Vocab v50

"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man."

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"Those that can make you believe absurdities can make you commit atrocities" - Voltaire

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"diverse" means now "not white"

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A compressed spring is heavier than a relaxed spring.

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Mold spores can be asexual (the products of mitosis) or sexual (the products of meiosis); many species can produce both types.

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The element Selenium conducts electricity only when a light is shined on it. In the dark, it is an insulator. As selenium(Se) element number is 34 having 2 ½ spins are vacancy. So, it mostly it acts as photocells which takes the energy from sun as solar energy as charge. Obviously, we can say it acts as conductor in light conditions and insulator in dark conditions. So, that again it needs light to act as conductor.

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Black hole starship

A black hole starship is a theoretical idea for enabling interstellar travel by propelling a starship by using a black hole as the energy source. The concept was first discussed in science fiction, notably in the book Imperial Earth by Arthur C. Clarke, and in the work of Charles Sheffield, in which energy extracted from a Kerr-Newman black hole is described as powering the rocket engines in the story "Killing Vector" (1978). In a more detailed analysis, a proposal to create an artificial black hole and using a parabolic reflector to reflect its Hawking radiation was discussed in 2009 by Louis Crane and Shawn Westmoreland.[2] Their conclusion was that it was on the edge of possibility, but that quantum gravity effects that are presently unknown will either make it easier, or make it impossible.[3] Similar concepts were also sketched out by Bolonkin. Although beyond current technological capabilities, a black hole starship offers some advantages compared to other possible methods. For example, in nuclear fusion or fission, only a small proportion of the mass is converted into energy, so enormous quantities of material would be needed. Thus, a nuclear starship would greatly deplete Earth of fissile and fusile material. One possibility is antimatter, but the manufacturing of antimatter is hugely energy-inefficient, and antimatter is difficult to contain. The Crane and Westmoreland paper states:

blackbody spectrum

A blackbody is a theoretical or model body which absorbs all radiation falling on it, reflecting or transmitting none. ... The spectral distribution of the thermal energy radiated by a blackbody (i.e. the pattern of the intensity of the radiation over a range of wavelengths or frequencies) depends only on its temperature.

hernia

A bulging of an organ or tissue through an abnormal opening. A hernia occurs when an organ pushes through an opening in the muscle or tissue that holds it in place. For example, the intestines may break through a weakened area in the abdominal wall. Many hernias occur in the abdomen between your chest and hips, but they can also appear in the upper thigh and groin areas

dust mite

A cosmopolitan pyroglyphidae that lives in human habitation. Allergens, such as Der p 1, produced by house dust mites are among the most common triggers of asthma. The average life cycle for a house dust mite is 65-100 days. A mated female house dust mite can live up to 70 days, laying 60 to 100 eggs in the last five weeks of her life. In a 10-week life span, a house dust mite will produce approximately 2,000 fecal particles and an even larger number of partially digested enzyme-covered dust particles. They feed on skin flakes from animals, including humans, and on some mold. Dermatophagoides farinae fungal food choices in 16 tested species commonly found in homes was observed in vitro to be Alternaria alternata, Cladosporium sphaerospermum, and Wallemia sebi, and they disliked Penicillium chrysogenum, Aspergillus versicolor, and Stachybotrys chartarum. House dust mites, due to their very small size and translucent bodies, are barely visible to the unaided eye.

Diode

A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diode vacuum tube or thermionic diode is a vacuum tube with two electrodes, a heated cathode and a plate, in which electrons can flow in only one direction, from cathode to plate. A semiconductor diode, the most commonly used type today, is a crystalline piece of semiconductor material with a p-n junction connected to two electrical terminals.[4] Semiconductor diodes were the first semiconductor electronic devices. The discovery of asymmetric electrical conduction across the contact between a crystalline mineral and a metal was made by German physicist Ferdinand Braun in 1874. Today, most diodes are made of silicon, but other materials such as gallium arsenide and germanium are also used. The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forward direction), while blocking it in the opposite direction (the reverse direction). As such, the diode can be viewed as an electronic version of a check valve. This unidirectional behavior is called rectification, and is used to convert alternating current (ac) to direct current (dc). Forms of rectifiers, diodes can be used for such tasks as extracting modulation from radio signals in radio receivers.

Flyback diode

A flyback diode is a diode connected across an inductor used to eliminate flyback, which is the sudden voltage spike seen across an inductive load when its supply current is suddenly reduced or interrupted. It is used in circuits in which inductive loads are controlled by switches, and in switching power supplies and inverters.

Fusion rocket

A fusion rocket is a theoretical design for a rocket driven by fusion propulsion which could provide efficient and long-term acceleration in space without the need to carry a large fuel supply. The design relies on the development of fusion power technology beyond current capabilities, and the construction of rockets much larger and more complex than any current spacecraft. A smaller and lighter fusion reactor might be possible in the future when more sophisticated methods have been devised to control magnetic confinement and prevent plasma instabilities. Inertial fusion could provide a lighter and more compact alternative, as might a fusion engine[1] based on a field-reversed configuration. Fusion nuclear pulse propulsion is one approach to using nuclear fusion energy to provide propulsion for rockets. For space flight, the main advantage of fusion would be the very high specific impulse, and the main disadvantage the (likely) large mass of the reactor. However, a fusion rocket may produce less radiation than a fission rocket, reducing the mass needed for shielding. The surest way of building a fusion rocket with current technology is to use hydrogen bombs as proposed in Project Orion, but such a spacecraft would also be massive and the Partial Nuclear Test Ban Treaty prohibits the use of nuclear bombs. Therefore, the use of nuclear bombs to propel rockets on Earth is problematic, but possible in space in theory. An alternate approach would be electrical (e.g. ion) propulsion with electric power generation via fusion power instead of direct thrust.

microbe

A microorganism, or microbe,[a] is a microscopic organism, which may exist in its single-celled form or in a colony of cells.

Quadrupole

A quadrupole or quadrapole is one of a sequence of configurations of things like electric charge or current, or gravitational mass that can exist in ideal form, but it is usually just part of a multipole expansion of a more complex structure reflecting various orders of complexity.

recombinant protein vaccine

A recombinant vaccine is a vaccine produced through recombinant DNA technology. This involves inserting the DNA encoding an antigen (such as a bacterial surface protein) that stimulates an immune response into bacterial or mammalian cells, expressing the antigen in these cells and then purifying it from them.

Resonant transformer

A resonant transformer is a transformer in which one or both windings has a capacitor across it and functions as a tuned circuit. Used at radio frequencies, resonant transformers can function as high Q factor bandpass filters. The transformer windings have either air or ferrite cores and the bandwidth can be adjusted by varying the coupling (mutual inductance). One common form is the IF (intermediate frequency) transformer, used in superheterodyne radio receivers. They are also used in radio transmitters.

Silverfish

A silverfish (Lepisma saccharina) is a small, primitive, wingless insect in the order Zygentoma (formerly Thysanura). Its common name derives from the animal's silvery light grey colour, combined with the fish-like appearance of its movements. The scientific name (L. saccharina) indicates the silverfish's diet consists of carbohydrates such as sugar or starches. Before silverfish reproduce, they carry out a ritual involving three phases, which may last over half an hour. In the first phase, the male and female stand face to face, their quivering antennae touching, then repeatedly back off and return to this position. In the second phase, the male runs away and the female chases him. In the third phase, the male and female stand side by side and head to tail, with the male vibrating his tail against the female.[10] Finally, the male lays a spermatophore, a sperm capsule covered in gossamer, which the female takes into her body via her ovipositor to fertilize her eggs. The female lays groups of fewer than 60 eggs at once, deposited in small crevices.[11] The eggs are oval-shaped, whitish, about 0.8 mm (0.031 in) long,[12] and take between two weeks and two months to hatch. A silverfish usually lays fewer than 100 eggs in her lifetime.[1]

Tattoo machine

A tattoo machine is a hand-held device generally used to create a tattoo, a permanent marking of the skin with indelible ink. Modern tattoo machines use electromagnetic coils to move an armature bar up and down. Connected to the armature bar is a barred needle grouping that pushes ink into the skin. Tattoo artists generally use the term "machine", pen, or even "iron", to refer to their equipment. The word "gun" is occasionally used but is widely considered derogatory or even offensive by some professional artists. In addition to "coiled" tattoo machines, there are also rotary tattoo machines, which are powered by regulated motors rather than electromagnetic coils. "The basic machine is pretty much unchanged today, in recent years variations of the theme have crept into the market, namely Manfred Kohr's Rotary machine of 1976 or Carson Hill's pneumatic machine that uses compressed air rather than electricity, but the principle is essentially the same."[1]

Thyristor

A thyristor (/θaɪˈrɪstər/) is a solid-state semiconductor device with four layers of alternating P- and N-type materials. It acts exclusively as a bistable switch, conducting when the gate receives a current trigger, and continuing to conduct until the voltage across the device is reversed biased, or until the voltage is removed (by some other means). There are two designs, differing in what triggers the conducting state. In a three-lead thyristor, a small current on its Gate lead controls the larger current of the Anode to Cathode path. In a two-lead thyristor, conduction begins when the potential difference between the Anode and Cathode themselves is sufficiently large (breakdown voltage). The first thyristor devices were released commercially in 1956. Because thyristors can control a relatively large amount of power and voltage with a small device, they find wide application in control of electric power, ranging from light dimmers and electric motor speed control to high-voltage direct-current power transmission. Thyristors may be used in power-switching circuits, relay-replacement circuits, inverter circuits, oscillator circuits, level-detector circuits, chopper circuits, light-dimming circuits, low-cost timer circuits, logic circuits, speed-control circuits, phase-control circuits, etc. Originally, thyristors relied only on current reversal to turn them off, making them difficult to apply for direct current; newer device types can be turned on and off through the control gate signal. The latter is known as a gate turn-off thyristor, or GTO thyristor. A thyristor is not a proportional device like a transistor. In other words, a thyristor can only be fully on or off, while a transistor can lie in between on and off states. This makes a thyristor unsuitable as an analog amplifier, but useful as a switch.

