics, do not have a good understanding of Many-Worlds.

However, polls have been taken among theorists who study such things, and have revealed that most of them believe that the Many-Worlds Interpretation represents, in some sense, an accurate description of the way the world really is. The polls also show that many of them would rather not discuss the subject.

It’s not hard to see why so many people find these ideas disturbing. For if they are correct, they have profound implications for our understanding of the nature of the Soul, because the Soul (if there is such a thing) must branch along with the worlds that contain it. It would appear that the writings on which many contemporary religions are based make no mention of such an idea.

It is commonly thought that Many-Worlds is an unprovable hypothesis, experimentally indistinguishable from the Copenhagen Interpretation, but this may not be the case. It may be possible to observe experimentally one of the predicted effects of Many-Worlds: quantum interference between adjacent worlds. It has even been suggested that the Heisenberg Uncertainty Principle derives from this quantum interference; after you make a measurement (which of course splits the world), you can’t be sure about the subsequent state of the observed system, because you can’t be sure which world you are in.

This brief description is not very rigorous, in a technical sense, and is intended for the lay reader. Others, far more qualified than I, have written much better on the subject; you can find some of their works by following the links below.

Let’s start blogging and see where I can hold out.

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