There exist animals that are sensitive to various types of infrared, but not by means of quantum-absorption. Infrared sensing in snakes depends on a kind of natural thermal imaging, in which tiny packets of cellular water are raised in temperature by the infrared radiation. EMR in this range causes molecular vibration and heating effects, which is how these animals detect it.

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Sunlight provides the energy that green plants use to create sugars mostly in the form of starches, which release energy into the living things that digest them. This process of photosynthesis provides virtually all the energy used by living things. Some species of animals generate their own light, a process called bioluminescence. For example, fireflies use light to locate mates and vampire squid use it to hide themselves from prey.

On the trails, the Energy Foam midsole delivered a snappy and efficient ride. The firm cushioning provided a direct connection to the ground, allowing for precise foot placement and agile maneuvering on the technical terrain. While the lack of plushness might not be ideal for long distances or runners who prefer a softer feel, it proved to be a winning formula for the fast-paced ascents and descents of my favorite Boulder trail, Fern Canyon via Bear Peak.

Overlays now extend down and wrap the front of the midsole to provide more stability than in the S/Lab Pulsar 2  (RTR Review) which, while I did not test, RTR Editor Sam tells me was very soft at the edges of the front of the platform and for him overly pliable upfront.

John R. Klauder, George Sudarshan, Roy J. Glauber, and Leonard Mandel applied quantum theory to the electromagnetic field in the 1950s and 1960s to gain a more detailed understanding of photodetection and the statistics of light (see degree of coherence). This led to the introduction of the coherent state as a concept which addressed variations between laser light, thermal light, exotic squeezed states, etc. as it became understood that light cannot be fully described just referring to the electromagnetic fields describing the waves in the classical picture. In 1977, H. Jeff Kimble et al. demonstrated a single atom emitting one photon at a time, further compelling evidence that light consists of photons. Previously unknown quantum states of light with characteristics unlike classical states, such as squeezed light were subsequently discovered.

Your imageina plane mirror is

The speed of light in vacuum is defined to be exactly 299 792 458 m/s (approx. 186,282 miles per second). The fixed value of the speed of light in SI units results from the fact that the metre is now defined in terms of the speed of light. All forms of electromagnetic radiation move at exactly this same speed in vacuum.

However, the Pulsar 3's performance-oriented design comes with some trade-offs. The firm cushioning and narrow toe box might not be ideal for runners who prioritize comfort or have wider feet. Additionally, the minimal protection might not be sufficient for ultra-distance runners or those who prefer a plusher ride.

The peak of the black-body spectrum is in the deep infrared, at about 10 micrometre wavelength, for relatively cool objects like human beings. As the temperature increases, the peak shifts to shorter wavelengths, producing first a red glow, then a white one and finally a blue-white colour as the peak moves out of the visible part of the spectrum and into the ultraviolet. These colours can be seen when metal is heated to "red hot" or "white hot". Blue-white thermal emission is not often seen, except in stars (the commonly seen pure-blue colour in a gas flame or a welder's torch is in fact due to molecular emission, notably by CH radicals emitting a wavelength band around 425 nm and is not seen in stars or pure thermal radiation).

Various sources define visible light as narrowly as 420–680 nm[7][8] to as broadly as 380–800 nm.[9][10] Under ideal laboratory conditions, people can see infrared up to at least 1,050 nm;[11] children and young adults may perceive ultraviolet wavelengths down to about 310–313 nm.[12][13][14]

The effective velocity of light in various transparent substances containing ordinary matter, is less than in vacuum. For example, the speed of light in water is about 3/4 of that in vacuum.

Eventually quantum mechanics came to picture light as (in some sense) both a particle and a wave, and (in another sense) as a phenomenon which is neither a particle nor a wave (which actually are macroscopic phenomena, such as baseballs or ocean waves). Instead, under some approximations light can be described sometimes with mathematics appropriate to one type of macroscopic metaphor (particles) and sometimes another macroscopic metaphor (waves).

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Light is measured with two main alternative sets of units: radiometry consists of measurements of light power at all wavelengths, while photometry measures light with wavelength weighted with respect to a standardized model of human brightness perception. Photometry is useful, for example, to quantify Illumination (lighting) intended for human use.

