I think this is a job for statistical analysis ie what are the chances of a photon interacting with randomly distributed hydrogen atoms over a distance of 10^26 meters given c. 3 hydrogen atoms per cubic meter line of site
I only say this because I think that system7 is quite good at rambling and vague calculations.
How does that work for the entire Universe? Cube it, surely. 😀
What do we get? 😕
56 x 10^ 78. Not far from the current estimate of atoms in the Universe.
About 10^ 80. Happy with that. 🙂
How does that work for the entire Universe? Cube it, surely. 😀
What do we get? 😕
56 x 10^ 78. Not far from the current estimate of atoms in the Universe.
About 10^ 80. Happy with that. 🙂
A photon with energy above 13.6 electron volts can tear the sole electron away from a hydrogen atom, and thus completely ionize it. Young massive stars, supernovae and accreting black holes are prodigious producers of these ionizing photons.
Below this energy, some photons have the specific energy required to excite the neutral hydrogen atom, raising its sole electron to higher energy levels as opposed to removing it completely. The excited electrons eventually fall back down to the ground state and re-emit photons corresponding to wavelengths which are beyond our vision, except in the case of very distant sources where the expansion of the universe has redshifted them to visible wavelengths.
Cosmic Calorimetry or: How I Learned to Stop Worrying and Love Hydrogen - Ideas | Institute for Advanced Study
I took line of sight to try to make it easier to calculate.
You have photon frequencies ranging from low RF thru to far ultra violet and higher and if it’s c. 3 atoms per cubic meter line of sight that’s 30^26 atoms.
So maybe the question to ask, what percentage of photons don’t make it from a Galaxy 32 BLY away ie are scattered?
(There 7 x 10^26 atoms in a human body if I counted the zeroes right 🙂 )
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So the photon energies have to be just right to ionize hydrogen - too low and they don’t, too high and they don’t.
I suppose if this were not the case, spectral lines would just all mash into one. This sort of explains why the universe is transparent.
I suppose if this were not the case, spectral lines would just all mash into one. This sort of explains why the universe is transparent.
When electromagnetic radiation enters a denser medium, it slows down and gets scattered. As Einstein pointed out, this is a major source of relativistic distortion in audio amplifiers.
I wonder if the photons travelling through space move the atoms in vacuum. Perhaps some kind of draft or current could be caused by all the light and radiation.
Hah! Indeed, but then you're talking about "absolute vacuum" which afaik is purely theoretical, and not "relative vacuum" which does exist.
Perhaps in a theoretical ‘vacuum’ but in the space between galaxies which as far as I know is the best vacuum we are aware of, there are a few free hydrogen atoms per cubic meter - read Galu’s article above. There’s been a lot of investigation into the ‘Inter Galactic Medium’
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According to QM findings applicable in our universe, even a perfect vacuum at 0°K is frothing with particle pairs popping in and out of the Dirac sea. I have no idea what kind of law applies in his.
I accept that.
The only thing I know with absolute certainty is that there's an insurmountable heap of knowledge I will never have. I have little interest in theory, and I have a vast number of flaws in my personality as well as my physical condition. For all purposes and intents, I am lacking and inadequate. I am not, by any stretch of the imagination, perfect.
Now, back to the matter at hand. (nice pun, eh? 😀)
I guess it could be said that: Perfect vacuum may exist somewhere. Which IMO is just as likely as there is a "perfect me" hiding in some alternative dimension somewhere.
But so far it seems that there is some kind of matter anywhere you look, noone have been able to make/create/prove it (perfect vacuum) exists and like previous discussion points out: there's always a few atoms and stuff floating about.
Now, we do know that any and all forms of light or radiation equals some kind of energy. This energy is travelling through a space where the density of matter is extremely low.
Does anyone disagree so far?
Further:
If we look at calculations and simulations for a loudspeaker in an enclosure, the best approximations to reality seem to be: Fluid dynamics.
How does fluid dynamics work with air? Well, to answer that it is easier to look at relations and properties. What is air compared to for instance water? It is a mix of various gases with lower density of mass, so if you use the same caltulations as you would in fluid dynamics but change the values of mass density and viscosity then you get very good results that favourably compare to what we get when we build the experiment/loudspeaker and test it in the real world.
What is vacuum? Well, the ideal vacuum would be completely devoid of any matter. But so far the ideal vacuum seems a bit elusive, so we have to settle for the less than perfect: Vacuum is a volume with lower density of mass. There is more distance between the fragments of matter, but there is still matter.
In an Ocean, light can pass through it, there are currents and temperature changes, things like radiation can have an effect.
In air, light can pass through it, there are currents and temperature changes, things like radiation can have an effect.
I wonder:
In space, light can pass through it, there are currents and temperature changes, things like radiation can have an effect.
And here we are again, I do hope you managed to get hrough my post. Because here, at the end of my post I find myself repeating my question:
I wonder if the photons travelling through space move the atoms in vacuum. Perhaps some kind of draft or current could be caused by all the light and radiation.
It is an honest question, I think it is very likely that light could have an effect on the matter in RELATIVE vacuum, because fluid dynamics would dictate that: the matter density and viscosity, in space, would be comparatively lower than that of air or water, there is therefore less resistance, it is therefore more likely that the small amount of mass in that same relative vacuum would require even less energy to be influenced by any and all amount of energy or mass.
People, please understand what I am asking you.
Don't be dense (Sorry! Another pun, could not resist! Hah! Resist!😀 )
Wrote this on my phone, expect grammatical errors and various other faults.
Photons which interact with either ionised or neutral hydrogen atoms do cause movement, but only movement of the electrons associated with those atoms - not a wholesale movement of the atoms themselves.
Photons which interact with the free electrons of ionised hydrogen atoms cause the electrons to oscillate (Thomson scattering).
Photons which interact with the bound states of electrons of neutral hydrogen atoms cause the electrons to jump to higher energy states within the atom.
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