Voltage multiplier

A voltage multiplier is an electrical circuit that converts AC electrical power from a lower voltage to a higher DC voltage, typically using a network of capacitors and diodes. Voltage multipliers can be used to generate a few volts for electronic appliances, to millions of volts for purposes such as high-energy physics experiments and lightning safety testing. The most common type of voltage multiplier is the half-wave series multiplier, also called the Villard cascade (but actually invented by Heinrich Greinacher).

full e=mc equation

Also E=mc^2 is the low-momentum approximation, the full equation is E^2 = m^2 c^4 + p^2 c^2 where p is the relativistic momentum. Gravity and quantum mechanics can alter the results given by special relativity.

spacetime interval

An "interval" in spacetime is analogous to a "distance" in space or a "duration" in time. Where a distance is the difference in location between two points in space, and a duration is the difference between to instants in time, an interval is the difference between two events in spacetime.

Einstein ring

An Einstein ring, also known as an Einstein-Chwolson ring or Chwolson ring, is created when light from a galaxy or star passes by a massive object on route to the Earth. Due to gravitational lensing, the light is diverted, making it seem to come from different places.

LC circuit

An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together. The circuit can act as an electrical resonator, an electrical analogue of a tuning fork, storing energy oscillating at the circuit's resonant frequency. LC circuits are used either for generating signals at a particular frequency, or picking out a signal at a particular frequency from a more complex signal; this function is called a bandpass filter. They are key components in many electronic devices, particularly radio equipment, used in circuits such as oscillators, filters, tuners and frequency mixers.

Antimatter rocket

An antimatter rocket is a proposed class of rockets that use antimatter as their power source. There are several designs that attempt to accomplish this goal. The advantage to this class of rocket is that a large fraction of the rest mass of a matter/antimatter mixture may be converted to energy, allowing antimatter rockets to have a far higher energy density and specific impulse than any other proposed class of rocket. Antimatter rockets can be divided into three types of application: those that directly use the products of antimatter annihilation for propulsion, those that heat a working fluid or an intermediate material which is then used for propulsion, and those that heat a working fluid or an intermediate material to generate electricity for some form of electric spacecraft propulsion system. The propulsion concepts that employ these mechanisms generally fall into four categories: solid core, gaseous core, plasma core, and beamed core configurations. The alternatives to direct antimatter annihilation propulsion offer the possibility of feasible vehicles with, in some cases, vastly smaller amounts of antimatter but require a lot more matter propellant.[2] Then there are hybrid solutions using antimatter to catalyze fission/fusion reactions for propulsion.

Angiotensin converting enzyme 2 (ACE2)

An enzyme attached to the outer surface (cell membranes) of cells in the lungs, arteries, heart, kidney, and intestines. ACE2 lowers blood pressure by catalysing the cleavage of angiotensin II (a vasoconstrictor peptide) into angiotensin 1-7 (a vasodilator). ACE2 also serves as the entry point into cells for some coronaviruses. ACE2 counters the activity of the related angiotensin-converting enzyme (ACE) by reducing the amount of angiotensin-II and increasing Ang(1-7)[11] making it a promising drug target for treating cardiovascular diseases. ACE2 is a single-pass type I membrane protein, with its enzymatically active domain exposed on the surface of cells in lungs and other tissues.[14] The extracellular domain of ACE2 is cleaved from the transmembrane domain by another enzyme known as sheddase, and the resulting soluble protein is released into the blood stream and ultimately excreted into urine. Furthermore, according to studies conducted on mice, the interaction of the spike protein of the coronavirus with ACE2 induces a drop in the levels of ACE2 in cells through internalization and degradation of the protein and hence may contribute to lung damage.

Uninterruptible power supply

An uninterruptible power supply or uninterruptible power source (UPS) is an electrical apparatus that provides emergency power to a load when the input power source or mains power fails. A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions, by supplying energy stored in batteries, supercapacitors, or flywheels. The on-battery run-time of most uninterruptible power sources is relatively short (only a few minutes) but sufficient to start a standby power source or properly shut down the protected equipment. It is a type of continual power system. A UPS is typically used to protect hardware such as computers, data centers, telecommunication equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss. UPS units range in size from units designed to protect a single computer without a video monitor (around 200 volt-ampere rating) to large units powering entire data centers or buildings. The world's largest UPS, the 46-megawatt Battery Electric Storage System (BESS), in Fairbanks, Alaska, powers the entire city and nearby rural communities during outages.[1]

battery

Batteries convert chemical energy directly to electrical energy. In many cases, the electrical energy released is the difference in the cohesive[13] or bond energies of the metals, oxides, or molecules undergoing the electrochemical reaction.[3] For instance, energy can be stored in Zn or Li, which are high-energy metals because they are not stabilized by d-electron bonding, unlike transition metals. Batteries are designed such that the energetically favorable redox reaction can occur only if electrons move through the external part of the circuit. A battery consists of some number of voltaic cells. Each cell consists of two half-cells connected in series by a conductive electrolyte containing metal cations. One half-cell includes electrolyte and the negative electrode, the electrode to which anions (negatively charged ions) migrate; the other half-cell includes electrolyte and the positive electrode, to which cations (positively charged ions) migrate. Cations are reduced (electrons are added) at the cathode, while metal atoms are oxidized (electrons are removed) at the anode.[14] Some cells use different electrolytes for each half-cell; then a separator is used to prevent mixing of the electrolytes while allowing ions to flow between half-cells to complete the electrical circuit.

how perseus killed medusa?

Because the gaze of Medusa turned all who looked at her to stone, Perseus guided himself by her reflection in a shield given him by Athena and beheaded Medusa as she slept. He then returned to Seriphus and rescued his mother by turning Polydectes and his supporters to stone at the sight of Medusa's head.

Commodore 64

Best selling computer of all time brought gaming into homes The Commodore 64, also known as the C64 or the CBM 64, is an 8-bit home computer introduced in January 1982 by Commodore International.

Bloody Bosons

Bosons and fermions behave quite differently. It is impossible for two fermions to ever be in the same sate: that's why electrons in atom must have different orbits and not stay all in the lower-energy one which, in turn, is why we have Chemistry. However, bosons have no problem occupying the same state: you can fit as many as you like in a crowded room. In the comic above, the guy with the little laces in his head is a photon, which is a type of boson. The guy with the crazy hair is a strange quark, which is a type of fermion. At normal temperatures, bosons and fermions behave very similarly. However, at lower temperatures most particles want to be in the lowest energy state. Fermions don't have a choice: only one of them can be fortunate enough to chill in low-energy paradise. But bosons don't have to compromise: each and every one of them can have that lowest energy. This is what allows phenomena such as superconductivity, where all electrons form pairs that behave just like bosons, allowing electric current to flow without resistance. This is the principle behind technological feats like the Maglev train. It is also the physical principle that allows the existence of Bose-Einstein condensates, a state of matter different from solids, gases, liquids or plasmas. In Bose-Einstein condensates, all bosons occupy the lower energy state and therefore behave as if they were only one particle. This allows them to perform seemingly illogical feats, like escaping out of a recipient by climbing its walls.

Bug zapper

Bug zappers are usually housed in a protective cage of plastic or grounded metal bars to prevent people or larger animals from touching the high voltage grid. A light source is fitted inside, often a fluorescent lamp designed to emit both visible and ultraviolet light, which is visible to insects and attracts them.[4] [5] The light is surrounded by a pair of interleaved bare wire grids or spirals. The distance between adjacent wires is typically about 2 mm (0.079 in). A high-voltage power supply powered by mains electricity, which may be a simple transformerless voltage multiplier circuit made with diodes and capacitors, generates a voltage of 2,000 volts or more, high enough to conduct through the body of an insect which bridges the two grids, but not high enough to spark across the air gap. Enough electric current flows through the small body of the insect to heat it to a high temperature.[6] The impedance of the power supply and the arrangement of the grid is such that it cannot drive a dangerous current through the body of a human. Many bug zappers are fitted with trays that collect the electrocuted insects; other models are designed to allow the debris to fall to the ground below. Some use a fan to help to trap the insect.

interferometer

Collection of two or more telescopes working together as a team, observing the same object at the same time and at the same wavelength. The effective diameter of an interferometer is equal to the distance between its outermost telescopes.

how many satellites does earth have?

Currently there are over 2218 artificial satellites orbiting the Earth. Heliocentric orbit: An orbit around the Sun. In our Solar System, all planets, comets, and asteroids are in such orbits, as are many artificial satellites and pieces of space debris.

how do our cells proofread DNA after its copied?

During DNA synthesis, most DNA polymerases "check their work," fixing the majority of mispaired bases in a process called proofreading. Immediately after DNA synthesis, any remaining mispaired bases can be detected and replaced in a process called mismatch repair. If DNA gets damaged, it can be repaired by various mechanisms, including chemical reversal, excision repair, and double-stranded break repair.