In about 300 BC, Euclid wrote Optica, in which he studied the properties of light. Euclid postulated that light travelled in straight lines and he described the laws of reflection and studied them mathematically. He questioned that sight is the result of a beam from the eye, for he asks how one sees the stars immediately, if one closes one's eyes, then opens them at night. If the beam from the eye travels infinitely fast this is not a problem.[32]

Atoms emit and absorb light at characteristic energies. This produces "emission lines" in the spectrum of each atom. Emission can be spontaneous, as in light-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc.) and flames (light from the hot gas itself—so, for example, sodium in a gas flame emits characteristic yellow light). Emission can also be stimulated, as in a laser or a microwave maser.

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Refraction is the bending of light rays when passing through a surface between one transparent material and another. It is described by Snell's Law:

Furthermore, the shoe's dynamic response and narrow last make it a suitable road shoe for shorter, faster efforts. However, I found that the outsole might provide more resistance than desired for a local 5K road race. In my opinion, the design is better suited for occasional on-road approaches and road intermissions during trail outings.

Refractioncauses the bottom of a swimming pool to appear

John: Salomon, a brand synonymous with innovation in trail running footwear, has once again pushed the boundaries with the S/Lab Pulsar 3. This shoe represents the culmination of Salomon's dedication to creating high-performance gear for competitive athletes.

Generally, electromagnetic radiation (EMR) is classified by wavelength into radio waves, microwaves, infrared, the visible spectrum that we perceive as light, ultraviolet, X-rays and gamma rays. The designation "radiation" excludes static electric, magnetic and near fields.

John: The Salomon S/Lab Pulsar 3 delivers a ride experience that's synonymous with speed and agility. From the first stride, the shoe's nimbleness is evident, encouraging a quick foot turnover and a playful, almost effortless stride. The low stack height and flexible design facilitate natural movement, allowing the foot to adapt seamlessly to the ever-changing terrain. Whether navigating tight switchbacks or leaping over rock gardens, the Pulsar 3's responsiveness shines through, reacting instantaneously to your every move.

Great question Ryan! The Catamount Agil and Pulsar prioritize lightweight performance for short, technical runs. Both are solid shoes for precise foot placement, agility, and aggressive running. I find the Agil offers a slightly more forgiving ride and broader (more stable) platform with a flexible plate and moderate cushioning, while the Pulsar emphasizes an aggressive, propulsive feel with better traction on rock surfaces and capabilities on steep uphills.

John: The Contragrip MA outsole, designed for maximum grip on a variety of surfaces, truly excelled on the Bear Peak trail, which ascends 2,500+ ft in 2.5 miles with a mix of smooth and rocky trail, along with some low grade scrambling.

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A mirage is a result of atmospheric

Newton's theory could be used to predict the reflection of light, but could only explain refraction by incorrectly assuming that light accelerated upon entering a denser medium because the gravitational pull was greater. Newton published the final version of his theory in his Opticks of 1704. His reputation helped the particle theory of light to hold sway during the eighteenth century. The particle theory of light led Pierre-Simon Laplace to argue that a body could be so massive that light could not escape from it. In other words, it would become what is now called a black hole. Laplace withdrew his suggestion later, after a wave theory of light became firmly established as the model for light (as has been explained, neither a particle or wave theory is fully correct). A translation of Newton's essay on light appears in The large scale structure of space-time, by Stephen Hawking and George F. R. Ellis.

Two independent teams of physicists were said to bring light to a "complete standstill" by passing it through a Bose–Einstein condensate of the element rubidium, one team at Harvard University and the Rowland Institute for Science in Cambridge, Massachusetts and the other at the Harvard–Smithsonian Center for Astrophysics, also in Cambridge.[18] However, the popular description of light being "stopped" in these experiments refers only to light being stored in the excited states of atoms, then re-emitted at an arbitrary later time, as stimulated by a second laser pulse. During the time it had "stopped", it had ceased to be light.

In 1900 Max Planck, attempting to explain black-body radiation, suggested that although light was a wave, these waves could gain or lose energy only in finite amounts related to their frequency. Planck called these "lumps" of light energy "quanta" (from a Latin word for "how much"). In 1905, Albert Einstein used the idea of light quanta to explain the photoelectric effect and suggested that these light quanta had a "real" existence. In 1923 Arthur Holly Compton showed that the wavelength shift seen when low intensity X-rays scattered from electrons (so called Compton scattering) could be explained by a particle-theory of X-rays, but not a wave theory. In 1926 Gilbert N. Lewis named these light quanta particles photons.[41]

Usually light momentum is aligned with its direction of motion. However, for example in evanescent waves momentum is transverse to direction of propagation.[30]

