Register to reply

Is Light Matter?

by swerdna
Tags: light, matter
Share this thread:
swerdna
#1
Sep12-07, 04:57 PM
P: 251
Is light a physical thing, in other words, is it matter?
Phys.Org News Partner Physics news on Phys.org
Physicists discuss quantum pigeonhole principle
First in-situ images of void collapse in explosives
The first supercomputer simulations of 'spin?orbit' forces between neutrons and protons in an atomic nucleus
lanman
#2
Sep12-07, 07:53 PM
P: 8
Light is another name for electromagnetic radiation, which is the transmission of energy. It is energy. Einstein's equation shows that energy and matter are the same concept, so in a way, it is.
meopemuk
#3
Sep12-07, 08:25 PM
P: 1,746
Quote Quote by swerdna View Post
Is light a physical thing, in other words, is it matter?
Light is a flow of a huge number of particles - photons. Photons have zero mass, but this doesn't make them any "less" matter than electrons or protons.

Eugene.

Claude Bile
#4
Sep12-07, 09:04 PM
Sci Advisor
P: 1,474
Is Light Matter?

Quote Quote by lanman View Post
Einstein's equation shows that energy and matter are the same concept, so in a way, it is.
E = mc^2 is the equivalence of mass and energy, not matter and energy.

Matter is traditionally regarded as stuff with rest mass, i.e. protons, neutrons, electrons and so forth, and is distinct from inertial mass.

Claude.
DaveC426913
#5
Sep12-07, 09:15 PM
DaveC426913's Avatar
P: 15,319
Quote Quote by meopemuk View Post
this doesn't make them any "less" matter than electrons or protons.

Eugene.
In fact, it does.

Light is not matter. Light is energy. This is not a point of debate.
swerdna
#6
Sep12-07, 10:17 PM
P: 251
Quote Quote by DaveC426913 View Post
In fact, it does.

Light is not matter. Light is energy. This is not a point of debate.
I agree, but I think there are plenty who will debate this (I hope). Not being smart, just trying to learn,
DaveC426913
#7
Sep12-07, 10:44 PM
DaveC426913's Avatar
P: 15,319
Quote Quote by swerdna View Post
I agree, but I think there are plenty who will debate this (I hope). Not being smart, just trying to learn,
You agree, but you're looking for debate? Are you just looking to stir a pot or something?

Really. There's no debate. It's not open to interpretation.
cesiumfrog
#8
Sep12-07, 10:51 PM
P: 2,050
Quote Quote by DaveC426913 View Post
Light is energy.
But such a statement does not distinguish it from matter. Nonetheless, distinction from radiation is a practical meaning for modern use of the term "matter".

On the other hand, language is fluid: "Space-time tells matter how to move".
swerdna
#9
Sep12-07, 10:58 PM
P: 251
My purpose is not to stir. There are many people who argue that light is matter, and I would like to learn what their argument is and how credible it is. One of the hardest things with learning modern science is that there seems to be so many conflicting conclusions, it's hard to know which to believe.
cesiumfrog
#10
Sep12-07, 11:16 PM
P: 2,050
Swerdna, are you sure those people weren't merely asserting that light has (relativistic) mass?
castlegates
#11
Sep12-07, 11:32 PM
P: 48
Matter to me is localized energy. In this instance light is matter. Thats my take anyway.
swerdna
#12
Sep12-07, 11:57 PM
P: 251
Quote Quote by cesiumfrog View Post
Swerdna, are you sure those people weren't merely asserting that light has (relativistic) mass?
If they are, they aren’t making that point clear. Does that light has “relativistic mass” mean it is matter?
swerdna
#13
Sep13-07, 12:07 AM
P: 251
This argument has been put to me . . .

If E = mc^2, and light = E, then light = mc^2. Therefore light is matter.

Given, as Claude Bile stated (post #4), “E = mc^2 is the equivalence of mass and energy, not matter and energy”, I guess they are saying that because light has relativistic mass it is matter.
swerdna
#14
Sep13-07, 12:20 AM
P: 251
Quote Quote by castlegates View Post
Matter to me is localized energy. In this instance light is matter. Thats my take anyway.
Matter contains energy, but how does that make energy matter? A sponge can contain water, but that doesn't make the sponge water.
prasannapakkiam
#15
Sep13-07, 05:28 AM
P: n/a
While we are on the topic. Does this prove that light cannot have mass?:

m=m0*(Gamma)
ZapperZ
#16
Sep13-07, 05:39 AM
Emeritus
Sci Advisor
PF Gold
ZapperZ's Avatar
P: 29,239
Quote Quote by swerdna View Post
My purpose is not to stir. There are many people who argue that light is matter, and I would like to learn what their argument is and how credible it is. One of the hardest things with learning modern science is that there seems to be so many conflicting conclusions, it's hard to know which to believe.
Can you point out who "these people" are? I mean, if you're referring to crackpots who barely know physics, then we're wasting out time here, aren't we?

There is a FAQ in here that addresses the misuse of that Einstein equation. You may want to start with that. After you've done that, then maybe you should then proceed with defining what you mean by "matter". Only after you do these two, then maybe we can use that criteria of what "matter" is to see if light has such a property. I think this is the only sensible way to approach such a thing, using valid definitions and a clear understanding of what we are talking about. The way this thread has proceeded appears to be more of a "make it up as I go along" type.

Zz.
DaveC426913
#17
Sep13-07, 08:20 AM
DaveC426913's Avatar
P: 15,319
Quote Quote by castlegates View Post
Matter to me is localized energy. In this instance light is matter. Thats my take anyway.
Algebraically, this is what you've said:
A = Matter
B = Energy
c = localized (a modifier)

Your argument is
Since A = cB, therefore B=A. (Where did the c go?)

Because matter is localized energy does not make light matter. Not the least reason of which is because light is not localized; it moves at c. And If it didn't, it wouldn't be light.
castlegates
#18
Sep13-07, 10:41 PM
P: 48

Because matter is localized energy does not make light matter.
Thats exactly what it makes it .... if true.
Not the least reason of which is because light is not localized; it moves at c.
Didn't say that light does not move at C, only that if it is localized, it can take on the characteristics of matter. A solor sail for instance one could consider as a situation where light is very briefly localized, by which light takes on a characteristic of mass by which a sail can be pushed.

Light could be said to move in a straight line, but what if it follows an orbital pattern. I.E. localization.


Register to reply

Related Discussions
Please educate me on light/matter General Physics 5
Light as solid matter Beyond the Standard Model 0
Does the light transform a matter? General Physics 21
Light =======>Matter General Physics 31
Matter and Light in Flatland? High Energy, Nuclear, Particle Physics 0