Electrical resonance

Electrical resonance occurs in an electric circuit at a particular resonant frequency when the impedances or admittances of circuit elements cancel each other. In some circuits, this happens when the impedance between the input and output of the circuit is almost zero and the transfer function is close to one. Resonance of a circuit involving capacitors and inductors occurs because the collapsing magnetic field of the inductor generates an electric current in its windings that charges the capacitor, and then the discharging capacitor provides an electric current that builds the magnetic field in the inductor. This process is repeated continually. An analogy is a mechanical pendulum, and both are a form of simple harmonic oscillator.

inflationary multiverse

Eternal inflation is a hypothetical inflationary universe model, which is itself an outgrowth or extension of the Big Bang theory. According to eternal inflation, the inflationary phase of the universe's expansion lasts forever throughout most of the universe. Because the regions expand exponentially rapidly, most of the volume of the universe at any given time is inflating. Eternal inflation, therefore, produces a hypothetically infinite multiverse, in which only an insignificant fractal volume ends inflation. It's hard to build models of inflation that don't lead to a multiverse. It's not impossible, so I think there's still certainly research that needs to be done. But most models of inflation do lead to a multiverse, and evidence for inflation will be pushing us in the direction of taking the idea of a multiverse seriously.[21] According to Linde, "It's possible to invent models of inflation that do not allow a multiverse, but it's difficult. Every experiment that brings better credence to inflationary theory brings us much closer to hints that the multiverse is real."[21]

Electron-positron annihilation

Every particle has its antiparticle, which is an exact copy of itself with opposite charge. Sometimes antiparticles have special names, like the positron, the anti-particle of the electron. Sometimes those names are boring: the muon has the anti-muon, the neutrino has the anti-neutrino and so on. Because particles and antiparticles are equal in all aspects except for charge, they can annihilate: when they meet, they vaporize into a bunch of photons, at least two of them. A classic example of this is electron-positron annihilation, which happens when an electron bumps into a positron. Antiparticles were predicted for the first time by Paul Dirac. Dirac's suggestion was a bit weird: he thought we live in a sea of negative-energy particles and that positrons are "holes" in that sea. Nowadays we have abandoned the idea of a negative-energy sea, but the positron has stayed with us. So what is a positron exactly? One way to look at it is as an electron going back in time. This was a favorite of Richard Feynman, though other physicists may tell you that positrons are just regular, positively-charged particles and that's that. I will stick to the "going back in time" picture because it is way cooler. To understand how this work, we need to know a bit about how quantum particles work, Quantum particles come with a timer on them. You can imagine it as a tiny clock that spins as time passes. How fast this clock spins is related to the energy of the particle: a high-energy particle's clock will spin faster. In quantum mechanics we call this the "phase" of the particle and it is an abstract mathematical property, but you can imagine it as a clock and you won't be far from the truth. What happens when the energy is negative? It turns out the clock spins the opposite way. So negative energy is really related to how this particle moves in time, just like momentum is related to how it moves in space. By convention, positive momentum tells us a particle moves to the right; by convention, positive-energy particles move towards the future, whereas the other ones do so towards the past. So what will a particle travelling back in time do? Exactly the opposite as one that travels forward. If, for example, the electron is attracted to a proton, then the positron will be repelled. Which means that the positron appears, to all intents an purposes, as an exact copy of the electron with positive charge. Antiparticles do not have negative energy. If they did, when they annihilated with an electron there would be nothing left. Instead, we get photons with a combined energy of roughly twice the mass of an electron. However, is it possible that anti-particles have negative mass? The short answer is we don't know. Gravity is really hard to probe at small distances, because any other force is way, way stronger. So there is no way, for now, to measure the gravitational force between, say, an electron and a positron. If anti-particles did have mass, they would attract each other and be repelled by regular particles. The fact that anti-particles have positive energy would point to the fact that they also need to have positive mass, if you believe in Einstein's theory. Like everything in physics, we won't know until we do the experiment.

time is dependent on motion

Example: time dilation and the speed of light Yes, both motion and time are interdependent. ... If we see closely very motion notations here (Speed, Velocity, acceleration) are dependent upon change in time (they are inversely proportional to time). On basic level, this explains the concept of motion- time relation.

superluminal speeds

Faster-than-light communications and travel are the conjectural propagation of information or matter faster than the speed of light. The special theory of relativity implies that only particles with zero rest mass may travel at the speed of light.

What would happen if you wore anything metallic during an MRI?

Ferromagnetic metals? - Bad times ahead. Ferromagnetic metals include your irons, steels, cobalt and nickel. Even stainless steels designed to be non-magnetic can become magnetic if manipulated inappropriately, or exposed to a high enough magnetic field. There are sad case reports of patients being injured or killed by magnetic objects brought into the room with them - often oxygen cylinders. Within a person, ferrous clips for aneurysm repair, metal shards in the eyes from welding, shrapnel from combat injuries... all can cause damage when accelerated towards the magnet. I should also mention that the fields will wipe bank cards and potentially destroy or cause damage to expensive electronics. As for pacemakers, the older devices which contain ferromagnetic materials... see above. If you wear a gold necklace during an MRI scan, you will burn your neck.

Formaldehyde

Formaldehyde (systematic name methanal) is a naturally occurring organic compound with the formula CH2O (H−CHO). It is the simplest of the aldehydes (R−CHO). The common name of this substance comes from its similarity and relation to formic acid. Formaldehyde is an important precursor to many other materials and chemical compounds. In 1996, the installed capacity for the production of formaldehyde was estimated at 8.7 million tons per year.[13] It is mainly used in the production of industrial resins, e.g., for particle board and coatings.

Which subatomic particle does each company use in quantum computing?

Google, IBM and Rigetti use transmon qubits; these are basically fancy LC circuits where there is a josephson junction coupled to a superconducting island. Because of this, they are also often referred to as superconducting qubits. The qubit states are the various charge levels that can exist on the circuit; since the lowest two levels are separated in energy with respect to the higher levels, a two-level system arises. Intel also used superconducting qubits, but lately has also been interested in quantum dot qubits. A quantum dot is like a 0-dimensional island on which a single electron can be placed; since the electron is a fermion it has only two natural states (and therefore makes a good qubit). The encoding can also be different, by encoding the qubit into two rather than one electron in the quantum dot. These quantum dots are built on semiconductors (like silicium, known as the go-to material in classical computing). Therefore they are also known as semiconducting qubits. Microsoft is trying a different route: they are trying to built a topological quantum computer. This is a different type of quantum computer where the qubits are encoded in topological states of matter, using quasi-particles known as (non-Abelian) anyons. A likely candidate for a physical implementation is the Majorana fermion, which can act as an anyon. You can think of these quasi-particles as a delocalized pair of electrons on a super-conducting bridge. It is worth noting that this is a considerably harder design than your 'run of the mill' transmons etc, but these topological states are intrinsically protect to many types of noise, thereby reducing or even omitting the need for quantum error correction. D-Wave's systems is based on a yet more different method of quantum computing: the adiabatic quantum computer. The way computations are performed on these computers are not alike the circuit model (which is the most used model, exploited by transmons, super-conducting and semi-conducting qubits and the like). Moreover, the qubits themselves act very differently, and the comparison of 'adiabatic-syle' qubits and 'circuit-type' qubits is not a good or well-defined comparison. An adiabatic quantum computer needs many more qubits to have the same computational power as a circuit-based quantum computer, but they are (at least on paper) equally powerful (in terms of complexity classes). There are also other types of qubits (that are not used by any of the companies you listed). Two to look out for are: Trapped-ion qubits. Qubits are encoded into states of ions; these ions are trapped by optical tweezers (light) and therefore localized and isolated. Photonic quantum computation. Qubits are encoded into degrees of freedom of photons (=light), most often the polarization. These photonic machines normally use the computation model of measurement based or one-way quantum computation, which is comparable to the circuit model but creates all entanglement in the beginning of the computation. There is no clear best implementation (yet). Transmon qubits are the most mature by most standards, but they are relatively big which will give big implications and problems when these devices will be scaled to include millions of qubits. Semiconducting qubits are a very interesting candidate because they are much smaller and implemented on (the very well developed technology of) semiconductors, but not much has been developed. Trapped ions are promising as well, but they can only be manufactured in a line (as a one-dimensional array of qubits). I'm interested to see what will happen with photonic quantum computers; they can be very promising but not many large companies are working on them; the measurement based model of QC is less popular. A topological quantum computer is the dream of many, but for now it seems out of reach in the near future, due to the exceedingly exotic nature of its design.

universe event horizon

In cosmology, the event horizon of the observable universe is the largest comoving distance from which light emitted now can ever reach the observer in the future. ... The boundary past which events cannot ever be observed is an event horizon, and it represents the maximum extent of the particle horizon. A paradox in which you would try to reach the edge of the observable universe at the speed of light while chasing something that is out of your observable view and is also moving at the speed of light. Dark energy accelerates stuff outside of the observable universe so we are unable to see how vast it really is.

Daisy chain (electrical engineering)

In electrical and electronic engineering, a daisy chain is a wiring scheme in which multiple devices are wired together in sequence or in a ring,[1] similar to a garland of daisy flowers. Other than a full, single loop, systems which contain internal loops cannot be called daisy chains.

Antiparallel (electronics)

In electronics, two anti-parallel or inverse-parallel devices are connected in parallel but with their polarities reversed. One example is the TRIAC, which is comparable to two thyristors connected back-to-back (in other words, reverse parallel), but on a single piece of silicon. Two LEDs can be paired this way, so that each protects the other from reverse voltage. A series string of such pairs can be connected to AC or DC power, with an appropriate resistor. Some two-color LEDs are constructed this way, with the 2 dies connected anti-parallel in one chip package. With AC, the LEDs in each pair take turns emitting light, on alternate half-cycles of supply power, greatly reducing the strobing effect to below the normal flicker fusion threshold of the human eye, and making the lights brighter. On DC, polarity can be switched back and forth so as to change the color of the lights, such as in Christmas lights that can be either white or colored.

