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6,500 | Yet other operating systems are used almost exclusively in academia, for operating systems education or to do research on operating system concepts. A typical example of a system that fulfills both roles is MINIX, while for example Singularity is used purely for research. Another example is the Oberon System designed a... | https://en.wikipedia.org/wiki?curid=22194 |
6,501 | Other operating systems have failed to win significant market share, but have introduced innovations that have influenced mainstream operating systems, not least Bell Labs' Plan 9. | https://en.wikipedia.org/wiki?curid=22194 |
6,502 | The components of an operating system all exist in order to make the different parts of a computer work together. All user software needs to go through the operating system in order to use any of the hardware, whether it be as simple as a mouse or keyboard or as complex as an Internet component. | https://en.wikipedia.org/wiki?curid=22194 |
6,503 | With the aid of firmware and device drivers, the kernel provides the most basic level of control over all of the computer's hardware devices. It manages memory access for programs in the RAM, it determines which programs get access to which hardware resources, it sets up or resets the CPU's operating states for optimal... | https://en.wikipedia.org/wiki?curid=22194 |
6,504 | The operating system provides an interface between an application program and the computer hardware, so that an application program can interact with the hardware only by obeying rules and procedures programmed into the operating system. The operating system is also a set of services which simplify development and exec... | https://en.wikipedia.org/wiki?curid=22194 |
6,505 | An interrupt (also known as abort, exception, "fault", signal and "trap") provides an efficient way for most operating systems to react to the environment. Interrupts cause the central processing unit (CPU) to have a control flow change away from the currently running program to an interrupt handler, also known as an i... | https://en.wikipedia.org/wiki?curid=22194 |
6,506 | A software interrupt is a message to a process that an event has occurred. This contrasts with a "hardware interrupt" — which is a message to the central processing unit (CPU) that an event has occurred. Software interrupts are similar to hardware interrupts — there is a change away from the currently running process. ... | https://en.wikipedia.org/wiki?curid=22194 |
6,507 | Software interrupts may be normally occurring events. It is expected that a time slice will occur, so the kernel will have to perform a context switch. A computer program may set a timer to go off after a few seconds in case too much data causes an algorithm to take too long. | https://en.wikipedia.org/wiki?curid=22194 |
6,508 | Software interrupts may be error conditions, such as a malformed machine instruction. However, the most common error conditions are division by zero and accessing an invalid memory address. | https://en.wikipedia.org/wiki?curid=22194 |
6,509 | Users can send messages to the kernel to modify the behavior of a currently running process. For example, in the command-line environment, pressing the "interrupt character" (usually Control-C) might terminate the currently running process. | https://en.wikipedia.org/wiki?curid=22194 |
6,510 | To generate "software interrupts" for x86 CPUs, the INT assembly language instruction is available. The syntax is codice_1, where codice_2 is the offset number (in hexadecimal format) to the interrupt vector table. | https://en.wikipedia.org/wiki?curid=22194 |
6,511 | To generate "software interrupts" in Unix-like operating systems, the codice_3 system call will send a signal to another process. codice_4 is the process identifier of the receiving process. codice_5 is the signal number (in mnemonic format) to be sent. (The abrasive name of codice_6 was chosen because early implementa... | https://en.wikipedia.org/wiki?curid=22194 |
6,512 | In Unix-like operating systems, "signals" inform processes of the occurrence of asynchronous events. To communicate asynchronously, interrupts are required. One reason a process needs to asynchronously communicate to another process solves a variation of the classic reader/writer problem. The writer receives a pipe fro... | https://en.wikipedia.org/wiki?curid=22194 |
6,513 | Input/Output (I/O) devices are slower than the CPU. Therefore, it would slow down the computer if the CPU had to wait for each I/O to finish. Instead, a computer may implement interrupts for I/O completion, avoiding the need for polling or busy waiting. | https://en.wikipedia.org/wiki?curid=22194 |
6,514 | Some computers require an interrupt for each character or word, costing a significant amount of CPU time. Direct memory access (DMA) is an architecture feature to allow devices to bypass the CPU and access main memory directly. (Separate from the architecture, a device may perform direct memory access to and from main ... | https://en.wikipedia.org/wiki?curid=22194 |