A transparent object allows light to transmit or pass through. Conversely, an opaque object does not allow light to transmit through and instead reflecting or absorbing the light it receives. Most objects do not reflect or transmit light specularly and to some degree scatters the incoming light, which is called glossiness. Surface scatterance is caused by the surface roughness of the reflecting surfaces, and internal scatterance is caused by the difference of refractive index between the particles and medium inside the object. Like transparent objects, translucent objects allow light to transmit through, but translucent objects also scatter certain wavelength of light via internal scatterance.[19]

With a rubber compound designed for optimal grip during dynamic movements, the outsole offered a sense of reassurance with each step. While my road testing revealed excellent performance at faster paces, the shoes were less effective during extended, slower efforts.

The fact that light could be polarized was for the first time qualitatively explained by Newton using the particle theory. Étienne-Louis Malus in 1810 created a mathematical particle theory of polarization. Jean-Baptiste Biot in 1812 showed that this theory explained all known phenomena of light polarization. At that time the polarization was considered as the proof of the particle theory.

There are many sources of light. A body at a given temperature emits a characteristic spectrum of black-body radiation. A simple thermal source is sunlight, the radiation emitted by the chromosphere of the Sun at around 6,000 K (5,730 °C; 10,340 °F). Solar radiation peaks in the visible region of the electromagnetic spectrum when plotted in wavelength units,[20] and roughly 44% of the radiation that reaches the ground is visible.[21] Another example is incandescent light bulbs, which emit only around 10% of their energy as visible light and the remainder as infrared. A common thermal light source in history is the glowing solid particles in flames, but these also emit most of their radiation in the infrared and only a fraction in the visible spectrum.

Different physicists have attempted to measure the speed of light throughout history. Galileo attempted to measure the speed of light in the seventeenth century. An early experiment to measure the speed of light was conducted by Ole Rømer, a Danish physicist, in 1676. Using a telescope, Rømer observed the motions of Jupiter and one of its moons, Io. Noting discrepancies in the apparent period of Io's orbit, he calculated that light takes about 22 minutes to traverse the diameter of Earth's orbit.[15] However, its size was not known at that time. If Rømer had known the diameter of the Earth's orbit, he would have calculated a speed of 227000000 m/s.

Another more accurate measurement of the speed of light was performed in Europe by Hippolyte Fizeau in 1849.[16] Fizeau directed a beam of light at a mirror several kilometers away. A rotating cog wheel was placed in the path of the light beam as it traveled from the source, to the mirror and then returned to its origin. Fizeau found that at a certain rate of rotation, the beam would pass through one gap in the wheel on the way out and the next gap on the way back. Knowing the distance to the mirror, the number of teeth on the wheel and the rate of rotation, Fizeau was able to calculate the speed of light as 313000000 m/s.

Hey Brian...I haven't had the opportunity to run in the NNormal Kjerag, but from what I know the Pulsar is slightly lighter and more race-focused with a rocker shape for explosive energy return. The Kjerag prioritizes stability and longer distances with a wider platform, and more traditional heel-to-toe transition

EMR in the visible light region consists of quanta (called photons) that are at the lower end of the energies that are capable of causing electronic excitation within molecules, which leads to changes in the bonding or chemistry of the molecule. At the lower end of the visible light spectrum, EMR becomes invisible to humans (infrared) because its photons no longer have enough individual energy to cause a lasting molecular change (a change in conformation) in the visual molecule retinal in the human retina, which change triggers the sensation of vision.

Note also the opening in the front of the Pulsar 2 which made it overly flexible, not very stable and not well protected according to RTR Editor Sam. We now have full rubber coverage upfront.

The Pulsar 3 fits like a glove. The Matryx upper provided a snug, sock-like fit, thanks to its unique ability to mold to the shape of the foot.

The study of light and the interaction of light and matter is termed optics. The observation and study of optical phenomena such as rainbows and the aurora borealis offer many clues as to the nature of light.

In true form, Salomon incorporates feedback from their elite athletes like Rémi Bonnet, and has refined the Pulsar 3 to deliver a truly optimized running experience. The shoe's Matryx technology, Energy Foam midsole, Contragrip MA outsole, and Quicklace system are all testaments to Salomon's commitment to pushing the boundaries of innovation in trail running footwear.

John: Only slightly heavier at 7.5 oz vs 7.15 oz, the Zinal 2 stands out for its agility and responsiveness, making it an ideal trail shoe for demanding adventures. Its profile features a rocker shape and an aggressive outsole that ensures excellent traction. In comparison to the Pulsar 3, the Zinal 2 provides a marginally softer feel, making it a suitable choice for longer distances.

