Photons in Empty Space: Is Space Full?

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Discussion Overview

The discussion revolves around the nature of photons in empty space and whether the presence of photons affects the definition of a vacuum. Participants explore concepts related to the properties of photons, the definition of a vacuum, and the implications of radiation in space.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that the emission of photons from a source like the sun implies that empty space is not truly empty.
  • Others argue that while space contains various forms of radiation, including photons, this does not necessarily negate the definition of a vacuum, which is typically associated with the absence of matter.
  • One participant notes that photons are not considered matter, and thus their presence does not affect the vacuum status of a space.
  • Another point raised is that photons can occupy the same space without interacting, which may support the idea that they do not "fill" a volume in the same way matter does.
  • There is a discussion about neutrinos and their properties, with some participants mentioning that they can also be present in space without affecting the vacuum definition.
  • The concept of photons not having a specific location once emitted is debated, with some participants questioning this assertion based on the context of enclosed spaces.
  • Questions about the superposition of photons are also raised, indicating uncertainty about their spatial properties.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the implications of photons in defining a vacuum, and the discussion remains unresolved with no consensus reached.

Contextual Notes

There are limitations in the definitions of vacuum and the properties of photons that are not fully explored, including assumptions about the interaction of photons with matter and the implications of quantum mechanics.

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If a sun is giving off photons in every direction in space, does that not mean that all of empty space is full of photons? I know photons have no mass but that still means it is not a perfect vacuum right?
 
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It's correct that open space isn't a perfect vacuum because you can always find at least a few hydrogen atoms floating around. If you're still in the solar system you'll get whatever type of particles the sum is throwing off too, normally different types of radiation. I'm not sure if the presence of photons technically negates a vacuum though. My guess is no, you could in theory create a vacuum in a lab, shine a light though it, and its still a vacuum. I could be wrong though.
 
Normally, "vacuum" is a word used for an absence (or low density) of matter. Photons are not matter.
 
Since space is permeated by all kinds of radiation, not just visible light (microwave, radio, infrared), no volume of space will ever be devoid of photons.

As Dr. LoW points out, 'vacuum' refers to matter.
 
Don't forget the zillions of neutrinos whizzing about...
 
BTW, it is worth pointing out that photons, being bosons, can occupy the same space without bumping into each other, meaning you can't "fill up" a volume of space with photons. (This would explain why they aren't counted when assessing a vacuum. If you can forever fill a container with something, yet it is never full, then it might as well be empty.)


This is unlike matter (electrons, protons, neutrons), which is fermionic. Fermions take up space, meaning it is possible to "fill up" a volume of space with matter.


Neutrinos are leptons, so they do take up space, but since they are electrically neutral, they almost never interact with regular matter. I suppose, if you could figure out a way to manipulate them, you could fill up a volume of space with neutrinos.
 
photons, once emitted, are not in any particular location.
 
jnorman said:
photons, once emitted, are not in any particular location.

Not sure why you claim that. If the volume of space in question is enclosed by an opaque box, we can certainly say that a photon, once emitted, is inside (or, alternately, outside) the box.
 
DaveC426913 said:
Not sure why you claim that. If the volume of space in question is enclosed by an opaque box, we can certainly say that a photon, once emitted, is inside (or, alternately, outside) the box.

Cant photons be in superposition?
 

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