Supersymmetry

In particle physics, supersymmetry (SUSY) is a conjectured relationship between two basic classes of elementary particles: bosons, which have an integer-valued spin, and fermions, which have a half-integer spin. A type of spacetime symmetry, supersymmetry is a possible candidate for undiscovered particle physics, and seen by some physicists as an elegant solution to many current problems in particle physics if confirmed correct, which could resolve various areas where current theories are believed to be incomplete. A supersymmetrical extension to the Standard Model could resolve major hierarchy problems within gauge theory, by guaranteeing that quadratic divergences of all orders will cancel out in perturbation theory. In supersymmetry, each particle from one group would have an associated particle in the other, which is known as its superpartner, the spin of which differs by a half-integer. These superpartners would be new and undiscovered particles. For example, there would be a particle called a "selectron" (superpartner electron), a bosonic partner of the electron. In the simplest supersymmetry theories, with perfectly "unbroken" supersymmetry, each pair of superpartners would share the same mass and internal quantum numbers besides spin. Since we expect to find these "superpartners" using present-day equipment, if supersymmetry exists then it consists of a spontaneously broken symmetry allowing superpartners to differ in mass. Spontaneously broken supersymmetry could solve many mysterious problems in particle physics including the hierarchy problem. Direct confirmation would entail production of superpartners in collider experiments, such as the Large Hadron Collider (LHC). The first runs of the LHC found no previously-unknown particles other than the Higgs boson which was already suspected to exist as part of the Standard Model, and therefore no evidence for supersymmetry. Indirect methods include the search for a permanent electric dipole moment (EDM) in the known Standard Model particles, which can arise when the Standard Model particle interacts with the supersymmetric particles. The current best constraint on the electron electric dipole moment put it to be smaller than 10−28 e·cm, equivalent to a sensitivity to new physics at the TeV scale and matching that of the current best particle colliders.[8] A permanent EDM in any fundamental particle points towards time-reversal violating physics, and therefore also CP-symmetry violation via the CPT theorem. Such EDM experiments are also much more scalable than conventional particle accelerators and offer a practical alternative to detecting physics beyond the standard model as accelerator experiments become increasingly costly and complicated to maintain.

Resonance

In physics, resonance describes the phenomena of amplification[citation needed] that occurs when the frequency of a periodically applied force is in harmonic proportion[citation needed] to a natural frequency of the system on which it acts. When an oscillating force is applied at a resonant frequency of a dynamical system, the system will oscillate at a higher amplitude than when the same force is applied at other, non-resonant frequencies. Frequencies at which the response amplitude is a relative maximum are also known as resonant frequencies or resonance frequencies of the system.[3] Small periodic forces that are near a resonant frequency of the system have the ability to produce large amplitude oscillations in the system due to the storage of vibrational energy. Resonance phenomena occur with all types of vibrations or waves: there is mechanical resonance, acoustic resonance, electromagnetic resonance, nuclear magnetic resonance (NMR), electron spin resonance (ESR) and resonance of quantum wave functions. Resonant systems can be used to generate vibrations of a specific frequency (e.g., musical instruments), or pick out specific frequencies from a complex vibration containing many frequencies (e.g., filters). Resonance occurs when a system is able to store and easily transfer energy between two or more different storage modes (such as kinetic energy and potential energy in the case of a simple pendulum). However, there are some losses from cycle to cycle, called damping. When damping is small, the resonant frequency is approximately equal to the natural frequency of the system, which is a frequency of unforced vibrations. Some systems have multiple, distinct, resonant frequencies.

Rayleigh-Jeans law

In physics, the Rayleigh-Jeans Law is an approximation to the spectral radiance of electromagnetic radiation as a function of wavelength from a black body at a given temperature through classical arguments.

Transmon

In quantum computing, and more specifically in superconducting quantum computing, a transmon is a type of superconducting charge qubit that was designed to have reduced sensitivity to charge noise. The transmon was developed by Robert J. Schoelkopf, Michel Devoret, Steven M. Girvin and their colleagues at Yale University in 2007.[1][2] Its name is an abbreviation of the term transmission line shunted plasma oscillation qubit; one which consists of a Cooper-pair box "where the two superconductors are also capacitatively shunted in order to decrease the sensitivity to charge noise, while maintaining a sufficient anharmonicity for selective qubit control".

Kugelblitz (astrophysics)

In theoretical physics, a kugelblitz (German: "ball lightning") is a concentration of heat, light or radiation so intense that its energy forms an event horizon and becomes self-trapped: according to general relativity and the equivalence of mass and energy, if enough radiation is aimed into a region, the concentration of energy can warp spacetime enough for the region to become a black hole, although this would be a black hole whose original mass-energy had been in the form of radiant energy rather than matter.[1] In simpler terms, a kugelblitz is a black hole formed from radiation as opposed to matter. Such a black hole would nonetheless have properties identical to one of equivalent mass and angular momentum formed in a more conventional way, in accordance with the no-hair theorem. The best-known reference to the kugelblitz idea in English is probably John Archibald Wheeler's 1955 paper "Geons",[2] which explored the idea of creating particles (or toy models of particles) from spacetime curvature, called geons. Wheeler's paper on geons also introduced the idea that lines of electric charge trapped in a wormhole throat might be used to model the properties of a charged particle-pair. Kugelblitz drives have been considered as possible future black hole starship engines.

how many people have stepped on the moon?

In total 12 astronauts have walked on the moon, including Armstrong and Aldrin. The other 10 who made it to the moon took part in five further Nasa launches, between 1969 and 1972. These missions were undertaken by Apollo 12, Apollo 14, Apollo 15, Apollo 16 and Apollo 17

Why do most aircraft use 400 Hz AC instead of 60hz AC?

Induction motors turn at a speed proportional to frequency, so a high frequency power supply allows more power to be obtained for the same motor volume and mass. Transformers and motors for 400 Hz are much smaller and lighter than at 50 or 60 Hz, which is an advantage in aircraft (and ships). Transformers can be made smaller because the magnetic core can be much smaller for the same power level. Thus, a United States military standard MIL-STD-704 exists for aircraft use of 400 Hz power. So why not use 400 Hz everywhere? Such high frequencies cannot be economically transmitted long distances, since the increased frequency greatly increases series impedance due to the inductance of transmission lines, making power transmission difficult. Consequently, 400 Hz power systems are usually confined to a building or vehicle.

Quark Color

Just like electrons have charge, quarks have color. Of course, they are not actual colors: those are simply wavelengths of electromagnetic radiation. We call them colors because there are three of them, so it seemed a good way to label them. So "quark color" is a funny way of talking about quark charge. There are two types of electrical charge: plus and minus. This seems natural, but only because you're used to it. Why aren't there three types? Or forty? This is the case for the strong interaction: there are three types of "charge" that we call "blue", "red" and "green". In fact, there's also the "anti" version of each, so we have six types: blue and anti-blue, red and anti-red, green and anti-green. The difference between the strong interaction and the electric force is that the strong interaction is much stronger (hence the name). Imagine for a moment that the electric force was really, really strong: would you ever see a charged object? Probably not: if the force was so large, it would be almost impossible to separate negative and positive charges, so you would only see neutral objects. Anything that got a charge would instantly be attracted to something with the opposite charge and get neutralized. This is what happens with the strong interaction: it is so strong that we never see a combination of quarks that is not "neutral." In this case, "neutral" means that the color combination has to add up to white. In fact, it is impossible to see a quark on its own: this phenomenon is called confinement. three different quarks with a different color each: red, blue and green make white, just like with actual, real-life colors. The other way is to take two quarks with opposite colors: blue and anti-blue, red and anti-red, etc. Just like opposite charges cancel out, so do opposite colors. All particles made of quarks are called "hadrons." The proton is an example of a white particle with three quarks. We call these particles "baryons." A proton has two "up" quarks and a "down" quark. Each quark has a different colour, like in the picture to the right. The neutron is made of two "down" quarks and an "up" quark and is also "white" like the proton. In fact, as far as the strong force is concerned, the proton and neutron are pretty much the same particle. The other type of white particle is called a "meson". Mesons are made of a quark and an anti-quark, so that the anti-quark has an anti-color. For example, the π+ is made of an up and an anti-down quark. If the up is blue, then the anti-down will be anti-bue and so on. There are many different mesons which typically do not last much.

Cherenkov radiation

Light emitted by fast-moving charged particles traversing a dense transparent medium faster than the speed of light in that medium. Cherenkov radiation is electromagnetic radiation emitted when a charged particle passes through a dielectric medium at a speed greater than the phase velocity of light in that medium. The characteristic blue glow of an underwater nuclear reactor is a completely normal phenomenon due to Cherenkov radiation. image is of a nuclear reactor

Mismatch repair

Many errors are corrected by proofreading, but a few slip through. Mismatch repair happens right after new DNA has been made, and its job is to remove and replace mis-paired bases (ones that were not fixed during proofreading). Mismatch repair can also detect and correct small insertions and deletions that happen when the polymerases "slips," losing its footing on the template. How does mismatch repair work? First, a protein complex (group of proteins) recognizes and binds to the mispaired base. A second complex cuts the DNA near the mismatch, and more enzymes chop out the incorrect nucleotide and a surrounding patch of DNA. A DNA polymerase then replaces the missing section with correct nucleotides, and an enzyme called a DNA ligase seals the gap. One thing you may wonder is how the proteins involved in DNA repair can tell "who's right" during mismatch repair. That is, when two bases are mispaired (like the G and T in the drawing above), which of the two should be removed and replaced? In bacteria, original and newly made strands of DNA can be told apart by a feature called methylation state. An old DNA strand will have methyl (-CH3) groups attached to some of its bases, while a newly made DNA strand will not yet have gotten its methyl group. In eukaryotes, the processes that allow the original strand to be identified in mismatch repair involve recognition of nicks (single-stranded breaks) that are found only in the newly synthesized DNA.

