Brief History of the Atom
Modern atomic theory began with Democritus, a Greek philosopher - he states that atomos were the smallest bits of matter, were indivisible and will always be in motion. Democritus concluded that if you cut a piece of matter into smaller and smaller pieces, you’d eventually reach a point where you could not cut anymore - the atom. In fact, atomos actually means “that which cannot be cut.”
Many centuries later, John Dalton (1766-1844) proposed a new atomic theory. It had four parts, and stated that:
- All matter is composed of atoms, which are indivisible and indestructible.
- All atoms of a given element are identical in mass and properties.
- Compounds are formed by a combination of two or more different kinds of atoms.
- A chemical reaction is nothing more than a rearrangement of atoms.
Then, in 1897, J.J. Thomson (1856-1940) discovered the electron. Scientists at the time were surprised to find that atoms were divisible. In 1911, Ernest Rutherford (1871-1937) proved that the atomic nucleus was small and dense, and that atoms were composed of mostly empty space - via the gold foil experiment. Two years later, in 1913, Niels Bohr (1855-1962) devised his own model of the atom - one in which electrons orbit the nucleus and are separated from each other like rungs on a ladder. According to Bohr, electrons could jump from one rung to another, but could not be in between.
The twentieth century saw a more sophisticated and thorough understanding of the atom - assisted by Albert Einstein’s (1879-1955) conclusion that energy and matter were two different sides of the same coin, and could be transformed into another. Einstein’s famous formula, E=mc2, concludes that if bits of matter were to be collided at high energies, the energy of their motion upon collision could transform into other bits of matter. This is the basic concept behind modern particle colliders!
During the 1980s, the Standard Model was born - a system which captures all that was known about particle physics. However, we also know that the Standard Model must be incomplete - because it doesn’t match up to all observations. One example of this is that neutrinos have mass - something not predicted by the Standard Model.There is so much that modern scientists are unsure about, but this is a thrilling time to be following physics, as major breakthroughs such as the discovery of the Higgs Boson seem to be right around the corner.
We have come a long way since Democritus - but we still have so much more to discover.
Quantumaniac is where it’s at - and by ‘it’ I mean awesome. Over here I post a ton of physics / math / general interesting science related posts. I try to be as informative as possible, all while posting fascinating things that hopefully enlighten us both a little to the mysteries of our truly wondrous universe(s?). However, I am fully aware that physics is not the most popular thing on tumblr, but I’d love to spread my blog to anyone that would be interested in reading it! So, let’s show those Justin Bieber kids where the real fun is - please check out Quantumaniac! Plus, how would you know if the blog exists or not unless you observe it? Boom, just pulled the Schrödinger’s cat card. Now you have to check it out - trust me, it said so in an equation somewhere.
Please reblog this - I’d really, sincerely appreciate it!
the-star-stuff asked: "Wow great books! Where did you buy it? Are those all for just Php 500, or 500 for each book? I’ve been looking for physics/astronomy books for a while now." ----I bought it somewhere here in the Philippines, Manila City Hall. 200php for Cosmos and Contact and 100php for Black Holes and Baby Universes.
Ooh cool! Thanks! I’m also live here in Manila. Do they still have copies and other books left?
The Sudbury Neutrino Observatory (SNO)
Located 6,800 feet underground in Creighton Mine, Sudbury, Ontario, the Canadian Neutrino Observatory had been detecting Solar Neutrinos that came directly from core of our Sun for about 7 years, since its launch on May 1999 until its detector shutdown on November 2006.
The Observatory is distinguished for being the first one to experimentally confirm that neutrinos oscillate, where neutrinos with mass change into other flavors as they travel through space, which had resolved the Solar Neutrino Problem.
Since the late 60s, former and previous neutrino detectors and experiments around the world had only detected around a third to a half of the number of solar neutrinos that was calculated and predicted by the Standard Solar Model.
However, by the late 50s to early 60s, Italian nuclear physicist Bruno Pontecorvo had already first put forward the idea that neutrinos oscillate. The idea that neutrinos oscillate, or change into other flavors, requires them to have mass and that neutrinos actually have three different flavors: electron, muon, and tau neutrinos.
It turned out that these earlier previous experiments and observatories had commonly detected only one flavor (type) of neutrino: electron neutrinos (though later modern observatories prior to SNO had began detecting other neutrino flavors, but not all flavors).