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Light exerts physical pressure on objects in its path, a phenomenon which can be deduced by Maxwell's equations, but can be more easily explained by the particle nature of light: photons strike and transfer their momentum. Light pressure is equal to the power of the light beam divided by c, the speed of light.  Due to the magnitude of c, the effect of light pressure is negligible for everyday objects.  For example, a one-milliwatt laser pointer exerts a force of about 3.3 piconewtons on the object being illuminated; thus, one could lift a U.S. penny with laser pointers, but doing so would require about 30 billion 1-mW laser pointers.[22]  However, in nanometre-scale applications such as nanoelectromechanical systems (NEMS), the effect of light pressure is more significant and exploiting light pressure to drive NEMS mechanisms and to flip nanometre-scale physical switches in integrated circuits is an active area of research.[23] At larger scales, light pressure can cause asteroids to spin faster,[24] acting on their irregular shapes as on the vanes of a windmill.  The possibility of making solar sails that would accelerate spaceships in space is also under investigation.[25][26]

Although the motion of the Crookes radiometer was originally attributed to light pressure, this interpretation is incorrect; the characteristic Crookes rotation is the result of a partial vacuum.[27] This should not be confused with the Nichols radiometer, in which the (slight) motion caused by torque (though not enough for full rotation against friction) is directly caused by light pressure.[28] As a consequence of light pressure, Einstein in 1909 predicted the existence of "radiation friction" which would oppose the movement of matter.[29] He wrote, "radiation will exert pressure on both sides of the plate. The forces of pressure exerted on the two sides are equal if the plate is at rest. However, if it is in motion, more radiation will be reflected on the surface that is ahead during the motion (front surface) than on the back surface. The backwardacting force of pressure exerted on the front surface is thus larger than the force of pressure acting on the back. Hence, as the resultant of the two forces, there remains a force that counteracts the motion of the plate and that increases with the velocity of the plate. We will call this resultant 'radiation friction' in brief."

John: In comparison to the Pulsar 3, the Sky provides a firmer ride while maintaining similar responsiveness and ground feel. The Sky distinguishes itself as a lightweight and agile trail shoe, featuring a carbon-fiber plate that enhances propulsion.

In 55 BC, Lucretius, a Roman who carried on the ideas of earlier Greek atomists, wrote that "The light & heat of the sun; these are composed of minute atoms which, when they are shoved off, lose no time in shooting right across the interspace of air in the direction imparted by the shove." (from On the nature of the Universe). Despite being similar to later particle theories, Lucretius's views were not generally accepted. Ptolemy (c. second century) wrote about the refraction of light in his book Optics.[33]

The behavior of EMR depends on its wavelength. Higher frequencies have shorter wavelengths and lower frequencies have longer wavelengths. When EMR interacts with single atoms and molecules, its behavior depends on the amount of energy per quantum it carries.

To explain the origin of colours, Robert Hooke (1635–1703) developed a "pulse theory" and compared the spreading of light to that of waves in water in his 1665 work Micrographia ("Observation IX"). In 1672 Hooke suggested that light's vibrations could be perpendicular to the direction of propagation. Christiaan Huygens (1629–1695) worked out a mathematical wave theory of light in 1678 and published it in his Treatise on Light in 1690. He proposed that light was emitted in all directions as a series of waves in a medium called the luminiferous aether. As waves are not affected by gravity, it was assumed that they slowed down upon entering a denser medium.[36]

The Matryx upper's breathability was immediately apparent as I tested them on my favorite trail up Bear Peak in Boulder. The woven fabric efficiently wicks away moisture, keeping my feet cool and dry as the spring temperatures have begun to increase.

Magnification by a lens would be greater iflight

In ancient India, the Hindu schools of Samkhya and Vaisheshika, from around the early centuries AD developed theories on light. According to the Samkhya school, light is one of the five fundamental "subtle" elements (tanmatra) out of which emerge the gross elements. The atomicity of these elements is not specifically mentioned and it appears that they were actually taken to be continuous.[34] The Vishnu Purana refers to sunlight as "the seven rays of the sun".[34]

When a beam of light crosses the boundary between a vacuum and another medium, or between two different media, the wavelength of the light changes, but the frequency remains constant. If the beam of light is not orthogonal (or rather normal) to the boundary, the change in wavelength results in a change in the direction of the beam. This change of direction is known as refraction.

