What are mass and energy?

[attofishpi]

Mass is what fat people have an abundance of, energy is what they have a deficiency of.

So fat people are more (gravitationally) attractive?

Yes, and they lay on their backs and get pregnant with extreme ease.

[HexHammer]

...
..so yes I do understand what Einstein said. Most people learn, but u'll never learn.

Do you? Well given that only a few physicists understand what he said I won't take your word for it.

Then let me rephrase, I know some of the basics of what he said, the main stream stuff, time, length contraction, E=MC2..

[Arising_uk]

Have you read his book for the layman, "Relativity"?

[surreptitious57]

Mass and energy are interchangeable so objects at rest shall still have energy
Fat people have more energy than thin people because they have more mass

[Hobbes' Choice]

Mass and energy are interchangeable so objects at rest shall still have energy
Fat people have more energy than thin people because they have more mass

Useless observations.
The interchangeability of matter and energy is only expressed in the violence of nuclear fission and fusion.

Objects at rest have different types of energy regardless of their matter.

[attofishpi]

God said "I am the light."
Light is composed of photons, so we could ask if the photon has mass. The answer is then definitely "no": the photon is a massless particle. According to theory it has energy and momentum but no mass

However, it is interesting that 'HE' still insists on having Mass.
The Mass or Eucharist is the central act of divine worship in the Catholic Church, which describes it as "the source and summit of the Christian life".

[Noax]

God said "I am the light."
Light is composed of photons, so we could ask if the photon has mass. The answer is then definitely "no": the photon is a massless particle. According to theory it has energy and momentum but no mass

You sort of imply that God stated that he's composed of photons. Not sure what that had to do with any of this.

Anyway, photons have mass, else they could not have momentum. Photons have no rest-mass, which is not the same thing as having no mass.

[Hobbes' Choice]

God said "I am the light."
Light is composed of photons, so we could ask if the photon has mass. The answer is then definitely "no": the photon is a massless particle. According to theory it has energy and momentum but no mass

However, it is interesting that 'HE' still insists on having Mass.
The Mass or Eucharist is the central act of divine worship in the Catholic Church, which describes it as "the source and summit of the Christian life".

You poor confused sod.

[attofishpi]

God said "I am the light."
Light is composed of photons, so we could ask if the photon has mass. The answer is then definitely "no": the photon is a massless particle. According to theory it has energy and momentum but no mass

You sort of imply that God stated that he's composed of photons. Not sure what that had to do with any of this.

My point is that God is everything - right down to the finite point of the binary universe.

Anyway, photons have mass, else they could not have momentum. Photons have no rest-mass, which is not the same thing as having no mass.

I could be wrong here, but no, i disagree -if photons had mass then they would have copious amounts of mass at the speed they travel, since anything with mass as it approaches the speed of light becomes extremely 'massive'.

[attofishpi]

God said "I am the light."
Light is composed of photons, so we could ask if the photon has mass. The answer is then definitely "no": the photon is a massless particle. According to theory it has energy and momentum but no mass

However, it is interesting that 'HE' still insists on having Mass.
The Mass or Eucharist is the central act of divine worship in the Catholic Church, which describes it as "the source and summit of the Christian life".

You poor confused sod.

At least i'm not a naive fool as you are.

[Noax]

Anyway, photons have mass, else they could not have momentum. Photons have no rest-mass, which is not the same thing as having no mass.

I could be wrong here, but no, i disagree -if photons had mass then they would have copious amounts of mass at the speed they travel, since anything with mass as it approaches the speed of light becomes extremely 'massive'.

Anything with rest mass (can exist at rest in some inertial reference frame) does this as it is considered in frames where it moves close to light speed. Photons do not approach light speed. They are light speed. It is a different solution to the same math you're referencing.

E=MC2 says that mass is proportional to energy, and in fact is energy. If something has energy (like a photon), then it has mass, else that formula is invalid. A charged cell phone exerts (trivially) more gravity than the same one with the battery run down since it has more energy (and thus mass), despite the same number of particles.

[surreptitious57]

Photons are massless particles. Or else they would not be capable of travelling at light speed. The mass
is associated with their momentum. They have zero rest mass because their speed in vacuum remains a
constant but changes when encountering a difference in density. Such as from air to water for example

[Noax]

Photons are massless particles. Or else they would not be capable of travelling at light speed. The mass
is associated with their momentum. They have zero rest mass because their speed in vacuum remains a
constant but changes when encountering a difference in density. Such as from air to water for example

Apparently the mass (momentum/velocity) of a thing is the sum of its fixed rest mass and its frame-dependent relativistic mass. Photons have none of the former so the mass of the photon is only its relativistic mass, which interestingly is still frame dependent.

For me to say 'photons have mass' is somewhat ambiguous since rest-mass (not total mass) is usually suggested by the general term. I stand corrected.