Mold

Molds are a large and taxonomically diverse number of fungal species in which the growth of hyphae results in discoloration and a fuzzy appearance, especially on food.[3] The network of these tubular branching hyphae, called a mycelium, is considered a single organism. The hyphae are generally transparent, so the mycelium appears like very fine, fluffy white threads over the surface. Cross-walls (septa) may delimit connected compartments along the hyphae, each containing one or multiple, genetically identical nuclei. The dusty texture of many molds is caused by profuse production of asexual spores (conidia) formed by differentiation at the ends of hyphae. The mode of formation and shape of these spores is traditionally used to classify molds.[4] Many of these spores are colored, making the fungus much more obvious to the human eye at this stage in its life-cycle. Molds are considered to be microbes and do not form a specific taxonomic or phylogenetic grouping, but can be found in the divisions Zygomycota and Ascomycota. In the past, most molds were classified within the Deuteromycota. Molds cause biodegradation of natural materials, which can be unwanted when it becomes food spoilage or damage to property. They also play important roles in biotechnology and food science in the production of various foods, beverages, antibiotics, pharmaceuticals and enzymes. Some diseases of animals and humans can be caused by certain molds: disease may result from allergic sensitivity to mold spores, from growth of pathogenic molds within the body, or from the effects of ingested or inhaled toxic compounds (mycotoxins) produced by molds. There are thousands of known species of molds, which have diverse life-styles including saprotrophs, mesophiles, psychrophiles and thermophiles and a very few opportunistic pathogens of humans.[6] They all require moisture for growth and some live in aquatic environments. Like all fungi, molds derive energy not through photosynthesis but from the organic matter on which they live, utilising heterotrophy. Typically, molds secrete hydrolytic enzymes, mainly from the hyphal tips. These enzymes degrade complex biopolymers such as starch, cellulose and lignin into simpler substances which can be absorbed by the hyphae. In this way, molds play a major role in causing decomposition of organic material, enabling the recycling of nutrients throughout ecosystems. Many molds also synthesise mycotoxins and siderophores which, together with lytic enzymes, inhibit the growth of competing microorganisms. Molds can also grow on stored food for animals and humans, making the food unpalatable or toxic and are thus a major source of food losses and illness.[7] Many strategies for food preservation (salting, pickling, jams, bottling, freezing, drying) are to prevent or slow mold growth as well as growth of other microbes. Molds reproduce by producing large numbers of small spores,[6] which may contain a single nucleus or be multinucleate. Mold spores can be asexual (the products of mitosis) or sexual (the products of meiosis); many species can produce both types. Some molds produce small, hydrophobic spores that are adapted for wind dispersal and may remain airborne for long periods; in some the cell walls are darkly pigmented, providing resistance to damage by ultraviolet radiation. Other mold spores have slimy sheaths and are more suited to water dispersal. Mold spores are often spherical or ovoid single cells, but can be multicellular and variously shaped. Spores may cling to clothing or fur; some are able to survive extremes of temperature and pressure.

Forces do not exist

Most people first hear about forces in high school, with Newton. But the reality is that forces do not exist. Instead, what we have is something similar to particle physics tennis: two particles exchange another one and get either closer and closer or further and further apart. Imagine you're in outer space with a friend. You take a tennis ball and you throw it at your friend: now, you are thrown backwards because of recoil. In more physical terms, this is an example of momentum conservation: the momentum the tennis ball carries has to be equal to your momentum going the other way. When your friend catches the ball, they will also be pushed, in this case in the direction of the ball. If they now return the ball to you, the process will happen again and you and your friend will be moving further and further apart from each other. It's as if there was a force pushing you apart: however, there is no force. You are just passing a tennis ball around. With particles, something very similar happens. An electron will give off a photon, a type of boson, which will be caught by another electron. The momentum of that photon will propel both particles in opposite directions, causing what looks as a repulsive force. The force between opposite charges The situation for opposite charges is a bit more complex. My explanation may strike as unorthodox to some particle physicists, but it is the only intuitive one I could find. The trick is to consider opposite charges as if they were moving back in time. Back when Quantum Mechanics was starting, Paul Dirac made a startling discovery: the electron had to have an evil twin with positive charge, which he called the positron. Later on, Richard Feynman suggested you could view these positrons as electrons travelling back in time: a positron will do exactly the opposite of an electron, which means you can't tell between a video of a positron and a video of an electron being played backwards. When dealing with the effects of photons, this becomes important. Imagine an electron gives off a photon, which then hits the positron. An electron would be pushed forward, so the positron will do the exact opposite: it will move towards the electron! Then the positron will also give off photons, but those photons will also do the opposite of what the electron's photons would do: this means that, instead of pushing the electron away, they will pull it closer together! This means that oppositely charged particles will attract, whereas same-charge particles will repel. We can explain all of this using only particles: forces do not exist. Virtual and real particles The story above is understandable and quite close to reality, but far from a complete description. For example, if electrons are giving off photons in all directions, there shouldn't feel pushed in any direction more than any other. The trick here is that only the photon that ends up being absorbed by a nearby particle "counts": the other ones have energies that are too small to have an effect. In fact, all of those photons, including the one that gets absorbed, are undetectable and live only in our calculations: we call them virtual photons. Only the photons we get to detect are real photons. Virtual photons live within the uncertainty principle. They are allowed to exist for a brief time, as long as their energy does not exceed a certain threshold. The less energy they have, the longer they can survive. This is why forces that are transmitted by massive particles, like the weak nuclear force, have such a short range: the virtual particles are not allowed to exist for long enough to get far! However you consider this, one thing is still clear: forces do not exist. They are a side-effect of particle exchange, but have no existence of their own.

After given several talks on NN's, I always have a skeptic that wants a real measure of how well the model is. How do you know the model is truly accurate?

Neural networks are essentially a black box, especially big ones. You could know even how it is designed and how it is training, but you really do not know how it is working in the end. In my work lots of people want to understand the model instead of using "black box" models. This is the reason why companies choose to use linear regressions and polynomial models instead of using stronger machine learning algorithms, like LightGBM and Neural Networks. I never found a true answer to this question. Some engineers are taught that you cannot use models that you cannot understand. Therefore every model that is a "black box" is not usable for them. This means that most of machine learning models are magic and heresy for them. Though take this with a grain of salt, this is my subjective experience. Sometimes as the time passes these people are more willing to use data science methods because it becomes mainstream. They start to trust the methods, because others use them. The situation is different on the higher level. For high-tier managers it matters less how to interpret the model, but more what results it could give you. They are more willing to try, especially if there is a hype of something, like "artificial intelligence", "data science". As a result, I could only give you an advice to find some good support higher in the hierarchy of the company. Someone who believes in data science more and who has more power in the company. In data science community the performance of the model on the test dataset is one of the most important things people look at. Just look at the competitions on kaggle.com. They are extremely focused on test dataset and the performance of these models is really good. The only problem with performance on the test dataset is that it depends on the data in the test dataset. If in real life you will have completely different data that will be outside of the bounds of the test dataset, then the test dataset will not be able to give a good approximation of the performance of the model in real life.

300 Trillion Neutrinos Walk into a Bar

Neutrinos are a type of fermion which has no charge and is extremely light, so much so that most physicists believed it had no mass until quite recently. The thing about neutrinos is that they barely interact with anything: billions go through you every minute without you even noticing. The story of how we found out about neutrinos is great for showing how discoveries are made in science. It all started by looking at a particular type of radioactive decay called beta decay, in which a nucleus gives off an electron. Scientists were expecting to see electrons that were always shot with the same energy, as they had seen in many other decay processes. However, they found that the electrons had a range of energies. Some energy was missing. From there, somebody guessed that the energy had to be carried by another particle, since it couldn't have just vanished. The particle couldn't have any charge, because otherwise the total charge would not add up. And it had to be very light because, if it weren't, it would have to carry a huge chunk of the energy, but there were times when the electron had almost all of it. So we have a small, neutral particle: the neutrino. This chain of reasoning may seem like a bunch of patches on top of patches. Our theory does not predict the right outcome? Add a particle! Wait, but then how does the electron take most of the energy sometimes? It must be light! And why haven't we seen it yet? It has no charge! However, this is how science works: we look for a plausible explanation, which we refine using the data at our disposal. We make new predictions and see if they fit. If not, we throw the new idea away. In some cases, our idea survives and we have a new theory or a new particle, in this case the neutrino. To be precise, the neutrinos from the beta decay are actually antineutrinos: particles which, when set in contact with a neutrino, will annihilate into photons. However, since the neutrinos have no charge, it is almost identical to its anti-particle.

Why Did the Electron Cross the Road?

One of the most surprising properties of elementary particles is that they can be in several places at the same time, at least until they are observed. This happens because particles behave also as waves and, just like those, they can spread, diffract and interfere. A typical case of this is an electron going through a double slit, like in the picture below. However, the electrons are clearly particles: each electron crashes at a particular location, not everywhere on the screen. Even so, the pattern that they create as a whole is the same as that of two waves interfering. It is almost as if what behaved as a wave was the probability of finding the electron there. This is, in fact, what happens. Before being observed, electrons behave as something called a "probability wave": it is like a regular wave, but cannot be observed. When you observe the electron, it stops behaving like a wave and starts behaving like a particle, taking up a definite position just like a regular particle. However, until you observe it, the electron or, at least, its associated probability wave, can be in several places at once. It is possible to take this experiment even further. For example, we could place an electron detector at the slits to find out through which one it really went. This should clear out the confusion and get rid of all that nonsense about the electron going through both slits. If you do this, you will find that the electron does choose one slit instead of going through both: however, the interference pattern will also disappear! Since you observed the electron, it stopped behaving as a wave and started doing what you would expect a bullet to do. So are electrons particles? Are they waves? I find the question doesn't really make sense. We humans are used to seeing rocks and water waves, but that's not what the universe is made of. This is not the "real" stuff. The real stuff is electrons, which are both waves and particles. They are wavicles. It may seem bizarre to use because we have nothing familiar to compare it with. But nature couldn't care less about what we find familiar. Nature does whatever it wants and it is up to us to get rid of our prejudices about reality and listen to what she has to say.

