I'll go and look it up, David, and I'll get back to you if I can make sense of what you're saying.
I don't see why, David.
Physicists and philosophers have been addressing this exact question for centuries - and we don't seem to have found a certain answer yet... so why do you say it's a silly question ?
To know the exactr nature of given thing is not possible? We are limited by the constraints of organic existance and the nature of the thing we are trying to study. It would appear that certain things can not be known exactly. In general human thoughts are maps of the reality we appear to exist in. They are approximations of the reality. We can approximate and predict the future behavior of the reality through the process of oberserving reality and testing theories through the methods of science. But the "law of gravity" does not exist, in an exact sense, it is a cognitive model that predicts the behavior of observed reality.
So to question if light is a wave or a partcile is silly, because it behaves as though it is both at the same time. that is what we observe, it is a wave all the time. it has the properties of a particle as well, as limited by the Schoedinger wave form and HIP.
Wave vs. particle is a cognitive construct.
As gayak says
you then say :
... but not at the same time, David, isn't that the point ?
Both all the time, not just at a given moment. We may only measure at one time, but it has the properties (cognitive asssociative groups used to characterise the observed behaviors of 'objects'.) of both a wave and a particle at the same time, all the time.
At any moment, you have to choose; one or the other.
If you want to see something wierd, look for pictures of Bose-Einstien Condensate. You will see that 'solid' things like Cesium atoms in a clump act like they are waves and 'collapse' to a single point. They are particles and waves at the same time. Partcicles are waves, waves are particles all the time.
And surely, then you also have to specify where the observer is in relation to what is being measured, and particularly how fast the observer is moving.
Because that effects the length of object being measured.
Which in this case, is the length of a light-wave.
Hence the Doppler effect and red-shift, right ?
You can measure the frequency (wave) of a single photon (particle). Wavelenth is dependant upon the relative motions of the participants. the speed of light is constant which provides for the frequency shift. But the quanta come in discrete lumps, they have a size limited by quantum mechanics (those are particle properties) and they have frequency and travel through a blobby area of speace and are subject to Schroedinger equations (those are wave properties).
They appear to do so all the time.
So the wave-nature of light (or the particle nature) is dependant on the circumstances of the observer.
No, not really. It is both all the time.
But I'm interested in the objective nature of light (what it is, irrespective of observers). So models of waves or particles are inadequate.
Unknowable, can not be determined, can only be approximated and observed and tested. Photons could be really small monkeys on motor scooters , as long as they follow the observations. (However they would probably break apart in a gravitational field. Which is not observed.)
In other words...
My question is : What was the nature of the universe 4 billion years ago ?
Before life. Before sense-organs.
(I'm assuming no extra-terrestial life exists - if it does, go back another 2 billlion years to before that life evolved).
What did the universe look like 4 billion years ago ?
Now, that's a silly question, David.
No that is not a silly question, and I am sorry there are no silly questions, just silly answers.
I will respond below.
At that time, there were no eyes, so the universe couldn't look like anything.
How could it ?
Before the advent of life, the universe was completely dark, (or invisible), inaudible, unsmellable, untasteable, and untouchable.
And so on, for whatever different sense-impressions different life-forms might eventually evolve....
Because all those qualities are a function of life.
And 4 billion years ago, there was no life.
Good question and it has an answer, or at least an approximate explanation which matches observations.
Light takes time to traverse space, the speed of light appears to be a constant. this is supported by observations of the spectra of distant stars, there is some reason that the spectra would be different if the speed
c was not a constant.
So it would appear that
c is constant. And so one can assume that certain things we observe about distant objects are also true. Or at least observationaly true, could be the
World of Tiers. So the compostion of materials in distant stars is likely to be observationaly true, as is the expansion of the universe and a host of other things.
So if we look at the obect with the deepest redshift
z we can observe the light from an object that is very close to the begining of time. And we can make assumptions about the objects that generated that light a very long time ago.
So we can observe events that look as though they occured a very long time ago . I think the deepest red shift
z is like 13 billions years old.
That is a very long time ago. The background microwave radiation comes from a time 'shortly' after the Big Band Event. Even longer ago.
Unless we are Brain in Vats.
Genesis, Chapter 1, verses 1 and 2 :
"In the beginning, God created the heaven and the earth".
"And the earth was without form, and void; and darkness was upon the face of the deep".
Since I'm not a Christian, I would re-state the first verse as :
"In the beginning, the heaven and the earth started in a Big Bang".
Huh, the Cow came and licked the Ice.
Thoth and Nu got it on.
Otherwise, it fits what I'm saying. From the creation of the universe 13 billion years ago until the development of life on this planet 3.5 billion years ago, the universe ("the earth") was 'without form'.
So the light from teh Andromeda galaxy came from where?
The light from early galaxies came from where?
So, describing light 4 billion years ago using models such as wave or particle, or invoking concepts such as 'vision', is invalid, because it assumes observers who can perceive light as waves or particles, and who can experience 'vision'.
Solipism?
In fact, there were no observers at that time.
So what was the nature of light, at that time ?
the same as it is now. Apparently , a wave and a particle at the same time.
Gnu.
, qwe all swim in the pool you are as capable as every body else. perhaps not familiar with the nature of the JREF.
smiley or the