Posts tagged physics

what is an object? Philosophers are always saying, “Well, just take a chair for example.” The moment they say that, you know…

Feynman, objects, physics, philopsophy, OOO, aproximation, idealization, 1963

“what is an object? Philosophers are always saying, “Well, just take a chair for example.” The moment they say that, you know that they do not know what they are talking about any more. What is a chair? Well, a chair is a certain thing over there … certain?, how certain? The atoms are evaporating from it from time to time—not many atoms, but a few—dirt falls on it and gets dissolved in the paint; so to define a chair precisely, to say exactly which atoms are chair, and which atoms are air, or which atoms are dirt, or which atoms are paint that belongs to the chair is impossible. So the mass of a chair can be defined only approximately. In the same way, to define the mass of a single object is impossible, because there are not any single, left-alone objects in the world—every object is a mixture of a lot of things, so we can deal with it only as a series of approximations and idealizations.”

Richard Feynman,The Feynman Lectures on Physics Vol. I Ch. 12

ALPHA observes light spectrum of antimatter for first time

antimatter, ALPHA, physics, light, spectral, antihydrogen

Today’s ALPHA result is the first observation of a spectral line in an antihydrogen atom, allowing the light spectrum of matter and antimatter to be compared for the first time. Within experimental limits, the result shows no difference compared to the equivalent spectral line in hydrogen. This is consistent with the Standard Model of particle physics, the theory that best describes particles and the forces at work between them, which predicts that hydrogen and antihydrogen should have identical spectroscopic characteristics. ALPHA is a unique experiment at CERN’s Antiproton Decelerator facility, able to produce antihydrogen atoms and hold them in a specially-designed magnetic trap, manipulating antiatoms a few at a time. Trapping antihydrogen atoms allows them to be studied using lasers or other radiation sources.

via http://phys.org/news/2016–12-alpha-spectrum-antimatter.html

gravitational waves

physics, gravity, gravitational waves, LIGO

For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed. The gravitational waves were detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (9:51 a.m. UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA.

http://www.ligo.org/news.php

David Fathi - Wolfgang

Photography, Wolfgang Pauli, David Fathi, physics, Cern, history

Science isn’t fiction, science is weirder than fiction. Teleportation, ubiquity, levitation, spontaneous appearance. Inconceivable on a human scale, but totally logical on the scale of elementary particles. Working in the field of quantum mechanics is a wild ride, and even though the mythical Pauli Effect was a private joke among highly scientific minds, some of them were nonetheless superstitious enough to ban Wolfgang Pauli from even entering their lab. In quantum physics as well as in photography, the act of observing is not a neutral act. It participates in the outcome of a scene. These photos are sometimes real, sometimes completely fabricated. The observer is actor in fixing what is science and what is myth.

http://www.davidfathi.com/wolfgang.php

There are, by weight, more ships in the ocean than fish

xkcd, what if, physics, mass, weight, shipping, fish, oceans, marine conservation

Current fish wet biomass is about 2 billion tons, so removing them won’t make a dent either. (Marine fish biomass dropped by 80% over the last century, which—taking into consideration the growth rate of the world’s shipping fleet—leads to an odd conclusion: Sometime in the last few years, we reached a point where there are, by weight, more ships in the ocean than fish.)

https://what-if.xkcd.com/33/

Experimental Simulation of Closed Timelike Curves

physics, quantum physics, time travel, close timelike curves, quantum computing, gravity

Closed timelike curves are among the most controversial features of modern physics. As legitimate solutions to Einstein’s field equations, they allow for time travel, which instinctively seems paradoxical. However, in the quantum regime these paradoxes can be resolved leaving closed timelike curves consistent with relativity. The study of these systems therefore provides valuable insight into non-linearities and the emergence of causal structures in quantum mechanics-essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the non-linear behaviour of a qubit interacting unitarily with an older version of itself, addressing some of the fascinating effects that arise in systems traversing a closed timelike curve. These include perfect discrimination of non-orthogonal states and, most intriguingly, the ability to distinguish nominally equivalent ways of preparing pure quantum states. Finally, we examine the dependence of these effects on the initial qubit state, the form of the unitary interaction, and the influence of decoherence.

http://arxiv.org/abs/1501.05014

The Sound So Loud That It Circled the Earth Four Times

science, nature, krakatoa, volcano, physics, infrasound, 1883

On 27 August 1883, the Earth let out a noise louder than any it has made since. It was 10:02 AM local time when the sound emerged from the island of Krakatoa, which sits between Java and Sumatra in Indonesia. […] By 1883, weather stations in scores of cities across the world were using barometers to track changes in atmospheric pressure. Six hours and 47 minutes after the Krakatoa explosion, a spike of air pressure was detected in Calcutta. By 8 hours, the pulse reached Mauritius in the west and Melbourne and Sydney in the east. By 12 hours, St. Petersburg noticed the pulse, followed by Vienna, Rome, Paris, Berlin, and Munich. By 18 hours the pulse had reached New York, Washington DC, and Toronto. Amazingly, for as many as 5 days after the explosion, weather stations in 50 cities around the globe observed this unprecedented spike in pressure re-occuring like clockwork, approximately every 34 hours. That is roughly how long it takes sound to travel around the entire planet.