6,515 | When a computer user types a key on the keyboard, typically the character appears immediately on the screen. Likewise, when a user moves a mouse, the cursor immediately moves across the screen. Each keystroke and mouse movement generates an "interrupt" called "Interrupt-driven I/O". An interrupt-driven I/O occurs when ... | https://en.wikipedia.org/wiki?curid=22194 |
6,516 | Devices such as hard disk drives, solid state drives, and magnetic tape drives can transfer data at a rate high enough that interrupting the CPU for every byte or word transferred, and having the CPU transfer the byte or word between the device and memory, would require too much CPU time. Data is, instead, transferred ... | https://en.wikipedia.org/wiki?curid=22194 |
6,517 | If a computer program executes a system call to perform a block I/O "write" operation, then the system call might execute the following instructions: | https://en.wikipedia.org/wiki?curid=22194 |
6,518 | While the writing takes place, the operating system will context switch to other processes as normal. When the device finishes writing, the device will "interrupt" the currently running process by "asserting" an interrupt request. The device will also place an integer onto the data bus. Upon accepting the interrupt req... | https://en.wikipedia.org/wiki?curid=22194 |
6,519 | Modern computers support multiple modes of operation. CPUs with this capability offer at least two modes: user mode and supervisor mode. In general terms, supervisor mode operation allows unrestricted access to all machine resources, including all MPU instructions. User mode operation sets limits on instruction use and... | https://en.wikipedia.org/wiki?curid=22194 |
6,520 | At power-on or reset, the system begins in supervisor mode. Once an operating system kernel has been loaded and started, the boundary between user mode and supervisor mode (also known as kernel mode) can be established. | https://en.wikipedia.org/wiki?curid=22194 |
6,521 | Supervisor mode is used by the kernel for low level tasks that need unrestricted access to hardware, such as controlling how memory is accessed, and communicating with devices such as disk drives and video display devices. User mode, in contrast, is used for almost everything else. Application programs, such as word pr... | https://en.wikipedia.org/wiki?curid=22194 |
6,522 | In user mode, programs usually have access to a restricted set of processor instructions, and generally cannot execute any instructions that could potentially cause disruption to the system's operation. In supervisor mode, instruction execution restrictions are typically removed, allowing the kernel unrestricted access... | https://en.wikipedia.org/wiki?curid=22194 |
6,523 | The term "user mode resource" generally refers to one or more CPU registers, which contain information that the running program isn't allowed to alter. Attempts to alter these resources generally cause a switch to supervisor mode, where the operating system can deal with the illegal operation the program was attempting... | https://en.wikipedia.org/wiki?curid=22194 |
6,524 | Among other things, a multiprogramming operating system kernel must be responsible for managing all system memory which is currently in use by the programs. This ensures that a program does not interfere with memory already in use by another program. Since programs time share, each program must have independent access ... | https://en.wikipedia.org/wiki?curid=22194 |
6,525 | Cooperative memory management, used by many early operating systems, assumes that all programs make voluntary use of the kernel's memory manager, and do not exceed their allocated memory. This system of memory management is almost never seen any more, since programs often contain bugs which can cause them to exceed the... | https://en.wikipedia.org/wiki?curid=22194 |
6,526 | Memory protection enables the kernel to limit a process' access to the computer's memory. Various methods of memory protection exist, including memory segmentation and paging. All methods require some level of hardware support (such as the 80286 MMU), which doesn't exist in all computers. | https://en.wikipedia.org/wiki?curid=22194 |
6,527 | In both segmentation and paging, certain protected mode registers specify to the CPU what memory address it should allow a running program to access. Attempts to access other addresses trigger an interrupt, which causes the CPU to re-enter supervisor mode, placing the kernel in charge. This is called a segmentation vio... | https://en.wikipedia.org/wiki?curid=22194 |
6,528 | Windows versions 3.1 through ME had some level of memory protection, but programs could easily circumvent the need to use it. A general protection fault would be produced, indicating a segmentation violation had occurred; however, the system would often crash anyway. | https://en.wikipedia.org/wiki?curid=22194 |
