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emz
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Why is photon gas pressure = photon energy density (per volume) divided by 3?
Thank you
Thank you
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Basically it's down to a photon's energy being equal to its momentum, and the division by three comes from the three dimensions of space (energy is a scalar, independent of direction, but momentum has direction, and pressure is the average momentum of particles traveling in a given direction).emz said:Why is photon gas pressure = photon energy density (per volume) divided by 3?
Thank you
If you just take classical electromagnetism, yes, you can pack as many as you like into whatever volume you like.easyrider said:Not to hijack the thread, but is there a physical limit to how high electromagnetic energy density can go, like a certain point where you can't pack anymore photons in a given volume at all? I imagine now there would come a point where a black hole would form, but in the beginning, it seems like you could have just about any amount of photons in a cerain space.
Photon pressure is the force exerted by photons, or particles of light, on an object. This force arises from the transfer of momentum when photons collide with the surface of an object.
Photon pressure is directly proportional to the energy density of the photons. This means that the higher the energy density of photons, the greater the amount of pressure they can exert on an object.
The formula for calculating photon pressure is P = u/c, where P is the pressure, u is the energy density, and c is the speed of light. This formula is known as the photon pressure equation.
Photon pressure plays a critical role in the dynamics of stars and other celestial bodies. It is a major driving force for nuclear fusion in stars, and can also counteract the gravitational force, helping to maintain the stability of stars.
Yes, photon pressure can be observed in everyday life. For example, solar sails use photon pressure from sunlight to propel spacecraft through space. Additionally, the pressure from a laser beam can be strong enough to move small objects, demonstrating the force of photon pressure.