Fizika

[расејан]

2. razni poluprovodnici i izolatori ne reflektuju savrseno, jer ne mogu dovoljno efikasno da reaguju na spoljne elektricno polje i potpno ga poniste - nesto udje pa dalje jal podje jal se absorbuje.

Аха, ок сад је јасно. То је у гимназији било мало смандрљано, вероватно ни профа то није баш учио, а на факсу мислим да смо поларизацију само прелетели (јер смо физику слушали заједно са хемичарима...).Иначе, препоручујем да се набаве овакве наочари, забава је гарантована... којекакви шахтови, асфалт, барице, разна црна пластика по колима... све то буде некако јаче три-де него иначе, ма не треба ни пиво.п.с. хвала :) Edited February 21, 2010 by расејан

[Dionysos]

GooglevsWolfram Alphabonusко је у праву?

[betty]

celzijusi nemaju skalu sa realnom vec arbitrarnom nulom, tako da sabiranje nema nekog smisla. nula bi mogla da bude bilo gde. da je npr. 5 stepeni niza, onda bi tvoje pitanje glasilo koliko je 5+5 stepeni. iz istog razloga nema smisla reci da je neka temperatura u celzijusima npr. duplo veca od neke druge. jedino sto ima smisla je reci da je nesto za x stepeni razlicito (vece/manje) od neceg drugog. to je moje misljenje kao psihologa :D

[Dionysos]

celzijusi nemaju skalu sa realnom vec arbitrarnom nulom, tako da sabiranje nema nekog smisla. nula bi mogla da bude bilo gde. da je npr. 5 stepeni niza, onda bi tvoje pitanje glasilo koliko je 5+5 stepeni. iz istog razloga nema smisla reci da je neka temperatura u celzijusima npr. duplo veca od neke druge.

у суштини то ме је и занимало, који је приступ исправан, сабирати то Келвинима (Гугл) или Целзијима (Волфрам), без обзира што нема неког смисла

jedino sto ima smisla je reci da je nesto za x stepeni razlicito (vece/manje) od neceg drugog. to je moje misljenje kao psihologa :D

па да, то је и разлика (коју гугл прави) између

Google

и

bonus

тј. једно је 0 Целзија + 0 Целзија, а друго 0 Целзија увећано за 0 степени/подеока по Целзијевој скали

[betty]

pusticemo onda nekog strucnijeg da odgovori... ali samo da primetim da gugl nije prebacio u kelvine pa sabrao, nego sabrao 0+0 pa prebacio u kelvine.

[bigvlada]