John: The Pulsar 3 features Salomon's Energy Foam Midsole compound, a blend of EVA and Olefin (OBC) foams. This combination aims to strike a balance between lightweight cushion,responsiveness and impact protection. The midsole is notably firm, prioritizing energy return and propulsion over plush cushioning.

Development of short and ultrashort laser pulses—created by Q switching and modelocking techniques—opened the way to the study of what became known as ultrafast processes. Applications for solid state research (e.g. Raman spectroscopy) were found, and mechanical forces of light on matter were studied. The latter led to levitating and positioning clouds of atoms or even small biological samples in an optical trap or optical tweezers by laser beam. This, along with Doppler cooling and Sisyphus cooling, was the crucial technology needed to achieve the celebrated Bose–Einstein condensation.

Certain substances produce light when they are illuminated by more energetic radiation, a process known as fluorescence. Some substances emit light slowly after excitation by more energetic radiation. This is known as phosphorescence. Phosphorescent materials can also be excited by bombarding them with subatomic particles. Cathodoluminescence is one example. This mechanism is used in cathode-ray tube television sets and computer monitors.

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The reinforced toe cap, a crucial feature for technical trails, provided ample protection against the sharp rocks and roots that litter the path.

John: The Salomon S/Lab Pulsar 3 and Pulsar SG are both elite trail running shoes built for speed and agility, but with key differences tailored to specific conditions. The Pulsar 3, with its firmer Energy Foam midsole and versatile Contragrip MA outsole, excels on dry, technical trails where responsiveness and precision are paramount. The Pulsar SG, features a slightly softer midsole.

In physics, the term "light" may refer more broadly to electromagnetic radiation of any wavelength, whether visible or not.[4][5] In this sense, gamma rays, X-rays, microwaves and radio waves are also light. The primary properties of light are intensity, propagation direction, frequency or wavelength spectrum, and polarization. Its speed in vacuum, 299792458 m/s, is one of the fundamental constants of nature.[6] Like all types of electromagnetic radiation, visible light propagates by massless elementary particles called photons that represents the quanta of electromagnetic field, and can be analyzed as both waves and particles. The study of light, known as optics, is an important research area in modern physics.

Léon Foucault carried out an experiment which used rotating mirrors to obtain a value of 298 000 000 m/s[16] in 1862. Albert A. Michelson conducted experiments on the speed of light from 1877 until his death in 1931. He refined Foucault's methods in 1926 using improved rotating mirrors to measure the time it took light to make a round trip from Mount Wilson to Mount San Antonio in California. The precise measurements yielded a speed of 299 796 000 m/s.[17]

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Pierre Gassendi (1592–1655), an atomist, proposed a particle theory of light which was published posthumously in the 1660s. Isaac Newton studied Gassendi's work at an early age and preferred his view to Descartes's theory of the plenum. He stated in his Hypothesis of Light of 1675 that light was composed of corpuscles (particles of matter) which were emitted in all directions from a source. One of Newton's arguments against the wave nature of light was that waves were known to bend around obstacles, while light travelled only in straight lines. He did, however, explain the phenomenon of the diffraction of light (which had been observed by Francesco Grimaldi) by allowing that a light particle could create a localised wave in the aether.

In terms of sizing, the Pulsar 3 fits as expected for my US9 Men's shoe size. Unfortunately, I can't directly compare the fit of the Pulsar 3 to the SG because I only had the opportunity to try a larger size of the latter; but the SG did seem slightly wider notwithstanding.

Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye.[1] Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz. The visible band sits adjacent to the infrared (with longer wavelengths and lower frequencies) and the ultraviolet (with shorter wavelengths and higher frequencies), called collectively optical radiation.[2][3]

In 1845, Michael Faraday discovered that the plane of polarization of linearly polarized light is rotated when the light rays travel along the magnetic field direction in the presence of a transparent dielectric, an effect now known as Faraday rotation.[39] This was the first evidence that light was related to electromagnetism. In 1846 he speculated that light might be some form of disturbance propagating along magnetic field lines.[39] Faraday proposed in 1847 that light was a high-frequency electromagnetic vibration, which could propagate even in the absence of a medium such as the ether.[40]

The Matryx technology is a key feature of the shoe's upper. It's a woven fabric that blends Kevlar and polyamide fibers, providing a unique balance of durability, breathability, and flexibility. The result is a shoe that is  both lightweight and supportive, conforming to the foot's shape without sacrificing structure. Compared to the prior version’s Matryx material the upper here is smoother in feel.