6,529 | The use of virtual memory addressing (such as paging or segmentation) means that the kernel can choose what memory each program may use at any given time, allowing the operating system to use the same memory locations for multiple tasks. | https://en.wikipedia.org/wiki?curid=22194 |
6,530 | If a program tries to access memory that isn't in its current range of accessible memory, but nonetheless has been allocated to it, the kernel is interrupted in the same way as it would if the program were to exceed its allocated memory. (See section on memory management.) Under UNIX this kind of interrupt is referred ... | https://en.wikipedia.org/wiki?curid=22194 |
6,531 | When the kernel detects a page fault it generally adjusts the virtual memory range of the program which triggered it, granting it access to the memory requested. This gives the kernel discretionary power over where a particular application's memory is stored, or even whether or not it has actually been allocated yet. | https://en.wikipedia.org/wiki?curid=22194 |
6,532 | In modern operating systems, memory which is accessed less frequently can be temporarily stored on a disk or other media to make that space available for use by other programs. This is called swapping, as an area of memory can be used by multiple programs, and what that memory area contains can be swapped or exchanged ... | https://en.wikipedia.org/wiki?curid=22194 |
6,533 | "Virtual memory" provides the programmer or the user with the perception that there is a much larger amount of RAM in the computer than is really there. | https://en.wikipedia.org/wiki?curid=22194 |
6,534 | Multitasking refers to the running of multiple independent computer programs on the same computer, giving the appearance that it is performing the tasks at the same time. Since most computers can do at most one or two things at one time, this is generally done via time-sharing, which means that each program uses a shar... | https://en.wikipedia.org/wiki?curid=22194 |
6,535 | An operating system kernel contains a scheduling program which determines how much time each process spends executing, and in which order execution control should be passed to programs. Control is passed to a process by the kernel, which allows the program access to the CPU and memory. Later, control is returned to the... | https://en.wikipedia.org/wiki?curid=22194 |
6,536 | An early model which governed the allocation of time to programs was called cooperative multitasking. In this model, when control is passed to a program by the kernel, it may execute for as long as it wants before explicitly returning control to the kernel. This means that a malicious or malfunctioning program may not ... | https://en.wikipedia.org/wiki?curid=22194 |
6,537 | Modern operating systems extend the concepts of application preemption to device drivers and kernel code, so that the operating system has preemptive control over internal run-times as well. | https://en.wikipedia.org/wiki?curid=22194 |
6,538 | The philosophy governing preemptive multitasking is that of ensuring that all programs are given regular time on the CPU. This implies that all programs must be limited in how much time they are allowed to spend on the CPU without being interrupted. To accomplish this, modern operating system kernels make use of a time... | https://en.wikipedia.org/wiki?curid=22194 |
6,539 | On many single user operating systems cooperative multitasking is perfectly adequate, as home computers generally run a small number of well tested programs. AmigaOS is an exception, having preemptive multitasking from its first version. Windows NT was the first version of Microsoft Windows which enforced preemptive mu... | https://en.wikipedia.org/wiki?curid=22194 |
6,540 | Access to data stored on disks is a central feature of all operating systems. Computers store data on disks using files, which are structured in specific ways in order to allow for faster access, higher reliability, and to make better use of the drive's available space. The specific way in which files are stored on a d... | https://en.wikipedia.org/wiki?curid=22194 |
6,541 | Early operating systems generally supported a single type of disk drive and only one kind of file system. Early file systems were limited in their capacity, speed, and in the kinds of file names and directory structures they could use. These limitations often reflected limitations in the operating systems they were des... | https://en.wikipedia.org/wiki?curid=22194 |
6,542 | While many simpler operating systems support a limited range of options for accessing storage systems, operating systems like UNIX and Linux support a technology known as a virtual file system or VFS. An operating system such as UNIX supports a wide array of storage devices, regardless of their design or file systems, ... | https://en.wikipedia.org/wiki?curid=22194 |