helicity

Physicists call the property of the spin pointing in the same way as the movement "helicity." The problem with helicity is that it depends on who's looking at the particle, so it's not great for distinguishing between left- and right-handed electrons. The property that allows us to distinguish between those is called "chirality." The beauty of chirality is that it does not depend on who's looking; the disadvantage is that there's no easy way to show it in a picture. However, imagining the left- and right-handed particles as mirror images of one another is a good enough analogy. So why is it important to distinguish between left- and right-handed particles? It turns out there are many good reasons. For starters, some forces will only interact with right-handed particles, a bit like teachers in the 1950s. This creates a noticeable difference between the mirror universe and ours and is why the W+ boson in the comic is ignoring the poor left-handed electron. So are actual electrons right- or left-handed? It turns out they are neither. In fact, electrons are a combination of two particles: a right-handed and a left-handed electron. Right- and left-handed electrons are massless: they weigh nothing. Because of this, they travel at the speed of light, just like photons. But real electrons do have mass and do not travel at the speed of light, so what's going on? Right- and left-handed electrons are massless and travel at the speed of light. In fact, they travel at the speed of light because they are massless. But we can turn this reasoning around: they are massless because they travel at the speed of light, they are massless. Only massless things travel at the speed of light. So the reasoning doesn't go like this: Massless → Speed of light Or this: Speed of light → Massless But rather this: Speed of light ↔ Massless In a similar way, we can deduce that, if a particle does not travel at the speed of light, it has mass: Less than the speed of light ↔ Mass This is how the electron acquires mass. A right-handed electron travels at the speed of light and then bumps into a Higgs boson, which turns it into a left-handed electron travelling at an angle, at the speed of light. Then the left-handed electron bumps into another Higgs boson and turns into a right-handed electron, and so on. The result is a random zig-zag motion that, looked at from large enough distances, appears to be a negatively-charged particle travelling at less than the speed of light and therefore with mass. It also implies that the particle is not right- or left-handed but a combination of both. Summarizing: handed electrons have no mass, but "real" electrons do because they are a combination of left- and right-handed electrons. This combination can only happen because of the Higgs boson. That's why we say the Higgs boson gives particles mass.

Pulse-width modulation

Pulse width modulation (PWM), or pulse-duration modulation (PDM), is a method of reducing the average power delivered by an electrical signal, by effectively chopping it up into discrete parts. The average value of voltage (and current) fed to the load is controlled by turning the switch between supply and load on and off at a fast rate. The longer the switch is on compared to the off periods, the higher the total power supplied to the load. Along with MPPT maximum power point tracking, it is one of the primary methods of reducing the output of solar panels to that which can be utilized by a battery.[1] PWM is particularly suited for running inertial loads such as motors, which are not as easily affected by this discrete switching, because they have inertia to react slow. The PWM switching frequency has to be high enough not to affect the load, which is to say that the resultant waveform perceived by the load must be as smooth as possible. The rate (or frequency) at which the power supply must switch can vary greatly depending on load and application. For example, switching has to be done several times a minute in an electric stove; 120 Hz in a lamp dimmer; between a few kilohertz (kHz) and tens of kHz for a motor drive; and well into the tens or hundreds of kHz in audio amplifiers and computer power supplies. The main advantage of PWM is that power loss in the switching devices is very low. When a switch is off there is practically no current, and when it is on and power is being transferred to the load, there is almost no voltage drop across the switch. Power loss, being the product of voltage and current, is thus in both cases close to zero. PWM also works well with digital controls, which, because of their on/off nature, can easily set the needed duty cycle. PWM has also been used in certain communication systems where its duty cycle has been used to convey information over a communications channel. The term duty cycle describes the proportion of 'on' time to the regular interval or 'period' of time; a low duty cycle corresponds to low power, because the power is off for most of the time. Duty cycle is expressed in percent, 100% being fully on. When a digital signal is on half of the time and off the other half of the time, the digital signal has a duty cycle of 50% and resembles a "square" wave. When a digital signal spends more time in the on state than the off state, it has a duty cycle of >50%. When a digital signal spends more time in the off state than the on state, it has a duty cycle of <50%. Here is a pictorial that illustrates these three scenarios:

Quadrupole magnet

Quadrupole magnets, abbreviated as Q-magnets, consist of groups of four magnets laid out so that in the planar multipole expansion of the field, the dipole terms cancel and where the lowest significant terms in the field equations are quadrupole. Quadrupole magnets are useful as they create a magnetic field whose magnitude grows rapidly with the radial distance from its longitudinal axis. This is used in particle beam focusing. The simplest magnetic quadrupole is two identical bar magnets parallel to each other such that the north pole of one is next to the south of the other and vice versa. Such a configuration will have no dipole moment, and its field will decrease at large distances faster than that of a dipole. A stronger version with very little external field involves using a k=3 Halbach cylinder. In some designs of quadrupoles using electromagnets, there are four steel pole tips: two opposing magnetic north poles and two opposing magnetic south poles. The steel is magnetized by a large electric current in the coils of tubing wrapped around the poles. Another design is a Helmholtz coil layout but with the current in one of the coils reversed.

Quantum tunnelling

Quantum tunnelling or tunneling is the quantum mechanical phenomenon where a subatomic particle passes through a potential barrier. Quantum tunnelling is not predicted by the laws of classical mechanics where surmounting a potential barrier requires enough potential energy. good ole' superposition in action bell curves be boolin' doe

Rule 34

Rule 34 is an Internet meme and slang that states that, as a rule, Internet pornography exists concerning every conceivable topic. The concept is commonly depicted as fan art of normally non-erotic subjects engaging in sexual behavior.

Synchronverter

Synchronverters or virtual synchronous generators[1][2] are inverters which mimic synchronous generators[3] to provide "synthetic inertia" for ancillary services in electric power systems.[4] Inertia is a property of standard synchronous generators associated with the rotating physical mass of the system spinning at a frequency proportional to the electricity being generated. Inertia has implications towards grid stability as work is required to alter the kinetic energy the spinning physical mass and therefore opposes changes in grid frequency. Inverter based generation inherently lacks this property as the waveform is being created artificially via power electronics.

particle horizon

The "edge" of the universe. Light beyond this has not reached us yet. The particle horizon is the maximum distance from which light from particles could have traveled to the observer in the age of the universe.

dark matter bullet cluster

The Bullet Cluster (1E 0657-56) consists of two colliding clusters of galaxies. Gravitational lensing studies of the Bullet Cluster are claimed to provide the best evidence to date for the existence of dark matter. The major components of the cluster pair—stars, gas and the putative dark matter—behave differently during collision, allowing them to be studied separately. The stars of the galaxies, observable in visible light, were not greatly affected by the collision, and most passed right through, gravitationally slowed but not otherwise altered. The hot gas of the two colliding components, seen in X-rays, represents most of the baryonic, i.e. ordinary, matter in the cluster pair. The gases interact electromagnetically, causing the gases of both clusters to slow much more than the stars. The third component, the dark matter, was detected indirectly by the gravitational lensing of background objects. In theories without dark matter, such as Modified Newtonian dynamics (MOND), the lensing would be expected to follow the baryonic matter; i.e. the X-ray gas. However, the lensing is strongest in two separated regions near (possibly coincident with) the visible galaxies. This provides support for the idea that most of the mass in the cluster pair is in the form of two regions of dark matter, which bypassed the gas regions during the collision. This accords with predictions of dark matter as only weakly interacting, other than via the gravitational force.

Laser Interferometer Space Antenna (LISA)

The Laser Interferometer Space Antenna (LISA) is a mission led by the European Space Agency to detect and accurately measure gravitational waves[2]—tiny ripples in the fabric of space-time—from astronomical sources.[3] LISA would be the first dedicated space-based gravitational wave detector. It aims to measure gravitational waves directly by using laser interferometry. The LISA concept has a constellation of three spacecraft arranged in an equilateral triangle with sides 2.5 million km long, flying along an Earth-like heliocentric orbit. The distance between the satellites is precisely monitored to detect a passing gravitational wave. LIGO in space

Sloan Digital Sky Survey

The Sloan Digital Sky Survey has created the most detailed three-dimensional maps of the Universe ever made, with deep multi-color images of one third of the sky, and spectra for more than three million astronomical objects. Learn and explore all phases and surveys—past, present, and future—of the SDSS. The Sloan Digital Sky Survey (SDSS) is one of the most extensive and ambitious astronomical surveys undertaken by modern astronomers. In its first two stages, lasting from 2000 to 2008, SDSS mapped almost 30 percent of the northern sky using a dedicated 2.5 meter telescope at the Apache Point Observatory in New Mexico. The survey used a 120-megapixel camera to image over 350 million objects, and collected the spectra of hundreds of thousands of galaxies, quasars, and stars. Notable SDSS discoveries include some of the oldest known quasars and stars moving fast enough to escape from our galaxy. SDSS data has also been used to map the distribution of dark matter around galaxies through observations of weak gravitational lensing and to study the evolution of structure in the universe through observations of how both galaxies and quasars are distributed at different redshifts. The third phase of the survey is scheduled to end in 2014, and is expected to yield many exciting scientific discoveries.

Taser

The Taser fires two small dart-like electrodes, which stay connected to the main unit by conductive wire as they are propelled by small compressed nitrogen charges.[16][17] The cartridge contains a pair of electrodes and propellant for a single shot (or three shots in the X3 model) and is replaced after each use. Stun guns generate a high-voltage, low-amperage electrical charge. In simple terms, this means that the charge has a lot of pressure behind it, but not that much intensity. When you press the stun gun against someone and hold the trigger, the charge passes into that person's body. Conventional stun guns have a fairly simple design. They are about the size of a flashlight, and they work on ordinary 9-volt batteries. ... The circuitry includes multiple transformers, components that boost the voltage in the circuit, typically to between 20,000 and 150,000 volts, and reduce the amperage.

