- 3183 - QUANTUM - from atoms to a universe? The infant universe was smaller than an atom and was dominated by quantum fluctuations. Inflation caused the universe to grow rapidly before these fluctuations had a chance to fade away. This concentrated energy into some areas rather than others acted as seeds around which material could gather to form the clusters of galaxies we observe today.
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------------------------ 3183 - QUANTUM - from atoms to a universe?
- Albert Einstein won a Nobel Prize for proving that energy is quantized. It comes in lumps and is not continuous. Energy only comes in multiples of the same "quanta", hence “quantum physics“.
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- The quanta or the smallest size are called the “Planck constants” The name comes from Max Planck, the godfather of quantum physics. He was trying to solve a problem with our understanding of hot objects like the sun. Our best theories couldn’t match the observations of the energy they kick out. By proposing that energy is quantized, he was able to bring theory neatly into line with experiments.
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- Something can be both wave and particle J. J. Thomson won the Nobel Prize in 1906 for his discovery that electrons are particles. His son George won the Nobel Prize in 1937 for showing that electrons are waves. Who was right?
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- The answer is both of them. This “wave-particle duality” is a cornerstone of quantum physics. It applies to light as well as electrons. Sometimes we think about light as an electromagnetic wave, but at other times it’s more useful to picture it in the form of particles called “photons“.
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- A telescope can focus light waves from distant stars, and also acts as a giant light bucket for collecting photons. Charge-coupled-diodes, CCD’s , can collect individual photons over a period of time. Unlike our eyes.
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- It also means that light can exert pressure as photons slam into an object. This is something we already use to propel spacecraft with solar sails, and it may be possible to exploit it in order to maneuver a dangerous asteroid off a collision course with Earth.
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- “Wave-particle duality” is an example of superposition. A quantum object can be existing in multiple states at once. An electron is both ‘here’ and ‘there’ simultaneously. It’s only once we do an experiment to find out where it is that it settles down into one or the other.
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- This makes quantum physics all about “probabilities“. We can only say which state an object is most likely to be in once we look. These odds are encapsulated into a mathematical entity called the “wave function“.
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- Making an observation is said to ‘collapse’ the wave function, destroying the superposition and forcing the object into just one of its many possible states.
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- The idea that observation, which is photons reflecting off an object collapses, the wave function and forces a quantum ‘choice’ is known as the Copenhagen interpretation of quantum physics.
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- As far as a quantum particle is concerned, there is just one very reality consisting of many tangled-up layers. As we zoom out towards the larger scales that we experience day to day is a process called “de-coherence“.
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- Using a prism we can spread the spectrum of a light beam. The spectra of light from stars can tell us what elements they contain, giving clues to their age and other characteristic.
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- Danish physicist Niels Bohr showed us that the orbits of electrons inside atoms are also quantized. They come in predetermined sizes called energy levels.
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- When an electron drops from a higher energy level to a lower energy level, it spits out a photon with an energy equal to the size of the gap. Equally, an electron can absorb a particle of light and use its energy to leap up to a higher energy level.
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- Astronomers use this effect to determine what stars are made of. When we break up their light into a rainbow-like spectrum, we see colors that are missing. Different chemical elements have different energy level spacing’s, so we can work out the constituents of the sun and other stars from the precise colors that are absent.
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- Quantum tunneling is the finite possibility that a particle can break through an energy barrier. The sun makes its energy through a process called nuclear fusion. It involves two protons, the positively charged particles in an atom, sticking together.
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- However, their identical charges make them repel each other, just like two north poles of a magnet. Physicists call this the “Coulomb barrier“, and it’s like a wall between the two protons.
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- Think of protons as particles and they just collide with the wall and move apart: No fusion, no sunlight. Yet think of them as waves, and it’s a different story. When the wave’s crest reaches the wall, the leading edge has already made it through.
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- The wave’s height represents where the proton is most likely to be. So although it is unlikely to be where the leading edge is, it is there sometimes. It’s as if the proton has burrowed through the barrier, and fusion occurs, called "quantum tunneling".
