How Does Light Relate to Energy and Subatomic Particles?

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
9 replies · 3K views
JeremyL
Messages
22
Reaction score
0
If our eyes can perceive light and light is energy then why is energy defined as an indirectly observed quantity?
 
Physics news on Phys.org
It is incorrect to say "light is energy".

Energy is a property of physical systems. For example, energy is a property of light.
 
So is light instead matter?

I thought it was electromagnetic radiation which is energy.
 
Light is an electromagnetic wave with properties of both particles and waves. It carries energy with it. It is not matter.
Similarly, a water wave carries energy with it yet it is not energy itself.
 
Drakkith said:
Light is an electromagnetic wave with properties of both particles and waves. It carries energy with it. It is not matter.
Similarly, a water wave carries energy with it yet it is not energy itself.

I was under the impression that everything in the physical universe could be deduced down to either matter or energy. If light is not matter and also not energy then I was under the wrong impression.
 
JeremyL said:
I was under the impression that everything in the physical universe could be deduced down to either matter or energy. If light is not matter and also not energy then I was under the wrong impression.

This is strange.

Light isn't JUST energy. It also has other characteristics, such has having a momentum, and in the quantum picture, it also has a spin quantum number. Saying light is just energy is like saying all there is to you is your face, while the rest of your body is irrelevant.

Matter and energy are equivalent, but NOT IDENTICAL.

Zz.
 
JeremyL said:
I was under the impression that everything in the physical universe could be deduced down to either matter or energy. If light is not matter and also not energy then I was under the wrong impression.

No, energy isn't a "thing". It is carried with objects but isn't something that exists on its own. Light is considered a Boson, which is not normal matter. But there are plenty of other particles that are the same way, such as gluons, the W and Z bosons, and more.
 
Drakkith said:
No, energy isn't a "thing". It is carried with objects but isn't something that exists on its own. Light is considered a Boson, which is not normal matter. But there are plenty of other particles that are the same way, such as gluons, the W and Z bosons, and more.

Isn't a boson a subatomic particle? Aren't subatomic particles forms of matter?
 
JeremyL said:
Isn't a boson a subatomic particle? Aren't subatomic particles forms of matter?

You seem to think that it's just down to categorising things*. There's more to it than that. The relationships between things count too.
You also seem to be pointing out inconsistencies and errors in 'the System' (as you see it). Whilst it's by no means complete, do you really thing that it's as full of holes as you imply?

*You were probably taught about Solids, Liquids and Gases, at School. How long did it take for you to spot that a lot of things fall into none of those categories? It like that only more so with QM and fundamental particles.
 
JeremyL said:
Isn't a boson a subatomic particle? Aren't subatomic particles forms of matter?

No, not all subatomic particles are forms of matter. Photon's are not matter.