Gravitational waves

The key is something called "gravitational waves." In General Relativity, space and time are not passive spectators, but the source of what we called the gravitational "force." Matter bends space and time around it, which causes trajectories that were initially straight to curve, giving rise to the familiar orbits around the Sun, for example. There is no force: particles just move in a "straight" line, it's just that this straight line is in a curved space. This is similar to being on Earth and starting to walk forward: even though our path feels "straight", we will eventually arrive at the same point because the space we live in is curved. The moment you accept that matter bends space, you realise that the curvature should be able to travel around. If I move my rubber duck back and forth in my bath, it will create ripples moving through the water; in the same way, fast-moving, massive objects will create ripples that move through space. We call these ripples "gravitational waves." Everything creates gravitational waves. However, since gravity is such a weak force, they are really hard to detect. Only massive objects like black holes will emit waves powerful enough to be felt on Earth, at least with current technology. That's why people at LIGO expected to see only events such as the merger of two black holes, which are massive enough and move fast enough to create a noticeable effect. Waves carry energy, it's kind of their thing. The energy carried by a wave is proportional to its frequency (think about it: would you rather be hit in the head 2 or 20 times per second?). When two black holes spin around each other, the frequency of the waves they give off is the same as the frequency of their spin. As they get closer, the black holes spin faster, which means they give off higher energy waves, which means they lose energy faster and get even closer. Therefore, if we ever saw the gravitational waves given off by two black holes merging, we should see waves of a frequency that is increasing faster and faster. This is exactly what LIGO has seen, which is the graph on the last frame of the comic strip. The tricky part in all of this is, of course, seeing the gravitational waves. We know they are a ripple in space and time, but what does that translate to? A ripple in space and time should mean that space contracts and expands periodically between two points. That is, if a gravitational wave goes through you right now, your head will get a bit smaller, then a bit bigger, then back to normal. The problem is that rulers will also shrink and expand, so you can't use them to figure out whether a wave just passed you! Thankfully, there's a way around. What you can do is send a photon between the two points and see how long it takes. Since the speed of light has to be the same for everyone, you should see a difference in the time and use that to detect the wave. But measuring the time it takes for a photon to do anything is not easy, because photons take almost no time to travel between places. What LIGO does is use a phenomenon called interference: it sends two photons against each other and sees if they disappear. This is based on the idea of quantum clocks that I talked about here: every particle has a little timer attached to it, which spins faster or slower depending on the energy of the particle. If two identical particles (like two photons) meet at the same place and their clocks are pointing in opposite directions, they will annihilate: they'll both disappear. I can use this to figure out if a gravitational wave has gone through. To do that, I need an L-shaped device, where I send photons which are perpendicular to each other to a certain point. I make certain that, under normal conditions, the photons disappear: we call this destructive interference. Now, what happens if a gravitational wave goes through my L-shaped device? Then, the length of one of the arms will change. This means that those photons will take longer to reach the same point, which in turn means their quantum clocks will have run for longer than those in the other arm. Therefore, now the quantum clocks of the photons coming from both sides are not exactly opposite any more, which means I should see some photons where there were none. Therefore, every time I detect a photon, it means a gravitational wave went through my device. Clever! The problem, of course, is getting a device that is sensitive enough to detect these differences. In LIGO, the arms are roughly 4 km in length and there are two L-shaped devices, which allows them to pinpoint the location of the source of waves. In general, the bigger the arms, the easier it is to detect the waves, since the change in length is proportional to the length of the arm. In fact, there is already a project under way to build a gravitational wave detector in space! It will be called LISA and made up of satellites beaming lasers at each other. Now you're in a position to understand what LIGO will announce this Thursday: they have seen the merger of two black holes with masses equal to 36 and 29 Suns into a bigger black hole with 62 masses. Now, a some quick math will show you that the total mass of the two black holes is 36 + 29 = 65, whereas the resulting black hole only has 62 solar masses. Where did the 3 missing solar masses go? They were converted into the energy of the gravitational waves. Yes, that's right: just the waves carry the equivalent of 3 solar masses worth of energy. Mind-boggling stuff. Apparently, LIGO have seen the exact frequency increase predicted by Einstein's relativity, which is yet another confirmation of his theory. The merger has been seen by both their devices, with the correct delay between them, showing that gravitational waves travel at the speed of light. Exciting times to be a physicist!

Flashtube

The lamp comprises a hermetically sealed glass tube, which is filled with a noble gas, usually xenon, and electrodes to carry electrical current to the gas. Additionally, a high voltage power source is necessary to energize the gas as a trigger event. A charged capacitor is usually used to supply energy for the flash, so as to allow very speedy delivery of very high electrical current when the lamp is triggered.

Enough sunlight reaches the earth's surface each minute to satisfy the world's energy demands for an entire year.

The total solar energy per second on a surface perpendicular to the Sun is about 1350 Joules per square meter or about 0.275 watt-hours. Taking into account incidence angle and the surface area, the effective energy arriving at the Earth is about 1.75E17 Joules per second. A lot of that is reflected away from clouds.

upper vs lower respiratory tract

The upper airways or upper respiratory tract includes the nose and nasal passages, paranasal sinuses, the pharynx, and the portion of the larynx above the vocal folds (cords). The lower airways or lower respiratory tract includes the portion of the larynx below the vocal folds, trachea, bronchi and bronchioles.

difference between a neutrino and an antineutrino?

Their lepton number. An antineutrino is the antiparticle partner of the neutrino, meaning that the antineutrino has the same mass but opposite "charge" of the neutrino. Although neutrinos are electromagnetically neutral (they have no electric charge and no magnetic moment), they may carry another kind of charge: lepton number.

why pepper move away from soap in water?

This is because the pepper flakes are so light that the surface tension of the water keeps them floating on top. However, when you add a little dish soap, the surface tension of the water is disturbed. The water molecules move away from the soap taking the pepper with them

the universe was orange

Ultimately, the CMB dominated the early universe, and because of its properties (like its temperature and the wavelengths of light it absorbed), the universe appeared orange for a few million years.

How do viral mutations occur?

Viral mutations occur when the RNA or DNA is copied incorrectly.

The explanation of why the Earth pin is larger and Longer than the Phase and Neutral pins is that

We all know that the earth pin is used to protect the user in the event of a short circuit resulting in the leakage of current through any of the metal regions of an appliance. (i)If a conductor has a large cross sectional area the resistance offered by it is very less hence larger size (ii) Imagine the following scenario, An user is holding a plug in one hand and has the other hand in contact with an appliance that has a current leak through the metal body and is trying to connect it to a live socket(ref above diagram:the switch is already in ON position even before connecting the plug): If the earth pin is of normal size the user may get electrocuted due to short circuit and the surge current that may flow through the metal body due to the live socket. but if it is longer,the earth pin goes and sits in the socket first so whatever current that may flow through the user to ground will flow through the earth pin to ground,thus the user is protected.

What happens when you increase the mass of a neutron star?

When the mass is increased, the star radius decreases causing the star to shrink and the internal event horizon to expand. The mass at which the radius of the neutron star and the event horizon overlap, 3 solar masses, causes the event horizon to come into being. In other words, once a neutron star reaches 3 solar masses, a black hole is created. A black hole is created when the event horizon overtakes the neutron star radius, leading to the neutron star radius to submerge beneath the event horizon.

If the sun is constantly converting the mass into energy, then will its gravitational field continue decreasing?

Yes.

do neutrinos have spin?

Yes. 1/2 for both A neutrino is a fermion (an elementary particle with spin of 1/2) that interacts only via the weak subatomic force and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small (-ino) that it was long thought to be zero. For each neutrino, there also exists a corresponding antiparticle, called an antineutrino, which also has spin of 1/2 and no electric charge. Antineutrinos are distinguished from the neutrinos by having opposite signs of lepton number and right-handed instead of left-handed chirality. To conserve total lepton number (in nuclear beta decay), electron neutrinos only appear together with positrons (anti-electrons) or electron-antineutrinos, whereas electron antineutrinos only appear with electrons or electron neutrinos.

The Pauli Exclusion Principle

You may have heard that matter is 99.999% empty space. If that is the case, why doesn't matter go through other matter? There are two pieces to the answer: the first one is the electrical repulsion between electrons; the second is something called the Pauli exclusion principle. Fermions have quite a remarkable property: no two of them can be in the same quantum state. What does that mean? Every particle in the universe is described by a set of numbers that specify its state. Some of these numbers are its energy, its momentum or its position. There are also other things like spin, which tells us the way the particle is spinning. What the Pauli exclusion principle tells us is that no two particles can have exactly the same numbers. For example, in atoms electrons move in "orbits" around the nucleus. I say "orbits", but electrons are really spread around a certain location we call an "orbital" and only have a definite position when we measure it. Let's stick to orbits for now. It turns out that only some orbits are allowed: let's call them 1, 2, 3, etc, going from less to more energy. Now just like people, electrons want to be in the state of least possible energy, so they will tend to want to be in the first orbital. Let's say we have three electrons. Our first electron chooses first and goes to the first orbital, because it has the least energy. The second one also wants to be there: can it? According to Pauli's exclusion principle, it can if at least one of the numbers that describes it is different. If it stays in the same orbit, the energy will be the same: however, the electron can still have a different spin, so we can fit it in the first orbital. Now, the third electron has a problem, because if it were in the first orbital it would have an identical state to one of the two electrons. Therefore, it cannot stay there and has to go to the second orbital. This is what causes atoms to have different sizes: otherwise all electrons would just be in the least-energy orbital! This is what happens to our charm quark up there: being a fermion, it cannot be in the same state as its friend. So, even though it would love the steak, it has to settle for salad. Sucks being a quark. Now, once all electrons are happy in their orbits, the atom has some decent size. If I put it next to another atom, the electrons in the outer orbitals will repel each other and the atoms will not be able to touch. This is what prevents matter from going through other matter. First, the Pauli exclusion principle gives atoms sufficient size; then, the electric repulsion does the rest. Does This Work for Bosons? No, it does not. As explained here, bosons have no problem occupying the same state, which makes them capable of going right through each other. In fact, you can have as many bosons as you want in the lowest energy state. This is the basis for Bose-Einstein condensates. Why does this happen? Honestly? We don't have a clue. The usual, technical answer is something akin to "the wave-function of a group of fermions has to be anti-symmetrical" or "the creation-annihilation operators must follow certain anticommutation relations." Now, this probably sounds like Chinese to you as it refers to the mathematical structure of a quantum theory. However, even though either of the two conditions above are equivalent to the Pauli exclusion principle, both have to be introduced without justification: that is, we add them because they work. A theory with these properties gives the right experimental results. That's it. Why does nature behave this way? Nobody has a clue. If this seems unsatisfactory to you, bear in mind that we have exactly the same problem with the speed of light. You know that the speed of light has to be the same for every observer; but why? Again, we don't know. The constancy of the speed of light was introduced by Einstein as one of the two postulates of his theory. A postulate is a statement that you give without proof: its ultimate justification is that it agrees with experiment. We know that the speed of light is constant because we've measured it many, many times and always got the same answer. Could the universe be different? Most certainly. But it isn't. Maybe in the future we will find a deeper theory that explains both of these things. But this theory, by definition, will also have unjustified assumptions. This is the nature of science: we look for the theory with the minimum number of assumptions, but we cannot have one without any.

do bosons interact with the higgs field?

