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Radioactivity chain reaction
Radioactivity chain reaction
Blowing stuff up in the name of physics
(A stack of matches below hydrogen balloons)
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Capacitor Cake
This was produced by a student for an each-one-teach-one activity on capacitance a week or so ago.
I was really impressed by the dielectric etc. It makes a really good (and tasty) model of a capacitor. I’m wondering what else could be represented in this form.
Suggestions please!
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Quote of the week!
In physics, you don’t have to go around making trouble for yourself - nature does it for you.
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Mysteries of Physics
Wikipedia has a great list of phenomena that are, at the moment, lacking in proper explanation, I’ve plucked some of the best from the list;
Accelerating universe and the Cosmological constant
Why doesn’t the zero-point energy of the vacuum cause a large cosmological constant? What cancels it out? Is a non-total cancellation of the cosmological constant responsible for the observed accelerated expansion of the Universe? If it is, why is the energy density of the cosmological constant of the same magnitude as the density of matter at present when the two evolve quite differently over time; could it be simply that we are observing at exactly the right time? Or is the nature of the dark energy driving this acceleration differently?
Baryon asymmetry
Why is there far more matter than antimatter in the visible universe?
Entropy (arrow of time)
Why did the universe have such low entropy in the past, resulting in the distinction between past and future and the second law of thermodynamics?
Mass/Weight ratio of elementary particles
According to General Relativity, the mass/weight ratio of all elementary particles is the same. However, there is no experimental evidence for this. In particular, we do not know what the weight of a macroscopic lump of antimatter would be.
Accretion disc jets
Why do the accretion discs surrounding certain astronomical objects, such as the nuclei of active galaxies, emit relativistic jets along their polar axes?
Corona heating problem
Why is the Sun’s Corona (atmosphere layer) so much hotter than the Sun’s surface?
Pioneer anomaly:
What causes the apparent residual sunward acceleration of the Pioneer spacecraft?
High-temperature superconductors
What is the responsible mechanism that causes certain materials to exhibit superconductivity at temperatures much higher than around 50 Kelvin?[10]
Turbulence
Is it possible to make a theoretical model to describe the statistics of a turbulent flow (in particular, its internal structures)?
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No foundation for LHC based terror…
The LHC Safety Assessment Group have reviewed and updated a study first completed in 2003, which dispels fears of universe-gobbling black holes and of other possibly dangerous new forms of matter, and confirms that the switch-on will be completely safe.
The report, ‘Review of the Safety of LHC Collisions’, published in IOP Publishing’s Journal of Physics G: Nuclear and Particle Physics, proves that if particle collisions at the LHC had the power to destroy the Earth, we would never have been given the chance to exist, because regular interactions with more energetic cosmic rays would already have destroyed the Earth or other astronomical bodies.
The group also writes, “Nature has already conducted the equivalent of about a hundred thousand LHC experimental programmes on Earth – and the planet still exists,” which is hardly a scientific reassurance!
The report concludes that, since cosmic-ray collisions are more energetic than those in the LHC, but are incapable of producing vacuum bubbles or dangerous magnetic monopoles, we should not fear their creation by the LHC.
LHC collisions will differ from cosmic-ray collisions in that any exotic particles created will have lower velocities, but the Safety Assessment Group shows that even fast-moving black holes produced by cosmic rays would have stopped inside the Earth or other astronomical bodies. Their existence proves that any such black holes could not gobble matter at a risky rate.
“Each collision of a pair of protons in the LHC will release an amount of energy comparable to that of two colliding mosquitoes, so any black hole produced would be much smaller than those known to astrophysicists.”
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This week in Physics History
- Sept. 10, 1892 - American physicist Arthur Compton is born. Compton received the 1927 Nobel Prize in physics for his work in discovering the Compton effect, a form of scattering in which electromagnetic radiation (i.e. light waves) and matter interaction. This was a crucial discovery in the early development of quantum physics.
- Sept. 12, 1897 - French scientist Irene Joliot-Curie is born. She was the daughter of famed scientists Pierre & Marie Curie. Jointly with her husband, Frederic Joliot-Curie, she was awarded the 1935 Nobel Prize for Chemistry in recognition of their work in discovering artificial radioactivity.
- Sept. 14, 1959 - The Soviet probe Luna 2 becomes the first man-made object to reach the moon, as it crashes into the surface of the moon.
- Sept. 10, 1975 - English physicist George Paget Thomson dies. Thomson was the son of J.J. Thomson, the famous physicist & chemist who discovered the electron. George Thomson similarly went on to win a Nobel Prize in Physics in 1937 for his own work in discovering electron diffraction, which was a major step toward understanding the nature of wave particle duality.
- Sept. 10, 1983 - Swiss-born physicist Felix Bloch dies. Bloch received the 1952 Nobel Prize in Physics for his work in discovering the underlying principles of nuclear magnetic resonance which would ultimately lead to the invention of the magnetic resonance imaging (MRI) device.
- Sept. 10, 2008 - The Large Hadron collider is turned on for the first time at the CERN facility in Switzerland.
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This week in Physics history;
- Sept. 1, 1804 - German astronomer Karl Ludwig Harding discovers Juno, one of largest asteroids in the asteroid belt.
- Sept. 3, 1905 - American experimental physicist Carl David Anderson is born. Anderson would receive the 1936 Nobel Prize in Physics for his discovery of the positron.
- Sept. 5, 1906 - Austrian physicist Ludwig Boltzmann dies. Part of the illustrious Boltzmann family, which permeated nineteenth century European intellectual life in mathematics & the sciences, Ludwig is best known for his work in statistical mechanics and thermodynamics. He strongly advocated atomic theory, well before it was popular to do so.
- Sept. 3, 1976 - U.S. spacecraft Viking II arrived on Mars, landing at Utopia Planitia, and took the first pictures of the planet’s surface. Viking II was, of course, an unmanned spacecraft.
- Sept. 2, 1992 - The first automobile powered by natural gas is purchased. Fifty of these alternative fuel vehicles were purchased and put into service by the Southern California Gas Company.