Posts Tagged ‘Cosmology’
“Magnetism, you recall from physics class, is a powerful force that causes certain items to be attracted to refrigerators”*…
Of all the environmental amenities that this hospitable planet provides, the magnetic field is perhaps the strangest and least appreciated. It has existed for more than three and a half billion years but fluctuates daily. It emanates from Earth’s deep interior but extends far out into space. It is intangible and mostly invisible—except when it lights up in ostentatious greens and reds during the auroras—but essential to life. The magnetic field is our protective bubble; it deflects not only the rapacious solar wind, which could otherwise strip away Earth’s atmosphere over time, but also cosmic rays, which dart in from deep space with enough energy to damage living cells. Although sailors have navigated by the magnetic field for a millennium and scientists have monitored it since the eighteen-thirties, it remains a mysterious beast. Albert Einstein himself said that understanding its origin and persistence was one of the great unsolved problems in physics…
Direct measurements of the magnetic field now span almost two hundred years, and iron-rich volcanic rocks on the ocean floor provide a lower-fidelity chronicle of its erratic behavior—including wholesale reversals in polarity—back about a hundred and fifty million years. But reconstructing the field’s behavior between these two extremes has been difficult. The trick is to find an iron-bearing object that locked in a record of the magnetic field at a well-constrained time in the past, in the way that wine of a given vintage preserves an indirect record of that year’s weather conditions…
Last Monday, in a study published in Proceedings of the National Academy of Sciences, a team of Israeli and American archeologists and geophysicists reports the most detailed reconstruction yet of the magnetic field in pre-instrumental times, using a set of ceramic jars from Iron Age Judea…
In the geophysical community, the tales told by the Judean jars may cause unrest. Both the height and the sharpness of the spike they recount push up against the limits of what some geophysicists think Earth’s outer core is capable of doing. If the eighth-century-B.C. geomagnetic jeté is real, models for the generation of the magnetic field need significant revision. Given the importance of a stable magnetic field to our electricity-dependent, communications-obsessed culture, these questions are of more than academic interest…
More on these befuddling fields at “Earth’s mysterious magnetic field, stored in a jar.”
* Dave Barry
As we look for True North, we might send undulating birthday greetings to George Fitzgerald Smoot III; he was born on this date in 1945. An astrophysicist and cosmologist, Smoot discovered the signature of gravitational waves– ripples in space-time were first predicted by Albert Einstein– in his study of the cosmic microwave (“background”) radiation that originated with the Big Bang. He won the Nobel Prize in Physics in 2006; three years later he became the second person to run the board on the quiz show Are You Smarter than a 5th Grader?, and took home the $1 million grand prize.
An international study claims to have found first observed evidence that our universe is a hologram.
What is the holographic universe idea? It’s not exactly that we are living in some kind of Star Trekky computer simulation. Rather the idea, first proposed in the 1990s by Leonard Susskind and Gerard ‘t Hooft, says that all the information in our 3-dimensional reality may actually be included in the 2-dimensional surface of its boundaries. It’s like watching a 3D show on a 2D television…
Just when one thought that things couldn’t get any stranger: “Scientists Find First Observed Evidence That Our Universe May Be a Hologram.”
Pair with this piece on recent experimental confirmation of what Albert Einstein called “spooky action at a distance.”
* Hunter S. Thompson
As we batten down the hatches, we might send shady birthday greetings to Fritz Zwicky; he was born on this date in 1898. A distinguished astronomer who worked at Cal Tech most of his life, Zwicky is best remembered for being the first to infer the existence of “dark matter“: while examining the Coma galaxy cluster in 1933, he used the virial theorem to deduce the existence of what he then called dunkle Materie. Colleagues knew him as both both a genius and a curmudgeon. One of his favorite insults was to refer to people of whom he didn’t approve as “spherical bastards”– because, he explained, they were bastards no matter which way you looked at them.
[For more on dunkle Materie: “Will We Ever Know What Dark Matter Is?“]
Theoretical physicists and cosmologists deal with the biggest questions, like “Why are we here?” “When did the universe begin?” and “How?” Another questions that bugs them, and likely has bugged you, is “What happened before the Big Bang?”
To be perfectly clear, we can’t definitively answer this question—but we can speculate wildly, with the help of theoretical physicist Sean Carroll from the California Institute of Technology. Carroll gave a talk last month at the bi-annual meeting of the American Astronomical Society in Grapevine, Texas, where he walked through several pre-Bang possibilities that would result in a universe like ours…
Consider the options at: “What Was Our Universe Like Before the Big Bang?“
* Theoretical physicist Peter Woit, Columbia University
As we scrutinize the singularity, we might spare a thought for E. E. Barnard; he died on this date in 1923. Recognized as a gifted observational astronomer, he is probably best known for his discovery of the high proper motion of Barnard’s Star in 1916, which is named in his honor. But, drawing on his experience as a photographer’s assistant in his adolescence (and building on the work of John William Draper), Barnard also contributed mightily to the development of celestial photography.
Science has a habit of asking stupid questions. Stupid, that is, by the standards of common sense. But time and time again we have found that common sense is a poor guide to what really goes on in the world.
