- 3053 - ATOMS - spooky action for clocks? Physicists imagine a day when they will be able to design a clock that's so precise, it will be used to detect subtle disturbances in space-time or to find the elusive dark matter that tugs on everything yet emits no light. The ticking of this clock will be almost perfect.
- Physicists imagine a day when they will be able to design a clock that's so precise, it can detect dark matter.
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- The clock will be used to detect subtle disturbances in space-time or to find the elusive dark matter that tugs on everything yet emits no light.
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- Researchers has created a clock that, with some tweaks, could be four to five times more precise than the world's best clocks. To put that into perspective, if today's most precise clocks started ticking at the birth of the universe, they would be off by only half a second today; with more improvements, this new clock has the potential to be off by only 0.1 second.
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- Atomic clocks tick according to the movement of atoms. Since the 1960s, the atomic clocks that are responsible for keeping global time and defining "a second" are based on cesium atoms; these clocks bombard cesium atoms with microwaves and measure time as electrons oscillate from a lower energy level (called a ground state) to a higher one (an excited state).
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- Researchers have developed "optical clocks" that are 100 times more precise than cesium atomic clocks. These clocks use lasers to excite atoms of elements such as aluminum or ytterbium; visible light has a higher frequency than microwaves and thus can excite atoms to oscillate 100,000 times faster than microwaves can excite cesium atoms.
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- This faster oscillation adds more data points to the measurement of a second, making it more precise. Soon, there will be an official "redefinition of the second" using these much more precise optical clocks.
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- But even these nearly faultless optical atomic clocks cannot measure time perfectly, because they fall victim to the rules of quantum mechanics, the strange rules that govern the zoo of subatomic particles.
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- The atoms that run the clock are so small that their states can't be pinned down precisely, so they are defined by probabilities. Therefore, an electron isn't in an excited state or a ground state, but it has some probability of being in multiple energy levels at once.
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- Trying to measure the state of a single atom is like flipping a coin, as the actual measurement "forces" the atom to choose either the ground state or the excited state, but "you never find something in between“. This uncertainty in measurement makes it impossible to tell perfect time.
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- When you increase the number of atoms in the clock (which can be thought of as the number of coin tosses) and start taking the average of how many are excited and how many are not, measurements start to become more precise.
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- The more atoms you add, the smaller your error in measurement or uncertainty what the "standard quantum limit" will be. Because the precision of the measurement scales as the square root of the number of coin tosses, throwing 10,000 coins is 10 times more precise than throwing 100.
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- That's why today's optical clocks measure time by averaging the oscillations of thousands of atoms. But even that method can't get rid of the standard quantum limit.
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- Quantum entanglement, or "spooky action at a distance," as Albert Einstein famously called it, is the idea that the fates of tiny particles are linked to each other even if they're separated by long distances.
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- So, by entangling the atoms that keep time, the scientists might be able to keep each pair or group of entangled atoms in the same state and thus oscillating at similar frequencies, thereby allowing the clock to overcome the standard quantum limit and measure time more precisely.
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- Entangling the atoms makes the tosses less random, so to speak. The toss of each atom individually is still random, but all the tosses together have less randomness than those of independent atoms.
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- It is similar to placing 100 coins on a table, 50 heads up and 50 tails up. If you pick up any coin without looking, it will be randomly heads or tails. But once you pick up all the coins, there will be exactly equal numbers of heads and tails.
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- The research team placed 350 atoms of ytterbium between two mirrors. Then, they fired a laser beam that bounced back and forth between the mirrors. As the light hit the first atom, the atom altered the light. That light then altered the second atom, and then the third and then the rest, until they all became entangled and started oscillating with similar phases. Then, the team used another laser to measure the average frequency at which these atoms oscillated.
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- When the team ran two experiments, one with entangled atoms and one without, they found that the entangled atoms were able to measure time at the same precision, but four times faster. They also found that when the two clocks measured for the same amount of time, the entangled clock was more precise.
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- Extremely precise clocks may eventually have applications beyond telling time. Time depends on gravity. Because of relativity, massive objects (which have a higher gravitational force) warp space-time, slowing time down.
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- So, if you have two clocks and lift one of them 1 foot higher, at these two heights, time actually runs differently. As these clocks become more precise, they might be used to detect how time changes, thereby detecting subtle gravitational effects in the universe, such as ripples in space-time known as gravitational waves.
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- Because dark matter also exerts gravitational pull, minute changes in the ticking of time could reveal the nature of the dark matter that surrounds us.
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- There's even speculation that so-called absolute constants in the world of physics, such as the speed of light or the charge of electrons, may change as the universe expands.
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- And because these constants define the laws of physics that govern the energy levels in an atom, they may also change the measurement of time. So it's possible that the very essence of time changes as the universe expands. ---------------- other Reviews;
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- 3027 - ATOMS - how fine structure constant works? - This is a 100 year story of how physicists were able to figure out the mathematics that defines the behavior of an atom. They are still figuring, but, we have come a long way. One of the biggest issues was infinity, which is a very long way.
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- 3014 - ATOM - Nuclear Forces and Electron Volts? The Cosmic Ray is a proton traveling at nearly the speed of light. It was flung out of a galaxy that was 12 million lightyears away. It was so near light speed that after 12 million lightyears it was only behind a photon, released at the same time, by 46 nanometers. Because Relativity slows time at light speed the Cosmic Ray has only experienced 20 minutes of flight.
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- 2952 - ATOM - what happens on the inside? No one really knows what happens inside an atom. But two competing groups of scientists think they've figured it out. And both are racing to prove that their own vision is correct. Here's what we know for sure: Electrons whiz around "orbitals" in an atom's outer shell. Then there's a whole lot of empty space. Right in the center of that space, there's a tiny nucleus, a dense knot of protons and neutrons that give the atom most of its mass.
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-- 2913 - ATOM - can we see an atom? Well, that really depends on what we mean by “see.” We see something when light emitted or reflected from an object reaches our eyes and the signal is conducted to our brain.
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- 2867 - ATOM - and the electron cloud? The picture of the atom you were taught in high school is wrong, mainly because electrons aren’t point-like particles. Electrons are a‘fuzzy’ . They are tough to pin down due to their ‘Quantum Wave Function’, which is a complicated way of saying they exist as a field of “probability“, not as an individual particle.
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- 2709 - ATOMS - measuring how atoms work? - An atom can be viewed as a tiny electron orbiting a tiny nucleus at a certain radius. Let’s start with the hydrogen atom which is a single proton orbited by a single electron.
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- 2694 - ATOM - How can mathematics tell us how an atom works? It is 100 years of discovery. - It is how physicists were able to figure out the mathematics that defines the behavior of an atom. They are still figuring, but, we have come a long way.
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- 2685 - MOLECULE - how a molecule works? When there is more than one proton in the nucleus and more than one atom in orbit this classical physics math just becomes overwhelming. That is the reason the math of Quantum Mechanics was invented. When Quantum Mechanic’s math is used, the concept of the electron orbiting the proton completely disappears. The electron’s position around the nucleus becomes a probability distribution
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- 2377 - ATOM - defining the atom All the other elements in the periodic table above hydrogen and helium were created in the nuclear fusion of the stars The first stars formed with only hydrogen and helium. When they burned all their fuel and exploded as supernova they splattered the surrounding space with all the atoms in the higher level elements.
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- 2333 - Rainbows can tell us what the Universe is made of. Introduction to the science of spectroscopy.
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- 2318 - Brownian motion from atoms you can not see. My grandson, Michael, was 9 years old when he was looking at pond water under his microscope. He could see small plants and animals moving around in the water. But, he also saw all the little pieces of dust jiggling, almost vibrating, in a zigzag manner. He asked me what causes everything to move like that?
- 2315 - About how atoms were first discovered. How was the atom discovered, This review covers the first 100 years of discovery that started in 1808. John Dalton conclusively argued for the existence of the indivisible atom, and at the same time as Einstein was provided a way to directly measure those atoms, Thomson and Rutherford discovered that the atom wasn't indivisible at all. Instead, it was made of even tinier bits
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February 18, 2021 ATOMS - spooky action at for clocks? 3053
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