B Is all EM radiation light?

[vela]

I think that's bit of a stretch. Radio waves in the hundred metre range can't really be described as light by any but perhaps the most cloistered of radio astronomers, no?

I don't see why radio waves couldn't be called light. I often use the term light as a synonym for electromagnetic radiation.

 

[davenn]

It's all semantics. There is nothing uncommon about the statement "All light travels at speed c in a vacuum, regardless of its frequency".

No it's not, there are specific meanings
IR, vis, and UV "light" are just part of the EM spectrum, that travels at speed c in a vacuum
As DaveC said, you cannot refer to radio frequencies as light, no more than you call X-rays light

 

[paulb203]

No it's not, there are specific meanings
IR, vis, and UV "light" are just part of the EM spectrum, that travels at speed c in a vacuum
As DaveC said, you cannot refer to radio frequencies as light, no more than you call X-rays light

Thanks, davenn
What do you make of the definitions given above?
Here's two of them to save you looking for them. I'm not citing them as oracles, I'm just wondering who is correct, or if it's even a matter of who is correct or not.

Nasa;
“All EM radiation is light, but we can only see a small portion of this radiation, the portion we call visible light.”

Nasa Hubblesite;
“Other types of light include radio waves, microwaves, infrared radiation, ultraviolet rays, X-rays and gamma rays — all of which are imperceptible to human eyes.”

 

[weirdoguy]

there are specific meanings

Thus it's semantics. I often refer to all of EM spectrum as "light" because it's easier. When you give a 45+ minute lecture it's hard to say "electromagnetic waves" all the time, and also I try not to be very repetetive with my wording.

 

[sophiecentaur]

Thus it's semantics.

Of course it is. It's worse than a waste of time discussing this issue. To discuss it implies that there's more to the 'name' we give light.

Is a Lion a 'cat'? Would we spend 35 posts in that question?

Our communal brains love the idea of classification; particular the EM waves one. Seriously, a five minute discussion comparing and contrasting all the common features of EM waves would be far more fruitful and would involve Evidence and not just fancy. The behaviour of all wavelengths of EM is different in practice when EM interacts with physical media

 

[DrJohn]

And surely different people perceive different ranges of frequency or wavelength with their eyes, at both the red and violet ends of the "visible" spectrum. Just like different people can hear sounds in different frequency ranges.

While using a UV-Vis spectrometer, I found I could see a little bit into the IR and the UV range. The puzzled look on the students faces made me look at the dial I was turning, to realise I could but they couldn't see what I was pointing at.