Unlike the previous and early detectors and experiments who had commonly used light normal water Cherenkov detectors, the Observatory’s detector had used a tank of a thousand tons of heavy water, which was viewed with less than a thousand photomultiplier tubes (PMTs) that were mounted on a geodesic sphere. Incoming neutrinos reacted with the heavy water to produce flashes of light called Cherenkov radiation that were then detected by the array of PMTs. In this way, the detector had fully detected all three flavors of neutrinos. It was not until 2001 when this Observatory had presented its findings that confirmed Pontecorvo’s hypothesis and had resolved the Solar Neutrino Problem.
Presently, the Sudbury Neutrino Observatory had already shut down its detector. But an affiliate laboratory called the SNOLAB, still operates on the Observatory’s site complex, where they continue analyzing the data gathered by almost a decade of operation.
![the-star-stuff:
Strange Effects: The Mystifying History of Neutrino Experiments
What Is a Neutrino?
Neutrinos are tiny, elusive and very common. For every proton or electron in the universe there are at least a billion neutrinos. [continue…]
Beta Decay Puzzle
The tiny particles first came to scientists’ attention in beta decay, a radioactive process discovered at the end of the 19th century in which an atom’s nucleus emits an electron and transforms itself into a different atom. [continue…]
Neutrinos Discovered
In 1956, physicists studying neutrinos had some fancy new tools at their disposal. In the 25 years since the particles were first postulated, the U.S. had built several nuclear reactors for its atomic weapons program.
Many researchers realized that these reactors, which emitted 300 trillion neutrinos per square inch every second, could be harnessed to detect neutrinos. Though they hardly ever interact with matter, there’s a tiny probability that, given enough material, a neutrino will collide with something. In a process that’s basically the reverse of beta decay, this direct hit will generate gamma radiation. [continue…]
The Solar Puzzle
Astronomers want to detect those neutrinos because they contain important information about processes going on in the sun’s center. In 1964, physicist Ray Davis and astronomer John Bacall built an experiment in the Homestake mine in South Dakota to find these neutrinos. The detector needed to be placed deep underground because cosmic rays hitting the Earth’s atmosphere would interfere with the results. [continue…]
The Atmospheric Puzzle
In the 1980s, scientists were occupied with a problem not related to neutrinos in any way. Some theoreticians suggested that the proton – a stable particle by all accounts – might decay into other, lighter subatomic particles. If this occurred, it would be part of physicists’ long-sought dream: a grand unified theory that merged the electromagnetic, weak and strong forces. [continue…]
A New Neutrino?
In 1993, scientists constructed the Liquid Scintillator Neutrino Detector (LSND) experiment at Los Alamos National Lab. Their aim was to figure out if neutrinos can oscillate from one type to another. (Results from the Homestake and proton decay experiments weren’t yet conclusive.)
LSND remains famous among scientists because it saw a small excess of electron antineutrinos appear seemingly from nowhere. The best explanation for this odd anomaly required completely new physics. [continue…]
More Strangeness
Beginning in 2002, scientists began running a new experiment named MiniBooNE at Fermi National Accelerator Laboratory in Illinois. MiniBooNE’s aim was to confirm or deny the controversial LSND results. Their initial results seemed to disprove the LSND anomaly, but further data changed that picture. [continue…]
Image: A physicist sits inside the LSND detector. (Los Alamos National Laboratory)](http://25.media.tumblr.com/tumblr_m0nzqrnWBA1qe649zo1_500.jpg)
Strange Effects: The Mystifying History of Neutrino Experiments
What Is a Neutrino?
Neutrinos are tiny, elusive and very common. For every proton or electron in the universe there are at least a billion neutrinos. [continue…]
Beta Decay Puzzle
The tiny particles first came to scientists’ attention in beta decay, a radioactive process discovered at the end of the 19th century in which an atom’s nucleus emits an electron and transforms itself into a different atom. [continue…]
Neutrinos Discovered
In 1956, physicists studying neutrinos had some fancy new tools at their disposal. In the 25 years since the particles were first postulated, the U.S. had built several nuclear reactors for its atomic weapons program.