6,543 | A connected storage device, such as a hard drive, is accessed through a device driver. The device driver understands the specific language of the drive and is able to translate that language into a standard language used by the operating system to access all disk drives. On UNIX, this is the language of block devices. | https://en.wikipedia.org/wiki?curid=22194 |
6,544 | When the kernel has an appropriate device driver in place, it can then access the contents of the disk drive in raw format, which may contain one or more file systems. A file system driver is used to translate the commands used to access each specific file system into a standard set of commands that the operating syste... | https://en.wikipedia.org/wiki?curid=22194 |
6,545 | Various differences between file systems make supporting all file systems difficult. Allowed characters in file names, case sensitivity, and the presence of various kinds of file attributes makes the implementation of a single interface for every file system a daunting task. Operating systems tend to recommend using (a... | https://en.wikipedia.org/wiki?curid=22194 |
6,546 | Support for file systems is highly varied among modern operating systems, although there are several common file systems which almost all operating systems include support and drivers for. Operating systems vary on file system support and on the disk formats they may be installed on. Under Windows, each file system is ... | https://en.wikipedia.org/wiki?curid=22194 |
6,547 | A device driver is a specific type of computer software developed to allow interaction with hardware devices. Typically this constitutes an interface for communicating with the device, through the specific computer bus or communications subsystem that the hardware is connected to, providing commands to and/or receiving... | https://en.wikipedia.org/wiki?curid=22194 |
6,548 | The key design goal of device drivers is abstraction. Every model of hardware (even within the same class of device) is different. Newer models also are released by manufacturers that provide more reliable or better performance and these newer models are often controlled differently. Computers and their operating syste... | https://en.wikipedia.org/wiki?curid=22194 |
6,549 | Under versions of Windows before Vista and versions of Linux before 2.6, all driver execution was co-operative, meaning that if a driver entered an infinite loop it would freeze the system. More recent revisions of these operating systems incorporate kernel preemption, where the kernel interrupts the driver to give it ... | https://en.wikipedia.org/wiki?curid=22194 |
6,550 | Currently most operating systems support a variety of networking protocols, hardware, and applications for using them. This means that computers running dissimilar operating systems can participate in a common network for sharing resources such as computing, files, printers, and scanners using either wired or wireless ... | https://en.wikipedia.org/wiki?curid=22194 |
6,551 | Client/server networking allows a program on a computer, called a client, to connect via a network to another computer, called a server. Servers offer (or host) various services to other network computers and users. These services are usually provided through ports or numbered access points beyond the server's IP addre... | https://en.wikipedia.org/wiki?curid=22194 |
6,552 | Many operating systems support one or more vendor-specific or open networking protocols as well, for example, SNA on IBM systems, DECnet on systems from Digital Equipment Corporation, and Microsoft-specific protocols (SMB) on Windows. Specific protocols for specific tasks may also be supported such as NFS for file acce... | https://en.wikipedia.org/wiki?curid=22194 |
6,553 | A computer being secure depends on a number of technologies working properly. A modern operating system provides access to a number of resources, which are available to software running on the system, and to external devices like networks via the kernel. | https://en.wikipedia.org/wiki?curid=22194 |
6,554 | The operating system must be capable of distinguishing between requests which should be allowed to be processed, and others which should not be processed. While some systems may simply distinguish between "privileged" and "non-privileged", systems commonly have a form of requester "identity", such as a user name. To es... | https://en.wikipedia.org/wiki?curid=22194 |
6,555 | In addition to the allow or disallow model of security, a system with a high level of security also offers auditing options. These would allow tracking of requests for access to resources (such as, "who has been reading this file?"). Internal security, or security from an already running program is only possible if all... | https://en.wikipedia.org/wiki?curid=22194 |