You need to distinguish between the Higgs boson and the Higgs field. The Higgs field is the stuff that gives all other particles a mass. Every particle in our universe "swims" through this Higgs field. Through this interaction every particle gets its mass. Different particles interact with the Higgs field with different strengths, hence some particles are heavier (have a larger mass) than others. (Some particles have no mass. They don't interact with the Higgs field; they don't feel the field.) It is the opposite of people swimming in water. As people float in water they "become" lighter. Depending on size, shape, etc, some people float better than others. The Higgs field is not considered a force. It cannot accelerate particles, it doesn't transfer energy. However, it interacts universally with all particles (except the massless ones), providing their masses. The Higgs boson is a particle. It gets its mass like all other particles: by interacting with ("swimming in") the Higgs field. But as you can imagine, the Higgs particle differs from all the other particles we know. It can be thought of a dense spot in the Higgs field, which can travel like any other particle. Like a drop of water in water vapor. The Higgs boson has many more ways of interacting with all other kinds of particles than the Higgs field (which just causes a "drag" = mass). In this sense one might call the Higgs particle the mediating particle of the proposed Higgs field, like you wrote. The Higgs field is the silent field that gives the mass. We cannot directly probe for it. But discovering the Higgs boson, the "mediator", would prove the existence of the Higgs field. The Higgs particle, like many other elementary particles, is not a stable particle. Since it interacts with all kinds of other massive particles it can be created in collisions. (The Higgs particle does not interact with massless particles, such as a photon or a gluon. Since these particles don't interact with the Higgs field, the Higgs boson also doesn't interact with them.) Once the Higgs particle has been created, it will eventually decay. Though the Higgs particle interacts with all massive particles it prefers to interact with the heaviest elementary particles we know, especially the top quark, which was discovered at Fermilab in 1995. Because of this property of the Higgs boson physicists at Fermilab might have a chance to find evidence for the Higgs boson itself within the next five to six years. If they are not successful then an accelerator currently build at the CERN laboratory in Geneva, Switzerland, will have enough energy to produce the Higgs boson. Fermilab's accelerator currently is the world's most powerful accelerator, but physicists don't know whether it has enough power to create Higgs bosons. The new accelerator at CERN will have more power, but construction won't be finished until 2005. The Higgs particle is considered to be a carrier of a force. It is a boson, like the other force-transferring particles: photons, gluons, electroweak bosons. One may call the force mediated by the Higgs boson to be universal as the Higgs boson interacts with all kinds of massive particles, no matter whether they are quarks, leptons, or even massive bosons (the electroweak bosons). Only photons and gluons do not interact with the Higgs boson. Neutrinos, the lightest particles with almost zero mass, barely interact with a Higgs boson. Top quarks, which have about the mass of a Gold atom, have the strongest interaction with a Higgs boson.

The Strong Force

Yup, OK. Terrible joke. Pretty accurate, though: quarks are indeed "sticky." So sticky, indeed, that they can't separate themselves from each other. It is physically impossible to observe a single quark: they come in pairs or in threes (less often, in groups of four or even five) but, unlike the forever alone meme, they will never know loneliness. Quarks are sticky because of the strong force. This is just a force, just like gravity or the electromagnetic force. The messenger particle for the electromagnetic force is the photon; the messenger for the strong force is the gluon. However, the strong force is different from all the other forces in that it doesn't decrease with distance. Gravity, for example, gets weaker as you get further from its source. This is the reason why we don't all rush towards the Sun and instead just stick to good old Earth. But the strong force is always equally strong. If you try to pull two quarks apart, you will have to continue to push with exactly the same amount of force for all eternity. So what? You may think. Just pull enough. Eventually, they will be separated enough that we can see them. But things aren't so simple, thanks to Einstein's E = mc2. As we pull the two quarks away, we are giving them energy, in the same way that pulling on a rubber band gives it energy. But energy can be turned into mass, which means it can be used to create new particles! So, as we pull and pull, we give the system more energy and the energy is used to create more quarks, which again will be as close as they can possibly be. So then we can start pulling on the new quarks, but this will only have the effect of creating yet more quarks in a never-ending cycle. Long story short, we will never, ever, get two quarks far enough. There you have it: quarks are sticky and cannot be unstuck. They are forever doomed to spend their lives surrounded by their fellow quarks. Whether that's a good thing, you should probably ask them. Oh and, in case anyone wants to know, this pesky phenomenon is called confinement.

Inverter compressor

a compressor on a VFD? An inverter compressor is a gas compressor that is operated with an inverter. In the hermetic type, it can either be a scroll or reciprocating compressor. This type of compressor uses a drive to control the compressor motor speed to modulate cooling capacity. Capacity modulation is a way to match cooling capacity to cooling demand to application requirements.

Laureate

a person who is honored with an award for outstanding creative or intellectual achievement.

Low-pass filter

blocks high frequencies

error correction

immediate corrective feedback during reading instruction Error correction is the process of detecting errors in transmitted messages and reconstructing the original error-free data.

Dogs bark at cars' wheels because the engine produces high-pitch noises that humans can't hear, but dogs identify as a frightened dog inside.

maybe? get me an ultrasonic detector

LAGEOS

measures plate movement by bouncing laser beams between Earth stations and an orbiting satellite LAGEOS, Laser Geodynamics Satellite or Laser Geometric Environmental Observation Survey, are a series of two scientific research satellites designed to provide an orbiting laser ranging benchmark for geodynamical studies of the Earth. Each satellite is a high-density passive laser reflector in a very stable medium Earth orbit (MEO). The spacecraft are aluminum-covered brass spheres with diameters of 60 centimetres (24 in) and masses of 400 and 411 kilograms (882 and 906 pounds), covered with 426 cube-corner retroreflectors, giving them the appearance of giant golf balls. Of these retroreflectors, 422 are made from fused silica glass while the remaining 4 are made from germanium to obtain measurements in the infrared for experimental studies of reflectivity and satellite orientation.[6] They have no on-board sensors or electronics, and are not attitude-controlled. They orbit at an altitude of 5,900 kilometres (3,700 mi),[7] well above low earth orbit and well below geostationary orbit, at orbital inclinations of 109.8 and 52.6 degrees.

What is R0?

net reproductive rate In epidemiology, the basic reproduction number (sometimes called basic reproductive ratio, or incorrectly basic reproductive rate, and denoted R0, pronounced R nought or R zero[16]) of an infection can be thought of as the expected number of cases directly generated by one case in a population where all individuals are susceptible to infection. e.g. measles R0 = 12-18 meaning one infected person can infect 12-18

dopamine traps

social media, feedback loops, etc.

Lorentz transformation

the transformation, valid for all relative velocities, which describes how to relate coordinates and observations in one inertial frame to those in another such frame. In physics, the Lorentz transformations are a one-parameter family of linear transformations from a coordinate frame in spacetime to another frame that moves at a constant velocity relative to the former. The respective inverse transformation is then parametrized by the negative of this velocity.

Quantum entanglement

the unusual behavior of elementary particles where they become linked so that when something happens to one, something happens to the other; no matter how far apart they are. particles is generated, interact, or share spatial proximity in a way such that the quantum state of each particle of the pair or group cannot be described independently of the state of the others, even when the particles are separated by a large distance. The topic of quantum entanglement is at the heart of the disparity between classical and quantum physics. Measurements of physical properties such as position, momentum, spin, and polarization performed on entangled particles are found to be perfectly correlated. For example, if a pair of entangled particles is generated such that their total spin is known to be zero, and one particle is found to have clockwise spin on a first axis, then the spin of the other particle, measured on the same axis, will be found to be counterclockwise. However, this behavior gives rise to seemingly paradoxical effects: any measurement of a property of a particle results in an irreversible wave function collapse of that particle and will change the original quantum state. In the case of entangled particles, such a measurement will affect the entangled system as a whole.

hydronic cooling

using a chiller or geothermal Hydronic cooling is simply the removal of heat from the space utilizing chilled water as the heat exchange medium. As opposed to evaporative cooling which introduces humidity into the space, hydronic cooling is completely closed loop meaning no water is added to the space for the purpose of cooling

de broglie wavelength

λ = h/mv the wavelength associated with a moving particle According to wave-particle duality, the De Broglie wavelength is a wavelength manifested in all the objects in quantum mechanics which determines the probability density of finding the object at a given point of the configuration space. The de Broglie wavelength of a particle is inversely proportional to its momentum. Matter waves are a central part of the theory of quantum mechanics, being an example of wave-particle duality. All matter exhibits wave-like behavior. For example, a beam of electrons can be diffracted just like a beam of light or a water wave.