The refractive quality of lenses is frequently used to manipulate light in order to change the apparent size of images. Magnifying glasses, spectacles, contact lenses, microscopes and refracting telescopes are all examples of this manipulation.

The heel area is now more cantilevered compared to the Pulsar 2, again to increase stability and improve landing cushioning.

As in the case for radio waves and the X-rays involved in Compton scattering, physicists have noted that electromagnetic radiation tends to behave more like a classical wave at lower frequencies, but more like a classical particle at higher frequencies, but never completely loses all qualities of one or the other. Visible light, which occupies a middle ground in frequency, can easily be shown in experiments to be describable using either a wave or particle model, or sometimes both.

Above the range of visible light, ultraviolet light becomes invisible to humans, mostly because it is absorbed by the cornea below 360 nm and the internal lens below 400 nm. Furthermore, the rods and cones located in the retina of the human eye cannot detect the very short (below 360 nm) ultraviolet wavelengths and are in fact damaged by ultraviolet. Many animals with eyes that do not require lenses (such as insects and shrimp) are able to detect ultraviolet, by quantum photon-absorption mechanisms, in much the same chemical way that humans detect visible light.

when alightbeam emergesfromwater into air, the averagelightspeed

Descartes is not the first to use the mechanical analogies but because he clearly asserts that light is only a mechanical property of the luminous body and the transmitting medium, Descartes's theory of light is regarded as the start of modern physical optics.[35]

Deceleration of a free charged particle, such as an electron, can produce visible radiation: cyclotron radiation, synchrotron radiation and bremsstrahlung radiation are all examples of this. Particles moving through a medium faster than the speed of light in that medium can produce visible Cherenkov radiation. Certain chemicals produce visible radiation by chemoluminescence. In living things, this process is called bioluminescence. For example, fireflies produce light by this means and boats moving through water can disturb plankton which produce a glowing wake.

The Indian Buddhists, such as Dignāga in the fifth century and Dharmakirti in the seventh century, developed a type of atomism that is a philosophy about reality being composed of atomic entities that are momentary flashes of light or energy. They viewed light as being an atomic entity equivalent to energy.[34]

However, the narrow toe box might not be ideal for runners with wider feet, potentially causing discomfort on longer runs

In 1927, Paul Dirac quantized the electromagnetic field. Pascual Jordan and Vladimir Fock generalized this process to treat many-body systems as excitations of quantum fields, a process with the misnomer of second quantization. And at the end of the 1940s a full theory of quantum electrodynamics was developed using quantum fields based on the works of Julian Schwinger, Richard Feynman, Freeman Dyson, and Shinichiro Tomonaga.

Diffuse reflection occurs when the size of surface irregularities is

where θ1 is the angle between the ray and the surface normal in the first medium, θ2 is the angle between the ray and the surface normal in the second medium and n1 and n2 are the indices of refraction, n = 1 in a vacuum and n > 1 in a transparent substance.

I am curious about the comparison to the Catamount Agil as well. It is a shoe I have really enjoyed so far for fast trail racing.

In challenging environments like Bear Peak here in Boulder, the Pulsar 3's performance is undeniable. Its responsiveness, agility, and ground feel allow you to navigate technical terrain with confidence and speed, solidifying its position as a top-tier trail racing shoe.

Later, Fresnel independently worked out his own wave theory of light and presented it to the Académie des Sciences in 1817. Siméon Denis Poisson added to Fresnel's mathematical work to produce a convincing argument in favor of the wave theory, helping to overturn Newton's corpuscular theory.[dubious – discuss] By the year 1821, Fresnel was able to show via mathematical methods that polarization could be explained by the wave theory of light if and only if light was entirely transverse, with no longitudinal vibration whatsoever.[citation needed]

In the quantum theory, photons are seen as wave packets of the waves described in the classical theory of Maxwell. The quantum theory was needed to explain effects even with visual light that Maxwell's classical theory could not (such as spectral lines).

Rainbows are not usually seen as complete circles because

The weakness of the wave theory was that light waves, like sound waves, would need a medium for transmission. The existence of the hypothetical substance luminiferous aether proposed by Huygens in 1678 was cast into strong doubt in the late nineteenth century by the Michelson–Morley experiment.