Ovaj eksperiment su spremali i gradili duže nego Skadar na Bojani. Čitao sam o tome kako grade Gravitacionu probu B početkom devedesetih. Elem, Albert je bio u pravu. Einstein's relativity theory survives test in spaceBY STEPHEN CLARKSPACEFLIGHT NOWPosted: May 4, 2011 NASA released results Wednesday from a revolutionary satellite that probed Einstein's general theory of relativity, confirming the Earth's gravity and rotation warp space and time as predicted. Artist's concept of Gravity Probe B, Earth and the warped web of space and time. Credit: NASA/Stanford University Using fast-spinning gyroscopes in a satellite 400 miles above Earth, the Gravity Probe B mission measured how the tug of Earth's gravity and the planet's spin distorts space and time in our own cosmic neighborhood. The findings have far-reaching implications because they verify two crucial tenets of Albert Einstein's general theory of relativity, the standard of modern astrophysics that guides research into black holes, active galactic nuclei and gamma ray bursts, the most powerful explosions in the universe. More massive objects in the distant cosmos have more fundamental and obvious effects on space and time. "There is a strong link between Gravity Probe B and some of the most energetic and cataclysmic events in the universe," said Clifford Will, a physics professor at Washington University in St. Louis. Francis Everitt, Gravity Probe B's principal investigator from Stanford University, said the mission's results were nearly identical to what Einstein's theory predicted. "We completed this landmark experiment testing of Einstein's universe, and Einstein survives," Everitt said Wednesday. Earth bends space and time in two ways. First, the planet's immense gravity field warps the space-time continuum. And secondly, Earth's rotation drags space and time along as the planet spins on its axis. Earth's effect is so small it took custom-built gyroscopes, a specially-constructed glass telescope and nearly 50 years of development to produce the mission's indisputable results. "Imagine the Earth as if it were immersed in honey. As the planet rotates, the honey around it would swirl, and it's the same with space and time," Everitt said. "GP-B confirmed two of the most profound predictions of Einstein's universe, having far-reaching implications across astrophysics research. Likewise, the decades of technological innovation behind the mission will have a lasting legacy on Earth and in space." NASA started developing a relativity gyroscope experiment in 1963. Decades of innovation yielded technologies to control drag, magnetic fields and temperatures aboard the satellite, which had to be free of disturbances to ensure its results weren't polluted by other factors. Scientists finally launched the spacecraft on a Delta 2 rocket in April 2004. Thought to be the most perfectly round objects ever manufactured, Gravity Probe B's four niobium-coated quartz gyroscopes, each about the size of a ping pong ball, spun up to 5,000 rpm during the satellite's mission. An ultra-precise telescope made of fused quartz glass pointed at a guide star named IM Pegasi. The star served as a reference point for Gravity Probe B's measurements, which counted on the satellite's gyroscopes to wobble like a top. If the rotating gyros oscillated, it would support Einstein's theory. "Picture a gyroscope moving in orbit around the Earth and let's ask what happens," Everitt said. "If we live in (Isaac) Newton's universe where space-time is absolute, and you have a purely imaginary, perfect gryo, and you point it at a point in space, nothing will happen. Einstein's universe is different. In Einstein's universe, space and time are warped by gravity." It turns out the axis of the spinning gyroscopes drifted, but just barely. Sketch of the Gravity Probe B spacecraft. Credit: NASA/Stanford University "Basically you have a rotating top, so you look at its precession or how much it wobbles," said Colleen Hartman, a senior NASA advisor and professor at George Washington University. Gravity Probe B's science-gathering phase ended in late 2005, but researchers spent the next five years meticulously analyzing the mission's data, removing potential errors and tracking down inconsistencies in its measurements until they were satisfied the satellite upheld Einstein's theory. Calibration efforts showed Gravity Probe B's gyroscopes were exhibiting signs of unpredicted torques, or spinning. After extensive analysis, scientists concluded the torques were due to a resonance between the rotating gyros and movements of the spacecraft. Everitt said the science team calibrated the science data to account for the unexpected torque. In the end, researchers say Earth's gravity and rotation distorts space-time by about 1.1 inches in 25,000 miles, about what Einstein's theory forecasts. Gravity Probe B measured the effect of Earth's gravity, also known as the geodetic effect, is responsible for a bend of about 6,601.8 milliarcseconds per year in space and time. That's less than two one-thousandths of a degree. The "frame-dragging" effect, in which space-time is twisted by the Earth's rotation, accounts for about 37.2 milliarcseconds of warping each year, but the margin of error for that result is about 20 percent. A milliarcsecond is the width of a human hair as seen from a distance of 10 miles. The "amazingly sensitive" scientific instruments was immersed in 600 gallons of superfluid helium, a cryogenic liquid that cooled the experiment to nearly absolute zero, Everitt said. The helium naturally boiled off during the mission, limiting Gravity Probe B's science phase to 17 months. The frigid temperatures allowed the niobium-covered gyros to become superconducting, where the rotor loses electrical resistance and its magnetic field aligns with a spin axis determined through the moment generated by a spinning superconductor. The superconducting magnetic effect is known as the London moment. "The mission results will have a long-term impact on the work of theoretical physicists," said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington. "Every future challenge to Einstein's theories of general relativity will have to seek more precise measurements than the remarkable work GP-B accomplished."http://spaceflightnow.com/news/n1105/04gravityprobeb/

[bigvlada]

Zamka za Elektron

[bigvlada]

[bigvlada]

Wormholes May Save Physics From Black Hole InfernosBy Michael Moyer | August 23, 2013 | 29Are black holes surrounded by walls of fire? Does this imply that one (or more) of our most cherished physical principles—and here I’m talking about biggies like quantum theory, the conservation of information or Einstein’s equivalence principle—is wrong? Any may our savior come in the form of wormholes? These are the questions consuming some of the world’s foremost theoretical particle physicists as they argue about potential solutions to what has become known as the “black hole firewall” problem—perhaps the most important paradox in physics since Stephen Hawking proposed his first black hole information paradox nearly four decades ago.http://blogs.scientificamerican.com/observations/2013/08/23/wormholes-may-save-physics-from-black-hole-infernos/

[hooyadahoo]

pitanje.da li ce grupa atoma ili molekula koncentrisana u sredini sobe bez prisustva ikakve sile i u apsolutnom vakuumu krenuti da se "raspada" - cestice se udaljuju jedna od druge, ili ce ostati na okupu. zanima me sta kaze entropija u ovom slucaju.

[Braća Strugacki]

svaka vaška obaška

[hooyadahoo]

?

[Indy]

Mnogo teško pitanje za 1 forum?

[Braća Strugacki]

?

pa rekoh, svako sebično radi za sebeostaće na okupu ukoliko je apsolutna nula, inače kud koji mili moji

[hooyadahoo]

zasto?edit: e da, ako ce vec da krenu da se udaljavaju jedna od druge, onda je ocigledno da ce morati to da ucine sa pozitivnim ubrzanjem?

Edited August 28, 2013 by hooyadahoo