http://nautil.us/blog/the-sound-so-loud-that-it-circled-the-earth-four-times

English minus the non-Germanic words

language, physics, english, geman, germanic, conlang

The firststuffs have their being as motes called *unclefts*. These are mightly small; one seedweight of waterstuff holds a tale of them like unto two followed by twenty-two naughts. Most unclefts link together to make what are called *bulkbits*. Thus, the waterstuff bulkbit bestands of two waterstuff unclefts, the sourstuff bulkbit of two sourstuff unclefts, and so on. (Some kinds, such as sunstuff, keep alone; others, such as iron, cling together in ices when in the fast standing; and there are yet more yokeways.) When unlike clefts link in a bulkbit, they make *bindings*. Thus, water is a binding of two waterstuff unclefts with one sourstuff uncleft, while a bulkbit of one of the forestuffs making up flesh may have a thousand thousand or more unclefts of these two firststuffs together with coalstuff and chokestuff.

https://groups.google.com/forum/#!msg/alt.language.artificial/ZL4e3fD7eW0/_7p8bKwLJWkJ

First Direct Evidence of Cosmic Inflation

physics, cosmology, inflation, decelerator, BICEP2

This announcement has implications far beyond the field of cosmology. If the detection is confirmed, and inflation theory is eventually accepted, particle physicists will also be intrigued. According to inflation theory, a quantised particle called the inflaton exists, and is hypothesized to be responsible for cosmic inflation in the very early universe. So as physicist Richard Easther, points out, “we’re not just looking at the beginning of the universe, we are exploring undiscovered vistas in particle physics.”

http://decelerator.blogspot.sg/2014/03/first-direct-evidence-of-cosmic.html

The Quantum Mechanics of Fate

retrocausality, time, past, presetn, future, QM, physics, spacetime, arrow of time

As with so much else in quantum mechanics, this concept of retrocausality is limited in scope. Only in certain circumstances can we see the future influence the past. Although individual particle processes can move backward or forward in time, the universe as a whole is skewed in the forward direction, because its past endpoint was highly ordered, and its future endpoint is highly disordered. Our mortality is this asymmetry in microcosm.

http://nautil.us/issue/9/time/the-quantum-mechanics-of-fate

Turbulence, and Fluid Mechanics in General

Turbulence, fluid mechanics, physics, Navier-Stokes, references, cosmo shalizi

So what, you may ask, is the fabled “problem of turbulence”? In essence, this: what on Earth do our statistics and our equation have to do with each other? A solution to the problem of turbulence would be, more or less, a valid derivation from the Navier-Stokes equation (and statements about the appropriate conditions) of our measured statistics. Physicists are very far from this at present. Our current closest approach stems from the work of Kolmogorov, who, by means of some statistical hypotheses about small-scale motion, was able to account for the empirical laws I mentioned. Unfortunately, no one has managed to coax the hypotheses from the Navier-Stokes equation (sound familiar?) and the hypotheses hold exactly only in the limit of infinite Reynolds number, i.e. they are not true of any actual fluid.

http://vserver1.cscs.lsa.umich.edu/~crshalizi/notebooks/turbulence.html

[1210.8144] Possible Bubbles of Spacetime Curvature in the South Pacific

south pacific, spacetime, bubbles, matter, curvature, physics, occultism, HP Lovecraft

In 1928, the late Francis Wayland Thurston published a scandalous manuscript in purport of warning the world of a global conspiracy of occultists. Among the documents he gathered to support his thesis was the personal account of a sailor by the name of Gustaf Johansen, describing an encounter with an extraordinary island. Johansen`s descriptions of his adventures upon the island are fantastic, and are often considered the most enigmatic (and therefore the highlight) of Thurston`s collection of documents. We contend that all of the credible phenomena which Johansen described may be explained as being the observable consequences of a localized bubble of spacetime curvature. Many of his most incomprehensible statements (involving the geometry of the architecture, and variability of the location of the horizon) can therefore be said to have a unified underlying cause.

http://arxiv.org/abs/1210.8144

Experimental delayed-choice entanglement swapping

retrocausality, time-like, quantum, physics, entanglement, arxiv

Using four photons, we can actively delay the choice of measurement-implemented via a high-speed tunable bipartite state analyzer and a quantum random number generator-on two of the photons into the time-like future of the registration of the other two photons. This effectively projects the two already registered photons onto one definite of two mutually exclusive quantum states in which either the photons are entangled (quantum correlations) or separable (classical correlations). This can also be viewed as “quantum steering into the past”.

http://arxiv.org/abs/1203.4834