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Newton's corpuscular theory implied that light would travel faster in a denser medium, while the wave theory of Huygens and others implied the opposite. At that time, the speed of light could not be measured accurately enough to decide which theory was correct. The first to make a sufficiently accurate measurement was Léon Foucault, in 1850.[38] His result supported the wave theory, and the classical particle theory was finally abandoned (only to partly re-emerge in the twentieth century as photons in Quantum theory).

The Pulsar 3's platform design is characterized by a low stack height and a rockered profile. The low stack height (23mm in the forefoot and 29mm in the heel) keeps the foot close to the ground, enhancing body awareness and agility. The rockered profile, with its slightly curved shape, encourages a smooth and efficient transition from heel to toe, promoting a natural running gait.

Overall, the Pulsar 3's ride is a testament to Salomon's commitment to innovation and performance. The combination of lightweight construction, responsive midsole, aggressive outsole, and precise fit creates a shoe that excels on technical terrain. It's a shoe that encourages you to push your limits and find your flow on the trail.

The main source of natural light on Earth is the Sun. Historically, another important source of light for humans has been fire, from ancient campfires to modern kerosene lamps. With the development of electric lights and power systems, electric lighting has effectively replaced firelight.

John: The Cyklon is a versatile trail shoe with a comfortable sock-like fit and an aggressive outsole. While it offers comparable agility to the Pulsar 3, it provides a slightly softer and more protective ride. It is considerably heavier, about 4 oz / 113g  heavier than the Pulsar.

The Pulsar 3 is designed for speed demons who crave agility and responsiveness on technical terrain. Salomon's engineers have meticulously crafted a shoe that prioritizes lightness, grip, and precision, making it a formidable weapon for trail racers and fast-paced runners alike.

The Energy Foam midsole, despite its lightweight construction, packs a punch, delivering a surprisingly energetic ride. Each footstrike is met with a snappy rebound, propelling you forward with a noticeable pep, the Pro Feel protection assisting in propulsion. This energy return, combined with the smooth roll-through of the rockered platform, creates a sense of effortless efficiency that makes even steep climbs feel manageable.

Both shoes share a lightweight Matryx upper, but the Pulsar SG has added protection around the base for enhanced durability. Choosing between them comes down to your typical running terrain and personal preferences:  if you frequently encounter mud and slippery surfaces, the Pulsar SG's traction profile will be beneficial, while the Pulsar 3's firmer ride might be preferred for drier, more technical trails where agility and speed are key.

René Descartes (1596–1650) held that light was a mechanical property of the luminous body, rejecting the "forms" of Ibn al-Haytham and Witelo as well as the "species" of Roger Bacon, Robert Grosseteste and Johannes Kepler.[35] In 1637 he published a theory of the refraction of light that assumed, incorrectly, that light travelled faster in a denser medium than in a less dense medium. Descartes arrived at this conclusion by analogy with the behaviour of sound waves.[citation needed] Although Descartes was incorrect about the relative speeds, he was correct in assuming that light behaved like a wave and in concluding that refraction could be explained by the speed of light in different media.

The platform width at 70 mm heel / 40 mm midfoot / 95 mm forefoot is unchanged and very narrow for a trail shoe and especially so at the midfoot. This means those with wider feet might find the shoe to be too snug. However, for runners with narrow to medium-width feet like myself, this snug fit translates to exceptional precision and control, allowing for quick adjustments and confident foot placement on technical terrain.

The more aggressive lug pattern than the Pulsar 1 and 2 non soft ground with now higher 4mm lugs bit into loose gravel and scree, delivering unwavering traction on both the ascent and descent.

In 1924–1925, Satyendra Nath Bose showed that light followed different statistics from that of classical particles. With Einstein, they generalized this result for a whole set of integer spin particles called bosons (after Bose) that follow Bose–Einstein statistics. The photon is a massless boson of spin 1.

Faraday's work inspired James Clerk Maxwell to study electromagnetic radiation and light. Maxwell discovered that self-propagating electromagnetic waves would travel through space at a constant speed, which happened to be equal to the previously measured speed of light. From this, Maxwell concluded that light was a form of electromagnetic radiation: he first stated this result in 1862 in On Physical Lines of Force. In 1873, he published A Treatise on Electricity and Magnetism, which contained a full mathematical description of the behavior of electric and magnetic fields, still known as Maxwell's equations. Soon after, Heinrich Hertz confirmed Maxwell's theory experimentally by generating and detecting radio waves in the laboratory and demonstrating that these waves behaved exactly like visible light, exhibiting properties such as reflection, refraction, diffraction and interference. Maxwell's theory and Hertz's experiments led directly to the development of modern radio, radar, television, electromagnetic imaging and wireless communications.

