Modern Physics- what is that all about?
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I've heard a lot of people say that physics is old and boring. They think that after Newton and his 3 Laws of Motion, physics was pretty much done- we've known all there is to know for hundreds of years, and modern research has no place in physics. But like Stephen Hawking would tell you, that's just stupid talk. Physics has been alive throughout modern times, and it underwent some major revolutions since Galileo and Newton. Here are a few great examples: |
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Einstein's Relativity
Albert Einstein is probably one of the biggest names in modern physics, and for good reason. His theory of Special Relativity was one of the most important concepts of physics, ever. The foundations do lie with Galileo, but they completely break the Newtonian notions of absolute space and time.
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With the discovery of electromagnetic waves, physicists proposed the concept of "aether", a substance that existed in the universe which provided an absolute frame of reference and through which all waves and matter passed. However, Michelson-Morley experiment performed in the late 1880's, which was designed to measure ether, revealed that aether can't exist as a substance stationary to Earth's motion. The experiment reflected light at right angles and back, trying to detect changes in interference patterns which would have been caused by the Earth's rotation. However, the pattern proved no such thing- and thus it became the most famous failed experiment to date. |
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This meant that there's no such thing as an absolute frame of reference. Einstein could infer various results from this:
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First, all space and time are relative. Traveling at different relative speeds would cause time periods to seem different (time dilution).
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Simultaneity is also relative- 2 events that occur at the same time to an observer may occur at different times to an observer traveling at a different relative speed.
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Dimensions may also be measured differently for observers traveling at different speeds (Lorentz contraction).
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Speeds can never be higher than the speed of lights, so velocities cannot be added absolutely.
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Finally, energy and mass are equivalent, and
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Einstein's theory of special relativity supported Newton's theories in low speeds, and managed to combine Galileo's findings with more recent findings by Maxwell and the aether experiments. This completely revolutionized our thinking about space, time, speed, and everything!
Quantum mechanics
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In the early 1900s, Max Planck discovered that blackbody radiation depended on frequency of electromagnetic waves, not intensity. He published an equation about this relation which assumed to quantize radiations. He thus introduced the concept of discrete energy levels which lay the foundations for quantum mechanics. Einstein extended this to explain the photoelectric effect, suggesting that light and electromagnetic waves share a particle-wave duality. They're made of photons, which are discrete quantum of energy proportional to their frequency. |
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Niels Bohr applied this to Rutherford's solar model of the atom, the quantum atom. This atom had energy orbitals corresponding to discrete levels of energy, which explained a lot of unsolved problems with earlier atomic models. Further research by other scientists led us to develop a more complete model of the atom, by discovering neutrons, atomic arrangements, and more.
Louis de Broglie was another important name in quantum mechanics. His theory suggested that any moving particle or object had an associated wave. This united light and matter into wave mechanics. This also led to the development of electron microscopes, which are much better than earlier ones.
Big bangs
Rutherford, together with Soddy, achieved nuclear transmutation (converting one element to another). This, together with the equivalence of mass and energy, led in WWII to research for a nuclear war device. The Manhattan Project achieved its goal, creating nuclear chain reactions and explosions, and this led to the atomic bombings of Hiroshima and Nagasaki.
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Einstein expanded his special relativity to a more general relativity theory in gravitation. This idea described gravity as a geometric property of spacetime. The astrophysical implications of general relativity were immense- first of all, it suggested the existence of gravitational waves which can yield information about black holes, neutron stars, white dwarfs, and supernova implosions. Specifically, the theory supported the existence of black holes. |
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In the 40s, scientists like George Gamow proposed the Big Bang theory about the beginning of the universe. Although it faced many oppositions at first, it is now the cosmological model of the universe that is best supported by all lines of scientific evidence and observation. The basic idea of that theory is that the universe started as a tiny, concentrated point and has constantly been expanding outwards. It's still expanding now.
And then more stuff
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Quantum mechanics and wave mechanics evolved wildly. Schrödinger came up with a wave equation to explain things like particle motion, Pauli introduced the idea of spin for particles like electrons and protons, Heisenberg had his uncertainty principle, and many others made other discoveries to develop what we now know about matter, including phenomena such as crystal structures, semiconductivity, and superconductivity. |
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Engineering used the physics applications and discoveries to improve our lives. Consumer electronics, information technology, science, medicine, industry, law enforcement, entertainment, and the military all depend on the 20th century discoveries done in physics and science in general. From TVs to nuclear energy, it's all about the physics.
So what's in the future?
Physics is not done yet!
There are many mysteries that remain unsolved. What accounts for high-temperature superconductivity? Can we find better models for neutrinos? How do we explain ultra-high energy cosmic rays?
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A major area that requires looking into is the union of quantum physics with general relativity. We're all waiting for the next Einstein to take a step forward and unify the fundamental forces of the universe into one smooth theory. And you'll be surprised about the small things that are still unknown in physics. Complex systems and chaos theory remain nearly unstudied since they're not very simple. Turbulence is a phenomena that's yet to be fully understood, even though it has clear implications in science and technology. The formation of sand piles, nodes in trickling water, and the shape of water droplets are still not fully explained. |
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There's much to do!
In conclusion
Physics is not a dusty old subject that couldn't advance anywhere since Newton's times. The fields of relativity and quantum mechanics completely revolutionized our understanding of the huge universe out there and the tiny particles that compose it. There remains a lot more to research and discover.
Modern physics is alive and kicking!
Image Credit:hashmil ,hans.gerwitz ,oddharmonic ,Ethan Hein ,anomalous ,Augapfel
