Deep Thoughts, with actual member of Congress Steve King (R-Iowa).
Planck Time
What is the smallest unit of time you can conceive? A second? A millisecond? Hard to say seeing as how time is relative. Under the right circumstances, hours can fly by and seconds can feel like a lifetime. But unfortunately for physicists, time is not something that can be delt with so philosophically. And since they deal with cosmological forces both infinitesimally large and small, they need units that can objectively measure them. When it comes to dealing with the small, Planck Time is the measurement of choice. Named after German physicist Max Planck, the founder of quantum theory, a unit of Planck time is the time it takes for light to travel, in a vacuum, a single unit of Planck length. Taken together, they part of the larger system of natural units known as Planck units.
Originally proposed in 1899 by German physicist Max Planck, Planck units are physical units of measurement defined exclusively in terms of five universal physical constants. These are the Gravitational constant (G), the Reduced Planck constant (h), the speed of light in a vacuum (c), the Coulomb constant(ke or k), and Boltzmann’s constant (kB, sometimes k). Each of these constants can be associated with at least one fundamental physical theory: c with special relativity, G with general relativity and Newtonian gravity, with quantum mechanics, with electrostatics, and kB with statistical mechanics and thermodynamics. They were invented as a means of simplifying the particular algebraic expressions appearing in theoretical physics, especially in quantum mechanics.
Ultimately, Planck time is derived from the field of mathematical physics known as dimensional analysis, which studies units of measurement and physical constants. The Planck time is the unique combination of the gravitational constant G, the relativity constant c, and the quantum constant h, to produce a constant with units of time. They are often semi-humorously referred to by physicists as “God’s units” because eliminate anthropocentric arbitrariness from the system of units, unlike the meter and second, which exist for purely historical reasons and are not derived from nature. Some challenges to Planck’s Time have been mounted. For example, in 2003 during the analysis of the Hubble Space Telescope Deep Field images, some scientists speculated that where there are space-time fluctuations on the Planck scale, images of extremely distant objects should be blurry. The Hubble images, they claimed, were too sharp for this to be the case. Other scientists disagreed with this assumption however, with some saying the fluctuations would be too small to be observable, others saying that the speculated blurring effect that was expected was off by a very large magnitude. A unit of Planck Time can be expressed (in the third picture).
Read more: http://www.universetoday.com/79418/planck-time/#ixzz2U4Nz4Ov1
evil teachers
Three Possible Futures for the Universe via Chandra X-ray Observatory (Credit: NASA/CXC/M.Weiss)
“This illustration shows three possible futures for the Universe, depending on the behavior of dark energy, by showing how the scale of the Universe may change with time. If dark energy is constant, as the new Chandra results suggest, the expansion should continue accelerating forever. If dark energy increases, the acceleration may happen so quickly that galaxies, stars, and eventually atoms will be torn apart, in the so-called Big Rip. Dark energy may also lead to a recollapse of the Universe, in the Big Crunch. The illustration also shows the early decelerating expansion of the Universe, followed by the accelerating phase that started about 6 billion years ago.”
(via rafapinto)
Deep Thoughts, with actual member of Congress Steve King (R-Iowa).
Super Moon
— June 23, 2013
Be sure to look out for the Moon these next few months as it approaches Perigee, because the full moons during these times will appear exceptionally large. The Moon will be at its Perigee, or closest approach, in July 23 and it will reach full moon only a few minutes after it passes this point in its orbit.
These ‘super moons’ not only appear larger because they are physically closer but, combined with a full moon, the mind can play tricks on you to think they are much larger. This phenomena is called the Moon Illusion. Try to catch these full moons as they rise/set because the illusion works when there is an object in the foreground, like a tree, building or mountains.
(via thescienceofreality)
The story behind DNA’s double helix
The notorious race to uncover the structure of DNA, the molecule of inheritance, began in 1951, when American biologist James Watson arrived at the University of Cambridge. Here he met Francis Crick, an English physicist and the two began building scale models to test their ideas of what DNA’s appearance might be.
Meanwhile, two scientists at King’s College London called Maurice Wilkins and Rosalind Franklin were also studying DNA. They were attempting to crystallise the molecule to make an x-ray pattern of it. They hoped this would provide important clues about its structure.
Although the two institutions were effectively competing against each other, Francis Crick (University of Cambridge) and Maurice Wilkins (King’s College London) communicated regularly. Letters sent from Wilkins to Crick reveal their close personal relationship.
It was Rosalind Franklin’s famous x-ray image, nicknamed ‘Photo 51’, that finally revealed the structure of DNA in May 1952. The pattern appeared to contain ‘rungs’, like those on a ladder, set between two strands. The fuzzy “X” pattern indicated DNA’s helix shape. In early 1953, Wilkins showed Watson the image, seemingly without Franklin’s knowledge.
(via biomedicalephemera)