Many researchers realized that these reactors, which emitted 300 trillion neutrinos per square inch every second, could be harnessed to detect neutrinos. Though they hardly ever interact with matter, there’s a tiny probability that, given enough material, a neutrino will collide with something. In a process that’s basically the reverse of beta decay, this direct hit will generate gamma radiation. [continue…]
The Solar Puzzle
Astronomers want to detect those neutrinos because they contain important information about processes going on in the sun’s center. In 1964, physicist Ray Davis and astronomer John Bacall built an experiment in the Homestake mine in South Dakota to find these neutrinos. The detector needed to be placed deep underground because cosmic rays hitting the Earth’s atmosphere would interfere with the results. [continue…]
The Atmospheric Puzzle
In the 1980s, scientists were occupied with a problem not related to neutrinos in any way. Some theoreticians suggested that the proton – a stable particle by all accounts – might decay into other, lighter subatomic particles. If this occurred, it would be part of physicists’ long-sought dream: a grand unified theory that merged the electromagnetic, weak and strong forces. [continue…]
A New Neutrino?
In 1993, scientists constructed the Liquid Scintillator Neutrino Detector (LSND) experiment at Los Alamos National Lab. Their aim was to figure out if neutrinos can oscillate from one type to another. (Results from the Homestake and proton decay experiments weren’t yet conclusive.)
LSND remains famous among scientists because it saw a small excess of electron antineutrinos appear seemingly from nowhere. The best explanation for this odd anomaly required completely new physics. [continue…]
More Strangeness
Beginning in 2002, scientists began running a new experiment named MiniBooNE at Fermi National Accelerator Laboratory in Illinois. MiniBooNE’s aim was to confirm or deny the controversial LSND results. Their initial results seemed to disprove the LSND anomaly, but further data changed that picture. [continue…]
Image: A physicist sits inside the LSND detector. (Los Alamos National Laboratory)
Newton v. Leibniz - The Calculus Controversy
In Latin, the word ‘calculus’ means ‘pebble,’ meaning that small stones were used to calculate things. Calculus is essentially the study of change, and the pebbles represent small, gradual changes that can produce impressive results. The origin of calculus is not the work of a single man, not even the work of the two men pictured above - but like most major discoveries, a gradual build of overlapping discoveries, something very similar to calculus itself. The question over the creation of the branch of mathematics has become one of the fiercest rivalries in modern history - that between Isaac Newton and Gottfried Leibniz.
In 1666 (and perhaps earlier), when Newton was 23 - he had begun work on what he called “the method of fluxions and fluents,” effectively what we know as calculus. Newton’s discovery of calculus was mainly a result of practical use - he needed a method to solve problems in physics and geometry, and calculus was what resulted. On the other hand, Leibniz had become fascinated by the tangent line problem and began to study calculus around 1675.
The ideas of the two men were similar, although it is unlikely that either of them knew the specifics of the other’s work. The two men spoke in letters often, and discussed mathematics - and although the Royal Society found Leibniz effectively guilty of plagiarism later, this was not likely the case. Both men came to similar discoveries in different ways - Leibniz came to integration first, while Newton began his work with derivatives.
Although Newton discovered the principles of calculus first - he did not publish them until many years after Leibniz did. Leibniz published his first paper employing calculus in 1684, but Newton did not publish his fluxion notation form of calculus until 1693, and a complete version was not available until 1704! Nonetheless, Newton still came to the discovery first - and although both men are officially credited, Newton is the one that most people remember.
However, Newton doesn’t deserve all the credit here. The famous dy/dx notation that calculus students have come to love and hate was developed by Leibniz. Although Newton may have come to the discovery first, Leibniz attacked the problems with far better notation - and we have naturally adopted it. Instead of Leibniz’s dx/dt (shown below) notation for derivatives, Newton preferred ‘dot’ notation:
However, this dot notation can become confusing, especially when used for higher order derivatives, so it has been generally dismissed - except for hardcore Newton fanatics who insist on using his notation. Newton did not even have a standard notation for integration, but frequently switched; but Leibniz used the recognizable integration symbol:
This has developed into a fantastic controversy over the years - and has become as much of a moral question as it is scientific. Many Leibniz advocates belief that Newton doesn’t deserve full credit because he didn’t publish his findings first - while many others believe that Newton came to the discovery first, so the credit is his. Personally, I have to place myself on the side of Newton - although Leibniz’s notation is wonderful, Newton discovered the principles first.
Which side are you on?
Via Quantumaniac
About me
Musician, Historian, Mathematician, Scientist, Theorist, Idealist, Artist, Writer, and Entrepreneur.- www.kweba.livejournal.com