6,556 | External security involves a request from outside the computer, such as a login at a connected console or some kind of network connection. External requests are often passed through device drivers to the operating system's kernel, where they can be passed onto applications, or carried out directly. Security of operatin... | https://en.wikipedia.org/wiki?curid=22194 |
6,557 | Network services include offerings such as file sharing, print services, email, web sites, and file transfer protocols (FTP), most of which can have compromised security. At the front line of security are hardware devices known as firewalls or intrusion detection/prevention systems. At the operating system level, there... | https://en.wikipedia.org/wiki?curid=22194 |
6,558 | An alternative strategy, and the only sandbox strategy available in systems that do not meet the Popek and Goldberg virtualization requirements, is where the operating system is not running user programs as native code, but instead either emulates a processor or provides a host for a p-code based system such as Java. | https://en.wikipedia.org/wiki?curid=22194 |
6,559 | Internal security is especially relevant for multi-user systems; it allows each user of the system to have private files that the other users cannot tamper with or read. Internal security is also vital if auditing is to be of any use, since a program can potentially bypass the operating system, inclusive of bypassing a... | https://en.wikipedia.org/wiki?curid=22194 |
6,560 | Every computer that is to be operated by an individual requires a user interface. The user interface is usually referred to as a shell and is essential if human interaction is to be supported. The user interface views the directory structure and requests services from the operating system that will acquire data from in... | https://en.wikipedia.org/wiki?curid=22194 |
6,561 | Most of the modern computer systems support graphical user interfaces (GUI), and often include them. In some computer systems, such as the original implementation of the classic Mac OS, the GUI is integrated into the kernel. | https://en.wikipedia.org/wiki?curid=22194 |
6,562 | While technically a graphical user interface is not an operating system service, incorporating support for one into the operating system kernel can allow the GUI to be more responsive by reducing the number of context switches required for the GUI to perform its output functions. Other operating systems are modular, se... | https://en.wikipedia.org/wiki?curid=22194 |
6,563 | Many computer operating systems allow the user to install or create any user interface they desire. The X Window System in conjunction with GNOME or KDE Plasma 5 is a commonly found setup on most Unix and Unix-like (BSD, Linux, Solaris) systems. A number of Windows shell replacements have been released for Microsoft Wi... | https://en.wikipedia.org/wiki?curid=22194 |
6,564 | Numerous Unix-based GUIs have existed over time, most derived from X11. Competition among the various vendors of Unix (HP, IBM, Sun) led to much fragmentation, though an effort to standardize in the 1990s to COSE and CDE failed for various reasons, and were eventually eclipsed by the widespread adoption of GNOME and K ... | https://en.wikipedia.org/wiki?curid=22194 |
6,565 | Graphical user interfaces evolve over time. For example, Windows has modified its user interface almost every time a new major version of Windows is released, and the Mac OS GUI changed dramatically with the introduction of Mac OS X in 1999. | https://en.wikipedia.org/wiki?curid=22194 |
6,566 | A real-time operating system (RTOS) is an operating system intended for applications with fixed deadlines (real-time computing). Such applications include some small embedded systems, automobile engine controllers, industrial robots, spacecraft, industrial control, and some large-scale computing systems. | https://en.wikipedia.org/wiki?curid=22194 |
6,567 | An early example of a large-scale real-time operating system was Transaction Processing Facility developed by American Airlines and IBM for the Sabre Airline Reservations System. | https://en.wikipedia.org/wiki?curid=22194 |
6,568 | Embedded systems that have fixed deadlines use a real-time operating system such as VxWorks, PikeOS, eCos, QNX, MontaVista Linux and RTLinux. Windows CE is a real-time operating system that shares similar APIs to desktop Windows but shares none of desktop Windows' codebase. Symbian OS also has an RTOS kernel (EKA2) sta... | https://en.wikipedia.org/wiki?curid=22194 |
6,569 | Some embedded systems use operating systems such as Palm OS, BSD, and Linux, although such operating systems do not support real-time computing. | https://en.wikipedia.org/wiki?curid=22194 |
6,570 | A hobby operating system may be classified as one whose code has not been directly derived from an existing operating system, and has few users and active developers. | https://en.wikipedia.org/wiki?curid=22194 |