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- Eventually fusion in the sun will stop and our star will die. Gravity will win and the sun will collapse, but not indefinitely. The smaller it gets, the more material is crammed together.
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- Eventually a rule of quantum physics called the “Pauli exclusion principle” comes into play. This says that it is forbidden for certain kinds of particles, electrons, to exist in the same quantum state. As gravity tries to do just that, it encounters a resistance that astronomers call “degeneracy pressure“. The collapse stops, and a new Earth-sized object called a white dwarf forms.
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- Degeneracy pressure can only put up so much resistance. If a white dwarf grows and approaches a mass equal to 1.4 suns, it triggers a wave of fusion that blasts it to bits, an explosionType Ia supernova, and it’s bright enough to outshine an entire galaxy.
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- A quantum rule called the “Heisenberg uncertainty principle” says that it’s impossible to perfectly know two properties of a system simultaneously. The more accurately you know one, the less precisely you know the other. This applies to momentum and position, and separately to energy and time.
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- Stephen Hawking imagined this process occurring at the boundary of a blackhole, where one particle escapes (as Hawking radiation), but the other is swallowed. Over time the blackhole slowly evaporates.
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- Our best theory of the universe’s origin is the “Big Bang“. It was modified in the 1980s to include another theory called “inflation“. In the first trillionth of a trillionth of a trillionth of a second, the cosmos ballooned from smaller than an atom to about the size of a grapefruit. That’s a whopping 10^78 times bigger. Inflating a red blood cell by the same amount would make it larger than the entire observable universe today.
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- As it was initially smaller than an atom, the infant universe would have been dominated by quantum fluctuations linked to the Heisenberg uncertainty principle. Inflation caused the universe to grow rapidly before these fluctuations had a chance to fade away. This concentrated energy into some areas rather than others acting as seeds around which material could gather to form the clusters of galaxies we observe now.
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- As well as helping to prove that light is quantum, Einstein argued in favor of another effect that he dubbed ‘spooky action at distance’. Today we know that this ‘quantum entanglement’ is real, but we still don’t fully understand what’s going on.
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- If we bring two particles together in such a way that their quantum states are inexorably bound, or entangled. One is in state A, and the other in state B. The “Pauli exclusion principle” says that they can’t both be in the same state.
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- If we change one, the other instantly changes to compensate. This happens even if we separate the two particles from each other on opposite sides of the universe. It’s as if information about the change we’ve made has traveled between them faster than the speed of light, something Einstein said was impossible
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- 2580 - QUANTUM RANDOMNESS - Photons and Quasars? The nature of free will has long inspired philosophical debates, but it also raises a central question about the fundamental nature of the universe. Is the cosmos governed by strict physical laws that determine its fate from the big bang until the end of time? Or do the laws of nature sometimes allow for things to happen at random?
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- 2566 - QUANTUM ENTANGLEMENT - Is it for real? - The nature of free will has long inspired philosophical debates, but it also raises a central question about the fundamental nature of the universe. Is the cosmos governed by strict physical laws that determine its fate from the big bang until the end of time? Or do the laws of nature sometimes allow for things to happen at “random“?
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- Of course, randomness isn’t the only thing necessary for free will. But it does mean that your fate is not necessarily sealed. Maybe, just maybe, the choice was yours after all.
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- 2503 - To learn more of the math that is used in this experiment see Review 2503.
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- 2502 - how the universe entangled in property pairs defies all reason?
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- 2501 - how quantum entanglement is faster than the speed of light? This Review gives the history of these discoveries.
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- 2500 - we can not explain the quantum world?
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- 2211 - macro - micro extremes.
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- 2208 - quantum entanglement.
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- 1957 - weird science.
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- 1950 - new mysteries in science.
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- 1838 - where is the missing link between quantum mechanics and general relativity?
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- 1828 - is the entire universe a space-time interconnected fabric?
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- 1801 - what are wormholes?
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- 1949 - how quantum computers will change cryptography?
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- 1818 - how quantum computing will change your life?
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- 1733 - quantum dots and valleytronics?
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- 1457 - quantum dots are a 10 nanometer window.
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- June 6, 2021 QUANTUM - from atoms to a universe? 3183
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