What is light?

xelasnave · #1 15-10-2009, 12:41 PM

Isnt it funny how things so simple become so complex... what is gravity for example

...
So what is light?
We know so much but do we..it is so important to astronomy ..everything really.
So I ask what do I know... not much... I understand it acts both like a wave and like a particle... and focus on the words...acts like... that implies it is something else but behaves both as we would expect a particle to behave and also as we expect a wave to behave... the double slit experiment is perplexing as it sort of confirms both properties...so is it a wave or a particle or something else that just acts like these things but is not either...

I read about photons... a packet of light... getting more confused as I get more information... who puts the light in these little packets anyway... and exactly what is in a packet? do we get a separate packet for each colour ...

All I read on redshift suggests light does not get tired and so far I am under the impression it lasts forever..and that sounds reasonable becasue light is energy..it is energy isnt it??? yes it must be EME of course..energy cant be destroyed... so light lasts forever..right? If that is the case will the Universe just get brighter and brighter?

I have read that photons dont even know their age or if they do they hide it like some many humans will do.

Is dark a form of anti light

So what are your views and questions about light...

alex

Barrykgerdes · #2 15-10-2009, 12:51 PM

What is light:

That is easy. It is usually associated with ale and comes in bottles or on tap. A few of them will help you see the light. A few too many will most likely turn out the light.

Baz

Robh (Rob) · #3 15-10-2009, 02:11 PM

Hi Alex,
Your brain has been working overtime! Not that I'm complaining, gives the rest of us something to think about.

This is my thought ...
Electromagnetic energy is ultimately due to moving particles. In this case the photon. The moving particle produces an oscillating electromagnetic field (analogous to a vibration). The energy of the particle can be measured as an electromagnetic wave of a certain amplitude and frequency. However, the particle itself is moving in a straight line (ignoring space curvature).

Regards, Rob

mojo (Terry) · #4 15-10-2009, 03:16 PM

Here's something for you to think about, Alex... Without light, we wouldn't see anything. We only see something when light hits an object. But we can't actually see light on it's own. That is, we can't see photons.

So, without light, it's dark. But even light is dark.

TrevorW · #5 15-10-2009, 03:25 PM

There is no such thing as darkness just the absence of visible light

http://www.howstuffworks.com/light2.htm

Baddad (Marty) · #6 15-10-2009, 04:07 PM

Hi Alex,

Stop this. The gravity thing made my brain hurt. You are hell bent on punishing us.

Many hands make LIGHT work???

I can simply flick a switch.

Cheers Marty

renormalised (Carl) · #7 15-10-2009, 07:10 PM

Light is nothing more than the harmonic resonance of a string of a particular waveform

There's more to ponder

beamq (Todd) · #8 15-10-2009, 07:21 PM

Light is bright.To a blind man, light is warm. To darkness, light is enemy

Nesti (Mark) · #9 15-10-2009, 07:50 PM

What is 'Light'?

Definition: Not heavy; weighing relatively little.

Geez some people ask dumb questions!

Nesti (Mark) · #10 15-10-2009, 07:53 PM

Light is what yonder window breaks! It is also the East, Juliet being obviously the Sun

Derr!!!!

bloodhound31 · #11 15-10-2009, 08:02 PM

Quote:

Originally Posted by Baddad

Hi Alex,

Stop this. The gravity thing made my brain hurt. You are hell bent on punishing us.

Many hands make LIGHT work???

I can simply flick a switch.

Cheers Marty

That's why it's impossible to tell how many cockroaches it takes to change a light bulb, because as soon as you turn it on, they all scatter....

Nesti (Mark) · #12 15-10-2009, 08:09 PM

Seriously...What is ‘Light’?

How about; light is the removal of the potential difference formed between two spatially and temporally distant particles, which are undergoing an ‘association’ induced by an evolution of states and values. The speed of the potential transfer can be defined by both the properties of the carrier (photon) and the properties of the space (spacetime).

That is pretty much all I can safely say.

Cheers
Mark

star1961 (Lisa) · #13 15-10-2009, 08:49 PM

could that be why the universe is speeding up as it expands to keep ahead of the never ending photons?
or is it slowing down now?

Nesti (Mark) · #14 15-10-2009, 09:05 PM

Quote:

Originally Posted by star1961

could that be why the universe is speeding up as it expands to keep ahead of the never ending photons?
or is it slowing down now?

Who are you responding to?

leinad (Dan) · #15 15-10-2009, 09:56 PM

Doesn't a blackhole devour light though?
So therefore it cannot be endless. And if it was endless, the universe would not be still expanding but would have an infinite distance.

Would not darkness though be defined as not being within the visible spectrum of the human eye. Therefore darkness and light are descriptive terms ? A blind person sees neither.

Redshift (Phil) · #16 15-10-2009, 10:00 PM

Light - the absence of darkness.

mick pinner · #17 15-10-2009, 10:31 PM

it doesn't matter and never will, it's just there.

michaellxv (Michael) · #18 15-10-2009, 10:32 PM

Is the question what is light? or what is electromagnetic radiation?

I would define light to specifically be that part of the electromagnetic spectrum which is detected by the eye. You then have to ask what is an eye. Here things start to fall apart as some animals can detect electromagnetic radiation at different parts of the spectrum.

Starting again, light is the detection of electromagnetic radiation by a living thing.

But I think you really wanted to know about the nature of electromagnetic radiation and if it is a particle (photon) or a wave.

I have not read anything that tries to define it more that this other than to say it exhibits the properties of both. Maybe if we worked out what it really was we would know more about gravity.

I will stick to just light as its easier to type.

You would think that with all the stars generating so much light that the universe should be getting brighter. But expansion spread it out so we don't see that.

Light is energy so yes it lasts forever unless it hits something in which case the engery is transferred to that object and the 'light' no longer exists.

I think I am wafling now.

Michael.

acropolite (Phil) · #19 15-10-2009, 10:33 PM

Quote:

Originally Posted by Mojo

So, without light, it's dark. But even light is dark.

I agree light is simply an optical illusion.

marki · #20 15-10-2009, 11:08 PM

Don't forget the dark sucker theory

Mark