6,571 | In some cases, hobby development is in support of a "homebrew" computing device, for example, a simple single-board computer powered by a 6502 microprocessor. Or, development may be for an architecture already in widespread use. Operating system development may come from entirely new concepts, or may commence by modeli... | https://en.wikipedia.org/wiki?curid=22194 |
6,572 | Application software is generally written for use on a specific operating system, and sometimes even for specific hardware. When porting the application to run on another OS, the functionality required by that application may be implemented differently by that OS (the names of functions, meaning of arguments, etc.) req... | https://en.wikipedia.org/wiki?curid=22194 |
6,573 | Unix was the first operating system not written in assembly language, making it very portable to systems different from its native PDP-11. | https://en.wikipedia.org/wiki?curid=22194 |
6,574 | This cost in supporting operating systems diversity can be avoided by instead writing applications against software platforms such as Java or Qt. These abstractions have already borne the cost of adaptation to specific operating systems and their system libraries. | https://en.wikipedia.org/wiki?curid=22194 |
6,575 | Another approach is for operating system vendors to adopt standards. For example, POSIX and OS abstraction layers provide commonalities that reduce porting costs. | https://en.wikipedia.org/wiki?curid=22194 |
6,576 | In quantum mechanics, Schrödinger's cat is a thought experiment that illustrates a paradox of quantum superposition. In the thought experiment, a hypothetical cat may be considered simultaneously both alive and dead, while it is unobserved in a closed box, as a result of its fate being linked to a random subatomic even... | https://en.wikipedia.org/wiki?curid=27856 |
6,577 | This thought experiment was devised by physicist Erwin Schrödinger in 1935, in a discussion with Albert Einstein, to illustrate what Schrödinger saw as the problems of the Copenhagen interpretation of quantum mechanics. The scenario is often featured in theoretical discussions of the interpretations of quantum mechanic... | https://en.wikipedia.org/wiki?curid=27856 |
6,578 | Schrödinger intended his thought experiment as a discussion of the EPR article—named after its authors Einstein, Podolsky, and Rosen—in 1935. The EPR article highlighted the counterintuitive nature of quantum superpositions, in which a quantum system such as an atom or photon can exist as a combination of multiple stat... | https://en.wikipedia.org/wiki?curid=27856 |
6,579 | The prevailing theory, called the Copenhagen interpretation, says that a quantum system remains in superposition until it interacts with, or is observed by the external world. When this happens, the superposition collapses into one or another of the possible definite states. The EPR experiment shows that a system with ... | https://en.wikipedia.org/wiki?curid=27856 |
6,580 | To further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a locked steel chamber, wherein the cat's life or death depended on the state of a radio... | https://en.wikipedia.org/wiki?curid=27856 |
6,581 | The idea that quantum superpositions of macroscopic states could be possible led to the Many-worlds interpretation of quantum theory. | https://en.wikipedia.org/wiki?curid=27856 |
6,582 | Since Schrödinger's time, various interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real, others do not. Intended as a critique of the Copenhagen interpretation (the prevailing orthodoxy in 1935), the Schrödinge... | https://en.wikipedia.org/wiki?curid=27856 |
6,583 | Schrödinger's famous thought experiment poses the question, ""when" does a quantum system stop existing as a superposition of states and become one or the other?" (More technically, when does the actual quantum state stop being a non-trivial linear combination of states, each of which resembles different classical stat... | https://en.wikipedia.org/wiki?curid=27856 |
6,584 | Note that the charge of gunpowder is not mentioned in Schrödinger's setup, which uses a Geiger counter as an amplifier and hydrocyanic poison instead of gunpowder. The gunpowder had been mentioned in Einstein's original suggestion to Schrödinger 15 years before, and Einstein carried it forward to the present discussion... | https://en.wikipedia.org/wiki?curid=27856 |
6,585 | Since Schrödinger's time, other interpretations of quantum mechanics have been proposed that give different answers to the questions posed by Schrödinger's cat of how long superpositions last and when (or "whether") they collapse. | https://en.wikipedia.org/wiki?curid=27856 |
6,586 | A commonly held interpretation of quantum mechanics is the Copenhagen interpretation. In the Copenhagen interpretation, a system stops being a superposition of states and becomes either one or the other when an observation takes place. This thought experiment makes apparent the fact that the nature of measurement, or o... | https://en.wikipedia.org/wiki?curid=27856 |
6,587 | In 1932 John von Neumann described in his book "Mathematical Foundations" a pattern where the radioactive source is observed by a device, which itself is observed by another device, and so on. It makes no difference in the predictions of quantum theory where along this chain of causal effects the superposition collapse... | https://en.wikipedia.org/wiki?curid=27856 |
6,588 | Wigner supposed that a friend opened the box and observed the cat without telling anyone. From Wigner's conscious perspective, the friend is now part of the wave function and has seen a live cat and seen a dead cat. To a third person's conscious perspective, Wigner himself becomes part of the wave function once Wigner ... | https://en.wikipedia.org/wiki?curid=27856 |
6,589 | One of the main scientists associated with the Copenhagen interpretation, Niels Bohr, offered an interpretation that is independent of a subjective observer-induced collapse of the wave function, or of measurement; instead, an "irreversible" or effectively irreversible process causes the decay of quantum coherence whic... | https://en.wikipedia.org/wiki?curid=27856 |
6,590 | A resolution of the paradox is that the triggering of the Geiger counter counts as a measurement of the state of the radioactive substance. Because a measurement has already occurred deciding the state of the cat, the subsequent observation by a human records only what has already occurred. Analysis of an actual experi... | https://en.wikipedia.org/wiki?curid=27856 |
6,591 | In 1957, Hugh Everett formulated the many-worlds interpretation of quantum mechanics, which does not single out observation as a special process. In the many-worlds interpretation, both alive and dead states of the cat persist after the box is opened, but are decoherent from each other. In other words, when the box is ... | https://en.wikipedia.org/wiki?curid=27856 |
6,592 | When opening the box, the observer becomes entangled with the cat, so "observer states" corresponding to the cat's being alive and dead are formed; each observer state is entangled or linked with the cat so that the "observation of the cat's state" and the "cat's state" correspond with each other. Quantum decoherence e... | https://en.wikipedia.org/wiki?curid=27856 |
6,593 | A variant of the Schrödinger's cat experiment, known as the quantum suicide machine, has been proposed by cosmologist Max Tegmark. It examines the Schrödinger's cat experiment from the point of view of the cat, and argues that by using this approach, one may be able to distinguish between the Copenhagen interpretation ... | https://en.wikipedia.org/wiki?curid=27856 |
6,594 | The ensemble interpretation states that superpositions are nothing but subensembles of a larger statistical ensemble. The state vector would not apply to individual cat experiments, but only to the statistics of many similarly prepared cat experiments. Proponents of this interpretation state that this makes the Schrödi... | https://en.wikipedia.org/wiki?curid=27856 |
6,595 | This interpretation serves to "discard" the idea that a single physical system in quantum mechanics has a mathematical description that corresponds to it in any way. | https://en.wikipedia.org/wiki?curid=27856 |
6,596 | The relational interpretation makes no fundamental distinction between the human experimenter, the cat, or the apparatus, or between animate and inanimate systems; all are quantum systems governed by the same rules of wavefunction evolution, and all may be considered "observers". But the relational interpretation allow... | https://en.wikipedia.org/wiki?curid=27856 |
6,597 | In the transactional interpretation the apparatus emits an advanced wave backward in time, which combined with the wave that the source emits forward in time, forms a standing wave. The waves are seen as physically real, and the apparatus is considered an "observer". In the transactional interpretation, the collapse of... | https://en.wikipedia.org/wiki?curid=27856 |
6,598 | On the other hand, the anti-Zeno effect accelerates the changes. For example, if you peek a look into the cat box frequently you may either cause delays to the fateful choice or, conversely, accelerate it. Both the Zeno effect and the anti-Zeno effect are real and known to happen to real atoms. The quantum system being... | https://en.wikipedia.org/wiki?curid=27856 |
6,599 | According to objective collapse theories, superpositions are destroyed spontaneously (irrespective of external observation), when some objective physical threshold (of time, mass, temperature, irreversibility, etc.) is reached. Thus, the cat would be expected to have settled into a definite state long before the box is... | https://en.wikipedia.org/wiki?curid=27856 |
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