Other remarkable results are the demonstration of quantum entanglement, quantum teleportation, and quantum logic gates. The latter are of much interest in quantum information theory, a subject which partly emerged from quantum optics, partly from theoretical computer science.

On the trails, the rockered platform worked in harmony with the Energy Foam midsole to create a fluid and dynamic ride. The shoe felt nimble and responsive, allowing me to easily adjust my stride and navigate the technical terrain with confidence. The low stack height provided a stable base, while the rockered profile facilitated a smooth roll-through, reducing fatigue on longer runs.

John: In my opinion the Pulsar 3 represents a nice evolution from the original S/Lab Pulsar, a faster, more dynamic, more protective, and more agile ride on technical trails. While the Pulsar 3 maintains the original's snug fit and lightweight construction, as well as the lightweight and agile nature of the original while gaining a small amount of weight, I find the Pulsar 3 more performant, grippy (given its higher lugs and more aggressive pattern), and is more capable in technical terrain.

John: Upon unboxing the Pulsar 3s, I was immediately struck by their incredibly lightweight design. Weighing in at a mere 7.15 ounces (202 grams) US9, they felt more like slippers than running shoes. This featherlight weight is achieved through a combination of Salomon's lightest midsole compound, Energy Foam (an EVA Olefin co-polymer block blend), and a minimalist Matryx upper.

Refractionoccurs whenlightpassingfromone medium to another

In the fifth century BC, Empedocles postulated that everything was composed of four elements; fire, air, earth and water. He believed that goddess Aphrodite made the human eye out of the four elements and that she lit the fire in the eye which shone out from the eye making sight possible. If this were true, then one could see during the night just as well as during the day, so Empedocles postulated an interaction between rays from the eyes and rays from a source such as the sun.[31]

John Tribbia (5' 6", 130lbs) is a former sponsored mountain/trail runner who has run with La Sportiva, Brooks/Fleet Feet, Pearl Izumi, and Salomon. Even though he competes less frequently these days, you can still find John enjoying the daily grind of running on any surface, though his favorite terrain is 30-40% grade climbs. He has won races such as America's Uphill, Imogene Pass Run, and the US Skyrunner Vertical Kilometer Series; and he's held several FKTs on several iconic mountains in Boulder, Colorado and Salt Lake City, Utah. If you follow him on Strava, you'll notice he runs at varying paces between 5 minutes/mile to 12 minutes/mile before the break of dawn almost every day.

The wave theory predicted that light waves could interfere with each other like sound waves (as noted around 1800 by Thomas Young). Young showed by means of a diffraction experiment that light behaved as waves. He also proposed that different colours were caused by different wavelengths of light and explained colour vision in terms of three-coloured receptors in the eye. Another supporter of the wave theory was Leonhard Euler. He argued in Nova theoria lucis et colorum (1746) that diffraction could more easily be explained by a wave theory. In 1816 André-Marie Ampère gave Augustin-Jean Fresnel an idea that the polarization of light can be explained by the wave theory if light were a transverse wave.[37]

The photometry units are different from most systems of physical units in that they take into account how the human eye responds to light. The cone cells in the human eye are of three types which respond differently across the visible spectrum and the cumulative response peaks at a wavelength of around 555 nm. Therefore, two sources of light which produce the same intensity (W/m2) of visible light do not necessarily appear equally bright. The photometry units are designed to take this into account and therefore are a better representation of how "bright" a light appears to be than raw intensity. They relate to raw power by a quantity called luminous efficacy and are used for purposes like determining how to best achieve sufficient illumination for various tasks in indoor and outdoor settings. The illumination measured by a photocell sensor does not necessarily correspond to what is perceived by the human eye and without filters which may be costly, photocells and charge-coupled devices (CCD) tend to respond to some infrared, ultraviolet or both.

The Pulsar 3's low stack height and thin Profeel Film layer enhance ground feel, providing a direct connection to the trail. This heightened awareness translates to increased confidence on technical descents, where precise foot placement is crucial. The shoe offers the feedback necessary to make split-second decisions, instilling a sense of trust in every stride.

But the Pulsar 3 is more than just a collection of technical features. It's a shoe that embodies the spirit of adventure and the pursuit of excellence. It's a shoe that empowers runners to push their limits, explore new trails, and achieve their personal best.

When the concept of light is intended to include very-high-energy photons (gamma rays), additional generation mechanisms include: