Search the Community
Showing results for tags 'atoms'.
Found 2 results
Some days, you might feel like a pretty substantial person. Maybe you have a lot of friends, or an important job, or a really big car. But it might humble you to know that all of those things – your friends, your office, your really big car, you yourself, and even everything in this incredible, vast Universe – are almost entirely, 99.9999999 percent empty space. Here’s the deal. As I previously wrote in a story for the particle physics publication Symmetry, the size of an atom is governed by the average location of its electrons: how much space there is between the nucleus and the atom’s amorphous outer shell. Nuclei are around 100,000 times smaller than the atoms they’re housed in. If the nucleus were the size of a peanut, the atom would be about the size of a baseball stadium. If we lost all the dead space inside our atoms, we would each be able to fit into a particle of dust, and the entire human species would fit into the volume of a sugar cube. So then where does all our mass come from? SciFri Energy! At a pretty basic level, we’re all made of atoms, which are made of electrons, protons, and neutrons. And at an even more basic, or perhaps the most basic level, those protons and neutrons, which hold the bulk of our mass, are made of a trio of fundamental particles called quarks. But, as I explained in Symmetry, the mass of these quarks accounts for just a tiny per cent of the mass of the protons and neutrons. And gluons, which hold these quarks together, are completely massless. A lot of scientists think that almost all the mass of our bodies comes from the kinetic energy of the quarks and the binding energy of the gluons. So if all of the atoms in the Universe are almost entirely empty space, why does anything feel solid? The idea of empty atoms huddling together, composing our bodies and buildings and trees might be a little confusing. If our atoms are mostly space, why can’t we pass through things like weird ghost people in a weird ghost world? Why don’t our cars fall through the road, through the centre of the Earth, and out the other side of the planet? Why don’t our hands glide through other hands when we give out high fives? It’s time to reexamine what we mean by empty space. Because as it turns out, space is never truly empty. It’s actually full of a whole fistful of good stuff, including wave functions and invisible quantum fields. You can think about the empty space in an atom as you might think about an electric fan with rotating blades. When the fan isn’t in motion, you can tell that a lot of what’s inside of that fan is empty space. You can safely stick your hand into the space between the blades and wiggle your fingers in the nothingness. But when that fan is turned on it’s a different story. If you’re silly enough to shove your hand into that 'empty space', those blades will inevitably swing around and smack into it… relentlessly. Technically electrons are point sources, which means they have no volume. But they do have something called a wave function occupying a nice chunk of the atom. And because quantum mechanics likes to be weird and confusing, the volume-less electron is somehow simultaneously everywhere in that chunk of space. The blades of the fan are akin to electrons zipping around the atom, occupying chunks of space with their wave functions. It’s a painful reminder that what might seem like empty space can feel pretty solid. You've never really touched anything in your life Elizabeth Ann Colette/Flickr Are you sitting down for this? Well, you’re not really. Your butt isn’t actually touching the chair you’re sitting on. Since the meat of your atoms is nestled away in nuclei, when you 'touch' someone (or something), you aren’t actually feeling their atoms. What you’re feeling is the electromagnetic force of your electrons pushing away their electrons. On a very, very technical level, you’re not actually sitting on that chair. You’re hovering ever so slightly above it. So to conclude: Your very important human body is really, kind of, in a way, just a misleading collection of empty spaces on an empty planet in an empty Universe. But at least you have a big car. Source BTW, If I am 99.99% space and I never touched anything, I don't exist. I reject sciences and its theories.
SwissMiss posted a topic in General News(Yaakov Fein/University of Vienna) In a Quantum First, Physicists Put 2,000 Atoms in Two Places at Once You might be familiar with the Schrödinger's cat thought experiment, where the eponymous feline in a box can be both alive or dead at the same time, often used to illustrate the multi-state paradox of quantum mechanics. Well, now scientists have managed to apply that theory to huge molecules made up of 2,000 atoms. Quantum superposition has been tested countless times on smaller systems, with physicists successfully showing that individual particles can be in two places at one time. But this type of experiment hasn't been carried out at this scale before. What the experiment does is allow scientists to refine the hypotheses of quantum mechanics and understand more about how this particularly mind-bending branch of physics actually works – and how the laws of quantum mechanics join up with the more traditional, larger scale, classical laws of physics. "Our results show excellent agreement with quantum theory and cannot be explained classically," state the researchers in their published paper. In particular, the new study involves the Schrödinger equation (yes, him again), which describes how even single particles can also act as waves in multiple places at once, interfering with each other just like ripples on a pond. To test this, the scientists set up a double-slit experiment - an experiment that's very familiar to quantum physicists. Traditionally, it involves projecting individual particles of lights (photons) through two slits. If the photons acted simply as particles, the resulting projection of light on the other side would simply show one band. But in reality, the light projected on the other side shows an interference pattern - multiple bands that interact, showing that light particles can also act as waves. (Johannes Kalliauer/Wikimedia, CC-BY-SA 3.0) It effectively seem as if the photons are in two places at once, just like Schrödinger's cat. But as most of us are aware, the cat is only in two states while it remains unobserved. As soon as the box is open, it's either confirmed as being alive or dead, not both. It's the same with photons. As soon as the light is measured or observed directly, this superposition disappears and the state of the photon is locked in. This is one of the conundrums at the heart of quantum mechanics. This same double-slit experiment has been done with electrons, atoms, and smaller molecules. And now physicists show it applies to massive molecules, too. In this take on the double-slit experiment, the team was able to use these heavy molecules, made up of as many as 2,000 atoms, to create quantum interference patterns, as if they were behaving as waves and being in more than one place. The molecules were known as "oligo-tetraphenylporphyrins enriched with fluoroalkylsulfanyl chains", and some were more than 25,000 times the mass of a hydrogen atom. But as molecules get bigger, they also get less stable, and the scientists were only able to get them interfering for seven milliseconds at a time, using a newly designed piece of equipment called a matter-wave interferometer (designed to measure atoms along different paths). Even factors like the Earth's rotation and gravitational pull had to be factored in. It was worth the effort though – we now know these giant molecules can be in two places at once, as well as much smaller atoms. As quantum mechanics traditionally comes into play on very small scales, and classical physics on larger scales, the bigger the molecules we can get working with the double slit experiment, the closer we get to that quantum-classical boundary line. A previous record for this kind of study involved molecules up to 800 atoms in size. "Our experiments show that quantum mechanics, with all its weirdness, is also amazingly robust, and I'm optimistic that future experiments will test it on an even more massive scale," says physicist Yaakov Fein, from the University of Vienna in Austria. The research has been published in Nature Physics. Source: In a Quantum First, Physicists Put 2,000 Atoms in Two Places at Once