When does light travel from a glowing iron rod to a sheet of paper?

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Discussion Overview

The discussion revolves around the nature of light emission from a glowing iron rod and its interaction with a sheet of paper located one meter away. Participants explore concepts related to the continuous emission of electromagnetic radiation, the timing of light travel, and the implications of these ideas on our understanding of light and visibility.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that light begins to travel the moment it leaves the rod.
  • Others argue that there is a delay in the light reaching the paper, approximately 1/300,000,000 of a second later.
  • One participant suggests that the rod is continuously radiating electromagnetic energy, and visibility occurs only when the temperature is sufficient for the emitted wavelength to fall within the visible spectrum.
  • Another viewpoint posits that the rod and paper are in a continuous relationship, questioning the notion of light "starting" to travel and suggesting that what is observed is merely a change in intensity.
  • A hypothesis is presented that if matter continuously emits radiation, the concept of light traveling may be flawed, as there is no clear start or stop to the emission.
  • Participants discuss the implications of the Big Bang Theory and the visibility of distant stars, with some asserting that light from ancient stars exists but may be too dim to detect.
  • There is a challenge regarding the understanding of when a hypothetical particle begins to emit light, with one participant noting that a particle older than the universe raises questions about its emission.

Areas of Agreement / Disagreement

The discussion contains multiple competing views regarding the nature of light emission and travel, with no consensus reached on the timing of light's journey from the rod to the paper or the implications of continuous emission.

Contextual Notes

Participants express uncertainty regarding the definitions of emission and visibility, and the discussion is limited by assumptions about the nature of light and electromagnetic radiation.

scott_sieger
light as a continuum

We have an iron rod and it is connected to a power supply.

One meter away there is a sheet of white paper hanging on a wall.
Both the rod and the paper are unlit.

Very slowly we increase the voltage passing through the iron rod.

Very slowly the rod starts to glow a dull red and then as we increase the voltage the rod gets brighter and brighter.

Simultaneously the sheet of white paper reflects the red glow of the rod and also gets brighter and brighter,

The rod eventually glows a bright white and so the paper also reflects this light.


The question is:

At what moment did the light start to travel to the paper one meter away?
 
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The light started to travel the moment it left the rod.
 
ha ha...good answer...but when was that?
 
Originally posted by scott_sieger
light as a continuum

We have an iron rod and it is connected to a power supply.

One meter away there is a sheet of white paper hanging on a wall.
Both the rod and the paper are unlit.

Very slowly we increase the voltage passing through the iron rod.

Very slowly the rod starts to glow a dull red and then as we increase the voltage the rod gets brighter and brighter.

Simultaneously the sheet of white paper reflects the red glow of the rod and also gets brighter and brighter,

Not simultaneously, but 1/300000000 of a sec later. Any change in the emission of light by the rod won't reach the paper until that much later.
 
It did not "start" radiating EM. Every body is continuously radiating EM according to its tempeature. In a warm room your body adsorps more energy then it radiates, there for you begin to sweat, this increases your rate of heat loss to help maintain a balance.

In a cold room you radiate more then you gain, therefore you feel cold.

Your steel bar is always radiating heat, it does not become visible until the temperature is such that its blackbody wavelength is in the visible spectrum.
 
so we can agree that the rod never started to radiate light (whether visible or not) or heat.?

We can go on to say that the rod will never cease to radiate light and heat. (it's temperature always being above absolute zero)

So,

WE have a continuum relationship with the paper on the wall and the rod. (and everything else)

So correct me if I'm wrong:

The rod is never on and the rod is never off.(same for the paper) So the obvious question is how can we determine that it's emmissions are traveling when in fact because it is never off or on it is never out of it's relationship with the paper.

Could it be we are just witnessing a change in intensity in this continuum relationship? And that change in intensity is measured as "c" even though the emmisions haven't traveled as they are already there.

Hypothesis

If "Matter" never stops emitting whether visible or not then it is in a continuous relationship with everything else. There for the concept of traveling seems to be proved wrong. All we are
witnessing is a delay in the increase or decrease in intensity.

If we are unable to determine a start or stop to the emmission then how can we determine it's speed.?

If there is no start and no stop then how do we know that it is traveling at all?
 
Last edited by a moderator:
Originally posted by scott_sieger
The rod is never on and the rod is never off.(same for the paper) So the obvious question is how can we determine that it's emmissions are traveling when in fact because it is never off or on it is never out of it's relationship with the paper.
Well, the relationship ends when you crumple up the paper and throw it away.
Could it be we are just witnessing a change in intensity in this continuum relationship? And that change in intensity is measured as "c" even though the emmisions haven't traveled as they are already there.
First part yes, second part yes and no. Emissions are already there? How exactly? If they are there, why can't they be detected? That doesn't make a whole lot of sense.

By blocking (unblocking) or otherwise changing emissions you can measure the speed at which they propagate.
 
at what moment does a 200 billion year old particle start to emit?
 
along time a ao according to theory there was an explosion and in time stars where formed. They weren't to far apart at this stage and so their light could be seen everywhere. AS the universe expanded the stars got further and further apart. And their light that they were shining slowly ceased to be able to be seen because they lacked the intensity to be visible. Soon they were so far away and their light was so dim that very few instruments could even detect that they existed at all.

Later...the instruments could not detect them at all and as far as we were concerned they didn't even exist.

So, the light started to exist with the big bang and has never gone out since...just to dim to see.

So, to look up at the sky and say that we can't see a star because the light hasn't got here yet because of it's "C" is just ludicrous.
 
Last edited by a moderator:
  • #10
So, to look up at the sky and say that we can't see a star because the light hasn't got here yet because of it's "C" is just ludicrous.

How come?
 
  • #11
Originally posted by scott_sieger
along time a ao according to theory...
I've never heard of a theory that says that. It sounds like a misunderstanding of the Big Bang Theory: the first stars not form until quite a while after the Big Bang.
 
  • #12
Originally posted by scott_sieger
at what moment does a 200 billion year old particle start to emit?

Wow! Your hypothetical particle is older then the universe
 

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