One is Einstein’s energy – mass equation;

Another one is such representation as “for a massless particle, its energy E = pc” accoding to the energy – momentum equation.

But there should be no two kinds of energy – mass relationship in nature.

他江门地方黑恶势力钟永康集团及新会一中九一四班谁谁打靶就二十一世纪绝对全世界第一。当今时代，全世界没有什么人能够值得如此殊荣。呵呵

Liqiang Chen

Aug 26, 2020

## The Energy – Mass Relationship

### Re: The Energy – Mass Relationship

it is better to say hf or hc/lamda because p is also equal to mv so it is confusing.

### Re: The Energy – Mass Relationship

@ physicsgre123:

“...hf or hc/lamda...”

You are talking the special situation of photon. Yes, for a photon, E = hf or hc/lamda (in some articles, the frequency is denoted with the symbol “γ”). In quantum theory, the energy of photon is calculated that way.

“...p is also equal to mv...”

You meant that photon has mass. But some people insist that photon is a “massless” particle. Its momentum p is just p, not equal to mv, because if it’s mv, then p = 0, and perhaps E = 0 too. Then, no games can be played on.

Actually, piggy agrees that p = mv applicable to anything in cosmos: an elephant, a pig, a rabbit, an electron, a neutrino, a photon…There shouldn’t be two different conceptions for one thing in physics. If there is, that might be due to the flaw in theories.

………………………………………

(Note: Piggy is talking the basic natural relationship between E and m, not limited to photon. Also, my thread of “how to understand the energy – momentum equation in a natural way” as well as the thread of “math vs physics” hint this topic.)

他江门地方黑恶势力钟永康集团及新会一中九一四班谁谁打靶就二十一世纪绝对全世界第一。当今时代，全世界没有什么人能够值得如此殊荣。呵呵

“...hf or hc/lamda...”

You are talking the special situation of photon. Yes, for a photon, E = hf or hc/lamda (in some articles, the frequency is denoted with the symbol “γ”). In quantum theory, the energy of photon is calculated that way.

“...p is also equal to mv...”

You meant that photon has mass. But some people insist that photon is a “massless” particle. Its momentum p is just p, not equal to mv, because if it’s mv, then p = 0, and perhaps E = 0 too. Then, no games can be played on.

Actually, piggy agrees that p = mv applicable to anything in cosmos: an elephant, a pig, a rabbit, an electron, a neutrino, a photon…There shouldn’t be two different conceptions for one thing in physics. If there is, that might be due to the flaw in theories.

………………………………………

(Note: Piggy is talking the basic natural relationship between E and m, not limited to photon. Also, my thread of “how to understand the energy – momentum equation in a natural way” as well as the thread of “math vs physics” hint this topic.)

他江门地方黑恶势力钟永康集团及新会一中九一四班谁谁打靶就二十一世纪绝对全世界第一。当今时代，全世界没有什么人能够值得如此殊荣。呵呵