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Is a photon matter?
I know a photon is considered a particle, but it is also massless.
I'm getting a little bit of everything on this so i'm just thinking that weather a photon is matter is arguable.
it is written in wikipedia (remember...'s favorite website) that photons cary light meaning that photons aren't light itself, and is it possible for energy to carry energy and if it's not energy then it would have to be matter, wouldn't it?
yet, photons don't take up space or have mass acording to bwo22 so how could it posobly be matter.
so if it isn't matter and isn't energy what is it??????
13 Answers
- remember.kellyLv 41 decade agoFavorite Answer
The question of whether a photon is matter or not is purely one of semantics - it depends on how you define what matter is. The word "matter" was used already long, long, long before the modern idea of photon existed, or for that matter (sorry) before most other particles of nature. So, it doesn't matter. Never mind either.
As far as evidence for a rest mass of the photon, as far as is known, it doesn't have any. If the photon did have a small rest mass that would mean that one of lower frequency would travel slightly slower than one of higher frequency. The effect of this would be observable on a cosmological scale: Short wavelength light coming from a super nova explosion very distant in the universe would reach the Earth a little before longer wavelengths. Even if something like that were observed, you would still have to show that this could not have been caused otherwise, although that might be relatively easy.
In reference to the web page mentioned above (J. of Theoretics), I wouldn't consider that an authority of any kind. For one, the properties of photons are extremely well understood, better than anything else we know of, at least mathematically. The problem is understanding them in terms of everyday terms, or even more difficult, explaining them to laymen.
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To bw022, below:
You state that only Fermions are considered to be "matter", a view that you apparently took from the Wikipaedia site. In other words, He4 is not matter according to your definition, nor would any other atom that has integer spin.
You also seem to imply that bosons do not have mass, again (an opinion I have seen previously stated in Yahoo.answers at least several times), do I have to conclude that He4 is massless?
I wish that people would not so readily quote Wikipaedia, in fact, I wish that more would return to reading books. I don't know how Wikipaedia operates, or who is resposible for quality control, but its reliability is very uneven.
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To letslearntothink:
The idea that a photon might have a very small mass does not contradict the laws of physics. Also, you would have to describe exactly how you would slow down a photon in order for your argument to make sense. What does make sense is that the law c=f*lambda would not apply to extremely long wavelengths, so you could test the hypothesis on that basis. But, perhaps we have never measured wavelengths long enough.
If the photon had mass, then the relation between frequency and wavelength (i.e. the photon dispersion relation) would become:
hf = sqrt[(hc/lamba)^2 + m^2 c^4 ],
where lambda=wavelength, f=frequency, m=photon mass, c=fundamental constant equal to speed of m=0 particles
The best hope of measuring it would probably be on the cosmological scale, as I described above.
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I marked this question as "interesting" more on a philosophical basis, but certainly not as a scientific question. My impression is that it is common for people who have never had a science course as part of their education to readily become tied up in matters of semantics, while those with even a little instruction already know how to avoid falling into that trap. Am I right?
- Anonymous5 years ago
Yes. Photons can create matter. In the process called pair production, a slightly over 1.1MEV gamma ray (photon) can create two particles; a positron an an electron, each having an equivalent total energy of 0.55MEV. However since the energy is converted to mass the masses created will no longer be moving at the speed of light but at slower velocities. Creating actual molecules out of photons alone however is a remote possibility because atoms consist of different particles with different characteristics and need not be created by photons alone. Most particles heavier than electrons are made of quarks.
- bw022Lv 71 decade ago
No. The general definition of matter is a particle which takes up space and has mass. It difficult to find any other definition, although the term 'matter' is generally avoided when getting into quantum mechanics and replaced by specific definitions based on spin, energy, mass, etc.
Only fermions - 1/2 spin particles such as quarks and leptons, plus heavier particles made up of these - are generally considered matter. They have mass and obey the exclusion principle (thus taking up space).
Photons are bosons - particles with integer spin. They may not have mass and they do not obey the exclusion principle (and thus don't take up space). These are considered force particles.
Source(s): http://en.wikipedia.org/wiki/Bosons http://en.wikipedia.org/wiki/Fermion http://en.wikipedia.org/wiki/Matter - 7 years ago
The Different wavelengths of visible light have different speeds in different objects as shown by a prism and the different angles of refractions which creates rainbows. By that logic it could easily be that matter is just photons torn apart and are being held together by opposing forces Which is how the electromagnetism comes in because electricity and magnets try to separate or go together so all photons could just be combinations of both together. Which goes in accordance with the new theory of how light can be turned into matter. http://www.universetoday.com/112044/physicists-pav...
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- ---Lv 51 decade ago
Scientists are still trying to figure out exactly what a photon is. A photon has both wave and particle-like properties, but it is either neither or both. There are also disagreements about whether a photon has mass. I have read both yes and no.
- Anonymous1 decade ago
NO MASS! Just momentum, p = hf
where
h = Planck's constant = 6.626068 × 10-34 m2 kg / s
f = the frequency of the photon
- Universal MindLv 41 decade ago
Photons are particles of light, You feel the heat of light when its photons clash against the molecules of your skin.The greater the intensity of the light and the more concentrated it is, the more friction it will generate when it collides with other matter
- 1 decade ago
I have read all the answers up till now. Let us assume photon has some mass, by that we mean rest mass like any other particle. Now you know by principle of relativity. any such particle can increase its speed by application of force only till it becomes just less than that of light but not equal to that of light. So such a particle should be able to travel with any velocity less than that of light. In case of photon we know that it can travel in vacuum with only speed of light neither a little smaller nor any higher. So photon cannot have any finite so called rest mass. Other particles which have non-zero rest mass can be brought to rest by applying force and so one can measure its rest mass. Can photon be brought to rest? Never! If you try to stop a photon it vanishes and gives its all energy to the system whichever tries to stop it. This also means that photon cannot have any nonzero rest mass which we can measure by bringing it to rest!
Now photon is a name given to the particle associated with electromagnetic waves. These waves have energy of their own as they exist in vacuum. They are not like mechanical waves whose energy is ultimately the energy of the particles of the medium in which they travel. According to the principle of relativity energy and mass are equivalent. Because photons have energy they must be having equivalent mass. Yes they have, it is equal to Planck's constant multiplied by frequency and divided by velocity of light squared. Particles having nonzero rest mass increase in mass as they travel with higher and higher velocity as it is obvious that their energy increases so their mass which is equivalent to energy must also increase. This consideration tells us that mass of a moving particle m1 is more that what it is, say m0 when particle is at rest. There is a formula for this m1 = m0/sqrt(1-v^2/c^2). If you apply this formula to photon, then you see that in order m1 to be finite(not infinite) for a particle moving with c m0 must be zero, because zero/zero in the limit could be any finite quantity.
- Anonymous1 decade ago
No, the photon is merely a packet of electromagnetic energy.
- 1 decade ago
photon is th smallest unit of energy of sunlight.yes it is massless.
SO I DONT THINK PHOTON IS A MATTER