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I don't see how it is pertinent, as space is not "a transparent medium", it is void. Pretty much all the photons emitted by a star that we can detect cross only
by henearkr 9y ago
I don't see how it is pertinent, as space is not "a transparent medium", it is void.
Pretty much all the photons emitted by a star that we can detect cross only the star's gas surrounding, then the emptiness of space, then our atmosphere.
So, it does not vary with the distance of the star, thus the author's argument does not hold (anyway, he was being super-speculative here).
- zamalek 9y ago> it is void Space is not a complete vacuum.
- henearkr 9y agoYeah, but sufficiently so that most photons are not encountering any other things on their way.
- Nomentatus 9y agoNot clear - have you taken virtual particles into account?
- henearkr 9y agoWell, actually it seems you are true. There are absorption rays for the inter-galactic medium, as shown in: https://ned.ipac.caltech.edu/level5/Madau6/Madau2.html https://ned.ipac.caltech.edu/level5/Madau6/Madau2.html So, please ignore my previous reply ↓
- fpoling 9y agoThe space is not void as there is non-zero density of matter that we see in absorbtion lines of quasars [1]. This implies that the space has to be treated as transparent medium with non-trivial optical properties. [1] - https://ned.ipac.caltech.edu/level5/Madau6/Madau_contents.html https://ned.ipac.caltech.edu/level5/Madau6/Madau_contents.ht...
- henearkr 9y agoOk, now I agree with you: https://ned.ipac.caltech.edu/level5/Madau6/Madau2.html https://ned.ipac.caltech.edu/level5/Madau6/Madau2.html