Yes, photons can collide with each other and with other particles. While single photons don't typically interact with each other in the way we might imagine a collision between billiard balls, they can interact under specific conditions, particularly at very high energies, or when interacting with charged particles like electrons. High-energy collisions: In extremely high-energy environments, like those found in particle colliders, photons can collide and create other particles, such as electron-positron pairs. This is known as the Breit-Wheeler process. Protons traveling at high speeds in colliders emit "virtual photons," which can then collide with other virtual photons from another proton, resulting in the creation of new particles. Recent experiments have provided the first clear evidence of the Breit-Wheeler process, demonstrating the creation of matter (electron-positron pairs) from photon-photon collisions. Photon-Particle Collisions: A photon can collide with an electron, transferring some of its energy to the electron and changing direction. This is known as Compton scattering. Conservation of energy and momentum: In photon-particle collisions, total energy and momentum are conserved, although the number of photons may not be. Photons can interact with each other and with other particles, particularly at high energies or when virtual photons are involved. Photon-photon collisions can result in the creation of matter and antimatter. These collisions are studied in high-energy physics experiments to explore fundamental interactions and potentially discover new physics beyond the Standard Model. K Rajaram IRS 4725
On Fri, 4 Jul 2025 at 13:40, Markendeya Yeddanapudi < [email protected]> wrote: > Can two photons collide?Then what will happen? > > > > > -- > *Mar*Great question! The idea of two photons "bumping" into each other > isn't something that happens in the classical sense, because photons are > not like traditional particles that collide in the way that, say, billiard > balls might. However, photons do interact with each other, just not in the > same way as ordinary objects. Let's break it down: > 1. *Photons and Classical Collisions:* > > - > > In classical mechanics, we imagine particles as objects that can > collide and exchange momentum and energy. However, photons are > *massless* and travel at the speed of light, so they don’t behave in > the way that objects with mass do. > - > > Two photons can’t simply “bump” into each other in the usual sense > because photons don’t exert forces on one another directly in classical > physics. > > 2. *Quantum Electrodynamics (QED) and Photon-Photon Interactions:* > > - > > In quantum field theory, particularly in *Quantum Electrodynamics > (QED)*, photons can interact indirectly under certain extreme > conditions, though these interactions are very weak and rare in typical > situations. > - > > *Photon-photon scattering* is theoretically possible but extremely > unlikely under normal circumstances. It occurs in *high-energy* > environments, like in *extreme electromagnetic fields* or in *high-energy > particle colliders*. These interactions occur because photons can > interact with virtual particles (such as virtual electron-positron pairs) > in certain situations. > - > > This is a very subtle effect and can’t be observed in everyday life, > as the probability of two photons directly interacting is incredibly low in > regular conditions. > > 3. *What Happens if Two Photons Do "Interact"?* > > - > > *In high-energy environments* (like inside a laser or a high-energy > particle accelerator), photons can interact through *nonlinear effects* > in the presence of strong electromagnetic fields. This can lead to > phenomena such as *photon-photon scattering* or the creation of > particle-antiparticle pairs under intense conditions. > - > > The phenomenon known as *photon-photon scattering* was experimentally > observed at very high photon intensities in particle colliders, but it's an > extremely rare and weak interaction. > - > > In most circumstances, when photons encounter each other, they *pass > through one another without any effect*. They don’t bounce off or > alter each other in any noticeable way because photons don’t "feel" each > other’s presence unless in a very specific quantum context. > > 4. *Other Interesting Photon Interactions:* > > - > > *Photon absorption and emission*: While photons don't collide with > each other, they can interact with matter. For example, when a photon > strikes an atom, it can be absorbed, and the atom may jump to a higher > energy level. Later, it may emit a photon when it drops back to a lower > energy level. > - > > *Interference*: While photons themselves don't directly collide, > *interference* can occur when multiple photons overlap in space. This > isn’t a direct collision, but it’s a quantum phenomenon where the > probability amplitudes of the photons interfere with each other, leading to > regions of constructive or destructive interference. > > 5. *The Extreme Case:* > > - > > In a *superintense electromagnetic field*, such as in the presence of > *ultra-strong > lasers* or the environment around a *black hole*, photons might > interact more strongly, but even then, it's not a simple "bump" like two > objects colliding. Instead, the interactions could involve complex > processes like the creation of particle-antiparticle pairs, leading to the > photon splitting into other particles or interacting with the > electromagnetic field. > > In Summary: > > Under normal conditions, photons don’t bump into each other in the way we > might imagine. They can *pass through* one another without interacting. > However, under extremely high-energy conditions, *photon-photon > interactions* can occur, but this is a rare and complex quantum > phenomenon. These interactions are generally only noticeable in *high-energy > physics experiments* or in the presence of intense electromagnetic fields. > > If you're thinking about how this relates to things like light behavior or > quantum mechanics, it's definitely fascinating how even the most > fundamental particles like photons can behave in such surprising ways! > > Does that make sense, or is there a specific aspect you're curious about > regarding photon interactions? > > -- > You received this message because you are subscribed to the Google Groups > "Thatha_Patty" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/thatha_patty/CACDCHC%2BFV_%3Dd4xv6mFaMtCLjmGDAB_OTMmp-%2BHcsBL1zY0Nueg%40mail.gmail.com > <https://groups.google.com/d/msgid/thatha_patty/CACDCHC%2BFV_%3Dd4xv6mFaMtCLjmGDAB_OTMmp-%2BHcsBL1zY0Nueg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. 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