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Megalithic tomb building continued into the Bronze Age when metal began to be worked for tools alongside the stone tools. The Bronze Age lasted approximately from 4,500 years ago to 2,500 years ago (2,500 BC to 500 BC). Archaeological remains from this period include stone alignments, stone circles and fulachta fiadh (early cooking sites). They continued to bury their chieftains in megalithic tombs which changed design during this period, more being of the wedge tomb type and cist burials.

9% of the population of County Mayo live in the Gaeltacht. The Gaeltacht Irish-speaking region in County Mayo is the third largest in Ireland with 10,886 inhabitants. Tourmakeady is the largest village in this area. All schools in the area use Irish as the language of instruction. Mayo has four gaelscoileanna in its four major towns, providing primary education to students through Irish.

The Colombian armed forces consist of: Military Forces: Colombian Army (Spanish: Ejrcito Nacional de Colombia) Colombian Navy (Spanish: Armada Nacional de Colombia) - and attached services Marines and Coast Guard Colombian Air Force (Spanish: Fuerza Area Colombiana) And, National Police of Colombia (Spanish: Polica Nacional de Colombia) Public Force strength as of April 2014. Military strength

According to the Copenhagen interpretation, physical systems generally do not have definite properties prior to being measured, and quantum mechanics can only predict the probabilities that measurements will produce certain results. The act of measurement affects the system, causing the set of probabilities to reduce to only one of the possible values immediately after the measurement. This feature is known as wave function collapse. There have been many objections to the Copenhagen interpretation over the years. These include: discontinuous jumps when there is an observation, the probabilistic element introduced upon observation, the subjectiveness of requiring an observer, the difficulty of defining a measuring device, and to the necessity of invoking classical physics to describe the "laboratory" in which the results are measured. Alternatives to the Copenhagen interpretation include the many-worlds interpretation, the De Broglie-Bohm (pilot-wave) interpretation, and quantum decoherence theories.

The nature of the Copenhagen Interpretation is exposed by considering a number of experiments and paradoxes. 1. Schrdinger's cat This thought experiment highlights the implications that accepting uncertainty at the microscopic level has on macroscopic objects. A cat is put in a sealed box, with its life or death made dependent on the state of a subatomic particle. Thus a description of the cat during the course of the experimenthaving been entangled with the state of a subatomic particlebecomes a "blur" of "living and dead cat." But this can't be accurate because it implies the cat is actually both dead and alive until the box is opened to check on it. But the cat, if it survives, will only remember being alive. Schrdinger resists "so naively accepting as valid a 'blurred model' for representing reality." How can the cat be both alive and dead? The Copenhagen Interpretation: The wave function reflects our knowledge of the system. The wave function ( | dead + | alive ) / 2 {\displaystyle (|{\text{dead}}\rangle +|{\text{alive}}\rangle )/{\sqrt {2}}} means that, once the cat is observed, there is a 50% chance it will be dead, and 50% chance it will be alive. 2. Wigner's Friend Wigner puts his friend in with the cat. The external observer believes the system is in the state ( | dead + | alive ) / 2 {\displaystyle (|{\text{dead}}\rangle +|{\text{alive}}\rangle )/{\sqrt {2}}} . His friend, however, is convinced that the cat is alive, i.e. for him, the cat is in the state | alive {\displaystyle |{\text{alive}}\rangle } . How can Wigner and his friend see different wave functions? The Copenhagen Interpretation: The answer depends on the positioning of Heisenberg cut, which can be placed arbitrarily. If Wigner's friend is positioned on the same side of the cut as the external observer, his measurements collapse the wave function for both observers. If he is positioned on the cat's side, his interaction with the cat is not considered a measurement. 3. Double-slit diffraction Light passes through double slits and onto a screen resulting in a diffraction pattern. Is light a particle or a wave? The Copenhagen Interpretation: Light is neither. A particular experiment can demonstrate particle (photon) or wave properties, but not both at the same time (Bohr's Complementarity Principle). The same experiment can in theory be performed with any physical system: electrons, protons, atoms, molecules, viruses, bacteria, cats, humans, elephants, planets, etc. In practice it has been performed for light, electrons, buckminsterfullerene, and some atoms. Due to the smallness of Planck's constant it is practically impossible to realize experiments that directly reveal the wave nature of any system bigger than a few atoms but, in general, quantum mechanics considers all matter as possessing both particle and wave behaviors. The greater systems (like viruses, bacteria, cats, etc.) are considered as "classical" ones but only as an approximation, not exact. 4. EPR (EinsteinPodolskyRosen) paradox Entangled "particles" are emitted in a single event. Conservation laws ensure that the measured spin of one particle must be the opposite of the measured spin of the other, so that if the spin of one particle is measured, the spin of the other particle is now instantaneously known. The most discomforting aspect of this paradox is that the effect is instantaneous so that something that happens in one galaxy could cause an instantaneous change in another galaxy. But, according to Einstein's theory of special relativity, no information-bearing signal or entity can travel at or faster than the speed of light, which is finite. Thus, it seems as if the Copenhagen interpretation is inconsistent with special relativity. The Copenhagen Interpretation: Assuming wave functions are not real, wave-function collapse is interpreted subjectively. The moment one observer measures the spin of one particle, he knows the spin of the other. However, another observer cannot benefit until the results of that measurement have been relayed to him, at less than or equal to the speed of light. Copenhagenists claim that interpretations of quantum mechanics where the wave function is regarded as real have problems with EPR-type effects, since they imply that the laws of physics allow for influences to propagate at speeds greater than the speed of light. However, proponents of many worlds and the transactional interpretation (TI) maintain that Copenhagen interpretation is fatally non-local. The claim that EPR effects violate the principle that information cannot travel faster than the speed of light have been countered by noting that they cannot be used for signaling because neither observer can control, or predetermine, what he observes, and therefore cannot manipulate what the other observer measures.

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