3 ms·

> if one is able to build a well-motivated model for the photon's source and path of propagation, one can extract still more. I think this is what the parent c

> if one is able to build a well-motivated model for the photon's source and path of propagation, one can extract still more. I think this is what the parent comment is getting at. How are you supposed to build a model of a black hole given the source is universe-scaled and the time-line for receipt of any particular photon is probably(?) vast and our observations are distant.

laingc 6y ago
Not to be flippant, but cosmology is essentially the science of dealing with these kinds of scales. It’s an entire field whose goal is to make questions like the above tractable.
- ISL 6y ago
  Completely agreed. In the era of concordance cosmology, one can, if desired, use the relative abundance of the elements, the distribution of galaxies in the sky, and the distance to far-away supernovae and, with two free fit parameters (dark-energy and dark-matter density) predict the properties of the Cosmic Microwave Background anisotropy. It's an incredible fact that one can do this -- predicting the properties of the photons emitted at the very first instant that the universe became willing to allow a photon to propagate freely. A young Randall Munroe could have picked from a number of really well-motivated reasons to state, "Science, It works...", but he picked this one: https://xkcd.com/54/ https://xkcd.com/54/ Modern precision cosmology works really, really well.
  - c22 6y ago
    Props for the first xkcd link I don't feel like I wasted my time clicking.
- TheSpiceIsLife 6y ago
  That’s a very good point, and obvious when you point it out. Still, I have a sneaking suspicion we are making flawed assumptions because our observations are from this point, and only this point, in space and time. Just my opinion, and it’ll probably turn out to be flawed itself like most of my opinions ;)

3 ms·

> if one is able to build a well-motivated model for the photon's source and path of propagation, one can extract still more. I think this is what the parent c

by TheSpiceIsLife 6y ago

laingc 6y ago
Not to be flippant, but cosmology is essentially the science of dealing with these kinds of scales. It’s an entire field whose goal is to make questions like the above tractable.
- ISL 6y ago
  Completely agreed. In the era of concordance cosmology, one can, if desired, use the relative abundance of the elements, the distribution of galaxies in the sky, and the distance to far-away supernovae and, with two free fit parameters (dark-energy and dark-matter density) predict the properties of the Cosmic Microwave Background anisotropy. It's an incredible fact that one can do this -- predicting the properties of the photons emitted at the very first instant that the universe became willing to allow a photon to propagate freely. A young Randall Munroe could have picked from a number of really well-motivated reasons to state, "Science, It works...", but he picked this one: https://xkcd.com/54/ https://xkcd.com/54/ Modern precision cosmology works really, really well.
  - c22 6y ago
    Props for the first xkcd link I don't feel like I wasted my time clicking.
- TheSpiceIsLife 6y ago
  That’s a very good point, and obvious when you point it out. Still, I have a sneaking suspicion we are making flawed assumptions because our observations are from this point, and only this point, in space and time. Just my opinion, and it’ll probably turn out to be flawed itself like most of my opinions ;)