So if your response to the question “Why does time always go forwards, not backwards?” is that this is a daft thing to ask, just be patient…
In our experience the past is the past and the future is the future, but sometimes the two can cross over; and while the past seems set in stone, some scientists believe that the future can change it: “The quantum origin of time.”
* William Faulkner,
As we head down the rabbit hole, we might spare a thought for Jules Henri Poincaré; he died on this date in 1912. A mathematician, theoretical physicist, engineer, and a philosopher of science, Poincaré is considered the “last Universalist” in math– the last mathematician to excel in all fields of the discipline as it existed during his lifetime.
Poincaré was a co-discoverer (with Einstein and Lorentz) of the special theory of relativity; he laid the foundations for the fields of topology and chaos theory; and he had a huge impact on cosmogony. His famous “Conjecture” held that if any loop in a given three-dimensional space can be shrunk to a point, the space is equivalent to a sphere; it remained unsolved until Grigori Perelman completed a proof in 2003.
“I used to think information was destroyed in black holes. This was my biggest blunder, or at least my biggest blunder in science”*…
Gravitational waves sent out from a pair of colliding black holes have been converted to sound waves, as heard in this animation. On September 14, 2015, LIGO [the Laser Interferometer Gravitational-wave Observatory] observed gravitational waves from the merger of two black holes, each about 30 times the mass of our sun. The incredibly powerful event, which released 50 times more energy than all the stars in the observable universe, lasted only fractions of a second.
In the first two runs of the animation, the sound-wave frequencies exactly match the frequencies of the gravitational waves. The second two runs of the animation play the sounds again at higher frequencies that better fit the human hearing range. The animation ends by playing the original frequencies again twice.
As the black holes spiral closer and closer in together, the frequency of the gravitational waves increases. Scientists call these sounds “chirps,” because some events that generate gravitation waves would sound like a bird’s chirp.
More background from LIGO:
* Stephen Hawking
As we scan the event horizon, we might send difficult-to-detect birthday greetings to Lawrence Maxwell Krauss; he was born on this date in 1954. A theoretical physicist and cosmologist, Dr. Krauss was among the first to propose the existence of the enigmatic dark energy that makes up most of the mass and energy in the universe. He directs the Origins Project, and has written several books on science for the general public, including Fear of Physics (1993), The Physics of Star Trek (1995), Quantum Man: Richard Feynman’s Life in Science (2011), and A Universe from Nothing (2012).
Last fall, a hand-picked group of the world’s top theoretical physicists received an invitation to a conference about the multiverse, a subject to which many of them had devoted the majority of their careers. Invitations like these were nothing unusual in their line of work. What was unusual was this conference was not being hosted by a university or research institute, but rather by a Scottish Duke.
And its organizer was not a physicist, but a landscape architect by the name of Charles Jencks.
The physicists were surprised to learn that Jencks had spent the past three years bringing their cosmological theories to life in the form of a massive land installation carved into the hills and pastures of the Nith Valley in southwest Scotland. It was titled “Crawick Multiverse” after the village where it was built, and its features, according to the brochure accompanying the invitation, included a Supercluster of Galaxies, twin Milky Way and Andromeda spiral mounds, the Sun Amphitheater (which seats 5,000), a Comet Walk, Black Holes (“in two different phases”), an Omphalos (a boulder-limned grotto symbolizing Earth’s “mythic navel” [pictured above]) and of course, the multiverse itself…
* Penny: What’s a multiverse?
Sheldon: GET HER OUT OF HERE!
– Big Bang Theory
As we note, with Rebecca Solnit, that a path is simply a prior interpretation of the best way to traverse a landscape, we might send perpetual birthday greetings to Jean Bernard Léon Foucault; he was born on this date in 1819. A physicist who made an early measurement of the speed of light, discovered eddy currents, and is credited with naming the gyroscope (although he did not invent it), Foucault is best remembered for the (eponymously-named) Foucault’s Pendulum– a long and heavy pendulum suspended from the roof of the Panthéon in Paris– demonstrating the effects of the Earth’s rotation. In fact, essentially the same experimental approach had been used by Vincenzo Viviani as early as 1661; but it was Foucault’s work that caught the public imagination: within years of his 1851 experiment, the were “Foucault’s Pendulums” hanging– and attracting crowds–in major cities across Europe and America.
“I believe alien life is quite common in the universe, although intelligent life is less so. Some say it has yet to appear on planet Earth”*…
If the range of habitable radii is sufficiently broad, most inhabited planets are likely to be closer in size to Mars than the Earth. Furthermore, since population density is widely observed to decline with increasing body mass, we conclude that most intelligent species are expected to exceed 300kg…
* Stephen Hawking
As we phone home, we might recall that it was on this date in 1960 that the first weather satellite, TIROS I, was launched from Cape Kennedy (or Canaveral, as then it was) and sent back the first television pictures from space. The first in a long series of launches in the TIROS program (Television Infrared Observation Satellite), it was NASA’s initial step, at a time when the effectiveness of satellite observations was still unproven, in determining if satellites could be useful in the study of the Earth. In the event, TIROS I and it successors proved extremely useful in weather forecasting.