mvbn said:For example, thermal energy exists and has no mass, but is carried by particles which have mass.
As davenn wrote, electomagnetic radiation is how I would consider thermal energy 'travels'. You may be speaking about kinetic energy when you mention particles that have mass, as in the collisions of molecules in a gas or their vibrations in a solid.mvbn said:For example, thermal energy exists and has no mass, but is carried by particles which have mass.
Photons are best thought of as the minimum amount (quanta) of light that can be transferred. You will read that light/photons exhibit a "wave/particle duality", but the experts will tell you this is an analogy, and it's better to think of photons as neither (they are their own unique, quantum object.)A photon is described as a particle
Light travels as electromagnetic waves - an excitation of the EM field.how can a photon exist on its own, travel in space
Light has energy and momentum. The E=mc^2 equation from Einstein that most folks are familiar with explains the relationship between energy and mass. But there is more to the right hand side of the equation that's frequently omitted - a momentum component for massless particles. The equation reduces to the simpler E=mc^2 when the momentum term iz zero. So light does indeed exert a pressure, albeit ever so small, from the momentum it carries.and even push other particles with mass if it has no mass itself?
I thought When One vibrating particle(atom) hits another vibrating particle and causes it to vibrate more that is transfer of thermal energy without photons. Am I wrong?.davenn said:radiated thermal energy is carried by infrared photons ( more precisely IR Electromagnetic radiation) massless particles <-- and I use that term broadly
http://en.wikipedia.org/wiki/Thermal_radiationmvbn said:I thought When One vibrating particle(atom) hits another vibrating particle and causes it to vibrate more that is transfer of thermal energy without photons. Am I wrong?.
Light has particle properties. Photons are particles.mvbn said:It says clearly that it is "elementary particle" and not just have particle properties.
You are not wrong. This is an example of conduction. There are additional ways to transfer heat. One, as A.T. pointed out, is radiation.mvbn said:I thought When One vibrating particle(atom) hits another vibrating particle and causes it to vibrate more that is transfer of thermal energy without photons. Am I wrong?.
A.T. said:Light has particle properties. Photons are particles.
bhobba said:Well first a correct analysis with photons really needs QED (Quantum Electrodynamics) since the photons are actually excitations of an underlying EM field... ...if they were actually quantum particles in the usual sense, which is the usual way its treated in beginning treatments - its wrong - but we all must start somewhere.
^ Excerpt from PF FAQ: "Is Light A Wave Or A Particle?"ZapperZ said:We still use the “duality” description of light when we try to describe light to laymen because wave and particle are behavior most people are familiar with. However, it doesn’t mean that in physics, or in the working of physicists, such a duality has any significance.
According to the theory of relativity, mass and energy are equivalent and can be converted into each other. Photons are particles of energy, and therefore do not have a rest mass.
While photons do not have a rest mass, they do have a momentum due to their energy. The equation E=mc^2, where E is energy, m is mass, and c is the speed of light, shows that energy and mass are interchangeable. This means that photons with energy also have momentum.
The lack of mass allows photons to travel at the speed of light, which is the maximum speed in the universe. It also allows them to be unaffected by gravitational forces, as mass is what creates and interacts with gravity.
Yes, a photon can exist in a vacuum without any other particles. In fact, photons are often described as the carriers of electromagnetic radiation in a vacuum.
The wave-particle duality of a photon is a result of the uncertainty principle in quantum mechanics. The lack of mass in a photon allows it to behave as both a wave and a particle, depending on the observation or interaction with other particles.