How to Build Time Machine. The hottest news in physics this fall was the alleged discovery at CERN that neutrinos travel slightly faster than light.
Physics for Beginners. Velocity-addition formula. In physics, a velocity-addition formula is an equation that relates the velocities of moving objects in different reference frames.
Galilean addition of velocities[edit]
Sean Carroll. Physics Lectures. Where is everybody? : Starts With A Bang. “If the Universe Is Teeming with Aliens… Where Is Everybody?”
-Stephen Webb As egocentric as we are, we know that not only are we but one planet of many orbiting our Sun, but that when we look up in the heavens, every point of light we see is another chance — another opportunity — for planets, for life, and even for intelligence. Image credit: Ned Wright, COBE / DIRBE, and NASA. With hundreds of billions of stars (visible here in infrared wavelengths) in our galaxy alone, we have many, many chances for life to have evolved similarly to how it did here on Earth. With hundreds of billions of galaxies in the Universe, it seems unfathomable to us that we would be alone as the only self-aware, intelligent, sentient lifeforms in the Universe. Image credit: Hubble Ultra Deep Field team, NASA, and STScI.
Translational symmetry. For translational invariant functions.
Cosmic Variance. Physical Science. Physics. Physics. Particle Physics. Cosmology. The megaquake connection: Are huge earthquakes linked? - environment - 16 March 2011. Read more: "Special report: After Japan's megaquake" The recent cluster of huge quakes around the Pacific Ocean has fuelled speculation that they are seismically linked.
New Scientist examines the evidence AT 2.46 pm local time on Friday last week, Japan shook like never before. Klystron. Low-power Russian reflex klystron from 1963.
The cavity resonator from which the output is taken, is attached to the electrodes labeled Externer Resonator. Reflex klystrons are almost obsolete now. A klystron is a specialized linear-beam vacuum tube, invented in 1937 by American electrical engineers Russel and Sigurd Varian,[1] which is used as an amplifier for high frequencies, from UHF radio frequencies up into the microwave range. Low-power klystrons are used as local oscillators in superheterodyne radar receivers, while high-power klystrons are used as output tubes in UHF television transmitters, microwave relay, satellite communication, and radar transmitters, and to generate the drive power for modern particle accelerators. Many klystrons use waveguides for coupling microwave energy into and out of the device, although it is also quite common for lower power and lower frequency klystrons to use coaxial cable couplings instead.
History[edit] Space charge. Space charge is a concept in which excess electric charge is treated as a continuum of charge distributed over a region of space (either a volume or an area) rather than distinct point-like charges.
This model typically applies when charge carriers have been emitted from some region of a solid—the cloud of emitted carriers can form a space charge region if they are sufficiently spread out, or the charged atoms or molecules left behind in the solid can form a space charge region. Agile* - Journal - D is for Domain. Domain is a term used to describe a variable for which a set of functions or signals are defined.
Time-domain describes functions or signals that change over time; depth-domain describes functions or signal that change over space. The oscillioscope, geophone, and heartrate monitor are tools used to visualize real-world signals in the time domain. The map, photograph, and well log are tools to describe signals in the depth (spatial) domain. Because seismic waves are recorded in time (jargon: time series), seismic data are naturally presented and interpreted with time as the z-axis. Routinely though, geoscientists must convert data and data objects between the time and depth domain. Gravitational waves. Vibrations in the fabric of spacetime which travel at the speed of light and are predicted by Einstein's general theory of relativity.
The most intense gravitational waves, resulting from large masses undergoing high accelerations, are expected to be produced when stars collapse or matter falls into a black hole. Although they have yet to be detected, compelling evidence for their existence has come from radio-wave observations of the only known binary star in which both components are neutron stars, and also from visible-light observations of a pair of white dwarfs. A gradual, minuscule increase in the orbital period of these systems can be accounted for exactly if energy is being lost by gravitational waves at the rate predicted by general relativity.
The physics of gravitational waves In general relativity, massive objects affect the way that spacetime curves. If general relativity is to be believed, the universe should be awash with gravitational waves. In principle.
Fusion. The Dark-Horse Lab That Just Might Figure Out Fusion. “Break-even” is the goal of all fusion researchers.
This is the point at which the amount of energy coming out of the fusion reactions equals the amount of energy needed to maintain the plasma. No fusion experiment has yet reached that point. Gravity-Wave Detector Takes a Break; Will Return Bigger & Badder. Gravity, by George Gamow [Special Archive Article] Editor's note: This article originally appeared in the March 1961 issue of Scientific American. In the days when civilized men believed that the world was flat they had no reason to think about gravity. There was up and down. All material things tended naturally to move downward, or to fall, and no one thought to ask why.
Dark Energy/Matter. Quantum Physics. The Mechanical Battery. In a world where everything from our automobiles to our underwear may soon run on electricity, more efficient portable power is a major concern. After a century of stagnation, chemical and ultracapacitor batteries have recently made some strides forward, and more are on the horizon. But the most promising way of storing energy for the future might come from a more unlikely source, and one that far predates any battery: the flywheel. In principle, a flywheel is nothing more than a wheel on an axle which stores and regulates energy by spinning continuously. Ongoing research, however, suggests that humanity has yet to seize the true potential of the flywheel.
Scientists Create the World’s First Anti-Laser.