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Louis Nardozi
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What is the mass of all photons emitted in the universe since the Big Bang?
ZeroLouis Nardozi said:What is the mass of all photons emitted in the universe since the Big Bang?
DrGreg said:Zero
It is.sophiecentaur said:Isn't n times Zero still zero?
... according to the new measurement, the number of photons (particles of visible light) that escaped into space after being emitted by stars translates to 4x1084
DrStupid said:That's the mass of each individual photon, but I think the OP reather asks for the total mass of all photons.
This actually raises all sorts of complications. The answer I gave in post #2 is really the answer to the question "What is the sum of all the the masses of photons emitted since the Big Bang?" But in relativity, the mass of a collection of particles is not necessarily equal to the sum of the masses of each particle. In special relativity, a collection of photons has a non-zero mass, unless all the photons travel in the same direction. In general relativity, the mass of a system isn't a well-defined concept. There are a number of different types of system mass, and some of them make sense only in special circumstances.sophiecentaur said:Isn't n times Zero still zero?
So zero times infinity?Also, isn't the "number of anything in the universe" entirely non-sensical? If the universe is both homogenous and infinite (both of which we assume) then the total number of photons is infinity, and has been since the electroweak epoch. Before which the number was exactly zero.DrStupid said:That's the mass of each individual photon, but I think the OP reather asks for the total mass of all photons.
newjerseyrunner said:So zero times infinity?
newjerseyrunner said:If the universe is both homogenous and infinite (both of which we assume) then the total number of photons is infinity, and has been since the electroweak epoch.
##10^{84}## is a fairly large number, but it's still a finite number.newjerseyrunner said:So zero times infinity?
Louis Nardozi said:I wanted to see how it matched up to the amount of "dark matter" or "dark energy" in the universe.
Louis Nardozi said:4*1084*Percentage of photons still traveling in space (gotta be close to unity)* mass of photon traveling in space. I wanted to see how it matched up to the amount of "dark matter" or "dark energy" in the universe.
In the context of photons, mass refers to the amount of energy that a photon possesses. Unlike traditional particles, photons do not have a rest mass, but they do have a relativistic mass which is determined by their energy and momentum.
The mass of photons can be calculated using Einstein's famous equation, E=mc2, where E represents the energy of the photon and c represents the speed of light. This equation shows that mass and energy are equivalent, and the mass of a photon is directly proportional to its energy.
The total mass of all the photons emitted in the universe is estimated to be around 4 x 1048 kg. This may seem like a large number, but in comparison to the total mass of the universe (around 1053 kg), it is relatively small.
While photons do have mass, they make up a very small percentage of the total mass of the universe. The majority of the mass in the universe is made up of dark matter and dark energy, with regular matter (including photons) making up only about 5% of the total mass.
No, the mass of photons cannot be measured directly. This is because photons do not have a rest mass and therefore cannot be weighed like traditional particles. However, their energy and momentum can be measured, and from this, their mass can be calculated using the equation E=mc2.